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To improve the service accuracy of the GNSS system and monitor the integrity of regional ionospheric activities, The BDSBAS system broadcasts the grid ionospheric correction parameters and GIVE to meet the precision approach needs. We use a planar fit algorithm to create an ionosphere map of the BDSBAS, in order to get a more accurate confidence bounds, we put forward a factor which is related to the Skewness and kurtosis of the residual distribution to control the decorrelation parameters to calculate the integrity parameter GIVE. The statistical results show that the ionospheric correction RMS of the BDSBAS grid-based single shell model is about 2~3 TECU, the correction percentage reaches 75%~79%; the GIVE envelope rate is better than 99.9%. Compared with the GPS basic navigation system, only adding the BDSBAS grid ionospheric correction can improve positioning accuracy by 20%~40%.

BeiDou Navigation Satellite System (BDS) integrates legacy PNT service and authorized SBAS service, where SBAS service provides differential corrections and integrity information for authorized users. Current BDS differential corrections include one-dimensional equivalent satellite clock and ionospheric grids corrections, which is derived based on CNMC-smoothed pseudo-range observations. To improve the performance of BDS SBAS service, an algorithm is developed to estimate the real-time satellite clock and orbit corrections. In the algorithm, phase smoothed pseudo-range observation is used to define absolute value, and epoch differenced phase observation is used to define epoch-wise variation of the satellite clock/orbit corrections. It is analyzed that the impact of data sampling rate and station number on the correction parameter estimation. Real-time data of the BDS tracking network in China is used to validate the new algorithm. Compared with the current system performance:① mean UDRE using the new algorithm is reduced by 27%,35% and 27% for GEO, IGSO and MEO satellites, ② mean positioning error using the new algorithm is reduced by 23%,32% and 52% in the North, East and Up components, respectively. Implementing the new algorithm, BDS SBAS service supports the user positioning requirement with accuracy better than 1 m.

BACKGROUND\ud \ud The selective conversion of cellulose to gluconic acid under mild conditions is challenging as it has abundant intra-and inter-molecular hydrogen bonds that protect the β-1,4-glycosidic bonds and make it intrinsically recalcitrant to deploymerize.\ud \ud \ud RESULTS\ud \ud Au-Pd/TiO2 and Au-Pt/TiO2 catalysts prepared by sol immobilization method without pre-treatment are active and selective for the oxidation of glucose and cellobiose to gluconic acid under base-free conditions. Important preparation parameters are the pre-treatment of the catalyst and the metal ratio.\ud \ud \ud CONCLUSION\ud \ud The optimized catalyst provided a good yield of gluconic acid from cellobiose and has opened up a new catalyst system for cellobiose conversion in terms of a heterogeneous catalyst.

Phase smoothing Pseudorange can effectively suppress the multipath effect on pseudorange, and there is no ambiguity problem, which has been widely studied and applied in the field of GNSS data processing. This paper made a systematic analysis and comparison of mathematical models for Hatch filter and CNMC phase smoothing pseudorange method. The ionsphere free combination of single frequency pseudorange through CNMC algorithm is proved equivalence with dual frequency hatch filter. On the assumption that there exists only random errors and the various measurements are independent, the accuracy expression of the CNMC method for smoothing pseudorange is deduced. Dual band hatch filter in the initialization period observation noise is bigger than CNMC smoothed pseudorange, but after a bit more than ten minutes, observation noise gradually gets better than CNMC smoothed pseudorange. BDS navigation system is qualified with serious and low-frequency characteristic for multipath errors through the comparison of OMC of double difference observation for real BDS short baseline, the conclusion that the phase smoothing pseudorange algorithm can greatly weaken the random error of original pseudorange, however, cant improve the system error is drawn. The system error of pseudorange smoothed by CNMC is at the save level with the original pseudorange, but the system error of pseudorange smoothed by double frequency hatch filter is increased. At last, relative positioning is carried through using the different kinds of phase smoothed pseudorange of that short baseline. The positioning results show that the positioning precision is improved from 0.797 m to 0.541 m using pseudorange smoothed by CNMC and the positioning precision is decreased to 1.160 m using pseudorange smoothed by hatch filter.