116 research outputs found
Underwater acoustic signal classification based on sparse time-frequency representation and deep learning
On the low regularity of the fifth order Kadomtsev-Petviashvili I equation
We consider the fifth order Kadomtsev-Petviashvili I (KP-I) equation as
while . We introduce an interpolated energy space
to consider the well-posedeness of the initial value problem (IVP) of the fifth
order KP-I equation. We obtain the local well-posedness of IVP of the fifth
order KP-I equation in for . To obtain the local
well-posedness, we present a bilinear estimate in the Bourgain space in the
framework of the interpolated energy space. It crucially depends on the dyadic
decomposed Strichartz estimate, the fifth order dispersive smoothing effect and
maximal estimate.
Key words: The fifth order KP-I equation, Bourgain space, Dyadic decomposed
Strichartz estimate, Dispersive smoothing effect, Maximal estimate.Comment: 30page
Low regularity solutions of two fifth-order KdV type equations
The Kawahara and modified Kawahara equations are fifth-order KdV type
equations and have been derived to model many physical phenomena such as
gravity-capillary waves and magneto-sound propagation in plasmas. This paper
establishes the local well-posedness of the initial-value problem for Kawahara
equation in with and the local well-posedness
for the modified Kawahara equation in with .
To prove these results, we derive a fundamental estimate on dyadic blocks for
the Kawahara equation through the multiplier norm method of Tao
\cite{Tao2001} and use this to obtain new bilinear and trilinear estimates in
suitable Bourgain spaces.Comment: 17page
Genetic mapping and functional analysis of a classical tassel branch number mutant Tp2 in maize
Tassel branch number is a key trait that contributes greatly to grain yield in maize (Zea mays). We obtained a classical mutant from maize genetics cooperation stock center, Teopod2 (Tp2), which exhibits severely decreased tassel branch. We conducted a comprehensive study, including phenotypic investigation, genetic mapping, transcriptome analysis, overexpression and CRISPR knock-out, and tsCUT&Tag of Tp2 gene for the molecular dissection of Tp2 mutant. Phenotypic investigation showed that it is a pleiotropic dominant mutant, which is mapped to an interval of approximately 139-kb on Chromosome 10 harboring two genes Zm00001d025786 and zma-miR156h. Transcriptome analysis showed that the relative expression level of zma-miR156h was significantly increased in mutants. Meanwhile, overexpression of zma-miR156h and knockout materials of ZmSBP13 exhibited significantly decreased tassel branch number, a similar phenotype with Tp2 mutant, suggesting that zma-miR156h is the causal gene of Tp2 and targets ZmSBP13 gene. Besides, the potential downstream genes of ZmSBP13 were uncovered and showed that it may target multiple proteins to regulate inflorescence structure. Overall, we characterized and cloned Tp2 mutant, and proposed a zma-miR156h-ZmSBP13 model functioning in regulating tassel branch development in maize, which is an essential measure to satisfy the increasing demands of cereals
An improved positioning algorithm in a long-range asymmetric perimeter security system
In this paper, an improved positioning algorithm is proposed for a long-range asymmetric perimeter security system. This algorithm employs zero-crossing rate to detect the disturbance starting point, and then utilizes an improved empirical mode decomposition to obtain the effective time-frequency distribution of the extracted signal. In the end, a cross-correlation is used to estimate the time delay of the effective extracted signal. The scheme is also verified and analyzed experimentally. The field test results demonstrate that the proposed scheme can achieve a detection of 96.60% of positioning errors distributed within the range of 0-±20 m at the sensing length of 75 km, which significantly improves the positioning accuracy for the long-range asymmetric fence perimeter application
Transformation between phreatic water and soil water during freeze–thaw periods
During freeze–thaw periods, the exchange between shallow groundwater and soil water is
unusually strong and bidirectional, which causes soil salinization and affects the accuracy of water
resources assessment. The objectives of this study were to explore the laws of transformation between
phreatic water and soil water through nine different groundwater table depths (GTDs) and three
kinds of lithologies during three successive freeze–thaw periods using field lysimeters. The results
showed that phreatic evaporation increased with smaller average soil particle sizes. The differences
between phreatic evaporation and recharge to groundwater (DPR) and GTDs were well fitted by the
semi-logarithmic model, and the regression coefficients A and B of the model were well fitted by the
linear relationship with the average soil particle size. With the increase of soil particle size, the change
of DPR decreased with the change rate of soil particle size. The extent of transformation between
phreatic water and soil water decreased with the increase of soil particle size. During the whole
freeze–thaw period, the negative value of DPR increased with an decrease in GTD. The groundwater
depths of zero DPR (D-zero) of sandy loam, fine sand and sandy soil during the freeze–thaw periods
were 2.79 m, 2.21 m and 2.12 m, respectively. This research is significant for the prevention of soil
salinization disasters and the accurate assessment of water resources
Tunable van Hove singularity without structural instability in Kagome metal CsTiBi
In Kagome metal CsVSb, multiple intertwined orders are accompanied by
both electronic and structural instabilities. These exotic orders have
attracted much recent attention, but their origins remain elusive. The newly
discovered CsTiBi is a Ti-based Kagome metal to parallel CsVSb.
Here, we report angle-resolved photoemission experiments and first-principles
calculations on pristine and Cs-doped CsTiBi samples. Our results
reveal that the van Hove singularity (vHS) in CsTiBi can be tuned in a
large energy range without structural instability, different from that in
CsVSb. As such, CsTiBi provides a complementary platform to
disentangle and investigate the electronic instability with a tunable vHS in
Kagome metals
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