A study on volunteer augmentation navigation technology

Navigation augmentation technology is one of the most common methods to increase the continuity,reliability and integrity of the global satellite navigation system.The concept of volunteer augmentation navigation (VNA) is proposed and the elements and topological structure of VNA are also analyzed in this paper.The study focuses on the neural network model that volunteers and ordinary users use modern communication information network to exchange self-organizing information.The neural cell model of Voluntee...     

Orbit determination and time synchronization for a GEO/IGSO satellite navigation constellation with regional tracking network

Aiming at regional services,the space segment of COMPASS (Phase I) satellite navigation system is a constellation of Geostationary Earth Orbit (GEO),Inclined Geostationary Earth Orbit (IGSO) and Medium Earth Orbit (MEO) satellites.Precise orbit determination (POD) for the satellites is limited by the geographic distribution of regional tracking stations.Independent time synchronization (TS) system is developed to supplement the regional tracking network,and satellite clock errors and orbit data may be obtai...     

Investigation of morphology selection for CBr_4-C_2Cl_6 alloy in three dimensions with multi-phase field method

With the multi-phase field model, the unidirectional solidification with constant velocity growth and variable velocity growth of the CBr4-C2Cl6 eutectic alloy is simulated in three dimensions. The simulated results with constant velocity growth show that with the increase of pulling velocity, the morphology of the CBr4-C2Cl6 alloy evolves in the sequence of lamellar merging →lamellar-rod transition→stable lamellar growth→oscillating growth→lamellar branching. A morphology selection map is established with ...     

Study of the primordial lithium abundance

Lithium isotopes have attracted an intense interest because the abundance of both 6Li and 6Li from big bang nucleosynthesis (BBN) is one of the puzzles in nuclear astrophysics. Many investigations of both astrophysical observation and nucleosynthesis calculation have been carried out to solve the puzzle, but it is not solved yet. Several nuclear reactions involving lithium have been indirectly measured at China Institute of Atomic Energy, Beijing. The Standard BBN (SBBN) network calculations are then perfo...     

Properties of the πh_(9/2)  νi_(13/2) band in odd-odd ~(188)Au

A new rotational band has been identified and assigned to 188Au for the first time using the 173Yb(19F,4nγ) reaction at the beam energies of 86 and 90 MeV. This band is proposed to be built on the πh9/2  νi13/2 configuration by comparing the band properties with known bands in neighboring nuclei. The prolate-to-oblate shape transition through triaxial shape has been proposed to occur around 188Au for the πh9/2  νi13/2 bands in odd-odd Au isotopes on the basis of total Routhian surface (TRS) calculations.     

Properties of the 3/2~-[521] band in the odd-N rare-earth nuclei

High-spin states in 161Er have been studied experimentally via the 150Nd(16O, 5n) reaction at a beam energy of 86 MeV. Three rotational bands built on the 5/2+[642], 3/2-[521], and 11/2-[505] configurations have been extended up to high-spin states, and particularly, the α = -1/2 branch of the ground state 3/2-[521] band has been revised significantly. It is found that signature inversion occurs in the 3/2-[521] band after the band crossing in 161Er. The systematics of the signature inversion associated wit...     

Microstructure and magnetic properties of CoFe_2O_4 thin films deposited on Si substrates with an Fe_3O_4 under-layer

The microstructure and magnetic properties of cobalt ferrite thin films deposited by the sputtering method on an Fe3O4 under-layer were investigated at different post-annealing temperatures.Results show that the Fe3O4 under-layer can accelerate the grain growth of cobalt ferrite films due to the phase transformation of the Fe3O4 under-layer at about 400°C-500°C.By introducing the Fe3O4 under-layer,cobalt ferrite nanocrystalline thin films with high coercivity can be obtained at lower post-annealing temperat...     

Growth and magnetic properties of single crystalline Ni nanowire arrays prepared by pulse DC electrodeposition

Highly textured Ni nanowire arrays were fabricated into anodic aluminum oxide(AAO) templates by pulse DC electrodeposition.The applied voltage and pH value of electrolytes were found strongly affecting the microstructure and magnetic properties of Ni nanowire arrays.Low applied potential and pH value both prefer to form polycrystalline fcc Ni nanowires.Increasing the applied potential or pH value favors the Ni [220] texture and even eventually forms the [220] oriented single crystal Ni wires,while exorbitan...     

Growth and micromagnetic simulation of magnetite nanoparticles

Magnetite nanoparticles with different sizes and different assemblies were synthesized via hydrothermal method.Micromagnetic simulation shows the magnetite nanocubes with different sizes have different energy states,which determines the assembly mode.Magnetite nanocubes with the side length of 30-60 nm tended to be dispersed while both nanochains and dispersed nanoparticles were found to grow for the nanocubes with the side length less than 30 nm,which can be explained in the fact that the above two assembl...     

Physics-based simultaneous retrieval of atmospheric temperature-humidity profiles and land surface temperature-emissivity by integrating Terra/Aqua MODIS measurements

Atmospheric temperature-humidity profiles and land or sea surface temperature are coupled actions in the earth system process. Based on the numerical perturbation form of the atmospheric radiative transfer equation, a physics-based algorithm is pre- sented to integrate four pairs of MODIS measurements from the Terra and Aqua satellites to retrieve simultaneously atmospheric temperature-humidity profile, land-surface temperature and emissivity. Three pairs of MODIS data at two field sites in China, Luancheng...