5,486 research outputs found
On echo intervals in gravitational wave echo analysis
Gravitational wave echoes, if they exist, could encode important information
of new physics from the strong gravity regime. Current echo searches usually
assume constant interval echoes (CIEs) a priori, although unequal interval
echoes (UIEs) are also possible. Despite of its simplicity, the using of CIE
templates need to be properly justified, especially given the high sensitivity
of future gravitational wave detectors. In this paper, we assess the necessity
of UIE templates in echo searches. By reconstructing injected UIE signals with
both CIE and UIE templates, we show that the CIE template may significantly
misinterpret the echo signals if the variation of the interval is greater than
the statistical errors of the interval, which is further confirmed by a
Bayesian analysis on model stelection. We also forecast the constraints on the
echo intervals given by future GW detectors such as Advanced LIGO and Einstein
Telescope.Comment: 7 pages,6 figures and 3 table
Are gravitational wave ringdown echoes always equal-interval ?
Gravitational wave (GW) ringdown waveforms may contain "echoes" that encode
new physics in the strong gravity regime. It is commonly assumed that the new
physics gives rise to the GW echoes whose intervals are constant. We point out
that this assumption is not always applicable. In particular, if the
post-merger object is initially a wormhole, which slowly pinches off and
eventually collapses into a black hole, the late-time ringdown waveform exhibit
a series of echoes whose intervals are increasing with time. We also assess how
this affects the ability of Advanced LIGO/Virgo to detect these new signals.Comment: 10 pages,5 figure
Systematic study of elliptic flow parameter in the relativistic nuclear collisions at RHIC and LHC energies
We employed the new issue of a parton and hadron cascade model PACIAE 2.1 to
systematically investigate the charged particle elliptic flow parameter
in the relativistic nuclear collisions at RHIC and LHC energies. With randomly
sampling the transverse momentum and components of the particles
generated in string fragmentation on the circumference of an ellipse instead of
circle originally, the calculated charged particle and
fairly reproduce the corresponding experimental data in the Au+Au/Pb+Pb
collisions at =0.2/2.76 TeV. In addition, the charged particle
and in the p+p collisions at =7 TeV as well as
in the p+Au/p+Pb collisions at =0.2/5.02 TeV are predicted.Comment: 7 pages, 5 figure
Zero-refraction in natural materials and the mechanism of metal superlens
We found that a single negative material has a character of zero-refraction
in near field, and point out that the mechanism of a metal superlens to image
with the resolution exceeding the diffraction limitation is different from that
of a perfect lens made of a double negative material. The principle of metal
superlens is disclosed. Our numerical results based on the zero-refraction
character coincide with the experimental results well. This work brings new
understanding about the single negative materials and will lead the
applications of metal superlens in right way.Comment: 11 pages, 4 figure
The mechanism of the polarization dependence of the optical transmission in subwavelength metal hole arrays
We investigate the mechanism of extraordinary optical transmission in
subwave-length metal hole arrays. Experimental results for the arrays
consisting of square or rectangle holes are well explained about the dependence
of transmission strength on the polarization direction of the incident light.
This polarization dependence occurs in each single-hole. For a hole array,
there is in addition an interplay between the adjacent holes which is caused by
the transverse magnetic field of surface plasmon polariton on the metal film
surfaces. Based on the detailed study of a single-hole and two-hole structures,
a simple method to calculate the total tranmissivity of hole arrays is
proposed.Comment: 34 pages, 7 figure
Using Improved Ant Colony Algorithm to Investigate EMU Circulation Scheduling Problem
High-speed railway is one of the most important ways to solve the long-standing travel difficulty problem in China. However, due to the high acquisition and maintenance cost, it is impossible for decision-making departments to purchase enough EMUs to satisfy the explosive travel demand. Therefore, there is an urgent need to study how to utilize EMU more efficiently and reduce costs in the case of completing a given task in train diagram. In this paper, an EMU circulation scheduling model is built based on train diagram constraints, maintenance constraints, and so forth; in the model solving process, an improved ACA algorithm has been designed. A case study is conducted to verify the feasibility of the model. Moreover, contrast tests have been carried out to compare the efficiency between the improved ACA and the traditional approaches. The results reveal that improved ACA method can solve the model with less time and the quality of each representative index is much better, which means that efficiency of the improved ACA method is higher and better scheduling scheme can be obtained
- …