7,042 research outputs found
Research of the active reflector antenna using laser angle metrology system
Active reflector is one of the key technologies for constructing large
telescopes, especially for the millimeter/sub-millimeter radio telescopes. This
article introduces a new efficient laser angle metrology system for the active
reflector antenna of the large radio telescopes, with a plenty of active
reflector experiments mainly about the detecting precisions and the maintaining
of the surface shape in real time, on the 65-meter radio telescope prototype
constructed by Nanjing Institute of Astronomical Optics and Technology (NIAOT).
The test results indicate that the accuracy of the surface shape segmenting and
maintaining is up to micron dimension, and the time-response can be of the
order of minutes. Therefore, it is proved to be workable for the sub-millimeter
radio telescopes.Comment: 10 pages, 15 figure
Layer Antiferromagnetic State in Bilayer Graphene : A First-Principle Investigation
The ground state of bilayer graphene is investigated by the density
functional calculations with local spin density approximation. We find a ground
state with layer antiferromagnetic ordering, which has been suggested by former
studies based on simplified model. The calculations prove that the layer
antiferromagnetic state (LAF) is stable even if the remote hopping and nonlocal
Coulomb interaction are included. The gap of the LAF state is about 1.8 meV,
comparable to the experimental value. The surface magnetism in BLG is of the
order of
4-[(2-Hydroxy-1-naphthyl)(piperidin-1-yl)methyl]benzonitrile
In the title compound, C23H22N2O, obtained from the condensation reaction of 4-formylbenzonitrile, 2-naphthol and piperidine, the dihedral angle between the naphthalene ring system and the benzene ring is 75.31 (4)°. The piperidine ring adopts a chair conformation. The crystal structure is stabilized by intermolecular C—H⋯N hydrogen bonds, which link the molecules into centrosymmetric dimers. An intramolecular O—H⋯N hydrogen bond is also present
Anderson Impurity in Helical Metal
We use a trial wave function to study the spin-1/2 Kondo effect of a helical
metal on the surface of a three-dimensional topological insulator. While the
impurity spin is quenched by conduction electrons, the spin-spin correlation of
the conduction electron and impurity is strongly anisotropic in both spin and
spatial spaces. As a result of strong spin-orbit coupling, the out-of-plane
component of the impurity spin is found to be fully screened by the orbital
angular momentum of the conduction electrons.Comment: The published versio
8-(4-Nitrobenzyloxy)quinoline
In the title compound, C16H12N2O3, the planar quinoline ring system [maximum deviation = 0.025 (3) Å] is oriented at a dihedral angle of 61.76 (7)° with respect to the benzene ring. In the crystal structure, intermolecular C—H⋯O interactions link the molecules into chains parallel to the b axis. π–π contacts between the quinoline rings [centroid–centroid distance = 3.623 (1) Å] may further stabilize the structure
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