第一篇 高中政治中英文互译
外文原文
Recently, according to the requirements of some important GPS rearch subjects in the fields of Geodesy, Geophysics, Space-Physics and navigation in China, we studied systematically how to correcting the effects of the ionosphere on GPS, with high-precision and accuracy. As the parts of the main contributions, the rearch projects focus mainly on how to improve GPS surveying by reducing ionospheric delay for dual/single frequency kinematic/static urs: high accuracy correction of ionospheric delay for single/dual frequency GPS urs on the earth and in space, China WAAS ionospheric modeling and the theory and method of monitoring of ionosphere using GPS.
一树寒梅白玉条佛经故事The main contents of this Ph.D paper consist of two parts:
Fisrt part---the outline of rearch background and the systematic introduction and summarization of the previous rearch results of this work.
Second part---the main contribution and rearch results of this paper are focud on as follows:
(1) How to u the measurements of a dual frequency GPS receiver to determine the ionospheric delay correction model for single frequency GPS of a local range;
(2) How to parate the instrumental bias with the ionospheric delays in GPS obrvation;
(3) How to establish a large range grid ionosphere model and u the GPS data of Chine crust movement obrvation network to investigate the change law of ionospheric TEC of China area;
(4) How to improve the effectiveness of correcting ionospheric delays for WAAS’s urs under adver conditions.
(5) How to establish the basic theory and the corresponding framework of monitoring the stochastic ionospheric disturbance using GPS
(6) How to improve the modelling ability of ionospheric delay according to its diurnal, asonal, annual variations bad on GPS;
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(7) How to meet the demand of correcting the ionospheric delay of high-precision orbit determination for low-earth satellite using a single frequency GPS receiver
1 Extracting (local) ionospheric information from GPS data with high-precision 世界最大的地震
The factors are systematically described and analyzed which limit the precision of using GPS data to extract ionospheric delays. The precision of determining ionospheric delay using GPS is improved bad on the further rearch of the related models and methods. The main achievements of this work include the some aspects as follows:
(1) Bad on a simple model with constant number of parameters, which consists of a t of trigonometric ries functions, a generalized ionospheric model is constructed who parameters can be adjusted. Due to the property of lecting the different parameters according to the change law of ionospheric delay, the new model has better availability in the field of the related theoretic rearch and engineering application. The experimental results show that the model can indicate the characteristic of ionospheric actions, improves further the modeling ability of local ionosphere and may be ud to correct efficiently ionospheric delay of the single frequency GPS us rviced by DGPS.
(2) Different calculating schemes are designed which are ud to analyze in detail the characteristics of the effect from instrumental bias (IB) in GPS obrvations on determining ionospheric delays. IB is different from noi in GPS obrvations. The experimental results show that the effect of IB is much larger than that of the noi on estimating ionospheic delay, and IB can cau ionospheric delay measurements to include systematic errors of the order of veral meters. Therefore, one must significantly take notice of IB and remove its negative effect, and should not casually consider IB as p
art of noi whenever GPS data are ud to fit ionospheric model or to directly calculate ionospheric delay.
(3) Stability of IB is studied with a refined method for parating it from ionospheric delay using multi-day GPS pha-smoothed code data. The experimental results show that, by using averaging of noi with pha-smoothed code obrvation，血透中心the effect of noi on parating IB from ION can be efficiently reduced, and satellite bias plus receiver bias are relatively stable and may be ud to predict the IBs of the next ssion or even that of the next veral days.
征婚启事(4) A new algorithm about static real time determination of ionospheric delay is prented on the basis of the predicted values of IB and the technique of real time averaging of noi and weighted-adjustment of dual P-code and carrier pha measurements. The preliminary results show that the new method, which is by post-processing pha-smoothed code data to calculate the IB and then with them to predict and to correct the IB of data needed to remove its effects in real time in the next obrvation periods, has r死亡证明村委会怎么写
elatively better accuracy and effectiveness in estimating ionospheric delay. It is very obvious that the scheme can relatively decrea the number of unknown parameters, can efficiently reduce the main negative effect from instrumental bias, and can be easily ud to directly and precily determine ionospheric delay with dual-frequency GPS data. Hence, the method may be considered as an available scheme to determine ionospheric delays for WAAS and many other large range GPS application systems.
