以个性化信息服务(Persionalized Information Service,简写为PIS)研究领域的2008年—2017年中国学术文献网络出版总库中的7 426篇文献为研究样本,以Ucinet软件为分析工具,通过建立关键词——作者2-模二部图,挖掘该研究领域中几个有代...以个性化信息服务(Persionalized Information Service,简写为PIS)研究领域的2008年—2017年中国学术文献网络出版总库中的7 426篇文献为研究样本,以Ucinet软件为分析工具,通过建立关键词——作者2-模二部图,挖掘该研究领域中几个有代表性的科研团队,并根据点度中心度这一网络特征指标对科研团队的核心人物及其主题研究热点进行探寻,为科研团队发现提供了一种新的视角和方法。展开更多
设{Y(t),-∞<t<∞}={X_k(t),-∞<t<∞}_k=1~∞是一个系数为γ_k和λ_k,K=1,2,…的独立的Ornstein-Uhlenbeck过程序列,也就是说,X_k(·)是一个Gauss过程,EX_k(t)=0,EX_k(s)X_k(t)=γ_k/λ_kexp(λ_k|t-s|),k=1,2,…,其中...设{Y(t),-∞<t<∞}={X_k(t),-∞<t<∞}_k=1~∞是一个系数为γ_k和λ_k,K=1,2,…的独立的Ornstein-Uhlenbeck过程序列,也就是说,X_k(·)是一个Gauss过程,EX_k(t)=0,EX_k(s)X_k(t)=γ_k/λ_kexp(λ_k|t-s|),k=1,2,…,其中λ_k≥0,λ_k>0.定义ι~2-模平方过程X^2(t)=||Y(t)||~2=sum from k=1 to ∞( X_k^2(t)),-∞<t<∞.文献[1～5]中研究过这个过程.特别是对于它的连续模,已有较理想的结果.展开更多
The establishment of crop yield estimating model based on microwave and optical satellite images can conduct the mutual verification of the accuracy of the reported crop yield and the precision of the estimating model...The establishment of crop yield estimating model based on microwave and optical satellite images can conduct the mutual verification of the accuracy of the reported crop yield and the precision of the estimating model. With Shou County and Huaiyuan County of Anhui Province as the experimental fields of winter wheat producing areas, the linear winter wheat yield estimating models were established by adopting backscattering coefficient and Normalized Difference Vegetation Index（NDVI） based on images from the synthetic aperture radar（SAR）—RDARSAT-2 and HJ satellite photographed in mid-April and early May, 2014, and then comparisons were conducted on the accuracy of the yield estimating models. The accuracies of the yield estimating models established using co-polarized（HH） and cross-polarized（HV） modes of SAR in Jiangou Town, Shou County were 68.37% and 74.01%, respectively, while the accuracies in Longkang Town, Huaiyuan County were 63.10%and 69.10%, respectively. Accuracies of yield estimating models established by HJ satellite data were 69.52% and 66.43% in Shou County and Huaiyuan County, respectively. Accuracies of winter yield estimating model based on HJ satellite data and that based on SAR were closed, and the yield difference of winter wheat in the lodging region was analyzed in detail. The model results laid the foundation and accumulated experience for the verification, parameters correction and promotion of the winter wheat yield estimating model.展开更多
Let L^2（[0, 1], x） be the space of the real valued, measurable, square summable functions on [0, 1] with weight x, and let n be the subspace of L2（[0, 1], x） defined by a linear combination of Jo（μkX）, where J...Let L^2（[0, 1], x） be the space of the real valued, measurable, square summable functions on [0, 1] with weight x, and let n be the subspace of L2（[0, 1], x） defined by a linear combination of Jo（μkX）, where Jo is the Bessel function of order 0 and {μk} is the strictly increasing sequence of all positive zeros of Jo. For f ∈ L^2（[0, 1], x）, let E（f, n） be the error of the best L2（[0, 1], x）, i.e., approximation of f by elements of n. The shift operator off at point x ∈[0, 1] with step t ∈[0, 1] is defined by T（t）f（x）=1/π∫0^π f（√x^2 ＋t^2-2xtcosO）dθ The differences （I- T（t））^r/2f = ∑j=0^∞（-1）^j（j^r/2）T^j（t）f of order r ∈ （0, ∞） and the L^2（[0, 1],x）- modulus of continuity ωr（f,τ） = sup{｜｜（I- T（t））^r/2f｜｜：0≤ t ≤τ] of order r are defined in the standard way, where T^0（t） = I is the identity operator. In this paper, we establish the sharp Jackson inequality between E（f, n） and ωr（f, τ） for some cases of r and τ. More precisely, we will find the smallest constant n（τ, r） which depends only on n, r, and % such that the inequality E（f, n）≤ n（τ, r）ωr（f, τ） is valid.展开更多
In this note the authors investigates the property of the GF(2)-modules for the wreath products Sz(q)wrCt,and establish some sufficient condition for a Sz(q)wrCt, GF(2)-module to be natural.
文摘以个性化信息服务(Persionalized Information Service,简写为PIS)研究领域的2008年—2017年中国学术文献网络出版总库中的7 426篇文献为研究样本,以Ucinet软件为分析工具,通过建立关键词——作者2-模二部图,挖掘该研究领域中几个有代表性的科研团队,并根据点度中心度这一网络特征指标对科研团队的核心人物及其主题研究热点进行探寻,为科研团队发现提供了一种新的视角和方法。
文摘设{Y(t),-∞<t<∞}={X_k(t),-∞<t<∞}_k=1~∞是一个系数为γ_k和λ_k,K=1,2,…的独立的Ornstein-Uhlenbeck过程序列,也就是说,X_k(·)是一个Gauss过程,EX_k(t)=0,EX_k(s)X_k(t)=γ_k/λ_kexp(λ_k|t-s|),k=1,2,…,其中λ_k≥0,λ_k>0.定义ι~2-模平方过程X^2(t)=||Y(t)||~2=sum from k=1 to ∞( X_k^2(t)),-∞<t<∞.文献[1～5]中研究过这个过程.特别是对于它的连续模,已有较理想的结果.
基金Supported by the National Natural Science Foundation of China(41205126)the Discipline Construction and Macroscopic Agricultural Research Project of Anhui Academy of Agricultural Sciences(13A1424)+2 种基金the Fund for Youth Innovation of Anhui Academy of Agricultural Sciences(14B1460)the Innovative Research Team for Agricultural Disaster Risk Analysis in Anhui ProvinceAnhui Academy of Agricultural Sciences(14C1409)~~
文摘The establishment of crop yield estimating model based on microwave and optical satellite images can conduct the mutual verification of the accuracy of the reported crop yield and the precision of the estimating model. With Shou County and Huaiyuan County of Anhui Province as the experimental fields of winter wheat producing areas, the linear winter wheat yield estimating models were established by adopting backscattering coefficient and Normalized Difference Vegetation Index（NDVI） based on images from the synthetic aperture radar（SAR）—RDARSAT-2 and HJ satellite photographed in mid-April and early May, 2014, and then comparisons were conducted on the accuracy of the yield estimating models. The accuracies of the yield estimating models established using co-polarized（HH） and cross-polarized（HV） modes of SAR in Jiangou Town, Shou County were 68.37% and 74.01%, respectively, while the accuracies in Longkang Town, Huaiyuan County were 63.10%and 69.10%, respectively. Accuracies of yield estimating models established by HJ satellite data were 69.52% and 66.43% in Shou County and Huaiyuan County, respectively. Accuracies of winter yield estimating model based on HJ satellite data and that based on SAR were closed, and the yield difference of winter wheat in the lodging region was analyzed in detail. The model results laid the foundation and accumulated experience for the verification, parameters correction and promotion of the winter wheat yield estimating model.
基金supported partly by National Natural Science Foundation of China (No.10471010)partly by the project"Representation Theory and Related Topics"of the"985 Program"of Beijing Normal University and Beijing Natural Science Foundation (1062004).
文摘Let L^2（[0, 1], x） be the space of the real valued, measurable, square summable functions on [0, 1] with weight x, and let n be the subspace of L2（[0, 1], x） defined by a linear combination of Jo（μkX）, where Jo is the Bessel function of order 0 and {μk} is the strictly increasing sequence of all positive zeros of Jo. For f ∈ L^2（[0, 1], x）, let E（f, n） be the error of the best L2（[0, 1], x）, i.e., approximation of f by elements of n. The shift operator off at point x ∈[0, 1] with step t ∈[0, 1] is defined by T（t）f（x）=1/π∫0^π f（√x^2 ＋t^2-2xtcosO）dθ The differences （I- T（t））^r/2f = ∑j=0^∞（-1）^j（j^r/2）T^j（t）f of order r ∈ （0, ∞） and the L^2（[0, 1],x）- modulus of continuity ωr（f,τ） = sup{｜｜（I- T（t））^r/2f｜｜：0≤ t ≤τ] of order r are defined in the standard way, where T^0（t） = I is the identity operator. In this paper, we establish the sharp Jackson inequality between E（f, n） and ωr（f, τ） for some cases of r and τ. More precisely, we will find the smallest constant n（τ, r） which depends only on n, r, and % such that the inequality E（f, n）≤ n（τ, r）ωr（f, τ） is valid.
文摘In this note the authors investigates the property of the GF(2)-modules for the wreath products Sz(q)wrCt,and establish some sufficient condition for a Sz(q)wrCt, GF(2)-module to be natural.
