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Traffic signal control using queueing theory
Traffic signal control has drawn considerable attention in the literatures thanks to its ability to improve the mobility of urban networks. Queueing models are capable of capturing performance or effectiveness of a queueing system. In this report, SOCPs (second order cone program) are proposed based on different queueing models as pre-timed signal control techniques to minimize total travel delay. Stochastic programs are developed in order to handle the uncertainties in the arrival rates. In addition, the superiority of the proposed model over Webster’s model has been validated in a microscopic traffic simulation software named CORSIM.Statistic
Fingerprint of Galactic Loop I on polarized microwave foregrounds
Context: Currently, detection of the primordial gravitational waves by the
B-mode of Cosmic Microwave Background (CMB) is primarily limited by our
knowledge of the polarized microwave foreground emissions. Thus improvements of
the foreground analysis are necessary. As revealed
in~\cite{2018arXiv180410382L}, the E-mode and B-mode of the polarized
foreground have noticeable different properties, both in morphology and
frequency spectrum, suggesting that they arise from different physical
processes, and need to be studied separately.
Aims: I will study the polarized emission from Galactic loops, especially
Loop I, and mainly focus on the following issues: Does it contribute
predominantly to the E-mode or B-mode? In which frequency bands and in which
sky regions can it be identified?
Methods: Based on a well known result about the magnetic field alignment in
supernova explosions, a theoretical expectation is established that the loop
polarizations should be predominantly E-mode. In particular, the expected
polarization angles of Loop I are compared with those from the real microwave
band data of WMAP and Planck.
Results and conclusions: The comparison between model and data shows
remarkable consistency between data and expectation at all bands and for a
large area of the sky. This result suggests that the polarized emission of
Galactic Loop I is a major polarized component in all microwave bands from 23
to 353 GHz, and a considerable part of the polarized foreground is likely
originated from a local bubble associated with Loop I, instead of the far more
distant Galactic emission. The result also provides a possible way to explain
the reported E-to-B excess~\citep{2016A&A...586A.133P} by contribution of the
loops. Finally, this work may also provide the first geometrical evidence that
the Earth was hit by a supernova explosion.Comment: Updated using the Planck 2018 data, and the main conclusion is now
even better supporte
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