39,296 research outputs found

### Self-deformation in a dc driven helium jet micro discharge

We report on the experimental observation of three dimensional
self-deformation in an atmospheric micro discharge of the helium microjet
through a tube into the ambient air upon a water electrode. The geometry of the
discharge system is axial symmetric. While decreasing the discharge current,
three dimensional collective motion of plasma filaments are directly observed.
The three dimensional configuration of the discharge self changed from an axial
symmetrical horn to a rectangular horn when the water acts as a cathode.Comment: 3 pages, 5 figures, accepted by Physics of plasma

### Non-linear macro evolution of a dc driven micro atmospheric glow discharge

We studied the macro evolution of the micro atmospheric glow discharge
generated between a micro argon jet into ambient air and static water. The
micro discharge behaves similarly to a complex ecosystem. Non-linear behaviors
are found for the micro discharge when the water acts as a cathode, different
from the discharge when water behaves as an anode. Groups of snapshots of the
micro discharge formed at different discharge currents are captured by an
intensified charge-coupled device with controlled exposure time, and each group
consisted of 256 images taken in succession. Edge detection methods are used to
identify the water surface and then the total brightness is defined by adding
up the signal counts over the area of the micro discharge. Motions of the water
surface at different discharge currents show that the water surface lowers
increasingly rapidly when the water acts as a cathode. In contrast, the water
surface lowers at a constant speed when the water behaves as an anode. The
light curves are similar to logistic growth curves, suggesting that a
self-inhibition process occurs in the micro discharge. Meanwhile, the total
brightness increases linearly during the same time when the water acts as an
anode. Discharge-water interactions cause the micro discharge to evolve. The
charged particle bomb process is probably responsible for the different
behavior of the micro discharges when the water acts as cathode and anode.Comment: 5 pages, 5 figures, accepted by physics of plasma

### Improved queue-size scaling for input-queued switches via graph factorization

This paper studies the scaling of the expected total queue size in an
$n\times n$ input-queued switch, as a function of both the load $\rho$ and the
system scale $n$. We provide a new class of scheduling policies under which the
expected total queue size scales as $O\left( n(1-\rho)^{-4/3} \log
\left(\max\{\frac{1}{1-\rho}, n\}\right)\right)$, over all $n$ and $\rho<1$,
when the arrival rates are uniform. This improves over the previously
best-known scalings in two regimes: $O\left(n^{1.5}(1-\rho)^{-1} \log
\frac{1}{1-\rho}\right)$ when $\Omega(n^{-1.5}) \le 1-\rho \le O(n^{-1})$ and
$O\left(\frac{n\log n}{(1-\rho)^2}\right)$ when $1-\rho \geq \Omega(n^{-1})$. A
key ingredient in our method is a tight characterization of the largest
$k$-factor of a random bipartite multigraph, which may be of independent
interest.Comment: 42 pages, 4 figure

### Information and Memory in Dynamic Resource Allocation

We propose a general framework, dubbed Stochastic Processing under Imperfect
Information (SPII), to study the impact of information constraints and memories
on dynamic resource allocation. The framework involves a Stochastic Processing
Network (SPN) scheduling problem in which the scheduler may access the system
state only through a noisy channel, and resource allocation decisions must be
carried out through the interaction between an encoding policy (who observes
the state) and allocation policy (who chooses the allocation). Applications in
the management of large-scale data centers and human-in-the-loop service
systems are among our chief motivations.
We quantify the degree to which information constraints reduce the size of
the capacity region in general SPNs, and how such reduction depends on the
amount of memories available to the encoding and allocation policies. Using a
novel metric, capacity factor, our main theorem characterizes the reduction in
capacity region (under "optimal" policies) for all non-degenerate channels, and
across almost all combinations of memory sizes. Notably, the theorem
demonstrates, in substantial generality, that (1) the presence of a noisy
channel always reduces capacity, (2) more memory for the allocation policy
always improves capacity, and (3) more memory for the encoding policy has
little to no effect on capacity. Finally, all of our positive (achievability)
results are established through constructive, implementable policies.Comment: 48 pages, 5 figures, 1 tabl

### Microscopic analysis of octupole shape transitions in neutron-rich actinides with relativistic energy density functional

Quadrupole and octupole deformation energy surfaces, low-energy excitation
spectra, and electric transition rates in eight neutron-rich isotopic chains --
Ra, Th, U, Pu, Cm, Cf, Fm, and No -- are systematically analyzed using a
quadrupole-octupole collective Hamiltonian model, with parameters determined by
constrained reflection-asymmetric and axially-symmetric relativistic mean-field
calculations based on the PC-PK1 energy density functional. The theoretical
results of low-lying negative-parity bands, odd-even staggering, average
octupole deformations $\langle\beta_3\rangle$, and $B(E3; 3^-_1\to 0^+_1)$ show
evidence of a shape transition from nearly spherical to stable
octupole-deformed, and finally octupole-soft equilibrium shapes in the
neutron-rich actinides. A microscopic mechanism for the onset of stable
octupole deformation is also discussed in terms of the evolution of
single-nucleon orbitals with deformation.Comment: 13 pages, 10 figures, Accepted for Publication in Chinese Physics C.
arXiv admin note: substantial text overlap with arXiv:1710.08230; text
overlap with arXiv:1402.6102 by other author

### Bihamiltonian Structure of the Two-component Kadomtsev-Petviashvili Hierarchy of type B

We employ a Lax pair representation of the two-component BKP hierarchy and
construct its bihamiltonian structure with R-matrix techniques.Comment: 20 page

### A Class of Infinite-dimensional Frobenius Manifolds and Their Submanifolds

We construct a class of infinite-dimensional Frobenius manifolds on the space
of pairs of certain even functions meromorphic inside or outside the unit
circle. Via a bi-Hamiltonian recursion relation, the principal hierarchies
associated to such Frobenius manifolds are found to be certain extensions of
the dispersionless two-component BKP hierarchy. Moreover, we show that these
infinite-dimensional Frobenius manifolds contain finite-dimensional Frobenius
submanifolds as defined on the orbit space of Coxeter groups of types B and D.Comment: Proposition 2.11 and its proof are revise

### An extension of the Kadomtsev-Petviashvili hierarchy and its Hamiltonian structures

In this note we consider a two-component extension of the
Kadomtsev-Petviashvili (KP) hierarchy represented with two types of
pseudo-differential operators, and construct its Hamiltonian structures by
using the $R$-matrix formalism.Comment: 21 pages, to appear in J. Geom. Phy

### Band gap anomaly and topological properties in lead chalcogenides

Band gap anomaly is a well-known issue in lead chalcogenides PbX (X=S, Se,
Te, Po). Combining ab initio calculations and tight-binding (TB) method, we
have studied the band evolution in PbX, and found that the band gap anomaly in
PbTe is mainly related to the high onsite energy of Te 5s orbital and the large
s-p hopping originated from the irregular extended distribution of Te 5s
electrons. Furthermore, our calculations show that PbPo is an indirect band gap
(6.5 meV) semiconductor with band inversion at L point, which clearly indicates
that PbPo is a topological crystalline insulator (TCI). The calculated mirror
Chern number and surface states double confirm this conclusion.Comment: 7 pages and 4 figure

### Learning Embeddings of Directed Networks with Text-Associated Nodes---with Applications in Software Package Dependency Networks

A network embedding consists of a vector representation for each node in the
network. Its usefulness has been shown in many real-world application domains,
such as social networks and web networks. Directed networks with text
associated with each node, such as software package dependency networks, are
commonplace. However, to the best of our knowledge, their embeddings have
hitherto not been specifically studied. In this paper, we propose PCTADW-1 and
PCTADW-2, two algorithms based on neural networks that learn embeddings of
directed networks with text associated with each node. We create two new
node-labeled such networks: The package dependency networks in two popular
GNU/Linux distributions, Debian and Fedora. We experimentally demonstrate that
the embeddings produced by our algorithms resulted in node classification with
better quality than those of various baselines on these two networks. We
observe that there exist systematic presence of analogies (similar to those in
word embeddings) in the network embeddings of software package dependency
networks. To the best of our knowledge, this is the first time that such
systematic presence of analogies is observed in network and document
embeddings. This may potentially open up a new instrument for better
understanding networks and documents algorithmically using their embeddings as
well as for better human understanding of network and document embeddings

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