A muon high-resolution pseudorange measurement method: Application to muon navigation in confined spaces

Confined spaces such as polar regions, deep earth and deep ocean are crucial navigation scenarios where traditional navigation techniques have difficulty in obtaining external signals for positioning. The cosmic ray muons, which carry the spatial and energetic information, are easy to penetrate these confined spaces. Therefore, the unique muon characteristic provides a new perspective to estimate detector position, which can be considered using in confined spaces navigation.In this paper, a well-developed theory of muon navigation is established by combining a muon pseudorange measurement method. Moreover, an Equivalent Velocity Calculation Model(EVCM)and a Muon Sequence Matching Technology(MSMT) are proposed. The first model corrects flight pseudorange error caused by the relativistic energy loss and the second technology compensates the random error in pseudorange measurement. Further, a series of simulations are performed to analyze the muon events number which can be received by detector in different scenarios with the variations of zenith angle, detector area, varied detector plates gap, and muon flight distance.Meanwhile, the simulation results demonstrate that the muon navigation update rate every 10 minutes can reach 5.989 in confined spaces at 100 m, and further pseudorange error analysis indicates that the meter-level positioning accuracy can be acquired. Finally, we construct a muon coincidence measurement scheme and verify that the laws of the muon positioning system for high-energy muons are consistent with the simulation results.

A novel temperature-compensation method based on correlation analysis for multi-FOG INS

Aimed at improving the bias stability of Fiber-Optic Gyroscope(FOG)-based inertial navigation systems in environments of various ambient temperatures,a novel temperaturecompensation method based on a correlation analysis of the same batch of FOGs is proposed.The empirical mode decomposition method was employed to filter the high-frequency noises of the FOGs.Then,the correlation information of the multiple FOGs was used to analyze the feasibility of the method.Eventually,the same residual error of the FOGs was compensated via the simple piecewise linear models.The experimental results indicate that excellent compensation effects for both high-and low-accuracy FOGs are achieved using the proposed method.Specifically,the accuracies of high-accuracy FOGs are improved by approximately 33.9%,20%,and 31.2%,while those of low-accuracy FOGs are improved by approximately 39.1%,20.8%,and 26.1%.The method exhibits the merits of simplicity,validity,and stability,and thus is expected to be widely used in engineering applications.

HMTA-assisted One-pot Synthesis of Greigite Nano-platelet and Its Magnetic Properties

A facile one-pot hydrothermal procedure for the synthesis of magnetic greigite was investigated in this work, by using FeSO4, thioacetamide, and a tiny amount of hexamethylenetetramine （HMTA） as starting materials. The HMTA molecule, which acted as a chelating agent and an oxidant, could not only tune the valence fluctuation of iron ions, but also direct the hydrothermal reaction towards the exclusive for- mation of greigite platelets with hundreds of nanometers in lateral size. In the presence of a static magnetic field during this synthesis, the greigite nano-platelets were apt to congregate to form 3D flower-like microspheres. A set of experiments suggested that the ferrous ions were at first partly oxidized by HMTA to form ferric intermediates, i.e., Fe（OH）3 and Fe2O3. Then excessive ferrous ions, along with the solid in- termediates, reacted with sulfide ions, and finally evolved into greigite, Taken into consideration that a similar process occurred in magnetotactic bacteria, our results may give a hint at the design of biomimetic synthesis strategies to produce nanomaterials, especially the magnetosome-like greigite.