21,621 research outputs found
Synchronization framework for modeling transition to thermoacoustic instability in laminar combustors
We, herein, present a new model based on the framework of synchronization to
describe a thermoacoustic system and capture the multiple bifurcations that
such a system undergoes. Instead of applying flame describing function to
depict the unsteady heat release rate as the flame's response to acoustic
perturbation, the new model considers the acoustic field and the unsteady heat
release rate as a pair of nonlinearly coupled damped oscillators. By varying
the coupling strength, multiple dynamical behaviors, including limit cycle
oscillation, quasi-periodic oscillation, strange nonchaos, and chaos can be
captured. Furthermore, the model was able to qualitatively replicate the
different behaviors of a laminar thermoacoustic system observed in experiments
by Kabiraj et al.~[Chaos 22, 023129 (2012)]. By analyzing the temporal
variation of the phase difference between heat release rate oscillations and
pressure oscillations under different dynamical states, we show that the
characteristics of the dynamical states depend on the nature of synchronization
between the two signals, which is consistent with previous experimental
findings.Comment: 18 pages, 7 figure
Right-Handed Quark Mixings in Minimal Left-Right Symmetric Model with General CP Violation
We present a systematic approach to solve analytically for the right-handed
quark mixings in the minimal left-right symmetric model which generally has
both explicit and spontaneous CP violations. The leading-order result has the
same hierarchical structure as the left-handed CKM mixing, but with additional
CP phases originating from a spontaneous CP-violating phase in the Higgs vev.
We explore the phenomenology entailed by the new right-handed mixing matrix,
particularly the bounds on the mass of and the CP phase of the Higgs vev.Comment: 8 pages, one postscript figure include
Code Completion with Neural Attention and Pointer Networks
Intelligent code completion has become an essential research task to
accelerate modern software development. To facilitate effective code completion
for dynamically-typed programming languages, we apply neural language models by
learning from large codebases, and develop a tailored attention mechanism for
code completion. However, standard neural language models even with attention
mechanism cannot correctly predict the out-of-vocabulary (OoV) words that
restrict the code completion performance. In this paper, inspired by the
prevalence of locally repeated terms in program source code, and the recently
proposed pointer copy mechanism, we propose a pointer mixture network for
better predicting OoV words in code completion. Based on the context, the
pointer mixture network learns to either generate a within-vocabulary word
through an RNN component, or regenerate an OoV word from local context through
a pointer component. Experiments on two benchmarked datasets demonstrate the
effectiveness of our attention mechanism and pointer mixture network on the
code completion task.Comment: Accepted in IJCAI 201
PSR B1828-11: a precession pulsar torqued by a quark planet?
The pulsar PSR B1828-11 has long-term, highly periodic and correlated
variations in both pulse shape and the rate of slow-down. This phenomenon may
provide evidence for precession of the pulsar as suggested previously within
the framework of free precession as well as forced one. On a presumption of
forced precession, we propose a quark planet model to this precession henomenon
instead, in which the pulsar is torqued by a quark planet. We construct this
model by constraining mass of the pulsar (), mass of the planet
() and orbital radius of the planet (). Five aspects
are considered: derived relation between and ,
movement of the pulsar around the center of mass, ratio of and
, gravitational wave radiation timescale of the planetary system,
and death-line criterion. We also calculate the range of precession period
derivative and gravitational wave strength (at earth) permitted by the model.
Under reasonable parameters, the observed phenomenon can be understood by a
pulsar () with a quark planet
() orbiting it. According to the calculations
presented, the pulsar would be a quark star because of its low mass, which
might eject a lump of quark matter (to become a planet around) during its
birth.Comment: 6 pages, 3 figures, accepted by MNRAS (Letters
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