887 research outputs found
Three-Dimensional Imaging Method Incorporating Range Points Migration and Doppler Velocity Estimation for UWB Millimeter-Wave Radar
High-resolution, short-range sensors that can be applied in optically challenging environments (e.g., in the presence of clouds, fog, and/or dark smog) are in high demand. Ultrawideband (UWB) millimeter-wave radars are one of the most promising devices for the above-mentioned applications. For target recognition using sensors, it is necessary to convert observational data into full 3-D images with both time efficiency and high accuracy. For such conversion algorithm, we have already proposed the range points migration (RPM) method. However, in the existence of multiple separated objects, this method suffers from inaccuracy and high computational cost due to dealing with many observed RPs. To address this issue, this letter introduces Doppler-based RPs clustering into the RPM method. The results from numerical simulations, assuming 140-GHz band millimeter radars, show that the addition of Doppler velocity into the RPM method results in more accurate 3-D images with reducing computational costs
On the kernel of the surgery map restricted to the 1-loop part
Every homology cylinder is obtained from Jacobi diagrams by clasper surgery.
The surgery map is surjective for , and its kernel is
closely related to the symmetry of Jacobi diagrams. We determine the kernel of
restricted to the 1-loop part after taking a certain quotient of
the target. Also, we introduce refined versions of the AS and STU relations
among claspers and study the abelian group for
.Comment: 33 pages, 4 figure
Magnetic activity variability from H line intensive monitoring for two F-type stars having a hot-Jupiter, Bootis A and Andromedae A
We report the results of intensive monitoring of the variability in the
H line for two F-type stars, Boo and And, during the
last four years 2019-2022, in order to investigate their stellar magnetic
activity. The 4-year H line intensity data taken with the 1.88-m
reflector at Okayama Branch Office, Subaru Telescope, shows the existence of a
possible 123-day magnetic activity cycle of Boo. The result of
the H variability as another tracer of the magnetic activity on the
chromosphere is consistent with previous studies of the Ca II H&K line and
suggests that the magnetic activity cycle is persisted in Boo. For
And, we suggest a quadratic long-term trend in the H
variability. Meanwhile, the short-term monitoring shows no significant period
corresponding to specific variations likely induced by their hot-Jupiter in
both cases ( 3.31 and 4.62 days, respectively). In this H
observation, we could not find any signature of the Star-Planet Magnetic
Interaction. It is speculated that the detected magnetic activity variability
of the two F-type stars is related to the stellar intrinsic dynamo.Comment: 27 pages, 20 figures, 1 table, Accepted by Publications of the
Astronomical Society of Japa
Magnetic activity variability of nearby bright Sun-like stars by 4-year intensive H line monitoring
We report intensive monitoring of the activity variability in the H
line for 10 Sun-like stars using the 1.88-m reflector at Okayama Branch Office,
Subaru Telescope, during the last four years 2019-2022. Our aim was to
investigate features of the stellar magnetic activity behaviors. We correlated
the H line variability of each star with the stellar activity levels
derived from the Ca II H&K line, suggesting its efficiency as a magnetic
activity indicator. In analyzing the H line variation, we observed that
some stars exhibited linear or quadratic trends during the observation period.
Among several G- and K-type stars expected to have co-existing activity cycles,
we confirmed the 2.9-yr short cycle of Eri (K2V) from the H
observations. Additionally, we established upper limits on the H
variability of Com (G0V) and Cet (G5V) concerning their
expected shorter cycles. We also detected the possibility of short-term
activity cycles in two F-type stars, Vir (F9V; 530 days) and
CMi (F5IV-V; 130 days). The cycle in CMi was observed
in only one season of our 4-yr observations, suggesting the temporal absence of
the cycle period. However, for stars with planets, we did not observe
significant magnetic activity variability likely associated with the planetary
orbital period. It is speculated that the impact of H variability on
radial velocity (RV) measurements may vary with spectral type.Comment: 27 pages, 12 figures, Accepted by PAS
A non-commutative Reidemeister-Turaev torsion of homology cylinders
We compute the Reidemeister-Turaev torsion of homology cylinders which takes
values in the -group of the -adic completion of the group ring
, and prove that its reduction to
is a finite-type
invariant of degree . We also show that the -loop part of the LMO
homomorphism and the Enomoto-Satoh trace can be recovered from the leading term
of our torsion.Comment: 48 pages, 7 figure
Monopole-fermion scattering and varying Fock space
We propose a four-dimensional interpretation of the outgoing state of the
scattering of a massless fermion off a Dirac monopole. It has been known that
such a state has fractional fermion numbers and is necessarily outside the Fock
space on top of ordinary perturbative vacuum, when more than two flavours of
charged Dirac fermions are considered. In this paper, we point out that the
Fock space of the fermions depends on the rotor degree of freedom of the
monopole and changes by a monopole-fermion s-wave scattering. By uplifting the
fermion-rotor system introduced by Polchinski, from two to four dimensions, we
argue that the outgoing state can be understood as a state in a different Fock
space.Comment: 27 pages, 2 figures, 1 tabl
Cooperative Binding of Ferrocenylnaphthalene Diimide Carrying β-Cyclodextrin Converts Double-Stranded DNA to a Rod-Like Structure
Ferrocenylnaphthalene diimide carrying β-cyclodextrin (β-CD), 1, intercalated into double-stranded DNA with a binding affinity of K = (6.6 ± 0.8) × 104 M–1 and a binding site size of n = 4, with a high positive cooperative parameter of ω = 14. β-CD and ferrocene moieties of the compound contributed to the formation of the intermolecular inclusion complex on DNA. Binding of 1 resulted in conversion of the DNA duplex to a rod-like form, which was cleaved upon adamantylamine addition
Reaction of layered carbon fluorides CₓF (x=2.5–3.6) and hydrogen
The layered carbon fluorides CₓF (x = 2.5, 2.8, 3.6), generally classified as fluorine–graphite intercalation compounds, were heat-treated in hydrogen gas. These fluorides are more reactive with hydrogen compared to (CF)ₙ and (C₂F)ₙ. Reduction of CₓF to graphite-like carbon starts at about 573 K, and proceeds gradually along with the elevation of temperature. Fluorine atoms in CₓF are eliminated as HF in the reduction process without being substituted by hydrogen atoms. Systematic difference was not found in the average crystallite sizes of the carbon material prepared from CₓF by the reduction with hydrogen and that by the pyrolysis in vacuum. On the other hand, interlayer distance and fluorine content of the former are smaller than those of the latter. In the case that the CₓF precursor maintains a large particle size, the reduced carbon as well as the pyrolytically prepared carbon possesses a foam-like shape due to the exfoliation during the heat treatment
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