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Abstract: Based on the superposition principle for potential field of Green's equivalent layers and frequency cutoff filtering by successive layer optimization, a new imaging method of normalized downward continuation of gravity and magnetic data by successive layer optimization (NDCSLO) is developed. Owing to noise interference is unavoidable in field gravity and magnetic data, the affect of noise interference is studied by NDCSLO tests with sphere and slab model data of different noise intensity, measurement grid spacing and anomaly strength. Ii is shown that the most affected interval is the first 1-2 grid spacing of continuation depth. Too small or big grid spacing will result in field energy dissipation and spurious imaging. With increasing source physical property and thus increasing anomaly strength, the signal-noise ratio will be enhanced and benefit improving the resolving power and accuracy of the downward continuation imaging. From NDCSLO test of field gravity and magnetic data in Southwest Sichuan, it is verified that the affect of measurement error is mainly on the first 2km of the continuation depth, and the middle to deep continuation imaging is less influenced. Therefore, it is suggested that if the field data is apparently affected by noise disturbance, a priori noise filtering be used before NDCSLO; otherwise the NDCSLO can be utilized directly, although the continuation imaging of less than the first 2km depth is not recommended to interpret qualitatively or quantitatively.Abstract: Based on the superposition principle for potential field of Green's equivalent layers and frequency cutoff filtering by successive layer optimization, a new imaging method of normalized downward continuation of gravity and magnetic data by successive layer optimization (NDCSLO) is developed. Owing to noise interference is unavoidable in field gravi...Learn More
Abstract: The high-precision 3D coordinate control network is the foundation for on-site installation of various large-scale modules in large-scale scientific facility. The scale of optical devices such as astronomical telescopes can usually reach tens of meters or more, and the installation accuracy of their large aperture optical mechanical modules can reach the sub-millimeter level. In response to the coordinate control requirements for the precise installation of large aperture optical mechanical modules in optical devices, this article intends to study the impact of the grid shape of the coordinate network on the accuracy and reliability of the coordinate network through measurement and analysis. Firstly, 29 measurement points and 4 stations are arranged within an 18m× 18m area in this article, and the coordinate values of each measurement point in the first station coordinate system are obtained through measurement and analysis, forming a 3D coordinate control network. Then, a fully connected network, a loop back close network, and a loop back open network are constructed through line screening. Finally, based on the generalized reliability theory of control networks, the accuracy of the network is evaluated from various aspects such as the uncertainty of each measurement point, the difference between the analyzed and measured values of the distance from each measurement point to the measurement station in the network, and the difference between the analyzed and nominal values of the length of the control network's long scale. The results indicate that the error of each measurement point in the fully connected network does not exceed 40 μ m. The fully connected network has the highest accuracy and reliability, while the loop open loop network has the lowest accuracy and reliability.Abstract: The high-precision 3D coordinate control network is the foundation for on-site installation of various large-scale modules in large-scale scientific facility. The scale of optical devices such as astronomical telescopes can usually reach tens of meters or more, and the installation accuracy of their large aperture optical mechanical modules can rea...Learn More
