39,991 research outputs found
Spectroscopic observations of a flare-related coronal jet
Coronal jets are ubiquitous in active regions (ARs) and coronal holes. In
this paper, we study a coronal jet related to a C3.4 circular-ribbon flare in
active region 12434 on 2015 October 16. Two minifilaments were located under a
3D fan-spine structure before flare. The flare was generated by the eruption of
one filament. The kinetic evolution of the jet was divided into two phases: a
slow rise phase at a speed of 131 km s and a fast rise phase at a
speed of 363 km s in the plane-of-sky. The slow rise phase may
correspond to the impulsive reconnection at the breakout current sheet. The
fast rise phase may correspond to magnetic reconnection at the flare current
sheet. The transition between the two phases occurred at 09:00:40 UT. The
blueshifted Doppler velocities of the jet in the Si {\sc iv} 1402.80 {\AA} line
range from -34 to -120 km s. The accelerated high-energy electrons are
composed of three groups. Those propagating upward along open field generate
type \textrm{III} radio bursts, while those propagating downward produce HXR
emissions and drive chromospheric condensation observed in the Si {\sc iv}
line. The electrons trapped in the rising filament generate a microwave burst
lasting for 40 s. Bidirectional outflows at the base of jet are manifested
by significant line broadenings of the Si {\sc iv} line. The blueshifted
Doppler velocities of outflows range from -13 to -101 km s. The
redshifted Doppler velocities of outflows range from 17 to 170 km
s. Our multiwavelength observations of the flare-related jet are in
favor of the breakout jet model and are important for understanding the
acceleration and transport of nonthermal electrons.Comment: 11 pages, 13 figures, accepted for publication in A&
Evaluating the symbiosis status of tourist towns: The case of Guizhou Province, China
This study examines the symbiosis status of tourist towns by analyzing the dynamism between two subsystems of tourist town development: the town subsystem and the tourism subsystem. Drawing on the Lotka-Volterra model, we first developed a model for evaluating the status of harmonious symbiosis development for tourist towns, and then formulated a set of indicators to measure the key components in the model. An empirical study applying the model was conducted focusing on 18 tourist towns in Guizhou Province, China. Recommendations were proposed for more harmonious development of the tourist towns. This is among the first tourism studies that adopt the symbiosis systems approach and our proposed model provides fresh insights into tourist town development
A comprehensive obstacle avoidance system of mobile robots using an adaptive threshold clustering and the morphin algorithm
To solve the problem of obstacle avoidance for a mobile robot in unknown environment, a comprehensive obstacle avoidance system (called ATCM system) is developed. It integrates obstacle detection, obstacle classification, collision prediction and obstacle avoidance. Especially, an Adaptive-Threshold Clustering algorithm is developed to detect obstacles, and the Morphin algorithm is applied for path planning when the robot predicts a collision ahead. A dynamic circular window is set to continuously scan the surrounding environment of the robot during the task period. The simulation results show that the obstacle avoidance system enables robot to avoid any static and dynamic obstacles effectively
Statefinder diagnosis in a non-flat universe and the holographic model of dark energy
In this paper, we study the holographic dark energy model in non-flat
universe from the statefinder viewpoint. We plot the evolutionary trajectories
of the holographic dark energy model for different values of the parameter
as well as for different contributions of spatial curvature, in the statefinder
parameter-planes. The statefinder diagrams characterize the properties of the
holographic dark energy and show the discrimination between this scenario and
other dark energy models. As we show, the contributions of the spatial
curvature in the model can be diagnosed out explicitly by the statefinder
diagrams. Furthermore, we also investigate the holographic dark energy model in
the plane, which can provide us with a useful dynamical diagnosis
complement to the statefinder geometrical diagnosis.Comment: 16 pages, 4 figures; final versio
The DArk Matter Particle Explorer mission
The DArk Matter Particle Explorer (DAMPE), one of the four scientific space
science missions within the framework of the Strategic Pioneer Program on Space
Science of the Chinese Academy of Sciences, is a general purpose high energy
cosmic-ray and gamma-ray observatory, which was successfully launched on
December 17th, 2015 from the Jiuquan Satellite Launch Center. The DAMPE
scientific objectives include the study of galactic cosmic rays up to
TeV and hundreds of TeV for electrons/gammas and nuclei respectively, and the
search for dark matter signatures in their spectra. In this paper we illustrate
the layout of the DAMPE instrument, and discuss the results of beam tests and
calibrations performed on ground. Finally we present the expected performance
in space and give an overview of the mission key scientific goals.Comment: 45 pages, including 29 figures and 6 tables. Published in Astropart.
Phy
Effect of initial configuration on network-based recommendation
In this paper, based on a weighted object network, we propose a
recommendation algorithm, which is sensitive to the configuration of initial
resource distribution. Even under the simplest case with binary resource, the
current algorithm has remarkably higher accuracy than the widely applied global
ranking method and collaborative filtering. Furthermore, we introduce a free
parameter to regulate the initial configuration of resource. The
numerical results indicate that decreasing the initial resource located on
popular objects can further improve the algorithmic accuracy. More
significantly, we argue that a better algorithm should simultaneously have
higher accuracy and be more personal. According to a newly proposed measure
about the degree of personalization, we demonstrate that a degree-dependent
initial configuration can outperform the uniform case for both accuracy and
personalization strength.Comment: 4 pages and 3 figure
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