In this paper,a new type of finite difference mapped weighted essentially non-oscillatory(MWENO)schemes with unequal-sized stencils,such as the seventh-order and ninthorder versions,is constructed for solving hyperbol...In this paper,a new type of finite difference mapped weighted essentially non-oscillatory(MWENO)schemes with unequal-sized stencils,such as the seventh-order and ninthorder versions,is constructed for solving hyperbolic conservation laws.For the purpose of designing increasingly high-order finite difference WENO schemes,the equal-sized stencils are becoming more and more wider.The more we use wider candidate stencils,the bigger the probability of discontinuities lies in all stencils.Therefore,one innovation of these new WENO schemes is to introduce a new splitting stencil methodology to divide some fourpoint or five-point stencils into several smaller three-point stencils.By the usage of this new methodology in high-order spatial reconstruction procedure,we get different degree polynomials defined on these unequal-sized stencils,and calculate the linear weights,smoothness indicators,and nonlinear weights as specified in Jiang and Shu(J.Comput.Phys.126:202228,1996).Since the difference between the nonlinear weights and the linear weights is too big to keep the optimal order of accuracy in smooth regions,another crucial innovation is to present the new mapping functions which are used to obtain the mapped nonlinear weights and decrease the difference quantity between the mapped nonlinear weights and the linear weights,so as to keep the optimal order of accuracy in smooth regions.These new MWENO schemes can also be applied to compute some extreme examples,such as the double rarefaction wave problem,the Sedov blast wave problem,and the Leblanc problem with a normal CFL number.Extensive numerical results are provided to illustrate the good performance of the new finite difference MWENO schemes.展开更多
Efficient numerical solver for the SchrSdinger equation is very important in physics and chemistry. The finite element discrete variable representation （FE-DVR） was first proposed by Rescigno and Mc-Curdy [Phys. Rev...Efficient numerical solver for the SchrSdinger equation is very important in physics and chemistry. The finite element discrete variable representation （FE-DVR） was first proposed by Rescigno and Mc-Curdy [Phys. Rev. A 62, 032706 （2000）] for solving quantum-mechanical scattering problems. In this work, an FE-DVR method in a mapped coordinate was proposed to improve the efficiency of the original FE-DVR method. For numerical demonstration, the proposed approach is applied for solving the electronic eigenfunctions and eigenvalues of the hydrogen atom and vibrational states of the electronic state 3E＋ of the Cs2 molecule which has long-range interaction potential. The numerical results indicate that the numerical efficiency of the original FE-DVR has been improved much using our proposed mapped coordinate scheme.展开更多
The lianghui, or the annual Two Sessions of the National People＇s Congress （NPC） and the Chinese People＇s Political Consultative Conference （CPPCC） National Committee, are always a great political event in China...The lianghui, or the annual Two Sessions of the National People＇s Congress （NPC） and the Chinese People＇s Political Consultative Conference （CPPCC） National Committee, are always a great political event in China, but more so this year, with groundbreaking outcomes.展开更多
We report on the photodissociation dynamics of CO2^＋ via its A2Пu,1/2 state using the scheme of [1＋1] photon excitation that is intermediated by the mode-selected A2Hu,1/2（Vl,V2,0） vibronic states. Photodissociat...We report on the photodissociation dynamics of CO2^＋ via its A2Пu,1/2 state using the scheme of [1＋1] photon excitation that is intermediated by the mode-selected A2Hu,1/2（Vl,V2,0） vibronic states. Photodissociation fragment exciation spectrum and images of photofragment CO＋ have been measured to obtain reaction dynamics parameters such as the available energy and the average translational energy. Combining with the potential energy functions of CO2^＋, the dissociation mechanism of CO2^＋ is discussed. The conformational variation of CO2^＋ from linear to bent on the photodissociation dynamics of CO2^＋ is verified.展开更多
Despite many studies on land degradation in the Highlands of Northern Ethiopia, quantitative information regarding long-term changes in land use/cover(LUC) is rare. Hence, this study aims to investigate the LUC change...Despite many studies on land degradation in the Highlands of Northern Ethiopia, quantitative information regarding long-term changes in land use/cover(LUC) is rare. Hence, this study aims to investigate the LUC changes in the Geba catchment(5142 km2), Northern Ethiopia, over 80 years(1935–2014). Aerial photographs(APs) of the 1930 s and Google Earth(GE) images(2014) were used. The point-count technique was utilized by overlaying a grid on APs and GE images. The occurrence of cropland, forest, grassland, shrubland, bare land, built-up areas and water body was counted to compute their fractions. A multivariate adaptive regression spline was applied to identify the explanatory factors of LUC and to create fractional maps of LUC. The results indicate significant changes of most types, except for forest and cropland. In the 1930 s, shrubland(48%) was dominant, followed by cropland(39%). The fraction of cropland in 2014(42%) remained approximately the same as in the 1930 s, while shrubland significantly dropped to 37%. Forests shrank further from a meagre 6.3% in the 1930 s to 2.3% in 2014. High overall accuracies(93% and 83%) and strong Kappa coefficients(89% and 72%) for point counts and fractional maps respectively indicate the validity of the techniques used for LUC mapping.展开更多
The bsd-pg（bundle sheath defective pale green） mutant is a novel maize mutation, controlled by a single recessive gene, which was isolated from offspring of maize plantlets regenerated from tissue callus of the maiz...The bsd-pg（bundle sheath defective pale green） mutant is a novel maize mutation, controlled by a single recessive gene, which was isolated from offspring of maize plantlets regenerated from tissue callus of the maize inbred line 501. The characterization was that the biogenesis and development of the chloroplasts was mainly interfered in bundle sheath cells rather than in mesophyll cells. For mapping the bsd-pg, an F2 population was derived from a cross between the mutant bsd-pg and an inbred line Xianzao 17. Using specific locus amplified fragment sequencing（SLAF-Seq） technology, a total of 5 783 polymorphic SLAFs were analysed with 1 771 homozygous alleles between maternal and paternal parents. There were 49 SLAFs, which had a ratio of paternal to maternal alleles of 2：1 in bulked normal lines, and three trait-related candidate regions were obtained on chromosome 1 with a size of 3.945 Mb. For the fine mapping, new simple sequence repeats（SSRs） markers were designed by utilizing information of the B73 genome and the candidate regions were localized a size of 850 934 bp on chromosome 1 between umc1603 and umc1395, including 35 candidate genes. These results provide a foundation for the cloning of bsd-pg by map-based strategy, which is essential for revealing the functional differentiation and coordination of the two cell types, and helps to elucidate a comprehensive understanding of the C4 photosynthesis pathway and related processes in maize leaves.展开更多
The displacement discontinuity method(DDM) is a kind of boundary element method aiming at modeling two-dimensional linear elastic crack problems. The singularity around the crack tip prevents the DDM from optimally co...The displacement discontinuity method(DDM) is a kind of boundary element method aiming at modeling two-dimensional linear elastic crack problems. The singularity around the crack tip prevents the DDM from optimally converging when the basis functions are polynomials of first order or higher. To overcome this issue,enlightened by the mapped finite element method(FEM) proposed in Ref. [13], we present an optimally convergent mapped DDM in this work, called the mapped DDM(MDDM). It is essentially based on approximating a much smoother function obtained by reformulating the problem with an appropriate auxiliary map. Two numerical examples of crack problems are presented in comparison with the conventional DDM. The results show that the proposed method improves the accuracy of the DDM; moreover, it yields an optimal convergence rate for quadratic interpolating polynomials.展开更多
基金the NSFC grant 11872210 and the Science Challenge Project,No.TZ2016002the NSFC Grant 11926103 when he visited Tianyuan Mathematical Center in Southeast China,Xiamen 361005,Fujian,Chinathe NSFC Grant 12071392 and the Science Challenge Project,No.TZ2016002.
文摘In this paper,a new type of finite difference mapped weighted essentially non-oscillatory(MWENO)schemes with unequal-sized stencils,such as the seventh-order and ninthorder versions,is constructed for solving hyperbolic conservation laws.For the purpose of designing increasingly high-order finite difference WENO schemes,the equal-sized stencils are becoming more and more wider.The more we use wider candidate stencils,the bigger the probability of discontinuities lies in all stencils.Therefore,one innovation of these new WENO schemes is to introduce a new splitting stencil methodology to divide some fourpoint or five-point stencils into several smaller three-point stencils.By the usage of this new methodology in high-order spatial reconstruction procedure,we get different degree polynomials defined on these unequal-sized stencils,and calculate the linear weights,smoothness indicators,and nonlinear weights as specified in Jiang and Shu(J.Comput.Phys.126:202228,1996).Since the difference between the nonlinear weights and the linear weights is too big to keep the optimal order of accuracy in smooth regions,another crucial innovation is to present the new mapping functions which are used to obtain the mapped nonlinear weights and decrease the difference quantity between the mapped nonlinear weights and the linear weights,so as to keep the optimal order of accuracy in smooth regions.These new MWENO schemes can also be applied to compute some extreme examples,such as the double rarefaction wave problem,the Sedov blast wave problem,and the Leblanc problem with a normal CFL number.Extensive numerical results are provided to illustrate the good performance of the new finite difference MWENO schemes.
文摘Efficient numerical solver for the SchrSdinger equation is very important in physics and chemistry. The finite element discrete variable representation （FE-DVR） was first proposed by Rescigno and Mc-Curdy [Phys. Rev. A 62, 032706 （2000）] for solving quantum-mechanical scattering problems. In this work, an FE-DVR method in a mapped coordinate was proposed to improve the efficiency of the original FE-DVR method. For numerical demonstration, the proposed approach is applied for solving the electronic eigenfunctions and eigenvalues of the hydrogen atom and vibrational states of the electronic state 3E＋ of the Cs2 molecule which has long-range interaction potential. The numerical results indicate that the numerical efficiency of the original FE-DVR has been improved much using our proposed mapped coordinate scheme.
文摘The lianghui, or the annual Two Sessions of the National People＇s Congress （NPC） and the Chinese People＇s Political Consultative Conference （CPPCC） National Committee, are always a great political event in China, but more so this year, with groundbreaking outcomes.
基金This work was supported by the Natural Science Foundation of Changzhou Institute of Technology （No.YN1507）, Undergraduate Training Program for Innovation of Changzhou Institute of Technology （No.J150245）, the China Postdoctoral Science Foundation （No.2013M531506）, the National Natural Science Foundation of China （No.21273212）.
文摘We report on the photodissociation dynamics of CO2^＋ via its A2Пu,1/2 state using the scheme of [1＋1] photon excitation that is intermediated by the mode-selected A2Hu,1/2（Vl,V2,0） vibronic states. Photodissociation fragment exciation spectrum and images of photofragment CO＋ have been measured to obtain reaction dynamics parameters such as the available energy and the average translational energy. Combining with the potential energy functions of CO2^＋, the dissociation mechanism of CO2^＋ is discussed. The conformational variation of CO2^＋ from linear to bent on the photodissociation dynamics of CO2^＋ is verified.
基金a scholarship of the Special Research Fund (BOF) obtained from Ghent University, Belgiumpartially covered by the RIP-MU (VLIR, Belgium) project
文摘Despite many studies on land degradation in the Highlands of Northern Ethiopia, quantitative information regarding long-term changes in land use/cover(LUC) is rare. Hence, this study aims to investigate the LUC changes in the Geba catchment(5142 km2), Northern Ethiopia, over 80 years(1935–2014). Aerial photographs(APs) of the 1930 s and Google Earth(GE) images(2014) were used. The point-count technique was utilized by overlaying a grid on APs and GE images. The occurrence of cropland, forest, grassland, shrubland, bare land, built-up areas and water body was counted to compute their fractions. A multivariate adaptive regression spline was applied to identify the explanatory factors of LUC and to create fractional maps of LUC. The results indicate significant changes of most types, except for forest and cropland. In the 1930 s, shrubland(48%) was dominant, followed by cropland(39%). The fraction of cropland in 2014(42%) remained approximately the same as in the 1930 s, while shrubland significantly dropped to 37%. Forests shrank further from a meagre 6.3% in the 1930 s to 2.3% in 2014. High overall accuracies(93% and 83%) and strong Kappa coefficients(89% and 72%) for point counts and fractional maps respectively indicate the validity of the techniques used for LUC mapping.
基金supported by the National Natural Science Foundation of China (30700476 and 31071057)the Beijing Natural Science Foundation, China (5083021)
文摘The bsd-pg（bundle sheath defective pale green） mutant is a novel maize mutation, controlled by a single recessive gene, which was isolated from offspring of maize plantlets regenerated from tissue callus of the maize inbred line 501. The characterization was that the biogenesis and development of the chloroplasts was mainly interfered in bundle sheath cells rather than in mesophyll cells. For mapping the bsd-pg, an F2 population was derived from a cross between the mutant bsd-pg and an inbred line Xianzao 17. Using specific locus amplified fragment sequencing（SLAF-Seq） technology, a total of 5 783 polymorphic SLAFs were analysed with 1 771 homozygous alleles between maternal and paternal parents. There were 49 SLAFs, which had a ratio of paternal to maternal alleles of 2：1 in bulked normal lines, and three trait-related candidate regions were obtained on chromosome 1 with a size of 3.945 Mb. For the fine mapping, new simple sequence repeats（SSRs） markers were designed by utilizing information of the B73 genome and the candidate regions were localized a size of 850 934 bp on chromosome 1 between umc1603 and umc1395, including 35 candidate genes. These results provide a foundation for the cloning of bsd-pg by map-based strategy, which is essential for revealing the functional differentiation and coordination of the two cell types, and helps to elucidate a comprehensive understanding of the C4 photosynthesis pathway and related processes in maize leaves.
基金the National Natural Science Foundation of China(No.11402146)the Young 1000 Talent Program of China
文摘The displacement discontinuity method(DDM) is a kind of boundary element method aiming at modeling two-dimensional linear elastic crack problems. The singularity around the crack tip prevents the DDM from optimally converging when the basis functions are polynomials of first order or higher. To overcome this issue,enlightened by the mapped finite element method(FEM) proposed in Ref. [13], we present an optimally convergent mapped DDM in this work, called the mapped DDM(MDDM). It is essentially based on approximating a much smoother function obtained by reformulating the problem with an appropriate auxiliary map. Two numerical examples of crack problems are presented in comparison with the conventional DDM. The results show that the proposed method improves the accuracy of the DDM; moreover, it yields an optimal convergence rate for quadratic interpolating polynomials.
文摘针对飞机复合材料缺陷红外图像分辨率较低、检测精度不高等导致缺陷特征难以准确表征的问题,本文提出了一种YOLOv7-FSE(YOLOv7 FReLU-SiLU-EIOU)的改进检测算法。该算法首先将YOLOv7中SiLU激活函数替换为漏斗激活函数FReLU,提高对缺陷特征的空间敏感性。然后使用SPD-Conv(Space to depth Convolution)卷积改进特征提取方式,提升算法对低分辨率红外图像缺陷复杂特征的表征能力。最后将EIOU损失函数替代CIOU损失函数,通过优化边界框识别权重使其聚焦于生成更高质量锚框提升整体检测性能。对比结果表明,本算法相较于其他检测方法如Faster-RCNN、YOLOv3的mAP精度值分别提高10.8%、10.1%。与YOLOv7算法相比,YOLOv7-FSE算法的P精确度由88.3%提高到94.9%,mAP由90.1%提高到97.7%。该算法可应用在飞机表面复合材料缺陷的红外检测中,在结合搭载嵌入式设备开展快速检测方面具有潜在应用前景。
