Precise Shearer Positioning Technology Using Shearer Motion Constraint and Magnetometer Aided SINS

The key technology to realize intelligent unmanned coal mining is the strapdown inertial navigation system (SINS); however, the gradual increase of cumulative error during the working process needs to be solved. On the basis of an SINS/odometer (OD)-integrated navigation system, this paper adds magnetometer (MAG)-aided positioning and proposes an SINS/OD/MAG-integrated shearer navigation system. The velocity observation equation is obtained from the speed constraints during shearer movement, and the yaw angle observation equation is obtained from the magnetometer output. The position information of the SINS output is calibrated using these two observations. In order to improve the fault tolerance of the integrated navigation system, an adaptive federated Kalman filter is established to complete the data fusion of the SINS. Experimental results show that the positioning accuracy of the SINS/OD/MAG-integrated navigation system is 75.64% and 74.01% higher in the east and north directions, respectively, than the SINS/OD-integrated navigation system.

Clinical observation of short-term on primary pars plana vitrectomy without perfluorocarbon fluids under the wide-angle observation system in treatment rhegmatogenous retinal detachment with PVR ≦C2

Background: To observe the short-term efficacy of vitrectomy for wide-angle observation system without perfluorocarbon liquid (PFCL )in the treatment of rhegmatogenous retinal detachment(RRD) with Proliferative vitreous retinopathy (PVR ) ≦C2.Methods: Retrospective analysis of the case data of patients with rhegmatogenous retinal detachment who did not use or use perfluorocarbon liquid during vitrectomy, including age, sex, course of disease, PVR classification, preoperative and stepwise best corrected positive vision , Perfluorocarbon liquid in the perfluorocarbon liquid group, the reposition state of the retina, the difference in visual acuity recovery and retina reset rate within and between groups.Results: There was no statistically significant difference in baseline data (age, sex, course of disease, PVR grade) between the non-perfluorocarbon liquid group and the perfluorocarbon liquid group (P> 0.05). The rate of initial reset at the time of discharge from the non-perfluorocarbon liquid group was 92.9%. The retinal reposition rate at 6 months after surgery was 100%. The rate of initial reduction at discharge was 93.5% in the group using perfluorocarbon liquid, and the final retinal reduction rate at 6 months after surgery was 100%. There was no statistically significant difference in logMAR BCVA of postoperative follow-up time between the two groups (P> 0.05). Without the use of perfluorocarbon liquid, there was no postoperative perfluorocarbon liquid residue, and the residual rate of perfluorocarbon liquid in the perfluorocarbon liquid group was 14.5%.Conclusion: Vitrectomy without the use of perfluorocarbon fluids under the wide-angle observation system is the first choice to treat rhegmatogenous retinal detachment with PVR≤C2.

Comparison of the Photochemical Reflectance Index and Solar-induced Fluorescence for Estimating Gross Primary Productivity

<p>Photochemical reflectance index (PRI) as a proxy for light use efficiency (LUE) has the potential to improve the estimates of vegetation gross primary productivity (GPP) using LUE model. Solar-induced fluorescence (SIF) has increasingly been shown to be a promising approach for directly estimating GPP. However, a number of factors including the view-geometry and environmental variables, which may disassociate PRI and SIF products from photosynthesis, are important for the estimation of GPP, but rarely investigated. In this study, we observed multi-angle SIF and PRI in a maize field during the 2018 growing season, and compared the PRI-based LUE model and SIF-based linear model in estimating GPP. Our results showed that the averaged PRI and SIF using the multi-angle observations performed better than the single angle observed PRI and SIF in estimating LUE and, GPP respectively. We also found that the seasonal GPP dynamics were better captured by the SIF-based linear model (R<sup>2</sup>=0.50) than the PRI-based LUE model (R<sup>2</sup>=0.45), while the PRI-based LUE model performed better in estimating the diurnal variations of GPP (R<sup>2</sup>=0.71). Random forest analysis demonstrated that PAR and RH were of the most importance in the estimation of diurnal GPP variations using the SIF-based and the PRI-based models, respectively. The PRI-based LUE model performed better than the SIF-based model under most environmental conditions, while SIF should be a preference under clear days (Q>2). Thus, our study confirmed the importance of multi-angle observation of SIF and PRI in estimating GPP and LUE, and suggested that the environmental effects should be considered for accurately estimating GPP using SIF and PRI.</p>