An experiment was performed in a sunflower field based on sunflower characters and relevant researches available to explore multiple-generation cultiva- tions in Hainan in order to establish a cultivation method of su...An experiment was performed in a sunflower field based on sunflower characters and relevant researches available to explore multiple-generation cultiva- tions in Hainan in order to establish a cultivation method of sunflower inbred line with three generations per year and reduce breeding process of inbred lines. The results showed that the cultivation site is chosen as per relevant standards that ef- fective accumulative temperature （≥5 ℃） is equal to or higher than 1 900 ~C within 110 d from sowing date. It is notable that a good choice of planting site is a guar- antee of the technology and to establish the method cultivating sunflowers with three generations per year is of great significance in terms of reducing breeding process of inbred lines and breeding costs. In addition to that, it provides refer- ences for rapid cultivation of multi-generation sunflowers and improving breeding effi- ciency.展开更多
As the introduction of triple-frequency signals in GNSS,the multi-frequency ionosphere correction technology has been fast developing.References indicate that the triple-frequency second order ionosphere correction is...As the introduction of triple-frequency signals in GNSS,the multi-frequency ionosphere correction technology has been fast developing.References indicate that the triple-frequency second order ionosphere correction is worse than the dual-frequency first order ionosphere correction because of the larger noise amplification factor.On the assumption that the variances of three frequency pseudoranges were equal,other references presented the triple-frequency first order ionosphere correction,which proved worse or better than the dual-frequency first order correction in different situations.In practice,the PN code rate,carrier-to-noise ratio,parameters of DLL and multipath effect of each frequency are not the same,so three frequency pseudorange variances are unequal.Under this consideration,a new unequal-weighted triple-frequency first order ionosphere correction algorithm,which minimizes the variance of the pseudorange ionosphere-free combination,is proposed in this paper.It is found that conventional dual-frequency first-order correction algorithms and the equal-weighted triple-frequency first order correction algorithm are special cases of the new algorithm.A new pseudorange variance estimation method based on the three carrier combination is also introduced.Theoretical analysis shows that the new algorithm is optimal.The experiment with COMPASS G3 satellite observations demonstrates that the ionosphere-free pseudorange combination variance of the new algorithm is smaller than traditional multi-frequency correction algorithms.展开更多
基金Supported by New Variety Breeding and Germplasm Innovation(2016AC027)Modern Key Agricultural S&T and Achievement Transformation Program of Xinjiang Corps(2016AC024)~~
文摘An experiment was performed in a sunflower field based on sunflower characters and relevant researches available to explore multiple-generation cultiva- tions in Hainan in order to establish a cultivation method of sunflower inbred line with three generations per year and reduce breeding process of inbred lines. The results showed that the cultivation site is chosen as per relevant standards that ef- fective accumulative temperature （≥5 ℃） is equal to or higher than 1 900 ~C within 110 d from sowing date. It is notable that a good choice of planting site is a guar- antee of the technology and to establish the method cultivating sunflowers with three generations per year is of great significance in terms of reducing breeding process of inbred lines and breeding costs. In addition to that, it provides refer- ences for rapid cultivation of multi-generation sunflowers and improving breeding effi- ciency.
文摘As the introduction of triple-frequency signals in GNSS,the multi-frequency ionosphere correction technology has been fast developing.References indicate that the triple-frequency second order ionosphere correction is worse than the dual-frequency first order ionosphere correction because of the larger noise amplification factor.On the assumption that the variances of three frequency pseudoranges were equal,other references presented the triple-frequency first order ionosphere correction,which proved worse or better than the dual-frequency first order correction in different situations.In practice,the PN code rate,carrier-to-noise ratio,parameters of DLL and multipath effect of each frequency are not the same,so three frequency pseudorange variances are unequal.Under this consideration,a new unequal-weighted triple-frequency first order ionosphere correction algorithm,which minimizes the variance of the pseudorange ionosphere-free combination,is proposed in this paper.It is found that conventional dual-frequency first-order correction algorithms and the equal-weighted triple-frequency first order correction algorithm are special cases of the new algorithm.A new pseudorange variance estimation method based on the three carrier combination is also introduced.Theoretical analysis shows that the new algorithm is optimal.The experiment with COMPASS G3 satellite observations demonstrates that the ionosphere-free pseudorange combination variance of the new algorithm is smaller than traditional multi-frequency correction algorithms.
