id
stringlengths 9
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stringlengths 67
2.61k
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stringlengths 5
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stringlengths 0
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stringlengths 5
315
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|---|---|---|---|---|---|---|
1507.06948
|
Software product line has emerged as an attractive phenomenon within
organizations dealing with software development process. It involves assembly
of products from existing core assets, commonly known as components, and
continuous growth in the core assets as production proceeds. Organizations
trying to incorporate the concept of software product line to reduce
development time and cost require certain rules to be followed for successful
development and management, they also require a direct procedure to evaluate
the current maturity level of the process. In this work certain rules for
developing and managing a software product line are put forward. Additionally,
a fuzzy logic based software product line process assessment tool (SPLPAT) has
been designed and implemented on the basis of developed rules for software
product line process assessment. SPLPAT can be used to assess the process
maturity level of software product line, and it provides an opportunity to
handle imprecision and uncertainty present in software process variables. Four
case studies were conducted to validate the framework, and results show that
SPLPAT provides a direct mechanism to evaluate current software product line
process maturity level within an organization. The results of the developed
software product line process assessment approach were compared with the
existing CMM-level of the organization in order to evaluate the reliability of
the presented approach and to find out how effectively an organization can
execute software product line process when it has already achieved a certain
CMM level.
|
[
"cs.SE"
] |
cs.SE
|
Software Engineering
| 6,626Software Engineering
|
|
hep-ex/0505020
|
The SuperKamiokande group assert that they have found an oscillatory
signature in atmospheric neutrinos through the analysis of \textit{Fully
Contained Events} and \textit{Partially Contained Events}. We have performed an
$L/E$ (length/energy) analysis of \textit{Upward Through-Going Muon Events} and
\textit{Stopping Muon Events} in a numerical computer simulations both with and
without neutrino oscillations but were unable to find an oscillatory signature.
We give likely explanations for the absence of the oscillatory signature in our
simulations and its apparent presence in the SuperKamiokande data.
|
[
"hep-ex",
"astro-ph",
"hep-ph"
] |
hep-ex
|
astro-ph
|
High Energy Physics - Experiment;Astrophysics;High Energy Physics - Phenomenology
| 3,063High Energy Physics - Experiment;Astrophysics;High Energy Physics - Phenomenology
|
2310.03281
|
The 5' UTR, a regulatory region at the beginning of an mRNA molecule, plays a
crucial role in regulating the translation process and impacts the protein
expression level. Language models have showcased their effectiveness in
decoding the functions of protein and genome sequences. Here, we introduced a
language model for 5' UTR, which we refer to as the UTR-LM. The UTR-LM is
pre-trained on endogenous 5' UTRs from multiple species and is further
augmented with supervised information including secondary structure and minimum
free energy. We fine-tuned the UTR-LM in a variety of downstream tasks. The
model outperformed the best-known benchmark by up to 42% for predicting the
Mean Ribosome Loading, and by up to 60% for predicting the Translation
Efficiency and the mRNA Expression Level. The model also applies to identifying
unannotated Internal Ribosome Entry Sites within the untranslated region and
improves the AUPR from 0.37 to 0.52 compared to the best baseline. Further, we
designed a library of 211 novel 5' UTRs with high predicted values of
translation efficiency and evaluated them via a wet-lab assay. Experiment
results confirmed that our top designs achieved a 32.5% increase in protein
production level relative to well-established 5' UTR optimized for
therapeutics.
|
[
"cs.LG",
"cs.AI"
] |
cs.LG
|
cs.AI
|
Machine Learning;Artificial Intelligence
| 3,892Machine Learning;Artificial Intelligence
|
2110.15426
|
Radiology reports are unstructured and contain the imaging findings and
corresponding diagnoses transcribed by radiologists which include clinical
facts and negated and/or uncertain statements. Extracting pathologic findings
and diagnoses from radiology reports is important for quality control,
population health, and monitoring of disease progress. Existing works,
primarily rely either on rule-based systems or transformer-based pre-trained
model fine-tuning, but could not take the factual and uncertain information
into consideration, and therefore generate false-positive outputs. In this
work, we introduce three sedulous augmentation techniques which retain factual
and critical information while generating augmentations for contrastive
learning. We introduce RadBERT-CL, which fuses these information into BlueBert
via a self-supervised contrastive loss. Our experiments on MIMIC-CXR show
superior performance of RadBERT-CL on fine-tuning for multi-class, multi-label
report classification. We illustrate that when few labeled data are available,
RadBERT-CL outperforms conventional SOTA transformers (BERT/BlueBert) by
significantly larger margins (6-11%). We also show that the representations
learned by RadBERT-CL can capture critical medical information in the latent
space.
|
[
"cs.LG",
"cs.CL"
] |
cs.LG
|
cs.CL
|
Machine Learning;Computation and Language
| 4,009Machine Learning;Computation and Language
|
1602.03920
|
With an instantaneous view of 70% of the sky, the Fermi Gamma-ray Burst
Monitor (GBM) is an excellent partner in the search for electromagnetic
counterparts to gravitational wave (GW) events. GBM observations at the time of
the Laser Interferometer Gravitational-wave Observatory (LIGO) event GW150914
reveal the presence of a weak transient above 50 keV, 0.4~s after the GW event,
with a false alarm probability of 0.0022 (2.9$\sigma$). This weak transient
lasting 1 s was not detected by any other instrument and does not appear
connected with other previously known astrophysical, solar, terrestrial, or
magnetospheric activity. Its localization is ill-constrained but consistent
with the direction of GW150914. The duration and spectrum of the transient
event are consistent with a weak short Gamma-Ray Burst arriving at a large
angle to the direction in which Fermi was pointing, where the GBM detector
response is not optimal. If the GBM transient is associated with GW150914, this
electromagnetic signal from a stellar mass black hole binary merger is
unexpected. We calculate a luminosity in hard X-ray emission between 1~keV and
10~MeV of $1.8^{+1.5}_{-1.0} \times 10^{49}$~erg~s$^{-1}$. Future joint
observations of GW events by LIGO/Virgo and Fermi GBM could reveal whether the
weak transient reported here is a plausible counterpart to GW150914 or a chance
coincidence, and will further probe the connection between compact binary
mergers and short Gamma-Ray Bursts.
|
[
"astro-ph.HE"
] |
astro-ph.HE
|
High Energy Astrophysical Phenomena
| 2,990High Energy Astrophysical Phenomena
|
|
2107.12251
|
We re-examine quantization via branes with the goal of understanding its
relation to geometric quantization. If a symplectic manifold $M$ can be
quantized in geometric quantization using a polarization ${\mathcal P}$, and in
brane quantization using a complexification $Y$, then the two quantizations
agree if ${\mathcal P}$ can be analytically continued to a holomorphic
polarization of $Y$. We also show, roughly, that the automorphism group of $M$
that is realized as a group of symmetries in brane quantization of $M$ is the
group of symplectomorphisms of $M$ that can be analytically continued to
holomorphic symplectomorphisms of $Y$. We describe from the point of view of
brane quantization several examples in which geometric quantization with
different polarizations gives equivalent results.
|
[
"hep-th",
"math.AG"
] |
hep-th
|
math.AG
|
High Energy Physics - Theory;Algebraic Geometry
| 3,267High Energy Physics - Theory;Algebraic Geometry
|
2101.04587
|
We prove that for a domain $\Omega \subset \mathbb{R}^n$, being
$(\epsilon,\delta)$ in the sense of Jones is equivalent to being an extension
domain for bmo$(\Omega)$, the nonhonomogeneous version of the space of function
of bounded mean oscillation on $\Omega$. In the process we demonstrate that
these conditions are equivalent to local versions of two other conditions
characterizing uniform domains, one involving the presence of length cigars
between nearby points and the other a local version of the quasi-hyperbolic
uniform condition. Our results show that the definition of bmo$(\Omega)$ is
closely connected to the geometry of the domain.
|
[
"math.FA"
] |
math.FA
|
Functional Analysis
| 2,549Functional Analysis
|
|
1505.03993
|
Hermite-Pad\'e approximants of type II are vectors of rational functions with
common denominator that interpolate a given vector of power series at infinity
with maximal order. We are interested in the situation when the approximated
vector is given by a pair of Cauchy transforms of smooth complex measures
supported on the real line. The convergence properties of the approximants are
rather well understood when the supports consist of two disjoint intervals
(Angelesco systems) or two intervals that coincide under the condition that the
ratio of the measures is a restriction of the Cauchy transform of a third
measure (Nikishin systems). In this work we consider the case where the
supports form two overlapping intervals (in a symmetric way) and the ratio of
the measures extends to a holomorphic function in a region that depends on the
size of the overlap. We derive Szeg\H{o}-type formulae for the asymptotics of
the approximants, identify the convergence and divergence domains (the
divergence domains appear for Angelesco systems but are not present for
Nikishin systems), and show the presence of overinterpolation (a feature
peculiar for Nikishin systems but not for Angelesco systems). Our analysis is
based on a Riemann-Hilbert problem for multiple orthogonal polynomials (the
common denominator).
|
[
"math.CA",
"math.CV"
] |
math.CA
|
math.CV
|
Classical Analysis and ODEs;Complex Variables
| 947Classical Analysis and ODEs;Complex Variables
|
1001.1239
|
The article discusses selected properties of the non- and superconducting
polycrystalline samples of RuSr2GdCu2O8 and comments the consequences of
introducing insignificant sub-stoichiometry of Ru into the nominal formula. The
magneto-resistive and the magnetic characteristics are interpreted in favour of
the formation of the intrinsically inhomogeneous superconducting phase, which
seems to be stabilized along with the structural modifications likely enhanced
with the modification of starting stoichiometry. The specific heat data reveals
the shift of temperature of the magnetic ordering T_{m}, suggesting the
dilution in magnetic sublattice of the Ru moments. The measurements of the
magnetic field dependences of the isothermal magnetocaloric coefficient M_{T}
show that there is no gain in magnetic entropy in a broad range of the accessed
fields and temperatures. Whereas the multi-component character of the probed
magnetic system precludes from concluding on the ground state for the Ru
ordering, the maximum in M_{T}(H) which occurs at weak magnetic fields for
temperature vicinity of T_{m} may reflect dominance of the ferromagnetic type
interactions with a constrained correlation range. The literature explored
models for the Ru magnetic ordering and possible phase separation in the
RuSr2GdCu2O8 are brought into the discussion.
|
[
"cond-mat.supr-con",
"cond-mat.mtrl-sci"
] |
cond-mat.supr-con
|
cond-mat.mtrl-sci
|
Superconductivity;Materials Science
| 7,079Superconductivity;Materials Science
|
0911.4315
|
The confined variational method is used to generate a basis of correlated
gaussians to describe the interaction region wave function for positron
scattering from the H$_2$ molecule. The scattering length was $\approx -2.7$
$a_0$ while the zero energy $Z_{\rm eff}$ of 15.7 is compatible with
experimental values. The variation of the scattering length and $Z_{\rm eff}$
with inter-nuclear distance was surprisingly rapid due to virtual state
formation at $R \approx 3.4$ $a_0$.
|
[
"physics.comp-ph",
"physics.atom-ph"
] |
physics.comp-ph
|
physics.atom-ph
|
Computational Physics;Atomic Physics
| 1,385Computational Physics;Atomic Physics
|
2009.03098
|
Most existing person re-identification methods compute pairwise similarity by
extracting robust visual features and learning the discriminative metric. Owing
to visual ambiguities, these content-based methods that determine the pairwise
relationship only based on the similarity between them, inevitably produce a
suboptimal ranking list. Instead, the pairwise similarity can be estimated more
accurately along the geodesic path of the underlying data manifold by exploring
the rich contextual information of the sample. In this paper, we propose a
lightweight post-processing person re-identification method in which the
pairwise measure is determined by the relationship between the sample and the
counterpart's context in an unsupervised way. We translate the point-to-point
comparison into the bilateral point-to-set comparison. The sample's context is
composed of its neighbor samples with two different definition ways: the first
order context and the second order context, which are used to compute the
pairwise similarity in sequence, resulting in a progressive post-processing
model. The experiments on four large-scale person re-identification benchmark
datasets indicate that (1) the proposed method can consistently achieve higher
accuracies by serving as a post-processing procedure after the content-based
person re-identification methods, showing its state-of-the-art results, (2) the
proposed lightweight method only needs about 6 milliseconds for optimizing the
ranking results of one sample, showing its high-efficiency. Code is available
at: https://github.com/123ci/PBCmodel.
|
[
"cs.CV",
"cs.AI"
] |
cs.CV
|
cs.AI
|
Computer Vision and Pattern Recognition;Artificial Intelligence
| 1,502Computer Vision and Pattern Recognition;Artificial Intelligence
|
1103.6073
|
In this note we introduce a new randomized algorithm for counting triangles
in graphs. We show that under mild conditions, the estimate of our algorithm is
strongly concentrated around the true number of triangles. Specifically, if $p
\geq \max{(\frac{\Delta \log{n}}{t}, \frac{\log{n}}{\sqrt{t}})}$, where $n$,
$t$, $\Delta$ denote the number of vertices in $G$, the number of triangles in
$G$, the maximum number of triangles an edge of $G$ is contained, then for any
constant $\epsilon>0$ our unbiased estimate $T$ is concentrated around its
expectation, i.e., $ \Prob{|T - \Mean{T}| \geq \epsilon \Mean{T}} = o(1)$.
Finally, we present a \textsc{MapReduce} implementation of our algorithm.
|
[
"cs.DS",
"cs.DM",
"cs.SI"
] |
cs.DS
|
cs.DM
|
Data Structures and Algorithms;Discrete Mathematics;Social and Information Networks
| 1,947Data Structures and Algorithms;Discrete Mathematics;Social and Information Networks
|
2103.15064
|
Based on improving the classical Bohr inequality, we get in this paper some
refined versions for a quasi-subordination family of functions, one of which is
key to build our results. By means of these investigations, for a family of
harmonic mappings defined in the unit disk $\D$, we establish an improved Bohr
inequality with refined Bohr radius under particular conditions. Along the line
of extremal problems concerning the refined Bohr radius, we derive a series of
results. % in a logical way. Here the family of harmonic mappings have the form
$f=h+\overline{g}$, where $g(0)=0$, the analytic part $h$ is bounded by 1 and
that $|g'(z)|\leq k|h'(z)|$ in $\D$ and for some $k\in[0,1]$.
|
[
"math.CV"
] |
math.CV
|
Complex Variables
| 1,135Complex Variables
|
|
1207.6494
|
The time evolution is studied for the Landau problem with a general time
dependent electric field ${\bf E}(t)$ in a plane perpendicular to the magnetic
field. A general and explicit factorization of the time evolution operator is
derived with each factor having a clear physical interpretation. The
factorization consists of a geometric operator (path-ordered magnetic
translation), a dynamical operator generated by the usual time-independent
Landau Hamiltonian, and a nonadiabatic operator that determines the transition
probabilities among the Landau levels. Since the path-ordered magnetic
translation and the nonadiabatic operators are, up to completely determined
numerical phase factors, just ordinary exponentials whose exponents are
explicitly expressible in terms of the canonical variables, all of the factors
in the factorization are explicitly constructed. The numerical phase factors
are quantum mechanical in nature and could be of significance in interference
experiments. The factorization is unique from the point of view of the quantum
adiabatic theorem and provides a demonstration of how the quantum adiabatic
theorem (incorporating the Berry phase phenomenon) is realized when infinitely
degenerate energy levels are involved. Since the factorization separates the
effect caused by the electric field into a geometric factor and a nonadiabatic
factor, it makes possible to calculate the nonadiabatic transition
probabilities near the adiabatic limit. A formula for matrix elements that
determines the mixing of the Landau levels for a general, non-adiabatic
evolution is also provided by the factorization.
|
[
"quant-ph",
"cond-mat.other"
] |
quant-ph
|
cond-mat.other
|
Quantum Physics;Other Condensed Matter
| 6,149Quantum Physics;Other Condensed Matter
|
1505.02074
|
This work aims to address the problem of image-based question-answering (QA)
with new models and datasets. In our work, we propose to use neural networks
and visual semantic embeddings, without intermediate stages such as object
detection and image segmentation, to predict answers to simple questions about
images. Our model performs 1.8 times better than the only published results on
an existing image QA dataset. We also present a question generation algorithm
that converts image descriptions, which are widely available, into QA form. We
used this algorithm to produce an order-of-magnitude larger dataset, with more
evenly distributed answers. A suite of baseline results on this new dataset are
also presented.
|
[
"cs.LG",
"cs.AI",
"cs.CL",
"cs.CV"
] |
cs.LG
|
cs.AI
|
Machine Learning;Artificial Intelligence;Computation and Language;Computer Vision and Pattern Recognition
| 3,899Machine Learning;Artificial Intelligence;Computation and Language;Computer Vision and Pattern Recognition
|
hep-ph/0005087
|
This work provides an elementary introduction to the Higgs sector
renormalisation within the Minimal Suppersymmetric Standard Model (MSSM)
framework. The MSSM tree-level relation $m_h^2+m_H^2=m_A^2+m_Z^2$ is
renormalised using the standard technique of direct computation of the relevant
one-loop Feynman diagrams. The expected cancellation of ultraviolet divergences
is explicitly checked and the well-known leading-log term is recovered.
|
[
"hep-ph"
] |
hep-ph
|
High Energy Physics - Phenomenology
| 3,129High Energy Physics - Phenomenology
|
|
1606.06429
|
In this paper, we investigate eigenvalues of the Dirichlet problem and the
closed eigenvalue problem of drifting Laplacian on the complete metric measure
spaces and establish the corresponding general formulas. By using those general
formulas, we give some upper bounds of consecutive gap of the eigenvalues of
the eigenvalue problems, which is sharp in the sense of the order of the
eigenvalues. As some interesting applications, we study the eigenvalue of
drifting Laplacian on Ricci solitons, self-shrinkers and product Riemannian
manifolds. We give the explicit upper bounds of the gap of the consecutive
eigenvalues of the drifting Laplacian. Since eigenvalues is invariant in the
sense of isometry, by the classifications of Ricci solitons and self-shrinkers,
we give the explicit upper bounds for the consecutive eigenvalues of the
drifting Laplacian on a large class metric measure spaces. In addition, we also
consider the case of product Riemannian manifolds with certain curvature
conditions and some upper bounds are obtained. Basing on the case of Laplace
operator, we also present a conjecture as follows: all of the eigenvalues of
the Dirichlet problem of drifting Laplacian on metric measure spaces satisfy:
$$\lambda_{k+1}-\lambda_{k}\leq(\lambda_{2}-\lambda_{1})k^{\frac{1}{n}}.$$We
note the conjecture is true in some special cases.
|
[
"math.DG",
"math.AP"
] |
math.DG
|
math.AP
|
Differential Geometry;Analysis of PDEs
| 2,022Differential Geometry;Analysis of PDEs
|
1909.12487
|
As progress is made on thin-film synthesis of Heusler compounds, a more
complete understanding of the surface will be required to control their
properties, especially as functional heterostructures are explored. Here, the
surface reconstructions of semiconducting half-Heusler NiTiSn(001), and
Ni1+xTiSn(001) (x=0.0-1.0) are explored as a way to optimize growth conditions
during molecular beam epitaxy. Density functional theory (DFT) calculations
were carried out to guide the interpretation of the experimental results. For
NiTiSn(001) a c(2x2) surface reconstruction was observed for Sn rich samples,
while a (1x1) unreconstructed surface was observed for Ti-rich samples. A
narrow range around 1:1:1 stoichiometry exhibited a (2x1) surface
reconstruction. Electrical transport is used to relate the observed reflection
high energy electron diffraction (RHEED) pattern during and after growth with
carrier concentration and stoichiometry. Scanning tunneling microscopy and
RHEED were used to examine surface reconstructions, the results of which are in
good agreement with density functional calculations. X-ray photoelectron
spectroscopy was used to determine surface termination and stoichiometry.
Atomic surface models are proposed, which suggest Sn-dimers form in
reconstructed Ni1+xTiSn(001) half-Heusler surfaces (x<0.25) with a transition
to Ni terminated surfaces for x > 0.25.
|
[
"cond-mat.mtrl-sci"
] |
cond-mat.mtrl-sci
|
Materials Science
| 4,287Materials Science
|
|
1906.03376
|
We revisit the optimal heat transport problem for Rayleigh-B\'enard
convection in which a rigorous upper bound on the Nusselt number, $Nu$, is
sought as a function of the Rayleigh number $Ra$. Concentrating on the
2-dimensional problem with stress-free boundary conditions, we impose the full
heat equation as a constraint for the bound using a novel 2-dimensional
background approach thereby complementing the `wall-to-wall' approach of
Hassanzadeh \etal \,(\emph{J. Fluid Mech.} \textbf{751}, 627-662, 2014).
Imposing the same symmetry on the problem, we find correspondence with their
result for $Ra \leq Ra_c:=4468.8$ but, beyond that, the optimal fields
complexify to produce a higher bound. This bound approaches that by a
1-dimensional background field as the length of computational domain
$L\rightarrow\infty$. On lifting the imposed symmetry, the optimal
2-dimensional temperature background field reverts back to being 1-dimensional
giving the best bound $Nu\le 0.055Ra^{1/2}$ compared to $Nu \le 0.026Ra^{1/2}$
in the non-slip case. % We then show via an inductive bifurcation analysis that
imposing the full time-averaged Boussinesq equations as constraints (by
introducing 2-dimensional temperature {\em and} velocity background fields) is
also unable to lower this bound. This then exhausts the background approach for
the 2-dimensional (and by extension 3-dimensional) Rayleigh-Benard problem with
the bound remaining stubbornly $Ra^{1/2}$ while data seems more to scale like
$Ra^{1/3}$ for large $Ra$. % Finally, we show that adding a velocity background
field to the formulation of Wen \etal\, (\emph{Phys. Rev. E.} \textbf{92},
043012, 2015), which is able to use an extra vorticity constraint due to the
stress-free condition to lower the bound to $ Nu \le O(Ra^{5/12})$, also fails
to improve the bound.
|
[
"physics.flu-dyn"
] |
physics.flu-dyn
|
Fluid Dynamics
| 2,452Fluid Dynamics
|
|
1406.4897
|
Let $F$ be a local non archimedian field of characteristic $0$, and $G$ a
non-connected reductive group over $F$. We denote $G^0$ the connected component
of the identity and assume the quotient $G/G^0$ is abelian. For $f$ a locally
constant compactly supported function on $G$ and $\pi$ a complex smooth
representation of $G$, we define the Fourier transform of $f$ evaluated at
$\pi$ to be $\pi(f) = \int_{G} f(g) \pi(g) \, dg$, which is an endomorphism of
the underlying vector space of $\pi$.
We give a description of the image of this Fourier transform map : given, for
every $\pi$ in a certain family of induced representations of $G$, an
endomorphism $\varphi(\pi)$ of the underlying vector space, we provide
necessary and sufficient conditions under which there exists a function $f$
(necessarily unique) such that $\pi(f) = \varphi(\pi)$ for all $\pi$ in the
family.
|
[
"math.RT"
] |
math.RT
|
Representation Theory
| 6,217Representation Theory
|
|
astro-ph/0601627
|
We present the catalog of X-ray sources detected in a shallow Chandra survey
of the inner 2 by 0.8 degrees of the Galaxy, and in two deeper observations of
the Radio Arches and Sgr B2. The catalog contains 1352 objects that are
highly-absorbed (N_H > 4e22 cm^-2 and are therefore likely to lie near the
Galactic center (D~8 kpc), and 549 less-absorbed sources that lie within <6 kc
of Earth. Based on the inferred luminosities of the X-ray sources and the
expected numbers of various classes of objects, we suggest that the sources
with L_X < 1e33 erg/s that comprise ~90% of the catalog are cataclysmic
variables, and that the ~100 brighter objects are accreting neutron stars and
black holes, young isolated pulsars, and Wolf-Rayet and O stars in
colliding-wind binaries. We find that the spatial distribution of X-ray sources
matches that of the old stellar population observed in the infrared, which
supports our suggestion that most of the X-ray sources are old cataclysmic
variables. However, we find that there is an apparent excess of ~10 bright
sources in the Radio Arches region. That region is already known to be the site
of recent star formation, so we suggest that the bright sources in this region
are young high-mass X-ray binaries, pulsars, or WR/O star binaries. We briefly
discuss some astrophysical questions that this catalog can be used to address.
|
[
"astro-ph"
] |
astro-ph
|
Astrophysics
| 463Astrophysics
|
|
0902.0272
|
The standard Grad-Shafranov equation for axisymmetric toroidal plasma
equilibrium is customary expressed in cylindrical coordinates with toroidal
contours, and through which benchmark equilibria are solved. An alternative
approach to cast the Grad-Shafranov equation in spherical coordinates is
presented. This equation, in spherical coordinates, is examined for toroidal
solutions to describe low $\beta$ Solovev and high $\beta$ plasma equilibria in
terms of elementary functions.
|
[
"physics.plasm-ph"
] |
physics.plasm-ph
|
Plasma Physics
| 5,556Plasma Physics
|
|
1507.01414
|
The general method for treating non-Gaussian wave functionals in the
Hamiltonian formulation of a quantum field theory, which was previously
proposed and developed for Yang--Mills theory in Coulomb gauge, is generalized
to full QCD. For this purpose the quark part of the QCD vacuum wave functional
is expressed in the basis of coherent fermion states, which are defined in term
of Grassmann variables. Our variational ansatz for the QCD vacuum wave
functional is assumed to be given by exponentials of polynomials in the
occurring fields and, furthermore, contains an explicit coupling of the quarks
to the gluons. Exploiting Dyson--Schwinger equation techniques, we express the
various $n$-point functions, which are required for the expectation values of
observables like the Hamiltonian, in terms of the variational kernels of our
trial ansatz. Finally the equations of motion for these variational kernels are
derived by minimizing the energy density.
|
[
"hep-th"
] |
hep-th
|
High Energy Physics - Theory
| 3,266High Energy Physics - Theory
|
|
2304.08705
|
In this paper we describe the control sets of the linear system on the
two-dimensional affine group when the trajectories has empty interior. In
particular, we show the existence of infinitely many control sets and of an
chain control set.
|
[
"math.OC"
] |
math.OC
|
Optimization and Control
| 5,234Optimization and Control
|
|
2106.09865
|
We report the discovery of a UHE gamma-ray source, LHAASO J2108+5157, by
analyzing the LHAASO-KM2A data of 308.33 live days. Significant excess of
gamma-ray induced showers is observed in both energy bands of 25-100 TeV and
$\gt$100 TeV with 9.5 sigma and 8.5 sigma, respectively. This source is not
significantly favored as an extensive source with the angular extension smaller
than the point-spread function of KM2A. The measured energy spectrum from 20 to
200 TeV can be approximately described by a power-law function with an index of
-2.83$\pm$ 0.18stat. A harder spectrum is demanded at lower energies
considering the flux upper limit set by Fermi-LAT observations. The position of
the gamma-ray emission is correlated with a giant molecular cloud, which favors
a hadronic origin. No obvious counterparts have been found, deeper
multiwavelength observations will help to shed new light on this intriguing UHE
source.
|
[
"astro-ph.HE"
] |
astro-ph.HE
|
High Energy Astrophysical Phenomena
| 2,990High Energy Astrophysical Phenomena
|
|
2203.10312
|
Our concern in this paper is to study the qualitative properties for harmonic
functions related to the fractional Laplacian. Firstly we classify the
polynomials in the whole space and in the half space for the fractional
Laplacian defined in a principle value sense at infinity. Secondly, we study
the fractional harmonic functions in half space with singularities on the
boundary and the related distributional identities.
|
[
"math.AP"
] |
math.AP
|
Analysis of PDEs
| 205Analysis of PDEs
|
|
1111.5919
|
We search for the $Z_1(4050)^+$ and $Z_2(4250)^+$ states, reported by the
Belle Collaboration, decaying to $\chi_{c1} \pi^+$ in the decays $\bar B^0 \to
\chi_{c1} K^- \pi^+$ and $B^+ \to \chi_{c1} K^0_S \pi^+$ where $\chi_{c1} \to
\jpsi \gamma$. The data were collected with the BaBar detector at the SLAC
PEP-II asymmetric-energy $e^+e^-$ collider operating at center-of-mass energy
10.58 GeV, and correspond to an integrated luminosity of 429 fb$^{-1}$. In this
analysis, we model the background-subtracted, efficiency-corrected
$\chi_{c1}\pi$ mass distribution using the $K \pi$ mass distribution and the
corresponding normalized $K \pi$ Legendre polynomial moments, and then test the
need for the inclusion of resonant structures in the description of the
$\chi_{c1}\pi$ mass distribution. No evidence is found for the $Z_1(4050)^+$
and $Z_2(4250)^+$ resonances, and 90% confidence level upper limits on the
branching fractions are reported for the corresponding $B$-meson decay modes.
|
[
"hep-ex"
] |
hep-ex
|
High Energy Physics - Experiment
| 3,059High Energy Physics - Experiment
|
|
cond-mat/0211405
|
The (Ca_xLa_(1-x))(Ba_(1.75-x)La_(0.25+x))Cu_(3)O_(y) system is ideal for
testing theories of high temperature superconductivity, since nearly the full
range of doping is controlled by y, and T_(c)^max is continuously controlled by
x, with minimal structural changes. We investigate this system with both
transverse and longitudinal field MuSR. This allows us to re-examine the Uemura
relation, the nature of the spontaneous magnetic fields below T_(c), and the
relation between their appearance temperature T_(g) and T_(c)^max . Our major
findings are: (I) the Uemura relation is respected by CLBLCO more adequately
than by other cuprates, (II) T_(g) and T_(c) are controlled by the same energy
scale, (III) the phase separation between hole poor and hole rich regions is a
microscopic one, and (IV) spontaneous magnetic fields appear gradually with no
moment size evolution.
|
[
"cond-mat.supr-con"
] |
cond-mat.supr-con
|
Superconductivity
| 7,066Superconductivity
|
|
1403.0151
|
High-temperature electronic materials are in constant demand as the required
operational range for various industries increases. Here we design
$(A,A^\prime)B_2$O$_6$ perovskite oxides with [111] ``rock salt" $A$-site
cation order and predict them to be potential high-temperature piezoelectric
materials. By selecting bulk perovskites which have a tendency towards only
out-of-phase $B$O$_6$ rotations, we avoid possible staggered ferroelectric to
paraelectric phase transitions while also retaining non-centrosymmetric crystal
structures necessary for ferro- and piezoelectricity. Using density functional
theory calculations, we show that (La,Pr)Al$_2$O$_6$ and (Ce,Pr)Al$_2$O$_6$
display spontaneous polarizations in their polar ground state structures; we
also compute the dielectric and piezoelectric constants for each phase.
Additionally, we predict the critical phase transition temperatures for each
material from first-principles to demonstrate that the piezoelectric responses,
which are comparable to traditional lead-free piezoelectrics, should persist to
high temperature. These features make the rock salt $A$-site ordered aluminates
candidates for high-temperature sensors, actuators, or other electronic
devices.
|
[
"cond-mat.mtrl-sci"
] |
cond-mat.mtrl-sci
|
Materials Science
| 4,287Materials Science
|
|
hep-th/0505069
|
We discuss the theory of knots, and describe how knot invariants arise
naturally in gravitational physics. The focus of this review is to delineate
the relationship between knot theory and the loop representation of
non-perturbative canonical quantum general relativity (loop quantum gravity).
This leads naturally to a discussion of the Kodama wavefunction, a state which
is conjectured to be the ground state of the gravitational field with positive
cosmological constant. This review can serve as a self-contained introduction
to loop quantum gravity and related areas. Our intent is to make the paper
accessible to a wider audience that may include topologists, knot-theorists,
and other persons innocent of the physical background to this approach to
quantum gravity.
|
[
"hep-th"
] |
hep-th
|
High Energy Physics - Theory
| 3,266High Energy Physics - Theory
|
|
2006.14656
|
We consider the tilting instability of a magnetically confined spheromak
using 3D MHD and relativistic PIC calculations with an application to
astrophysical plasmas, specifically those occurring in magnetar magnetospheres.
The instability is driven by the counter alignment of the spheromak's intrinsic
magnetic dipole with the external magnetic field. Initially the spheromak
rotates - tilts - trying to lower its magnetic potential energy. As a result a
current sheet forms between the internal magnetic field of a spheromak and the
confining field. Magnetic reconnection sets in; this leads to the annihilation
of the newly counter-aligned magnetic flux of the spheromak. This occurs on few
Alfv\'en time scales. In the case of higher order (second order) spheromak, the
internal core is first pushed out of the envelope, resulting in formation of
two nearly independent tilting spheromaks. Thus, the magnetically twisted outer
shell cannot stabilize the inner core. During dissipation, helicity of the
initial spheromak is carried away by torsional Alfv\'en waves, violating the
assumptions of the Taylor relaxation theorem. In applications to magnetars'
giant flares, fast development of tilting instabilities, and no stabilization
of the higher order spheromaks, make it unlikely that trapped spheromaks are
responsible for the tail emission lasting hundreds of seconds.
|
[
"physics.plasm-ph",
"astro-ph.HE"
] |
physics.plasm-ph
|
astro-ph.HE
|
Plasma Physics;High Energy Astrophysical Phenomena
| 5,582Plasma Physics;High Energy Astrophysical Phenomena
|
2002.08219
|
First-person interaction recognition is a challenging task because of
unstable video conditions resulting from the camera wearer's movement. For
human interaction recognition from a first-person viewpoint, this paper
proposes a three-stream fusion network with two main parts: three-stream
architecture and three-stream correlation fusion. Thre three-stream
architecture captures the characteristics of the target appearance, target
motion, and camera ego-motion. Meanwhile the three-stream correlation fusion
combines the feature map of each of the three streams to consider the
correlations among the target appearance, target motion and camera ego-motion.
The fused feature vector is robust to the camera movement and compensates for
the noise of the camera ego-motion. Short-term intervals are modeled using the
fused feature vector, and a long short-term memory(LSTM) model considers the
temporal dynamics of the video. We evaluated the proposed method on two-public
benchmark datasets to validate the effectiveness of our approach. The
experimental results show that the proposed fusion method successfully
generated a discriminative feature vector, and our network outperformed all
competing activity recognition methods in first-person videos where
considerable camera ego-motion occurs.
|
[
"cs.CV"
] |
cs.CV
|
Computer Vision and Pattern Recognition
| 1,498Computer Vision and Pattern Recognition
|
|
1806.04766
|
The energy dependence of the deflection angle is a common prediction in some
quantum gravity theories when the impact parameters are much larger than the
photon wavelength. For low energy photons, the deflection angle recovers to the
prediction of GR. But it reduces to zero for infinite energy photons. In this
paper, we develop an effective approach to calculate the trajectory of photons
and other deflection-related quantities semiclassically by replacing $h_{\mu
\nu}$ with $h_{\mu \nu} \times f(E)$ to include the correction of quantum
gravity. This approach could provide more information for photons traveling in
an external gravitational field. We compute the horizon of micro black hole
with this method and find that they are all energy dependent and decrease to
zero as the energy increases to infinity.
|
[
"gr-qc",
"astro-ph.HE",
"hep-th"
] |
gr-qc
|
astro-ph.HE
|
General Relativity and Quantum Cosmology;High Energy Astrophysical Phenomena;High Energy Physics - Theory
| 2,734General Relativity and Quantum Cosmology;High Energy Astrophysical Phenomena;High Energy Physics - Theory
|
1301.7424
|
Magnetic reconnection is best known from observations of the Sun where it
causes solar flares. Observations estimate the reconnection rate a small, but
non-negligible fraction of the Alfv\'en speed, so-called fast reconnection.
Until recently, the prevailing pictures of reconnection were referring to
either resistivity or plasma microscopic effects, which was contradictory to
the observed rates. The alternative picture was either reconnection due to the
stochasticity of magnetic field lines in turbulence or the tearing instability
of the thin current sheet. In this paper I simulated long-term
three-dimensional nonlinear evolution of a thin, planar current sheet subject
to fast oblique tearing instability using direct numerical simulations of
resistive-viscous MHD. The late-time evolution resembles generic turbulence
with -5/3 power spectrum and scale-dependent anisotropy, so I conclude that the
tearing-driven reconnection becomes turbulent reconnection. The turbulence is
local in scale, so microscopic diffusivity should not affect large-scale
quantities. This is confirmed by convergence of the reconnection rate towards
$\sim 0.015 v_A$ with increasing Lundquist number. In this spontaneous
reconnection with mean field and without driving the dissipation rate per unit
area also converge to $\sim 0.006 \rho v_A^3$, the dimensionless constants
$0.015$ and $0.006$ are governed only by self-driven nonlinear dynamics of the
sheared magnetic field. Remarkably, this also means that thin current sheet has
a universal fluid resistance depending only on its length to width ratio and to
$v_A/c$.
|
[
"astro-ph.SR",
"physics.plasm-ph"
] |
astro-ph.SR
|
physics.plasm-ph
|
Solar and Stellar Astrophysics;Plasma Physics
| 6,721Solar and Stellar Astrophysics;Plasma Physics
|
2301.07773
|
Temporal logic is a concise way of specifying complex tasks. But motion
planning to achieve temporal logic specifications is difficult, and existing
methods struggle to scale to complex specifications and high-dimensional system
dynamics. In this paper, we cast Linear Temporal Logic (LTL) motion planning as
a shortest path problem in a Graph of Convex Sets (GCS) and solve it with
convex optimization. This approach brings together the best of modern
optimization-based temporal logic planners and older automata-theoretic
methods, addressing the limitations of each: we avoid clipping and passthrough
by representing paths with continuous Bezier curves; computational complexity
is polynomial (not exponential) in the number of sample points; global
optimality can be certified (though it is not guaranteed); soundness and
probabilistic completeness are guaranteed under mild assumptions; and most
importantly, the method scales to complex specifications and high-dimensional
systems, including a 30-DoF humanoid. Open-source code is available at
https://github.com/vincekurtz/ltl_gcs.
|
[
"cs.RO",
"cs.FL",
"cs.SY",
"eess.SY"
] |
cs.RO
|
cs.FL
|
Robotics;Formal Languages and Automata Theory;Systems and Control;Systems and Control
| 7,267longtail
|
2107.04087
|
We show that all local martingales with respect to the initially enlarged
natural filtration of a vector of multivariate point processes can be weakly
represented up to the minimum among the explosion times of the components. We
also prove that a strong representation holds if any multivariate point process
of the vector has almost surely infinite explosion time and discrete mark's
space. Then we provide a condition under which the components of the
multidimensional local martingale driving the strong representation are
pairwise orthogonal.
|
[
"math.PR"
] |
math.PR
|
Probability
| 5,709Probability
|
|
1406.1347
|
The Min proteins from Escherichia coli can self-organize into traveling waves
on supported lipid bilayers. In Proc. Natl. Acad. Sci. USA 109, 15283 (2012) we
showed that these waves are guided along the boundaries of membrane patches. We
introduced an effective two-dimensional model reproducing the observed
patterns. In arXiv:1403.5934v1, Jacob Halatek and Erwin Frey contest the
ability of our effective two-dimensional model to describe the dynamics of Min
proteins on patterned supported lipid bilayers. We thank Halatek and Frey for
their interest in our work and for again highlighting the importance of
dimensionality and geometry for pattern formation by the Min proteins. Here we
reply in detail to the objections by Halatek and Frey and show that (1) our
effective two-dimensional model reproduces the observed patterns on isolated
patches and that (2) a three-dimensional version of our model produces similar
patterns on square patches.
|
[
"q-bio.SC"
] |
q-bio.SC
|
Subcellular Processes
| 7,056Subcellular Processes
|
|
1905.00741
|
Deep reinforcement learning has proven to be successful for learning tasks in
simulated environments, but applying same techniques for robots in real-world
domain is more challenging, as they require hours of training. To address this,
transfer learning can be used to train the policy first in a simulated
environment and then transfer it to physical agent. As the simulation never
matches reality perfectly, the physics, visuals and action spaces by necessity
differ between these environments to some degree. In this work, we study how
general video games can be directly used instead of fine-tuned simulations for
the sim-to-real transfer. Especially, we study how the agent can learn the new
action space autonomously, when the game actions do not match the robot
actions. Our results show that the different action space can be learned by
re-training only part of neural network and we obtain above 90% mean success
rate in simulation and robot experiments.
|
[
"cs.LG",
"cs.AI",
"cs.RO"
] |
cs.LG
|
cs.AI
|
Machine Learning;Artificial Intelligence;Robotics
| 3,980Machine Learning;Artificial Intelligence;Robotics
|
math/0308065
|
In these lecture notes, we combine recent homological methods of Kevin Whyte
with older dynamical methods developed by Benson Farb and myself, to obtain a
new quasi-isometric rigidity theorem for the mapping class group MCG(S) of a
once punctured surface S of genus at least 2: if K is a finitely generated
group quasi-isometric to MCG(S) then there is a homomorphism K -> MCG(S) with
finite kernel and finite index image. This theorem is joint with Kevin Whyte.
|
[
"math.GR",
"math.GT"
] |
math.GR
|
math.GT
|
Group Theory;Geometric Topology
| 2,950Group Theory;Geometric Topology
|
1506.02134
|
Graphane is graphene fully hydrogenated from both sides, forming a 1x1
structure, where all C atoms are in sp3 configuration. In silicene, the Si
atoms are in a mix-sp2/sp3 configuration, it is therefore natural to imagine
silicane in analogue to graphane. However, monoatomic silicene sheet grown on
substrates generally reconstructs into different phases, and only partially
hydrogenated silicene with reconstructions had been reported before. In this
report we produce half-silicane, where one Si sublattice is fully H-saturated
and the other sublattice is intact, forming a perfect 1x1 structure. By
hydrogenating various silicene phases on Ag(111) substrate, we found that only
the (2r3x2r3)R30{\deg} phase can produce half-silicane. Interestingly, this
phase was previous considered to be a highly defective or incomplete silicene
structure. Our results indicate that the structure of (2r3x2r3)R30{\deg} phase
involves a complete silicene-1x1 lattice instead of defective fragments, and
the formation mechanism of half-silicane was discussed with the help of first
principles calculations.
|
[
"cond-mat.mtrl-sci",
"cond-mat.mes-hall"
] |
cond-mat.mtrl-sci
|
cond-mat.mes-hall
|
Materials Science;Mesoscale and Nanoscale Physics
| 4,330Materials Science;Mesoscale and Nanoscale Physics
|
1807.05297
|
Let $V$ be an $n$-dimensional vector space over the finite field of order
$q$. The spherical building $X_V$ associated with $GL(V)$ is the order complex
of the nontrivial linear subspaces of $V$. Let $\mathfrak{g}$ be the local
coefficient system on $X_V$, whose value on the simplex $\sigma=[V_0 \subset
\cdots \subset V_p] \in X_V$ is given by $\mathfrak{g}(\sigma)=V_0$. Following
the work of Lusztig and Dupont, we study the homology module
$D^k(V)=\tilde{H}_{n-k-1}(X_V;\mathfrak{g})$. Our results include a
construction of an explicit basis of $D^1(V)$, and the following twisted
analogue of a result of Smith and Yoshiara: For any $1 \leq k \leq n-1$, the
minimal support size of a non-zero $(n-k-1)$-cycle in the twisted homology
$\tilde{H}_{n-k-1}(X_V;\wedge^k \mathfrak{g})$ is $\frac{(n-k+2)!}{2}$.
|
[
"math.CO"
] |
math.CO
|
Combinatorics
| 1,014Combinatorics
|
|
1310.4126
|
Recently Bingbing Liang and Hanfeng Li computed the mean dimension and metric
mean dimension for algebraic actions of amenable groups. We show how to extend
their computation of metric mean dimension to the case of sofic groups,
provided that the dual module is finitely generated. Additionally, we show that
when the dual module is finitely presented that the mean dimension is the von
Neumann rank. The proof also goes through introducing \ell^{p}-analogues of
metric mean dimension, which may be seen as an obstruction to the equality of
mean dimension and metric mean dimension.
|
[
"math.GR",
"math.DS",
"math.FA",
"math.OA"
] |
math.GR
|
math.DS
|
Group Theory;Dynamical Systems;Functional Analysis;Operator Algebras
| 7,267longtail
|
2009.07865
|
Excitons are neutral objects, that, naively, should have no response to a
uniform, electric field. Could the Berry curvature of the underlying electronic
bands alter this conclusion? In this work, we show that Berry curvature can
indeed lead to anomalous transport for excitons in 2D materials subject to a
uniform, in-plane electric field. By considering the constituent electron and
hole dynamics, we demonstrate that there exists a regime for which the
corresponding anomalous velocities are in the same direction. We establish the
resulting center of mass motion of the exciton through both a semiclassical and
fully quantum mechanical analysis, and elucidate the critical role of Bloch
oscillations in achieving this effect. We identify transition metal
dichalcogenide heterobilayers as candidate materials to observe the effect.
|
[
"cond-mat.str-el"
] |
cond-mat.str-el
|
Strongly Correlated Electrons
| 6,979Strongly Correlated Electrons
|
|
hep-th/9812244
|
We discuss alternative descriptions of four-dimensional self-dual Yang-Mills
fields in harmonic space with additional commuting spinor coordinates. In
particular, the linear analyticity equation and nonlinear covariant
harmonic-field equations are studied. A covariant harmonic field can be treated
as an infinite set of ordinary four-dimensional fields with higher spins. We
analyze different constructions of invariant harmonic-field actions
corresponding to the self-dual harmonic equations.
|
[
"hep-th"
] |
hep-th
|
High Energy Physics - Theory
| 3,266High Energy Physics - Theory
|
|
1801.03336
|
In this paper we study a class of combined regular and singular stochastic
control problems that can be expressed as constrained BSDEs. In the Markovian
case, this reduces to a characterization through a PDE with gradient
constraint. But the BSDE formulation makes it possible to move beyond Markovian
models and consider path-dependent problems. We also provide an approximation
of the original control problem with standard BSDEs that yield a
characterization of approximately optimal values and controls.
|
[
"math.OC"
] |
math.OC
|
Optimization and Control
| 5,234Optimization and Control
|
|
0910.0508
|
We present a bosonic model, in which two bosons may form a bound pair with
d-wave symmetry via the four-site ring exchange interaction. A d-wave pairing
superfluid as well as a d-wave density wave (DDW) state, are proposed to be
achievable in this system. This exotic bosonic system can be realized in the
BEC zone of a two-dimensional attractive p-band spinless fermionic system. By
the mean field approach, we find that at low densities, the d-wave pairs may
condensate, leading to a d-wave bosonic paired superfluid. At some particular
filling factors, a novel phase, d-wave density wave state, emerges. We study
this DDW state and its corresponding quantum phase transition in a two-leg
ladder by the time-evolving block decimation (TEBD) method.
|
[
"cond-mat.quant-gas",
"cond-mat.str-el"
] |
cond-mat.quant-gas
|
cond-mat.str-el
|
Quantum Gases;Strongly Correlated Electrons
| 5,974Quantum Gases;Strongly Correlated Electrons
|
hep-ph/9802303
|
We describe some detailed numerical simulations of Disoriented Chiral
Condensates (DCCs), using the chiral lagrangian as a controlled long-wavelength
description. We focus on the possibility of multiple, independently coherent
domains, and investigate the degree to which the DCC signal is attenuated. As
an intermediate step in our analysis we compute the expected number of detector
events in each isospin and momentum channel for a given asymptotic classical
field configuration. We find that for sufficiently large initial field
strengths, the non-linear interactions between domains become important and can
lead to a randomization of isospin orientations. Nevertheless, we argue that
viable signals exist for DCC detection, even in the case of multiple domains
and strong domain-domain interactions. We briefly discuss some long-lived
`pseudo-bound state' configurations which arise at large field strengths and
might be observable in HBT correlations.
|
[
"hep-ph",
"nucl-th"
] |
hep-ph
|
nucl-th
|
High Energy Physics - Phenomenology;Nuclear Theory
| 3,240High Energy Physics - Phenomenology;Nuclear Theory
|
cond-mat/0609144
|
We have analyzed a dissipative two level quantum system (TLS) which is
continuously and simultaneously irradiated by a high and low frequency
excitation. The interaction of the TLS with a high frequency excitation is
considered in the frame of the dressed state approach. A linear response of the
coupled TLS and corresponding photon field system to a signal whose frequency
is of the order of the Rabi frequency is found. The response exhibits undamped
low frequency oscillations, whose amplitude has a clear resonance at the Rabi
frequency with the width being dependent on the damping rates of the TLS. The
method can be useful for low-frequency Rabi spectroscopy in various physical
systems described by a two-level Hamiltonian, such as nuclei spins in NMR,
double well quantum dots, superconducting flux and charge qubits, etc. The
application of the method to a superconducting flux qubit and to the detection
of NMR is considered in detail.
|
[
"cond-mat.soft",
"cond-mat.mes-hall"
] |
cond-mat.soft
|
cond-mat.mes-hall
|
Soft Condensed Matter;Mesoscale and Nanoscale Physics
| 6,593Soft Condensed Matter;Mesoscale and Nanoscale Physics
|
1111.2351
|
Six-dimensional supergravity theories with N=(1,0) supersymmetry must satisfy
anomaly equations. These equations come from demanding the cancellation of
gravitational, gauge and mixed anomalies. The anomaly equations have
implications for the geometrical data of Calabi-Yau threefolds, since F-theory
compactified on an elliptically fibered Calabi-Yau threefold with a section
generates a consistent six-dimensional N=(1,0) supergravity theory. In this
paper, we show that the anomaly equations can be summarized by three
intersection theory identities. In the process we also identify the geometric
counterpart of the anomaly coefficients---in particular, those of the abelian
gauge groups---that govern the low-energy dynamics of the theory. We discuss
the results in the context of investigating string universality in six
dimensions.
|
[
"hep-th"
] |
hep-th
|
High Energy Physics - Theory
| 3,266High Energy Physics - Theory
|
|
2003.06169
|
Agile satellites with advanced attitude maneuvering capability are the new
generation of Earth observation satellites (EOSs). The continuous improvement
in satellite technology and decrease in launch cost have boosted the
development of agile EOSs (AEOSs). To efficiently employ the increasing
orbiting AEOSs, the AEOS scheduling problem (AEOSSP) aiming to maximize the
entire observation profit while satisfying all complex operational constraints,
has received much attention over the past 20 years. The objectives of this
paper are thus to summarize current research on AEOSSP, identify main
accomplishments and highlight potential future research directions. To this
end, general definitions of AEOSSP with operational constraints are described
initially, followed by its three typical variations including different
definitions of observation profit, multi-objective function and autonomous
model. A detailed literature review from 1997 up to 2019 is then presented in
line with four different solution methods, i.e., exact method, heuristic,
metaheuristic and machine learning. Finally, we discuss a number of topics
worth pursuing in the future.
|
[
"astro-ph.IM",
"cs.AI",
"eess.SP"
] |
astro-ph.IM
|
cs.AI
|
Instrumentation and Methods for Astrophysics;Artificial Intelligence;Signal Processing
| 7,267longtail
|
nucl-th/0003033
|
Dynamical screening in the magnetic part of the one-gluon exchange
interaction is included in the study of radiative energy loss of a fast parton
propagating inside a quark-gluon plasma. As a result the final radiative energy
loss is about twice as large as when only the electric part of one-gluon
exchange interaction is considered. A non-perturbative magnetic screening mass
is also used in the estimate of the mean-free-path of parton scattering in a
hot QCD matter.
|
[
"nucl-th",
"hep-ph"
] |
nucl-th
|
hep-ph
|
Nuclear Theory;High Energy Physics - Phenomenology
| 4,914Nuclear Theory;High Energy Physics - Phenomenology
|
2203.10004
|
Evanescently coupled waveguides are a powerful platform to study and
visualize the wave dynamics in tight-binding systems. Here, we investigate the
propagation of surface plasmon polaritons in arrays of dielectric loaded
surface plasmon polariton waveguides with a propagation constant gradient
acting as an effective external potential. Using leakage radiation microscopy,
we observe in real-space for single site excitation a periodic breathing of the
wavepacket and an oscillatory motion in the case of Gaussian excitation of
multiple waveguides. The corresponding momentum resolved spectra are composed
of sets of equally spaced modes. We interpret these observation as the
plasmonic analogues of Bloch oscillations and the Wannier-Stark ladder,
respectively.
|
[
"physics.optics"
] |
physics.optics
|
Optics
| 5,146Optics
|
|
2309.14820
|
Three-dimensional tracking of multiple objects from multiple views has a wide
range of applications, especially in the study of bio-cluster behavior which
requires precise trajectories of research objects. However, there are
significant temporal-spatial association uncertainties when the objects are
similar to each other, frequently maneuver, and cluster in large numbers.
Aiming at such a multi-view multi-object 3D tracking scenario, a current
statistical model based Kalman particle filter (CSKPF) method is proposed
following the Bayesian tracking-while-reconstruction framework. The CSKPF
algorithm predicts the objects' states and estimates the objects' state
covariance by the current statistical model to importance particle sampling
efficiency, and suppresses the measurement noise by the Kalman filter. The
simulation experiments prove that the CSKPF method can improve the tracking
integrity, continuity, and precision compared with the existing constant
velocity based particle filter (CVPF) method. The real experiment on fruitfly
clusters also confirms the effectiveness of the CSKPF method.
|
[
"cs.CV",
"q-bio.QM"
] |
cs.CV
|
q-bio.QM
|
Computer Vision and Pattern Recognition;Quantitative Methods
| 1,635Computer Vision and Pattern Recognition;Quantitative Methods
|
1707.04560
|
Statistical pattern recognition methods have provided competitive solutions
for variable star classification at a relatively low computational cost. In
order to perform supervised classification, a set of features is proposed and
used to train an automatic classification system. Quantities related to the
magnitude density of the light curves and their Fourier coefficients have been
chosen as features in previous studies. However, some of these features are not
robust to the presence of outliers and the calculation of Fourier coefficients
is computationally expensive for large data sets. We propose and evaluate the
performance of a new robust set of features using supervised classifiers in
order to look for new Be star candidates in the OGLE-IV Gaia south ecliptic
pole field. We calculated the proposed set of features on six types of variable
stars and on a set of Be star candidates reported in the literature. We
evaluated the performance of these features using classification trees and
random forests along with K-nearest neighbours, support vector machines, and
gradient boosted trees methods. We tuned the classifiers with a 10-fold
cross-validation and grid search. We validated the performance of the best
classifier on a set of OGLE-IV light curves and applied this to find new Be
star candidates. The random forest classifier outperformed the others. By using
the random forest classifier and colour criteria we found 50 Be star candidates
in the direction of the Gaia south ecliptic pole field, four of which have
infrared colours consistent with Herbig Ae/Be stars. Supervised methods are
very useful in order to obtain preliminary samples of variable stars extracted
from large databases. As usual, the stars classified as Be stars candidates
must be checked for the colours and spectroscopic characteristics expected for
them.
|
[
"astro-ph.IM"
] |
astro-ph.IM
|
Instrumentation and Methods for Astrophysics
| 3,689Instrumentation and Methods for Astrophysics
|
|
2306.09357
|
Deep learning techniques are required for the analysis of synoptic
(multi-band and multi-epoch) light curves in massive data of quasars, as
expected from the Vera C. Rubin Observatory Legacy Survey of Space and Time
(LSST). In this follow-up study, we introduced an upgraded version of a
conditional neural process (CNP) embedded in a multistep approach for analysis
of large data of quasars in the LSST Active Galactic Nuclei Scientific
Collaboration data challenge database. We present a case study of a stratified
set of the u-band light curves for 283 quasars with very low variability $\sim
0.03$. In this sample, CNP average mean square error is found to be $\sim 5\%
$($\sim 0.5$ mag). Interestingly, beside similar level of variability there are
indications that individual light curves show flare like features. According to
preliminary structure function analysis, these occurrences may be associated to
microlensing events with larger time scales $5-10$ years.
|
[
"astro-ph.IM",
"astro-ph.GA",
"astro-ph.HE"
] |
astro-ph.IM
|
astro-ph.GA
|
Instrumentation and Methods for Astrophysics;Astrophysics of Galaxies;High Energy Astrophysical Phenomena
| 3,696Instrumentation and Methods for Astrophysics;Astrophysics of Galaxies;High Energy Astrophysical Phenomena
|
2203.15411
|
In a heterogeneous medium, the wavefield can be decomposed as an infinite
series known as the Born expansion. Each term of the Born expansion corresponds
to a scattering order, it is thus theoretically possible to discriminate single
and multiple scattering field components. Experimentally, what is actually
measured is the total field in which all scattering orders interfere.
Conventional imaging methods usually rely on the assumption that the multiple
scattering contribution can be disregarded. In a back-scattering configuration,
this assumption is valid for small depths, and begins to fail for depths larger
than the scattering mean-free path $\ell_s$. It is therefore a key issue to
estimate the relative amount of single and multiple scattering in experimental
data. To this end, a single scattering estimator $\hat{\rho}$ computed from the
reflection matrix has been introduced in order to assess the weight of single
scattering in the backscattered wavefield. In this article, the meaning of this
estimator is investigated and a particular attention is given to recurrent
scattering. In a diffraction-limited experiment, a multiple scattering sequence
is said to be recurrent if the first and last scattering events occur in the
same resolution cell. Recurrent scattering is shown to be responsible for
correlations between single scattering and higher scattering orders of the Born
expansion, inducing a bias to the estimator $\hat{\rho}$ that should rather be
termed confocal scattering ratio. Interestingly, a more robust estimator is
built by projecting the reflection matrix in a focused basis. The argument is
sustained by numerical simulations as well as ultrasonic data obtained around
1.5~MHz in a model medium made of nylon rods immersed in water. From a more
general perspective, this work raises fundamental questions about the impact of
recurrent scattering on wave imaging.
|
[
"physics.app-ph",
"cond-mat.dis-nn"
] |
physics.app-ph
|
cond-mat.dis-nn
|
Applied Physics;Disordered Systems and Neural Networks
| 327Applied Physics;Disordered Systems and Neural Networks
|
2305.07690
|
We propose a tri-hypercharge (TH) embedding of the Standard Model (SM) in
which a separate gauged weak hypercharge is associated with each fermion
family. In this way, every quark and lepton multiplet carries unique gauge
quantum numbers under the extended gauge group, providing the starting point
for a theory of flavour. If the Higgs doublets only carry third family
hypercharge, then only third family renormalisable Yukawa couplings are
allowed. However, non-renormalisable Yukawa couplings may be induced by the
high scale Higgs fields (hyperons) which break the three hypercharges down to
the SM hypercharge, providing an explanation for fermion mass hierarchies and
the smallness of CKM quark mixing. Following a similar methodology, we study
the origin of neutrino masses and mixing in this model. Due to the TH gauge
symmetry, the implementation of a seesaw mechanism naturally leads to a low
scale seesaw, where the right-handed neutrinos in the model may be as light as
the TeV scale. We present simple examples of hyperon fields which can reproduce
all quark and lepton (including neutrino) masses and mixing. After a
preliminary phenomenological study, we conclude that one of the massive $Z'$
bosons can be as light as a few TeV, with implications for flavour-violating
observables, LHC physics and electroweak precision observables.
|
[
"hep-ph"
] |
hep-ph
|
High Energy Physics - Phenomenology
| 3,129High Energy Physics - Phenomenology
|
|
2212.06191
|
This study presents a vehicle-level distributed coordination strategy to
control a mixed traffic stream of connected automated vehicles (CAVs) and
connected human-driven vehicles (CHVs) through signalized intersections. We use
CAVs as mobile traffic controllers during a newly introduced white phase,
during which CAVs will negotiate the right-of-way to lead a group of CHVs while
CHVs must follow their immediate front vehicle. The white phase will not be
activated under low CAV penetration rates, where vehicles must wait for green
signals. We have formulated this problem as a distributed mixed-integer
non-linear program and developed a methodology to form an agreement among all
vehicles on their trajectories and signal timing parameters. The agreement on
trajectories is reached through an iterative process, where CAVs update their
trajectory based on shared trajectory of other vehicles to avoid collisions and
share their trajectory with other vehicles. Additionally, the agreement on
signal timing parameters is formed through a voting process where the most
voted feasible signal timing parameters are selected. The numerical experiments
indicate that the proposed methodology can efficiently control vehicle
movements at signalized intersections under various CAV market shares. The
introduced white phase reduces the total delay by 3.2% to 94.06% compared to
cooperative trajectory and signal optimization under different CAV market
shares in our tests. In addition, our numerical results show that the proposed
technique yields reductions in total delay, ranging from 40.2% - 98.9%,
compared to those of a fully-actuated signal control obtained from a
state-of-practice traffic signal optimization software.
|
[
"math.OC"
] |
math.OC
|
Optimization and Control
| 5,234Optimization and Control
|
|
2104.03358
|
Let $f$ be a positive multiplicative function and let $k\geq 2$ be an
integer. We prove that if the prime values $f(p)$ converge to $1$ sufficiently
slowly as $p\rightarrow +\infty$, in the sense that $\sum_{p}|f(p)-1|=\infty$,
there exists a real number $c>0$ such that the $k$-tuples
$(f(p+1),\ldots,f(p+k))$ are dense in the hypercube $[0,c]^k$ or in
$[c,+\infty)^k$. In particular, the values $f(p+1),\ldots,f(p+k)$ can be put in
any increasing order infinitely often. Our work generalises previous results of
De Koninck and Luca.
|
[
"math.NT"
] |
math.NT
|
Number Theory
| 4,945Number Theory
|
|
2209.06286
|
This paper defines geometric criteria which are then used to establish
sufficient conditions for persistency of excitation with vector functions
constructed from single hidden-layer neural networks with step or ReLU
activation functions. We show that these conditions hold when employing
reference system tracking, as is commonly done in adaptive control. We
demonstrate the results numerically on a system with linearly parameterized
activations of this type and show that the parameter estimates converge to the
true values with the sufficient conditions met.
|
[
"math.OC"
] |
math.OC
|
Optimization and Control
| 5,234Optimization and Control
|
|
1005.2550
|
There has been tremendous experimental progress in the last decade in
identifying the structure and function of biological pores (ion channels) and
fabricating synthetic pores. Despite this progress, many questions still remain
about the mechanisms and universal features of ionic transport in these
systems. In this paper, we examine the use of nanopores to probe ion transport
and to construct functional nanoscale devices. Specifically, we focus on the
newly predicted phenomenon of quantized ionic conductance in nanopores as a
function of the effective pore radius - a prediction that yields a particularly
transparent way to probe the contribution of dehydration to ionic transport. We
study the role of ionic species in the formation of hydration layers inside and
outside of pores. We find that the ion type plays only a minor role in the
radial positions of the predicted steps in the ion conductance. However, ions
with higher valency form stronger hydration shells, and thus, provide even more
pronounced, and therefore, more easily detected, drops in the ionic current.
Measuring this phenomenon directly, or from the resulting noise, with synthetic
nanopores would provide evidence of the deviation from macroscopic (continuum)
dielectric behavior due to microscopic features at the nanoscale and may shed
light on the behavior of ions in more complex biological channels.
|
[
"cond-mat.soft",
"physics.bio-ph"
] |
cond-mat.soft
|
physics.bio-ph
|
Soft Condensed Matter;Biological Physics
| 6,543Soft Condensed Matter;Biological Physics
|
math/0601220
|
This paper reviews results about free convection near a vertical flat plate
embedded in some saturated porous medium. We focus on a third order autonomous
differential equation that gives a special class of solutions called similarity
solutions. Two cases are under consideration: in the first one we prescribe the
temperature on the plate and in the second one we prescribe the heat flux on
it. We will also see that the same equation appears in other industrial
processes.
|
[
"math.CA"
] |
math.CA
|
Classical Analysis and ODEs
| 934Classical Analysis and ODEs
|
|
1004.3574
|
In general relativity coupled to Maxwell's electromagnetism and charged
matter, when the gravitational potential $W^2$ and the electric potential field
$\phi$ obey a relation of the form $W^{2}= a\left(-\epsilon\, \phi+ b\right)^2
+c$, where $a$, $b$ and $c$ are arbitrary constants, and $\epsilon=\pm1$ (the
speed of light $c$ and Newton's constant $G$ are put to one), a class of very
interesting electrically charged systems with pressure arises. We call the
relation above between $W$ and $\phi$, the Weyl-Guilfoyle relation, and it
generalizes the usual Weyl relation, for which $a=1$. For both, Weyl and
Weyl-Guilfoyle relations, the electrically charged fluid, if present, may have
nonzero pressure. Fluids obeying the Weyl-Guilfoyle relation are called
Weyl-Guilfoyle fluids. These fluids, under the assumption of spherical
symmetry, exhibit solutions which can be matched to the electrovacuum
Reissner-Nordstr\"om spacetime to yield global asymptotically flat cold charged
stars. We show that a particular spherically symmetric class of stars found by
Guilfoyle has a well-behaved limit which corresponds to an extremal
Reissner-Nordstr\"om quasiblack hole with pressure, i.e., in which the fluid
inside the quasihorizon has electric charge and pressure, and the geometry
outside the quasihorizon is given by the extremal Reissner-Nordstr\"om metric.
The main physical properties of such charged stars and quasiblack holes with
pressure are analyzed. An important development provided by these stars and
quasiblack holes is that without pressure the solutions, Majumdar-Papapetrou
solutions, are unstable to kinetic perturbations. Solutions with pressure may
avoid this instability. If stable, these cold quasiblack holes with pressure,
i.e., these compact relativistic charged spheres, are really frozen stars.
|
[
"gr-qc",
"astro-ph.SR",
"hep-th"
] |
gr-qc
|
astro-ph.SR
|
General Relativity and Quantum Cosmology;Solar and Stellar Astrophysics;High Energy Physics - Theory
| 2,776General Relativity and Quantum Cosmology;Solar and Stellar Astrophysics;High Energy Physics - Theory
|
1009.1634
|
Hyperaccreting disks around neutron stars or magnetars cooled via neutrino
emission can be the potential central engine of GRBs. The neutron-star disk can
cool more efficiently, produce much higher neutrino luminosity and neutrino
annihilation luminosity than its black hole counterpart with the same accretion
rate. The neutron star surface boundary layer could increase the annihilation
luminosity as well. An ultra relativistic jet via neutrino annihilation can be
produced along the stellar poles. Moreover, we investigate the effects of
strong fields on the disks around magnetars. In general, stronger fields give
higher disk densities, pressures, temperatures and neutrino luminosity; the
neutrino annihilation mechanism and the magnetically-driven pulsar wind which
extracts the stellar rotational energy can work together to generate and feed
an even stronger ultra-relativistic jet along the stellar magnetic poles.
|
[
"astro-ph.HE"
] |
astro-ph.HE
|
High Energy Astrophysical Phenomena
| 2,990High Energy Astrophysical Phenomena
|
|
2005.14004
|
NGC 4151 is among the most well-studied Seyfert galaxies that does not suffer
from strong obscuration along the observer's line-of-sight. This allows to
probe the central active galactic nucleus (AGN) engine with photometry,
spectroscopy, reverberation mapping or interferometry. Yet, the broadband
polarization from NGC 4151 has been poorly examined in the past despite the
fact that polarimetry gives us a much cleaner view of the AGN physics than
photometry or spectroscopy alone. In this paper, we compile the 0.15 -- 89.0
$\mu$m total and polarized fluxes of NGC 4151 from archival and new data in
order to examine the physical processes at work in the heart of this AGN. We
demonstrate that, from the optical to the near-infrared (IR) band, the
polarized spectrum of NGC 4151 shows a much bluer power-law spectral index than
that of the total flux, corroborating the presence of an optically thick,
locally heated accretion flow, at least in its near-IR emitting radii. Specific
signatures from the atmosphere of the accretion structure are tentatively found
at the shortest ultraviolet (UV) wavelengths, before the onset of absorption
opacity. Otherwise, dust scattering appears to be the dominant contributor from
the near-UV to near-IR polarized spectrum, superimposed onto a weaker electron
component. We also identify a change in the polarization processes from the
near-IR to the mid-IR, most likely associated with the transition from Mie
scattering to dichroic absorption from aligned dust grains in the dusty torus
or narrow-line region. Finally, we present and dicuss the very first
far-infrared polarization measurement of NGC 4151 at 89 $\mu$m.
|
[
"astro-ph.GA"
] |
astro-ph.GA
|
Astrophysics of Galaxies
| 464Astrophysics of Galaxies
|
|
1106.2389
|
We investigate the renormalization group(RG) evolution for the neutral scalar
field theory in the broken symmetry phase. By using the minimum condition of
the vacuum expectation value(VEV), we show that the RG evlution of the
effective potential in the broken symmetry phase is governed by the same RG
functions in case of the symmetric phase.
|
[
"hep-th"
] |
hep-th
|
High Energy Physics - Theory
| 3,266High Energy Physics - Theory
|
|
1506.05886
|
In data fusion analysts seek to combine information from two databases
comprised of disjoint sets of individuals, in which some variables appear in
both databases and other variables appear in only one database. Most data
fusion techniques rely on variants of conditional independence assumptions.
When inappropriate, these assumptions can result in unreliable inferences. We
propose a data fusion technique that allows analysts to easily incorporate
auxiliary information on the dependence structure of variables not observed
jointly; we refer to this auxiliary information as glue. With this technique,
we fuse two marketing surveys from the book publisher HarperCollins using glue
from the online, rapid-response polling company CivicScience. The fused data
enable estimation of associations between people's preferences for authors and
for learning about new books. The analysis also serves as a case study on the
potential for using online surveys to aid data fusion.
|
[
"stat.ME"
] |
stat.ME
|
Methodology
| 4,557Methodology
|
|
2103.13540
|
As more exoplanets are being discovered around ultracool dwarfs,
understanding their magnetic activity -- and the implications for habitability
-- is of prime importance. To find stellar flares and photometric signatures
related to starspots, continuous monitoring is necessary, which can be achieved
with spaceborn observatories like the Transiting Exoplanet Survey Satellite
(TESS). We present an analysis of TRAPPIST-1 like ultracool dwarfs with TESS
full-frame image photometry from the first two years of the primary mission. A
volume-limited sample up to 50 pc is constructed consisting of 339 stars closer
than 0.5 mag to TRAPPIST-1 on the Gaia colour-magnitude diagram. The 30-min
cadence TESS light curves of 248 stars were analysed, searching for flares and
rotational modulation caused by starspots. The composite flare frequency
distribution of the 94 identified flares shows a power law index similar to
TRAPPIST-1, and contains flares up to $E_\mathrm{TESS} = 3 \times 10^{33}$ erg.
Rotational periods shorter than 5 days were determined for 42 stars, sampling
the regime of fast rotators. The ages of 88 stars from the sample were
estimated using kinematic information. A weak correlation between rotational
period and age is observed, which is consistent with magnetic braking.
|
[
"astro-ph.SR"
] |
astro-ph.SR
|
Solar and Stellar Astrophysics
| 6,668Solar and Stellar Astrophysics
|
|
1006.2057
|
The economic crisis in Argentina around year 2002 provides a unique
opportunity for Econophysics studies. The available data on individual income
are analyzed to show that they correspond to non stationary states. However,
the rather restricted size of the data survey imposes difficulties that must be
overcome through a careful analysis, for a reliable use. A new method of data
treatment is presented that could be helpful in theoretical studies.
|
[
"q-fin.GN",
"physics.data-an",
"q-fin.ST"
] |
q-fin.GN
|
physics.data-an
|
General Finance;Data Analysis, Statistics and Probability;Statistical Finance
| 7,267longtail
|
1902.05386
|
License plate recognition is the key component to many automatic traffic
control systems. It enables the automatic identification of vehicles in many
applications. Such systems must be able to identify vehicles from images taken
in various conditions including low light, rain, snow, etc. In order to reduce
the complexity and cost of the hardware required for such devices, the
algorithm should be as efficient as possible. This paper proposes a license
plate recognition system which uses a new approach based on compressive sensing
techniques for dimensionality reduction and feature extraction. Dimensionality
reduction will enable precise classification with less training data while
demanding less computational power. Based on the extracted features, character
recognition and classification is done by a Support Vector Machine classifier.
|
[
"cs.CV",
"cs.MM",
"eess.SP"
] |
cs.CV
|
cs.MM
|
Computer Vision and Pattern Recognition;Multimedia;Signal Processing
| 7,267longtail
|
hep-th/0608159
|
We provide a method for obtaining simple models of supersymmetry breaking,
with all small mass scales generated dynamically, and illustrate it with
explicit examples. We start from models of perturbative supersymmetry breaking,
such as O'Raifeartaigh and Fayet models, that would respect an $R$ symmetry if
their small input parameters transformed as the superpotential does. By
coupling the system to a pure supersymmetric Yang-Mills theory (or a more
general supersymmetric gauge theory with dynamically small vacuum expectation
values), these parameters are replaced by powers of its dynamical scale in a
way that is naturally enforced by the symmetry. We show that supersymmetry
breaking in these models may be straightforwardly mediated to the
supersymmetric Standard Model, obtain complete models of direct gauge
mediation, and comment on related model building strategies that arise in this
simple framework.
|
[
"hep-th",
"hep-ph"
] |
hep-th
|
hep-ph
|
High Energy Physics - Theory;High Energy Physics - Phenomenology
| 3,348High Energy Physics - Theory;High Energy Physics - Phenomenology
|
2310.04213
|
Training Neural Networks able to capture the topology changes of the power
grid is one of the significant challenges towards the adoption of machine
learning techniques for N-k security computations and a wide range of other
operations that involve grid reconfiguration. As the number of N-k scenarios
increases exponentially with increasing system size this renders such problems
extremely time-consuming to solve with traditional solvers. In this paper, we
combine Physics-Informed Neural Networks with both a Guided-Dropout (GD) Neural
Network (which associates dedicated neurons with specific line
connections/disconnections) and an edge-varrying Graph Neural Neural Network
(GNN) architecture to learn the setpoints for a grid that considers all
probable single-line reconfigurations (all critical N-1 scenarios) and
subsequently apply the trained models to N-k scenarios.We demonstrate how
incorporating the underlying physical equations for the network equations
within the training procedure of the GD and the GNN architectures, performs
with N-1, N-2, and N-3 case studies. Using the AC Power Flow as a guiding
application, we test our methods on the 14-bus, 30-bus, 57-bus, and 118-bus
systems. We find that these topology-aware NNs not only achieve the task of
contingency screening with satisfactory accuracy but do this at up to 1000
times faster than the Newton Raphson power flow solver. Moreover, our results
provide a comparison of the GD and GNN models in terms of accuracy and
computational speed and provide recommendations on their adoption for
contingency analysis of power systems.
|
[
"eess.SY",
"cs.SY"
] |
eess.SY
|
cs.SY
|
Systems and Control;Systems and Control
| 7,220Systems and Control;Systems and Control
|
q-alg/9606016
|
We present a ``reasonable'' statement about Lie algebras that is equivalent
to the Four Color Theorem. The notions appearing in the statement also appear
in the theory of finite-type invariants of knots (Vassiliev invariants) and
3-manifolds.
|
[
"q-alg",
"math.QA"
] |
q-alg
|
math.QA
|
Quantum Algebra;Quantum Algebra
| 5,909Quantum Algebra;Quantum Algebra
|
2206.06845
|
We examine how disordering joint position influences the linear elastic
behavior of lattice materials via numerical simulations in two-dimensional beam
networks. Three distinct initial crystalline geometries are selected as
representative of mechanically isotropic materials low connectivity,
mechanically isotropic materials with high connectivity, and mechanically
anisotropic materials with intermediate connectivity. Introducing disorder
generates spatial fluctuations in the elasticity tensor at the local (joint)
scale. Proper coarse-graining reveals a well-defined continuum-level scale
elasticity tensor. Increasing disorder aids in making initially anisotropic
materials more isotropic. The disorder impact on the material stiffness depends
on the lattice connectivity: Increasing the disorder softens lattices with high
connectivity and stiffens those with low connectivity, without modifying the
scaling between elastic modulus and density (linear scaling for high
connectivity and cubic scaling for low connectivity). Introducing disorder in
lattices with intermediate fixed connectivity reveals both scaling: the linear
scaling occurs for low density, the cubic one at high density, and the
crossover density increases with disorder. Contrary to classical formulations,
this work demonstrates that connectivity is not the sole parameter governing
elastic modulus scaling. It offers a promising route to access novel mechanical
properties in lattice materials via disordering the architectures.
|
[
"cond-mat.soft",
"cond-mat.mtrl-sci"
] |
cond-mat.soft
|
cond-mat.mtrl-sci
|
Soft Condensed Matter;Materials Science
| 6,577Soft Condensed Matter;Materials Science
|
hep-ph/9701402
|
We summarize the activity of the Very Large Hadron Collider Physics and
Detector subgroup during Snowmass 96.
|
[
"hep-ph"
] |
hep-ph
|
High Energy Physics - Phenomenology
| 3,129High Energy Physics - Phenomenology
|
|
2202.12467
|
This article extends Scholze's six functor formalism for diamonds to a very
general class of stacky morphisms between v-stacks, using $\infty$-categorical
techniques developed by Liu-Zheng.
|
[
"math.AG",
"math.NT"
] |
math.AG
|
math.NT
|
Algebraic Geometry;Number Theory
| 137Algebraic Geometry;Number Theory
|
0908.3627
|
We present the complete differential decay rates for the process B_s -> J/psi
K^+ K^- including S-wave and P-wave angular momentum states for the K^+ K^-
meson pair. We examine the effect of an S-wave component on the determination
of the CP violating phase 2beta_s. Data from the B-factories indicate that an
S-wave component of about 10% may be expected in the phi(1020) resonance
region. We find that if this contribution is ignored in the analysis it could
cause a bias in the measured value of 2beta_s towards zero of the order of 10%.
When including the K^+K^- S-wave component we observe an increase in the
statistical error on 2beta_s by less than 15%. We also point out the
possibility of measuring the sign of cos2beta_s by using the interference
between the K^+K^- S-wave and P-wave amplitudes to resolve the strong phase
ambiguity. We conclude that the S-wave component can be properly taken into
account in the analysis.
|
[
"hep-ph"
] |
hep-ph
|
High Energy Physics - Phenomenology
| 3,129High Energy Physics - Phenomenology
|
|
gr-qc/0501026
|
An origin and necessity of so called conformal (or,Penrose-Chernikov-Tagirov)
coupling of scalar field to the metric of n-dimensional Riemannian space-time
is discussed in brief. The corresponding general-relativistic field equation
implies a one-particle (quantum mechanical) Schrodinger Hamiltonian which
depends on the space-time dimensionality n, contrary to the Hamiltonian
constructed by quantization of geodesic motion, which is the same for any value
of n. In general, the Hamiltonians can coincide only for n = 4, the
dimensionality of the ordinarily observed Universe. In view of the fundamental
role of a scalar field in various cosmological models, this fact may be of
interest for models of brane worlds where n > 4 .
|
[
"gr-qc",
"hep-th"
] |
gr-qc
|
hep-th
|
General Relativity and Quantum Cosmology;High Energy Physics - Theory
| 2,746General Relativity and Quantum Cosmology;High Energy Physics - Theory
|
2006.10546
|
In the setting of quaternionic Heisenberg group $\mathscr H^{n-1}$, we
characterize the boundedness and compactness of commutator $[b,\mathcal C]$ for
the Cauchy--Szeg\"o operator $\mathcal C$ on the weighted Morrey space
$L_w^{p,\,\kappa}(\mathscr H^{n-1})$ with $p\in(1, \infty)$, $\kappa\in(0, 1)$
and $w\in A_p(\mathscr H^{n-1}).$ More precisely, we prove that $[b,\mathcal
C]$ is bounded on $L_w^{p,\,\kappa}(\mathscr H^{n-1})$ if and only if $b\in
{\rm BMO}(\mathscr H^{n-1})$. And $[b,\mathcal C]$ is compact on
$L_w^{p,\,\kappa}(\mathscr H^{n-1})$ if and only if $b\in {\rm VMO}(\mathscr
H^{n-1})$.
|
[
"math.CV"
] |
math.CV
|
Complex Variables
| 1,135Complex Variables
|
|
1305.5178
|
Understanding the formation of the first stars is one of the frontier topics
in modern astrophysics and cosmology. Their emergence signaled the end of the
cosmic dark ages, a few hundred million years after the Big Bang, leading to a
fundamental transformation of the early Universe through the production of
ionizing photons and the initial enrichment with heavy chemical elements. We
here review the state of our knowledge, separating the well understood elements
of our emerging picture from those where more work is required. Primordial star
formation is unique in that its initial conditions can be directly inferred
from the Lambda Cold Dark Matter (LCDM) model of cosmological structure
formation. Combined with gas cooling that is mediated via molecular hydrogen,
one can robustly identify the regions of primordial star formation, the
so-called minihalos, having total masses of ~10^6 M_sun and collapsing at
redshifts z~20-30. Within this framework, a number of studies have defined a
preliminary standard model, with the main result that the first stars were
predominantly massive. This model has recently been modified to include a
ubiquitous mode of fragmentation in the protostellar disks, such that the
typical outcome of primordial star formation may be the formation of a binary
or small multiple stellar system. We will also discuss extensions to this
standard picture due to the presence of dynamically significant magnetic
fields, of heating from self-annihalating WIMP dark matter, or cosmic rays. We
conclude by discussing possible strategies to empirically test our theoretical
models.
|
[
"astro-ph.CO"
] |
astro-ph.CO
|
Cosmology and Nongalactic Astrophysics
| 1,725Cosmology and Nongalactic Astrophysics
|
|
1203.2286
|
The renormalization group framework can be applied to Quantum Field Theory on
curved space-time, but there is no proof whether the beta-function of the
gravitational coupling indeed goes to zero in the far infrared or not. In a
recent paper we have shown that the amount of dark matter inside spiral
galaxies may be negligible if a small running of the General Relativity
coupling G is present. Here we extend the proposed model to elliptical galaxies
and present a detailed analysis on the modeling of NGC 4494 (an ordinary
elliptical) and NGC 4374 (a giant elliptical). In order to compare our results
to a well known alternative model to the standard dark matter picture, we also
evaluate NGC 4374 with MOND. In this galaxy MOND leads to a significative
discrepancy with the observed velocity dispersion curve and has a significative
tendency towards tangential anisotropy. On the other hand, the approach based
on the renormalization group and general relativity (RGGR) could be applied
with good results to these elliptical galaxies and is compatible with lower
mass-to-light ratios (of about the Kroupa IMF type).
|
[
"astro-ph.CO",
"gr-qc"
] |
astro-ph.CO
|
gr-qc
|
Cosmology and Nongalactic Astrophysics;General Relativity and Quantum Cosmology
| 1,745Cosmology and Nongalactic Astrophysics;General Relativity and Quantum Cosmology
|
1605.07976
|
Let $X$ be an infinite compact metric space and let $h$ be a minimal
homeomorphism of $X$. We prove that the radius of comparison of the
transformation group C*-algebra of $h$ is at most $1$ plus $36$ times the mean
dimension of $h$.
|
[
"math.OA",
"math.DS"
] |
math.OA
|
math.DS
|
Operator Algebras;Dynamical Systems
| 5,118Operator Algebras;Dynamical Systems
|
2110.01387
|
Perovskite photovoltaics (PV) have achieved rapid development in the past
decade in terms of power conversion efficiency of small-area lab-scale devices;
however, successful commercialization still requires further development of
low-cost, scalable, and high-throughput manufacturing techniques. One of the
critical challenges of developing a new fabrication technique is the
high-dimensional parameter space for optimization, but machine learning (ML)
can readily be used to accelerate perovskite PV scaling. Herein, we present an
ML-guided framework of sequential learning for manufacturing process
optimization. We apply our methodology to the Rapid Spray Plasma Processing
(RSPP) technique for perovskite thin films in ambient conditions. With a
limited experimental budget of screening 100 process conditions, we
demonstrated an efficiency improvement to 18.5% as the best-in-our-lab device
fabricated by RSPP, and we also experimentally found 10 unique process
conditions to produce the top-performing devices of more than 17% efficiency,
which is 5 times higher rate of success than the control experiments with
pseudo-random Latin hypercube sampling. Our model is enabled by three
innovations: (a) flexible knowledge transfer between experimental processes by
incorporating data from prior experimental data as a probabilistic constraint;
(b) incorporation of both subjective human observations and ML insights when
selecting next experiments; (c) adaptive strategy of locating the region of
interest using Bayesian optimization first, and then conducting local
exploration for high-efficiency devices. Furthermore, in virtual benchmarking,
our framework achieves faster improvements with limited experimental budgets
than traditional design-of-experiments methods (e.g., one-variable-at-a-time
sampling).
|
[
"cs.LG",
"physics.app-ph"
] |
cs.LG
|
physics.app-ph
|
Machine Learning;Applied Physics
| 3,891Machine Learning;Applied Physics
|
1905.04024
|
Comprehending the dynamical behaviour of quantum systems driven by
time-varying Hamiltonians is particularly difficult. Systems with as little as
two energy levels are not yet fully understood as the usual methods including
diagonalisation of the Hamiltonian do not work in this setting. In fact, since
the inception of Magnus' expansion in 1954, no fundamentally novel mathematical
approach capable of solving the quantum equations of motion with a time-varying
Hamiltonian has been devised. We report here of an entirely different
non-perturbative approach, termed path-sum, which is always guaranteed to
converge, yields the exact analytical solution in a finite number of steps for
finite systems and is invariant under scale transformations of the quantum
state space. Path-sum can be combined with any state-space reduction technique
and can exactly reconstruct the dynamics of a many-body quantum system from the
separate, isolated, evolutions of any chosen collection of its sub-systems. As
examples of application, we solve analytically for the dynamics of all
two-level systems as well as of a many-body Hamiltonian with a particular
emphasis on NMR (Nuclear Magnetic Resonance) applications: Bloch-Siegert
effect, coherent destruction of tunneling and $N$-spin systems involving the
dipolar Hamiltonian and spin diffusion.
|
[
"quant-ph",
"cond-mat.mes-hall",
"physics.chem-ph"
] |
quant-ph
|
cond-mat.mes-hall
|
Quantum Physics;Mesoscale and Nanoscale Physics;Chemical Physics
| 6,120Quantum Physics;Mesoscale and Nanoscale Physics;Chemical Physics
|
2105.01353
|
As an effective technique to achieve the implementation of deep neural
networks in edge devices, model quantization has been successfully applied in
many practical applications. No matter the methods of quantization aware
training (QAT) or post-training quantization (PTQ), they all depend on the
target bit-widths. When the precision of quantization is adjusted, it is
necessary to fine-tune the quantized model or minimize the quantization noise,
which brings inconvenience in practical applications. In this work, we propose
a method to train a model for all quantization that supports diverse bit-widths
(e.g., form 8-bit to 1-bit) to satisfy the online quantization bit-width
adjustment. It is hot-swappable that can provide specific quantization
strategies for different candidates through multiscale quantization. We use
wavelet decomposition and reconstruction to increase the diversity of weights,
thus significantly improving the performance of each quantization candidate,
especially at ultra-low bit-widths (e.g., 3-bit, 2-bit, and 1-bit).
Experimental results on ImageNet and COCO show that our method can achieve
accuracy comparable performance to dedicated models trained at the same
precision.
|
[
"cs.CV"
] |
cs.CV
|
Computer Vision and Pattern Recognition
| 1,498Computer Vision and Pattern Recognition
|
|
physics/0505053
|
In order to understand the physics phenomea on the fundamental aspects, the
software simulations are a good exercise to succed in this way. Some work of
heat transport and molecular physics laboratory are studied in a comparative
mode experiments and software applications. The main ojbects structure ans some
program interfaces are presented.
|
[
"physics.ed-ph",
"physics.pop-ph"
] |
physics.ed-ph
|
physics.pop-ph
|
Physics Education;Popular Physics
| 5,460Physics Education;Popular Physics
|
0805.4214
|
Aims: morpholgies, number and energy distributions of Cosmological Shock
Waves from a set of ENZO cosmological simulations are produced, along with a
study of the connection with Cosmic Rays processes in different environments.
Method: we perform cosmological simulations with the public release of the PPM
code ENZO, adopt a simple and physically motivated numerical setup to follow
the evolution of cosmic structures at the resolution of 125kpc per cell, and
characterise shocks with a new post processing scheme. Results: we estimate the
efficency of the acceleration of Cosmic Ray particles and present the first
comparison of our results with existing limits from observations of galaxy
clusters.
|
[
"astro-ph"
] |
astro-ph
|
Astrophysics
| 463Astrophysics
|
|
1201.4802
|
Extreme value statistics, or extreme statistics for short, refers to the
statistics that characterizes rare events of either unusually high or low
intensity: climate disasters like floods following extremely intense rains are
among the principal examples. Extreme statistics is also found in fluctuations
of global magnitudes in systems in thermal equilibrium, as well as in systems
far from equilibrium. A remarkable example in this last class is fluctuations
of injected power in confined turbulence. Here we report results in a confined
von K\'arm\'an swirling flow, produced by two counter-rotating stirrers, in
which quantities derived from the same global magnitude ---the rotation rate of
the stirrers--- can display both, extreme and Gaussian statistics. On the one
hand, we find that underlying the extreme statistics displayed by the global
shear of the flow, there is a nearly Gaussian process resembling a white noise,
corresponding to the action of the normal stresses exerted by the turbulent
flow, integrated on the flow-driving surfaces of the stirrers. On the other
hand, the magnitude displaying Gaussian statistics is the global rotation rate
of the fluid, which happens to be a realization of a 1D diffusion where the
variance of the angular increments $\theta(t+\Delta t) - \theta(t)$ scales as
$\Delta t^{\nu}$, while the power spectral density of the rotation rate follows
a $1/f^{\alpha}$ scaling law. These scaling exponents are found to be $\alpha
\approx 0.37$ and $\nu \approx 1.36$, which implies that this process can be
described as a 1D superdiffusion.
|
[
"physics.flu-dyn",
"physics.data-an"
] |
physics.flu-dyn
|
physics.data-an
|
Fluid Dynamics;Data Analysis, Statistics and Probability
| 2,473Fluid Dynamics;Data Analysis, Statistics and Probability
|
2107.11667
|
In this paper, we study feedback dynamical systems with memoryless
controllers under imperfect information. We develop an algorithm that searches
for "adversarial scenarios", which can be thought of as the strategy for the
adversary representing the noise and disturbances, that lead to safety
violations. The main challenge is to analyze the closed-loop system's
vulnerabilities with a potentially complex or even unknown controller in the
loop. As opposed to commonly adopted approaches that treat the system under
test as a black-box, we propose a synthesis-guided approach, which leverages
the knowledge of a plant model at hand. This hence leads to a way to deal with
gray-box systems (i.e., with known plant and unknown controller). Our approach
reveals the role of the imperfect information in the violation. Examples show
that our approach can find non-trivial scenarios that are difficult to expose
by random simulations. This approach is further extended to incorporate model
mismatch and to falsify vision-in-the-loop systems against finite-time
reach-avoid specifications.
|
[
"eess.SY",
"cs.SY"
] |
eess.SY
|
cs.SY
|
Systems and Control;Systems and Control
| 7,220Systems and Control;Systems and Control
|
2006.03269
|
Recent efforts for finding novel computing paradigms that meet today's design
requirements have given rise to a new trend of processing-in-memory relying on
non-volatile memories. In this paper, we present HIPE-MAGIC, a technology-aware
synthesis and mapping flow for highly parallel execution of the memristor-based
logic. Our framework is built upon two fundamental contributions: balancing
techniques during the logic synthesis, mainly targeting benefits of the
parallelism offered by memristive crossbar arrays (MCAs), and an efficient
technology mapping framework to maximize the performance and area-efficiency of
the memristor-based logic. Our experimental evaluations across several
benchmark suites demonstrate the superior performance of HIPE-MAGIC in terms of
throughput and energy efficiency compared to recently developed synthesis and
mapping flows targeting MCAs, as well as the conventional CPU computing.
|
[
"cs.ET"
] |
cs.ET
|
Emerging Technologies
| 2,414Emerging Technologies
|
|
astro-ph/0508137
|
We present a study of the in-flight performance of the XMM-Newton EPIC MOS
and pn detectors, with focus on the influence of proton flares and vignetting
on the data. The very wide range in the conditions of our sample of
observations, in terms of exposure length and background intensities, allows
the detection of a wide range in the spectra of the proton flares, in contrast
to the hard-spectrum flares proposed by Lumb et al.(2002) or Read et al.(2003)
We also find an up to now unreported contamination in the low energy regime
(E<0.5 keV) of the MOS1 observations, consisting of a significant increase in
the measured intensities in two CCDs at the edges of the detector. This
contamination yields in "bright CCDs" in the observations. Its effect must be
taken into account for the study of sources detected in the affected CCDs. With
respect to vignetting, we present in-flight exposure maps and we propose a
method to repeat this calculation for user-definable energy bands. All the
results presented here, have the goal to enable the study of very faint
extended sources with XMM-Newton, like nearby galactic X-ray halos or the soft
X-ray background.
|
[
"astro-ph"
] |
astro-ph
|
Astrophysics
| 463Astrophysics
|
|
hep-ex/0304040
|
The status of our investigation of low-energy $K^+$Xe collisions in the Xenon
bubble chamber DIANA is reported. In the charge-exchange reaction $K^+Xe \to
K^0 p Xe'$ the spectrum of $K^0 p$ effective mass shows a resonant enhancement
with $M = 1539 \pm 2$ MeV/c$^2$ and $\Gamma \le 9 MeV/c$^2$. The statistical
significance of the enhancement is near $4.4\sigma$. The mass and width of the
observed resonance are consistent with expectations for the lightest member of
the anti-decuplet of exotic pentaquark baryons, as predicted in the framework
of the chiral soliton model.
|
[
"hep-ex"
] |
hep-ex
|
High Energy Physics - Experiment
| 3,059High Energy Physics - Experiment
|
|
1909.03750
|
Neural Machine Translation (NMT) models achieve their best performance when
large sets of parallel data are used for training. Consequently, techniques for
augmenting the training set have become popular recently. One of these methods
is back-translation (Sennrich et al., 2016), which consists on generating
synthetic sentences by translating a set of monolingual, target-language
sentences using a Machine Translation (MT) model.
Generally, NMT models are used for back-translation. In this work, we analyze
the performance of models when the training data is extended with synthetic
data using different MT approaches. In particular we investigate
back-translated data generated not only by NMT but also by Statistical Machine
Translation (SMT) models and combinations of both. The results reveal that the
models achieve the best performances when the training set is augmented with
back-translated data created by merging different MT approaches.
|
[
"cs.CL"
] |
cs.CL
|
Computation and Language
| 1,168Computation and Language
|
|
2307.14597
|
We consider coupled fast-slow stochastic processes, where the averaged slow
motion is given by a two-dimensional Hamiltonian system with multiple critical
points. On a proper time scale, the evolution of the first integral converges
to a diffusion process on the corresponding Reeb graph, with certain gluing
conditions specified at the interior vertices. This limiting process is similar
to that in the case of additive white noise perturbations of Hamiltonian
systems considered by M. Freidlin and A. Wentzell, but now the analysis of the
behavior near the critical points requires new interesting techniques.
|
[
"math.PR"
] |
math.PR
|
Probability
| 5,709Probability
|
|
1201.0482
|
We investigate the magnetization dynamics in circular Permalloy dots with
spatially separated magnetic vortices interconnected by domain walls (double
vortex state). We identify a novel type of quasi one-dimensional (1D) localised
spin wave modes confined along domain walls, connecting each of two vortex
cores with two edge half-antivortices. Variation of the mode eigenfrequencies
with the dot size is in quantitative agreement with the developed model, which
considers a dipolar origin of the localized 1D spin waves or so-called
Winter\'s magnons [J.M. Winter, Phys.Rev. 124, 452 (1961)]. These spin waves
are analogous to the displacement waves of strings, and could be excited in a
wide class of patterned magnetic nanostructures possessing domain walls, namely
in triangular, square, circular or elliptic magnetic dots.
|
[
"cond-mat.mes-hall",
"cond-mat.mtrl-sci"
] |
cond-mat.mes-hall
|
cond-mat.mtrl-sci
|
Mesoscale and Nanoscale Physics;Materials Science
| 4,493Mesoscale and Nanoscale Physics;Materials Science
|
2001.03596
|
An important step for photonic quantum technologies is the demonstration of a
quantum advantage through boson sampling. In order to prevent classical
simulability of boson sampling, the photons need to be almost perfectly
identical and almost without losses. These two requirements are connected
through spectral filtering, improving one leads to a decrease of the other. A
proven method of generating single photons is spontaneous parametric
downconversion (SPDC). We show that an optimal trade-off between
indistinguishability and losses can always be found for SPDC. We conclude that
a 50-photon scattershot boson-sampling experiment using SPDC sources is
possible from a computational complexity point of view. To this end, we
numerically optimize SPDC sources under the regime of weak pumping and with a
single spatial mode.
|
[
"quant-ph"
] |
quant-ph
|
Quantum Physics
| 5,985Quantum Physics
|
|
1404.1631
|
We consider hyperbolicity preserving operators with respect to a new linear
operator representation on $\mathbb{R}[x]$. In essence, we demonstrate that
every Hermite and Laguerre multiplier sequence can be diagonalized into a sum
of hyperbolicity preserving operators, where each of the summands forms a
classical multiplier sequence. Interestingly, this does not work for other
orthogonal bases; for example, this property fails for the Legendre basis. We
establish many new formulas concerning the $Q_k$'s of Peetre's 1959
differential representation for linear operators in the specific case of
Hermite and Laguerre diagonal differential operators. Additionally, we provide
a new algebraic characterization of the Hermite multiplier sequences and also
extend a recent result of T. Forg\'acs and A. Piotrowski on hyperbolicity
properties of the polynomial coefficients in hyperbolicity preserving Hermite
diagonal differential operators.
|
[
"math.CV"
] |
math.CV
|
Complex Variables
| 1,135Complex Variables
|
|
1904.03745
|
We find new characterizations for the points in the \textit{symmetrized
polydisc} $\mathbb G_n$, a family of domains associated with the spectral
interpolation, defined by \[ \mathbb G_n :=\left\{ \left(\sum_{1\leq i\leq n}
z_i,\sum_{1\leq i<j\leq n}z_iz_j \dots, \prod_{i=1}^n z_i \right): \,|z_i|<1,
i=1,\dots,n \right \}. \] We introduce a new family of domains which we call
\textit{the extended symmetrized polydisc} $\widetilde{\mathbb G}_n$, and
define in the following way: \begin{align*} \widetilde{\mathbb G}_n := \Bigg\{
(y_1,\dots,y_{n-1}, q)\in \mathbb C^n :\; q \in \mathbb D, \; y_j = \beta_j +
\bar{\beta}_{n-j} q, \; \beta_j \in \mathbb C &\text{ and }\\ |\beta_j|+
|\beta_{n-j}| < {n \choose j} &\text{ for } j=1,\dots, n-1 \Bigg\}.
\end{align*} We show that $\mathbb G_n=\widetilde{\mathbb G}_n$ for $n=1,2$ and
that ${\mathbb G}_n \subsetneq \widetilde{\mathbb G}_n$ for $n\geq 3$. We first
obtain a variety of characterizations for the points in $\widetilde{\mathbb
G}_n$ and we apply these necessary and sufficient conditions to produce an
analogous set of characterizations for the points in ${\mathbb G}_n$. Also we
obtain similar characterizations for the points in $\Gamma_n \setminus {\mathbb
G}_n$, where $\Gamma_n =\overline{{\mathbb G}_n}$. A set of $n-1$ fractional
linear transformations play central role in the entire program. We also show
that for $n\geq 2$, $\widetilde{\mathbb G}_n$ is non-convex but polynomially
convex and is starlike about the origin but not circled.
|
[
"math.CV"
] |
math.CV
|
Complex Variables
| 1,135Complex Variables
|
|
2310.05004
|
Learning from two-level voltage source converters, the existing
impedance-based stability analyses of modular multilevel converters (MMCs)
primarily focus on system modes with finite closed-loop transfer functions,
which consider perturbations of the current flowing into the public AC/DC
terminal as the input. However, this approach may be insufficient for MMCs due
to their actively controlled circulating circuit, resulting from the
distributed modulation of each arm and the circulating current control (CCC).
To address this limitation, two cases that are not covered by the AC/DC
terminal stability analysis are initially presented to support the conjecture.
Subsequently, an inner loop impedance for the circulating circuit is
established, which considers the dynamics of public terminals and divides the
injected voltage perturbation by the corresponding current perturbation at the
same frequency. To avoid the need for a right-half plane pole check when
applying the Nyquist criterion, a logarithmic derivative-based criterion is
proposed to directly identify the system modes. By utilizing the inner loop
impedance, it becomes possible to achieve CCC parameter tuning with stability
constraints and conduct an internal stability analysis of MMC-based systems.
This work provides a strong foundation for the integration of
power-electronicized power systems from the perspective of classical control
theories.
|
[
"eess.SY",
"cs.SY"
] |
eess.SY
|
cs.SY
|
Systems and Control;Systems and Control
| 7,220Systems and Control;Systems and Control
|
2107.03172
|
Common fully glazed facades and transparent objects present architectural
barriers and impede the mobility of people with low vision or blindness, for
instance, a path detected behind a glass door is inaccessible unless it is
correctly perceived and reacted. However, segmenting these safety-critical
objects is rarely covered by conventional assistive technologies. To tackle
this issue, we construct a wearable system with a novel dual-head Transformer
for Transparency (Trans4Trans) model, which is capable of segmenting general
and transparent objects and performing real-time wayfinding to assist people
walking alone more safely. Especially, both decoders created by our proposed
Transformer Parsing Module (TPM) enable effective joint learning from different
datasets. Besides, the efficient Trans4Trans model composed of symmetric
transformer-based encoder and decoder, requires little computational expenses
and is readily deployed on portable GPUs. Our Trans4Trans model outperforms
state-of-the-art methods on the test sets of Stanford2D3D and Trans10K-v2
datasets and obtains mIoU of 45.13% and 75.14%, respectively. Through various
pre-tests and a user study conducted in indoor and outdoor scenarios, the
usability and reliability of our assistive system have been extensively
verified.
|
[
"cs.CV",
"cs.HC",
"cs.RO"
] |
cs.CV
|
cs.HC
|
Computer Vision and Pattern Recognition;Human-Computer Interaction;Robotics
| 1,583Computer Vision and Pattern Recognition;Human-Computer Interaction;Robotics
|
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