The Quality Assessment of Non-Integer-Hour Data in GPS Broadcast Ephemerides and Its Impact on the Accuracy of Real- Time Kinematic Positioning Over the South China Sea

Abnormal effects in GPS broadcast ephemerides can have a significant effect on real-time navigation and positioning solutions that use the orbit and clock error data provided by GPS broadcast ephemerides.This paper describes three types of non-integerhour navigation data in GPS broadcast ephemeris data.Compared with GPST integer hour data,we find that there are two types of data blocks for non-integer-hour navigation containing gross errors with different levels of precision,which is reflected in the user range accuracy(URA)of the broadcast ephemeris.These gross errors can cause large deviations when using the GPS broadcast ephemeris for orbit calculation and lead to a decrease in the kinematic positioning accuracy.An improved weighting method which is based on the consistency relationship between the URA value and the orbital precision is proposed to improve the positioning accuracy by controlling the effect of gross errors in the broadcast ephemerides.The correction algorithm proposed in this paper was applied to real-time kinematic positioning with shipborne GPS data over the South China Sea.The results showed that the proposed positioning algorithm can effectively reduce the effects of gross errors in the broadcast ephemeris,and significantly improve the accuracy of the navigation and positioning.

引领未来:中国光伏产业发展路线图的挑战

Carbon neutrality aims to transform the global renewable energy industry[1].Solar photovoltaic(PV)generation has grown exponentially over the last decade,from 0.84 GW(solar installed capacity)in 2000 to 843 GW in 2021,faster than other renewable energy industries[2].Its technology has significant advantages such as safety,non-pollution,high efficiency,reliability,and convenient installation and maintenance.

Estimation of stature by using the dimensions of the right hand and right foot in Han Chinese adults

The Han Chinese people are the main ethnic group in China and the largest ethnic group in the world.The dimensions of the hands and feet have been successfully used for the estimation of stature.A total of 26,927 healthy adult subjects,comprising 13,221 men and 13,706 women,were recruited.The survey samples were chosen through random cluster sampling.The mean values were significantly higher in men than those in women for all measurements(P<0.001).All the measurements showed a statistically significant correlation with stature(P<0.01).The combination of the right hand length and the right foot length was the best predictor of stature because it had the lowest standard error of estimate.The use of multiple regression equations yielded better results than did the use of linear regression equations.The accuracy of stature prediction ranged from ±4.81 to ±6.39 cm.The present study was of great importance with regards to improving the physical anthropology database of ethnic groups in China.

Comparing the costs and benefits of virgin and urban mining

Resource and environmental management are shaping our society and economy.Virgin mining is rapidly becoming unsustainable as primary resources are in increasingly short supply and energy consumption continues to increase.Urban mining through a circular economy has emerged as a promising option for securing copper and aluminum resources.However,the sustainability and viability of this circular economy industry are heavily dependent on its profitability.Here,we demonstrate the economic benefits of urban mining for anthropogenic minerals:e-waste,end-of-life vehicles,waste wiring and cables.The material and cost flows associated with urban mining are deeply examined.Through life cycle cost and cost-benefit analysis,the cost of obtaining one ton of copper or aluminum is found to be,on average,3,000 US$or 1,660 US$,which is significantly lower than the cost of virgin mining.Moreover,in terms of the costs and benefits,copper may differ tremendously from aluminum depending on the type of anthropogenic mineral.Some additional regulations or policies enactment need to reinforce the urban mining and circular economy.