Hyperspectral images typically have high spectral resolution but low spatial resolution,which impacts the reliability and accuracy of subsequent applications,for example,remote sensingclassification and mineral identi...Hyperspectral images typically have high spectral resolution but low spatial resolution,which impacts the reliability and accuracy of subsequent applications,for example,remote sensingclassification and mineral identification.But in traditional methods via deep convolution neural net-works,indiscriminately extracting and fusing spectral and spatial features makes it challenging toutilize the differentiated information across adjacent spectral channels.Thus,we proposed a multi-branch interleaved iterative upsampling hyperspectral image super-resolution reconstruction net-work(MIIUSR)to address the above problems.We reinforce spatial feature extraction by integrat-ing detailed features from different receptive fields across adjacent channels.Furthermore,we pro-pose an interleaved iterative upsampling process during the reconstruction stage,which progres-sively fuses incremental information among adjacent frequency bands.Additionally,we add twoparallel three dimensional(3D)feature extraction branches to the backbone network to extractspectral and spatial features of varying granularity.We further enhance the backbone network’sconstruction results by leveraging the difference between two dimensional(2D)channel-groupingspatial features and 3D multi-granularity features.The results obtained by applying the proposednetwork model to the CAVE test set show that,at a scaling factor of×4,the peak signal to noiseratio,spectral angle mapping,and structural similarity are 37.310 dB,3.525 and 0.9438,respec-tively.Besides,extensive experiments conducted on the Harvard and Foster datasets demonstratethe superior potential of the proposed model in hyperspectral super-resolution reconstruction.展开更多
In this article, by applying the super-solution and sub-solution methods, instead of energy estimate methods, the authors investigate the critical extinction exponents for a polytropic filtration equation with a nonlo...In this article, by applying the super-solution and sub-solution methods, instead of energy estimate methods, the authors investigate the critical extinction exponents for a polytropic filtration equation with a nonlocal source and an absorption term, and give a classification of the exponents and coefficients for the solutions to vanish in finite time or not, which improve one of our results (Applicable Analysis, 92(2013), 636-650) and the results of Zheng et al (Math. Meth. Appl. Sci., 36(2013), 730-743).展开更多
—With the increase of converter-based renewable energy generation connected into the power grid, the interaction between renewable energy and grid impedance has introduced lots of new issues, among which the sub-and ...—With the increase of converter-based renewable energy generation connected into the power grid, the interaction between renewable energy and grid impedance has introduced lots of new issues, among which the sub-and super-synchronous oscillation phenomenon makes a big concern. The linear active disturbance rejection control(LADRC) is a potential way to improve the damping characteristics of the grid-connected system, but the key factors and influencing mechanism on system stability are unknown. This paper establishes the equivalent impedance and coupling admittance models of a typical three-phase grid-connected converter. Then, the influence of the key factors such as the bandwidth of the LADRC and grid impedance on the stability and frequency coupling effect is assessed in detail. Finally, the theoretical analysis results are verified by simulations and experiments.展开更多
Naturally allotetraploid cotton has been widely used as an ideal model to investigate gene expression remodeling as a consequence of polyploidization.However,the global gene pattern variation during early fiber develo...Naturally allotetraploid cotton has been widely used as an ideal model to investigate gene expression remodeling as a consequence of polyploidization.However,the global gene pattern variation during early fiber development was unknown.In this study,through RNA-seq technology,we comprehensively investigated the expression patterns of homologous genes between allotetraploid cotton(G.hirsutum)and its diploid progenitors(G.arboreum and G.raimondii)at the fiber early development stage.In tetraploid cotton,genes showed expression level dominance(ELD)bias toward the A genome.This phenomenon was explained by the up-/downregulation of the homologs from the nondominant progenitor(D genome).Gene ontology(GO)enrichment results indicated that the ELD-A genes might be a prominent cause responsible for fiber property change through regulating the fatty acid biosynthesis/metabolism and microtubule procession,and the ELD-D genes might be involved in transcription regulation and stress inducement.In addition,the number and proportion of completely A-and D-subfunctionalized gene were similar at different fiber development stages.However,for neofunctionalization,the number and proportion of reactivated D-derived genes were greater than those of A at 3 and 5 DPA.Eventually,we found that some homologous genes belonging to several specific pathways might create novel asymmetric transcripts between two subgenomes during polyploidization and domestication process,further making the fiber property meet the human demands.Our study identified determinate pathways and their involved genes between allotetraploid cotton and their progenitors at early fiber development stages,providing new insights into the mechanism of cotton fiber evolution.展开更多
Existence of positive solutions of a class of quasi-linear elliptic equation with a gradient term is obtained by using super-solution and sub-solution method. In par- ticular, we study the asymptotic behavior of the s...Existence of positive solutions of a class of quasi-linear elliptic equation with a gradient term is obtained by using super-solution and sub-solution method. In par- ticular, we study the asymptotic behavior of the solution near the boundary up to the second order under various assumptions on the growth of the coefficients of the equa- tion. The results of this paper is new and extend previously known results.展开更多
The modular multilevel converters(MMCs) are popularly used in high-voltage direct current(HVDC) transmission systems. However, for the direct modulation based MMC, its complex internal dynamics and the interaction wit...The modular multilevel converters(MMCs) are popularly used in high-voltage direct current(HVDC) transmission systems. However, for the direct modulation based MMC, its complex internal dynamics and the interaction with the grid impedance would induce the frequency coupling effect, which may lead to instability issues, especially in the case of weak grid. To effectively suppress the sub-and super-synchronous oscillations, this paper proposes a linear active disturbance rejection control(LADRC) based MMC control strategy. The LADRC mainly consists of the linear extended state observer(LESO) and the linear state error feedback(LSEF). And it is a potential method to enhance the system stability margin, attributing to its high anti-interference capability and good tracking performance. Thereupon, the system small-signal impedance model considering frequency coupling is established. And the effect of the introduction of the LADRC on the system stability is further investigated using the Nyquist criterion. Particularly, the influences of key control parameters on the stability are discussed in detail. Meanwhile, the impact of LADRC on the transient performance is explored through closed-loop zero poles. Finally, the correctness of the theoretical analysis and the effectiveness of the proposed control strategy are verified via electromagnetic simulations.展开更多
We study the existence of positive solutions of a population model with diffusion of the form {-△pu=aup-1-f(u)-c/ua,x∈Ω,u=0,x∈Ω where △p denotes the p-Laplacian operator defined by △pz =div(|z|P-2z), p 〉...We study the existence of positive solutions of a population model with diffusion of the form {-△pu=aup-1-f(u)-c/ua,x∈Ω,u=0,x∈Ω where △p denotes the p-Laplacian operator defined by △pz =div(|z|P-2z), p 〉 1, Ω is a bounded domain of RN with smooth boundary, α∈ C (0, 1), a and e are positive constants. Here f : [0, ∞) → R is a continuous function. This model arises in the studies of population biology of one species with u representing the concentration of the species. We discuss the existence of positive solution when f satisfies certain additional conditions. We use the method of sub- and super-solutions to establish our results.展开更多
基金the National Natural Science Foun-dation of China(Nos.61471263,61872267 and U21B2024)the Natural Science Foundation of Tianjin,China(No.16JCZDJC31100)Tianjin University Innovation Foundation(No.2021XZC0024).
文摘Hyperspectral images typically have high spectral resolution but low spatial resolution,which impacts the reliability and accuracy of subsequent applications,for example,remote sensingclassification and mineral identification.But in traditional methods via deep convolution neural net-works,indiscriminately extracting and fusing spectral and spatial features makes it challenging toutilize the differentiated information across adjacent spectral channels.Thus,we proposed a multi-branch interleaved iterative upsampling hyperspectral image super-resolution reconstruction net-work(MIIUSR)to address the above problems.We reinforce spatial feature extraction by integrat-ing detailed features from different receptive fields across adjacent channels.Furthermore,we pro-pose an interleaved iterative upsampling process during the reconstruction stage,which progres-sively fuses incremental information among adjacent frequency bands.Additionally,we add twoparallel three dimensional(3D)feature extraction branches to the backbone network to extractspectral and spatial features of varying granularity.We further enhance the backbone network’sconstruction results by leveraging the difference between two dimensional(2D)channel-groupingspatial features and 3D multi-granularity features.The results obtained by applying the proposednetwork model to the CAVE test set show that,at a scaling factor of×4,the peak signal to noiseratio,spectral angle mapping,and structural similarity are 37.310 dB,3.525 and 0.9438,respec-tively.Besides,extensive experiments conducted on the Harvard and Foster datasets demonstratethe superior potential of the proposed model in hyperspectral super-resolution reconstruction.
基金supported by NSFC(11271154,11401252)Key Lab of Symbolic Computation and Knowledge Engineering of Ministry of Education,the 985 program of Jilin University+1 种基金Fundamental Research Funds of Jilin University(450060501179)supported by Graduate Innovation Fund of Jilin University(2014084)
文摘In this article, by applying the super-solution and sub-solution methods, instead of energy estimate methods, the authors investigate the critical extinction exponents for a polytropic filtration equation with a nonlocal source and an absorption term, and give a classification of the exponents and coefficients for the solutions to vanish in finite time or not, which improve one of our results (Applicable Analysis, 92(2013), 636-650) and the results of Zheng et al (Math. Meth. Appl. Sci., 36(2013), 730-743).
基金supported in part by the National Natural Science Foundation of China (No. 52077222)the Fundamental Research Funds for the Central Universities (No. 19CX02016A)。
文摘—With the increase of converter-based renewable energy generation connected into the power grid, the interaction between renewable energy and grid impedance has introduced lots of new issues, among which the sub-and super-synchronous oscillation phenomenon makes a big concern. The linear active disturbance rejection control(LADRC) is a potential way to improve the damping characteristics of the grid-connected system, but the key factors and influencing mechanism on system stability are unknown. This paper establishes the equivalent impedance and coupling admittance models of a typical three-phase grid-connected converter. Then, the influence of the key factors such as the bandwidth of the LADRC and grid impedance on the stability and frequency coupling effect is assessed in detail. Finally, the theoretical analysis results are verified by simulations and experiments.
基金Funded by the National Key Research and Development Program of China(2016YFD0100203 and 2016YFD0100306)the Foundation and Frontier Research Grant of Henan Provincial Science and Technology Bureau(162300410171).
文摘Naturally allotetraploid cotton has been widely used as an ideal model to investigate gene expression remodeling as a consequence of polyploidization.However,the global gene pattern variation during early fiber development was unknown.In this study,through RNA-seq technology,we comprehensively investigated the expression patterns of homologous genes between allotetraploid cotton(G.hirsutum)and its diploid progenitors(G.arboreum and G.raimondii)at the fiber early development stage.In tetraploid cotton,genes showed expression level dominance(ELD)bias toward the A genome.This phenomenon was explained by the up-/downregulation of the homologs from the nondominant progenitor(D genome).Gene ontology(GO)enrichment results indicated that the ELD-A genes might be a prominent cause responsible for fiber property change through regulating the fatty acid biosynthesis/metabolism and microtubule procession,and the ELD-D genes might be involved in transcription regulation and stress inducement.In addition,the number and proportion of completely A-and D-subfunctionalized gene were similar at different fiber development stages.However,for neofunctionalization,the number and proportion of reactivated D-derived genes were greater than those of A at 3 and 5 DPA.Eventually,we found that some homologous genes belonging to several specific pathways might create novel asymmetric transcripts between two subgenomes during polyploidization and domestication process,further making the fiber property meet the human demands.Our study identified determinate pathways and their involved genes between allotetraploid cotton and their progenitors at early fiber development stages,providing new insights into the mechanism of cotton fiber evolution.
文摘Existence of positive solutions of a class of quasi-linear elliptic equation with a gradient term is obtained by using super-solution and sub-solution method. In par- ticular, we study the asymptotic behavior of the solution near the boundary up to the second order under various assumptions on the growth of the coefficients of the equa- tion. The results of this paper is new and extend previously known results.
基金supported in part by the National Natural Science Foundation of China (No.52077222)in part by the Natural Science Foundation of Shandong Province (No.ZR2020ME202)。
文摘The modular multilevel converters(MMCs) are popularly used in high-voltage direct current(HVDC) transmission systems. However, for the direct modulation based MMC, its complex internal dynamics and the interaction with the grid impedance would induce the frequency coupling effect, which may lead to instability issues, especially in the case of weak grid. To effectively suppress the sub-and super-synchronous oscillations, this paper proposes a linear active disturbance rejection control(LADRC) based MMC control strategy. The LADRC mainly consists of the linear extended state observer(LESO) and the linear state error feedback(LSEF). And it is a potential method to enhance the system stability margin, attributing to its high anti-interference capability and good tracking performance. Thereupon, the system small-signal impedance model considering frequency coupling is established. And the effect of the introduction of the LADRC on the system stability is further investigated using the Nyquist criterion. Particularly, the influences of key control parameters on the stability are discussed in detail. Meanwhile, the impact of LADRC on the transient performance is explored through closed-loop zero poles. Finally, the correctness of the theoretical analysis and the effectiveness of the proposed control strategy are verified via electromagnetic simulations.
文摘We study the existence of positive solutions of a population model with diffusion of the form {-△pu=aup-1-f(u)-c/ua,x∈Ω,u=0,x∈Ω where △p denotes the p-Laplacian operator defined by △pz =div(|z|P-2z), p 〉 1, Ω is a bounded domain of RN with smooth boundary, α∈ C (0, 1), a and e are positive constants. Here f : [0, ∞) → R is a continuous function. This model arises in the studies of population biology of one species with u representing the concentration of the species. We discuss the existence of positive solution when f satisfies certain additional conditions. We use the method of sub- and super-solutions to establish our results.