2,576 research outputs found
Potential of Constraining Propagation Parameters of Galactic Cosmic Rays with the High Energy cosmic-Radiation Detection facility onboard China's Space Station
Precise measurements of the spectra of secondary and primary cosmic rays are
crucial for understanding the origin and propagation of those energetic
particles. The High Energy cosmic-Radiation Detection (HERD) facility onboard
China`s Space Station, which is expected to operate in 2027, will push the
direct measurements of cosmic ray fluxes precisely up to PeV energies. In this
work, we investigate the potential of HERD on studying the propagation of
cosmic rays using the measurements of boron, carbon, and oxygen spectra. We
find that, compared with the current results, the new HERD measurements can
improve the accuracy of the propagation parameters by 8\% to 40\%. The
constraints on the injection spectra at high energies will also be improved.Comment: 10 pages, 4 figure
Optimized Design on the Width and Spacing of the Cross Passageway in Tunnels
AbstractCross passageways have been commonly applied in the evacuation system of tunnels, and the width and spacing of the cross passageways decide the evacuation capacity of the tunnel. In design, increasing the width of the cross passageways and reducing their spacing can improve the evacuation ability of tunnels. However, it will certainly increase the cost of the project. Under the precondition of meeting evacuation requirements, an optimization model was established in this article, which aimed at reducing the cost of the project. Finally, discussions on the application of this optimization model were carried on, and this method may provide reference for designing cross passageways
Why It Takes So Long to Connect to a WiFi Access Point
Today's WiFi networks deliver a large fraction of traffic. However, the
performance and quality of WiFi networks are still far from satisfactory. Among
many popular quality metrics (throughput, latency), the probability of
successfully connecting to WiFi APs and the time cost of the WiFi connection
set-up process are the two of the most critical metrics that affect WiFi users'
experience. To understand the WiFi connection set-up process in real-world
settings, we carry out measurement studies on million mobile users from
representative cities associating with million APs in billion WiFi
sessions, collected from a mobile "WiFi Manager" App that tops the Android/iOS
App market. To the best of our knowledge, we are the first to do such large
scale study on: how large the WiFi connection set-up time cost is, what factors
affect the WiFi connection set-up process, and what can be done to reduce the
WiFi connection set-up time cost. Based on the measurement analysis, we develop
a machine learning based AP selection strategy that can significantly improve
WiFi connection set-up performance, against the conventional strategy purely
based on signal strength, by reducing the connection set-up failures from
to and reducing time costs of the connection set-up
processes by more than times.Comment: 11pages, conferenc
Poly[[tetraaquaÂbis(μ3-1H-benzimidazole-5,6-dicarboxylÂato)dicobalt(II)] trihydrate]
The title complex, {[Co2(C9H4N2O4)2(H2O)4]·3H2O}n, was synthesized hydroÂthermally. The unique CoII ion is coordinÂated in a distorted octaÂhedral coordination environment by two water molÂecules and three symmetry-related 1H-benzimidÂazole-5,6-dicarboxylÂate (Hbidc) ligands. The Hbidc ligands coordinate via a bis-chelating and mono-chelating carboxylÂate group and by an imidazole group N atom, bridging the CoII ions and forming an extended two-dimensional structure in the ab plane. In the crystal structure, interÂmolecular N—H⋯O and O—H⋯O hydrogen bonds connect complex and solvent water molÂecules, forming a three-dimensional supermolecular network. One of the solvent water molÂecules lies on a twofold rotation axis
- …