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According to the application characteristics of the K-Rb-21Ne comagnetometer, a space-stable navigation mechanization is designed and the requirements of the comagnetometer prototype are presented. By analysing the error propagation rule of the space-stable Inertial Navigation System (INS), the three biases, the scale factor of the z-axis, and the misalignment of the x- and y-axis non-orthogonal with the z-axis, are confirmed to be the main error source. A numerical simulation of the mathematical model for each single error verified the theoretical analysis result of the system’s error propagation rule. Thus, numerical simulation based on the semi-physical data result proves the feasibility of the navigation scheme proposed in this paper. [ABSTRACT FROM AUTHOR]

The seepage calculation of water fluctuation is the crucial precondition for landslide stability evaluation. It is controlled by the initial condition, boundary condition, and soil or rock structure as well as geotechnical parameters. Although the geotechnical parameters and boundary condition have greater influence on seepage and the stability of landslides, the role of the initial groundwater position cannot be ignored. To investigate the influence of an initial groundwater table on landslides, especially the influence of cyclical reservoir water fluctuation on their long-term stability, seven different methods to determine the initial groundwater table were proposed in the presented study, among which one is the actual groundwater table, and the other six are obtained with simplified methods. According to the results of the calculations, at the beginning, there is some difference in the factor of safety among different initial groundwater tables. The maximum value of relative tolerance reduces to less than 1.0 % 160 days later. After a filling-drawdown cycle, the relative tolerance of all methods reduces to less than 0.8 %, which could be ignored. It is also observed that, the closer the hydraulic gradient of the proposed initial groundwater table is to the actual condition, the smaller is the relative tolerance. Therefore, to study the influence of cyclical reservoir water fluctuation on landslide long-term stability, the initial groundwater table could be proposed as (1) equal to reservoir water level and (2) on a straight line with the hydraulic gradient equal to the weighted average of actual groundwater table for simplification. [ABSTRACT FROM AUTHOR]

Zero velocity update (ZUPT) is widely discussed for error restriction in land vehicle Inertial Navigation Systems (INSs) and wearable pedestrian INSs to overcome the problems of Global Positioning System (GPS) unavailability in urban canyons or indoor scenarios. In this paper, an online smoothing method for ZUPT-aided INSs is presented. By introducing the Rauch–Tung–Striebel (RTS) smoothing method into the ZUPT-aided INS, position errors can be effectively restrained not only at stop points but during the whole trajectory. By integrating reverse navigation with a ZUPT smoother, the method realises forward and real-time processing. Compared with existing approaches, it can improve the position accuracy in real time without any other sensors, which is well suited for applications on high-accuracy navigation in GPS-challenging environments. Accuracy test results with different Inertial Measurement Units (IMUs) show that the developed method can significantly decrease position errors from hundreds or thousands of metres to below ten metres. During the whole trajectory, the online smoothing method ensures the maximum position errors at non-stop points can reach the same level of accuracy at stop points. A delay test result proves that the delay of the reverse online smoothing method proposed in this paper is much shorter than existing online smoothing methods. [ABSTRACT FROM AUTHOR]