70,385 research outputs found
Quakes in Solid Quark Stars
A starquake mechanism for pulsar glitches is developed in the solid quark
star model. It is found that the general glitch natures (i.e., the glitch
amplitudes and the time intervals) could be reproduced if solid quark matter,
with high baryon density but low temperature, has properties of shear modulus
\mu = 10^{30~34} erg/cm^3 and critical stress \sigma_c = 10^{18~24} erg/cm^3.
The post-glitch behavior may represent a kind of damped oscillations.Comment: 11 pages, 4 figures (but Fig.3 is lost), a complete version can be
obtained by http://vega.bac.pku.edu.cn/~rxxu/publications/index_P.htm, a new
version to be published on Astroparticle Physic
Hurst parameter analysis of radio pulsar timing noise
We present an analysis of timing residual (noise) of 54 pulsars obtained from
25-m radio telescope at Urumqi Observatory with a time span of 5~8 years,
dealing with statistics of the Hurst parameter. The majority of these pulsars
were selected to have timing noise that look like white noise rather than
smooth curves. The results are compared with artificial series of different
constant pairwise covariances. Despite the noise like appearance, many timing
residual series showed Hurst parameters significantly deviated from that of
independent series. We concluded that Hurst parameter may be capable of
detecting dependence in timing residual and of distinguishing chaotic behavior
from random processes.Comment: 7 pages, 3 figures, 2 tables, Submitted to MNRA
Delay-dependent robust stability of stochastic delay systems with Markovian switching
In recent years, stability of hybrid stochastic delay systems, one of the important issues in the study of stochastic systems, has received considerable attention. However, the existing results do not deal with the structure of the diffusion but estimate its upper bound, which induces conservatism. This paper studies delay-dependent robust stability of hybrid stochastic delay systems. A delay-dependent criterion for robust exponential stability of hybrid stochastic delay systems is presented in terms of linear matrix inequalities (LMIs), which exploits the structure of the diffusion. Numerical examples are given to verify the effectiveness and less conservativeness of the proposed method
Alternate proof of the Rowe-Rosensteel proposition and seniority conservation
For a system with three identical nucleons in a single- shell, the states
can be written as the angular momentum coupling of a nucleon pair and the odd
nucleon. The overlaps between these non-orthonormal states form a matrix which
coincides with the one derived by Rowe and Rosensteel [Phys. Rev. Lett. {\bf
87}, 172501 (2001)]. The propositions they state are related to the eigenvalue
problems of the matrix and dimensions of the associated subspaces. In this
work, the propositions will be proven from the symmetric properties of the
symbols. Algebraic expressions for the dimension of the states, eigenenergies
as well as conditions for conservation of seniority can be derived from the
matrix.Comment: 9 pages, no figur
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Cross-source sensing data fusion for building occupancy prediction with adaptive lasso feature filtering
Fusing various sensing data sources can significantly improve the accuracy and reliability of building occupancy detection. Fusing environmental sensors and wireless network signals are seldom studied for its computational and technical complexity. This study aims to propose an integrated adaptive lasso model that is able to extract critical data features for environmental and Wi-Fi probe dual sensing sources. Through rapid feature extraction and process simplification, the proposed method aims to improve the computational efficiency of occupancy detecting models. To validate the proposed model, an onsite experiment was conducted to examine two occupancy data resolutions, (real-time and four-level occupancy resolutions). The results suggested that, among all twelve features, eight features are most relevant. The mean absolute error of the real-time occupancy can be reduced to 2.18 and F1_accuracy is about 84.36% for the four-level occupancy
Quantising Higher-spin String Theories
In this paper, we examine the conditions under which a higher-spin string
theory can be quantised. The quantisability is crucially dependent on the way
in which the matter currents are realised at the classical level. In
particular, we construct classical realisations for the algebra,
which is generated by a primary spin- current in addition to the
energy-momentum tensor, and discuss the quantisation for . From these
examples we see that quantum BRST operators can exist even when there is no
quantum generalisation of the classical algebra. Moreover, we find
that there can be several inequivalent ways of quantising a given classical
theory, leading to different BRST operators with inequivalent cohomologies. We
discuss their relation to certain minimal models. We also consider the
hierarchical embeddings of string theories proposed recently by Berkovits and
Vafa, and show how the already-known strings provide examples of this
phenomenon. Attempts to find higher-spin fermionic generalisations lead us to
examine the whether classical BRST operators for ( odd)
algebras can exist. We find that even though such fermionic algebras close up
to null fields, one cannot build nilpotent BRST operators, at least of the
standard form.Comment: CTP TAMU-24/94, KUL-TF-94/11, SISSA-135/94/E
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