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| 1 | Sparse time-frequency representation of nonlinear and nonstationary data显示文摘Adaptive data analysis provides an important tool in extracting hidden physical information from multiscale data that arise from various applications.In this paper,we review two data-driven time-frequency analysis methods that we introduced recently to study trend and instantaneous frequency of nonlinear and nonstationary data.These methods are inspired by the empirical mode decomposition method(EMD)and the recently developed compressed(compressive)sensing theory.The main idea is to look for the sparsest representation of multiscale data within the largest possible dictionary consisting of intrinsic mode functions of the form{a(t)cos(θ(t))},wherea is assumed to be less oscillatory than cos(θ(t))andθ0.This problem can be formulated as a nonlinear l0optimization problem.We have proposed two methods to solve this nonlinear optimization problem.The frst one is based on nonlinear basis pursuit and the second one is based on nonlinear matching pursuit.Convergence analysis has been carried out for the nonlinear matching pursuit method.Some numerical experiments are given to demonstrate the efectiveness of the proposed methods. | HOU Thomas Yizhao SHI ZuoQiang | 2013 | Science China Mathematics2013，56，12： | 7 |
| 2 | Nitrous oxide emissions from black soils with different pH显示文摘N2O fluxes as a function of incubation time from soil with different available N contents and pH were determined.Cumulative carbon dioxide(CO2) emissions were measured to indicate soil respiration.A 144-hr incubation experiment was conducted in a slightly acidic agricultural soil(pHH2O 5.33) after the pH was adjusted to four different values(3.65,5.00,6.90 and 8.55).The experiments consisted of a control without added N,and with NH+4-N and NO3-N fertilization.The results showed that soil pH contributed significantly to N2O flux from the soils.There were higher N2O emissions in the period 0-12 hr in the four pH treatments,especially those enhanced with Nfertilization.The cumulative N2O-N emission reached a maximum at pH 8.55 and was stimulated by NO3-N fertilization(70.4 μg/kg).The minimum emissions appeared at pH 3.65 and were not stimulated by NO3-N or NH+4-N fertilization.Soil respiration increased significantly due to N-fertilization.Soil respiration increased positively with soil pH(R 2 = 0.98,P < 0.01).The lowest CO2-C emission(30.2 mg/kg) was presented in pH 3.65 soils without N-fertilization.The highest CO2-C emissions appeared in the pH 8.55 soils for NH+4-N fertilization(199 mg/kg).These findings suggested that N2O emissions and soil respiration were significantly influenced by low pH,which strongly inhibits soil microbial nitrification and denitrification activities.The content of NO3-N in soil significantly and positively affected the N2O emissions through denitrification. | Lianfeng Wang Huachao Du Zuoqiang Han Xilin Zhang | 2013 | Journal of Environmental Sciences2013，25，6： | 6 |
| 3 | Local-scale drivers of multi-stemmed tree formation in Acer,in a temperate forest of Northeast China显示文摘Acer is an important genus in temperate forests in Northeast China.Individual Acer trees can re-sprout from the root collar and can occur in clonal units,either as a single-stemmed or multi-stemmed tree.However,the factors that induce multiple-stems in Acer remain only partly understood.In this study,we determined the relative importance of abiotic and biotic variables in driving the production of multiple-stems in this genus,within a 25-hm^2experimental forest dynamics plot in Changbaishan(CBS)temperate forest.We used generalized linear mixed models to perform analyses at two levels(community-and specieslevel).We found seven Acer species in total within the plot,where they form a key part of the forest community.Our results show that abiotic factors play a more important role in producing multi-stemmed trees at the community level in CBS.At the species level,the relative importance of different factors varied among species.Shrub species tended to have a higher frequency of multi-stemmed trees under stressful conditions,whereas tree species tended to have more multi-stemmed trees in more suitable habitat.Our results indicate that the relative importance of different factors influencing the frequency of multi-stemmed individuals in Acer differs at the community and species level in the temperate forest. | Ji Ye Zhanqing Hao Xugao Wang Xuejiao Bai Dingliang Xing Zuoqiang Yuan | 2014 | Chinese Science Bulletin2014，59，3： | 6 |
| 4 | Impact of Urbanization on Low-Temperature Precipitation in Beijing during 1960–2008显示文摘Daily precipitation and temperature records at 13 stations for the period 1960–2008 were analyzed to identify climatic change and possible effects of urbanization on low-temperature precipitation [LTP, precipitation of 0.1 mm d 1occurring under a daily minimum temperature(Tmin) of 0 C] in the greater Beijing region(BJR), where a rapid process of urbanization has taken place over the last few decades. The paper provides a climatological overview of LTP in BJR. LTP contributes 61.7% to the total amount of precipitation in BJR in the cold season(November–March). There is a slight increasing trend [1.22 mm(10 yr) 1] in the amount of total precipitation for the cold season during 1960–2008. In contrast, the amount of LTP decreases by 0.6 mm(10 yr) 1. The warming rate of Tmin in BJR is 0.66 C(10 yr) 1. Correspondingly, the frequency of LTP decreases with increasing Tmin by 0.67 times per C. The seasonal frequency and amount of LTP in southeast BJR(mostly urban sites) are 17%–20% less than those in the northwestern(rural and montane sites). The intensity of LTP for the urban sites and northeastern BJR exhibited significant enhancing trends [0.18 and 0.15 mm d 1(10 yr) 1, respectively]. The frequency of slight LTP(<0.2 mm d 1) significantly decreased throughout BJR [by about 15.74%(10 yr) 1in the urban area and northeast BJR], while the contribution of the two heaviest LTP events to total LTP amount significantly increased by 3.2%(10 yr) 1. | HAN Zuoqiang YAN Zhongwei LI Zhen LIU Weidong WANG Yingchun | 2014 | Advances in Atmospheric Sciences2014，31，1： | 5 |
| 5 | Data-driven time–frequency analysis显示文摘 | Thomas Y. Hou Zuoqiang Shi | 2013 | Applied and Computational Harmonic Analysis2013，，2： | 2 |
| 6 | Point Integral Method for Solving Poisson-Type Equations on Manifolds from Point Clouds with Convergence Guarantees显示文摘Partial differential equations(PDE)on manifolds arise in many areas,including mathematics and many applied fields.Due to the complicated geometrical structure of the manifold,it is difficult to get efficient numerical method to solve PDE on manifold.In the paper,we propose a method called point integral method(PIM)to solve the Poisson-type equations from point clouds.Among different kinds of PDEs,the Poisson-type equations including the standard Poisson equation and the related eigenproblem of the Laplace-Beltrami operator are one of the most important.In PIM,the key idea is to derive the integral equations which approximates the Poisson-type equations and contains no derivatives but only the values of the unknown function.This featuremakes the integral equation easy to be discretized frompoint cloud.In the paper,we explain the derivation of the integral equations,describe the point integral method and its implementation,and present the numerical experiments to demonstrate the convergence of PIM. | Zhen Li Zuoqiang Shi Jian Sun | 2017 | Communications in Computational Physics2017，22，6： | 2 |
| 7 | Provenance of Late Mesozoic Strata and Tectonic Implications for the Southwestern Ordos Basin,North China:Evidence from Detrital Zircon U-Pb Geochronology and Hf Isotopes显示文摘In order to determine the provenance and variation characteristics of sandstone-type uranium deposits located in the southwest Ordos Basin,U-Pb geochronology and Hf isotope analyses were conducted on detrital zircons from the Late Mesozoic strata of the SD01 well in the Zhenyuan area.The detrital zircon U-Pb ages of four samples exhibited four main peaks at 250–330,420–500,1720–2000,and 2340–2580 Ma,with a small number of zircons dated at 770–1100 Ma.The detrital zircon age spectrum and further restriction provided by the in-situ Hf isotopic data suggest that the provenance of each stratum was mainly derived from the crystalline basement rock series(Khondalites,intermediate-acidic intrusive rocks,and metamorphic rocks)of the Alxa Block to the northwest and the Yinshan Block to the north,with minor amounts of Caledonian magmatic rocks and Jingning Period rocks from the western part of the northern Qilian orogenic belt to the west and the northern Qinling orogenic belt to the south.The provenance of the sandbody has not changed significantly and is of the Middle Jurassic–Early Cretaceous.The clear variations in the zircon ages of the samples from the Zhiluo and Anding formations were likely influenced by climate change during the Middle–Late Jurassic.The Triassic zircon age(<250 Ma)first appeared in Early Cretaceous strata,suggesting that tectonic activity was relatively strong in the northern Qinling orogenic belt during the Late Jurassic and produced extensive outcrops of Indo-Chinese granite,which were a source of basin sediments. | Zuoqiang Li Fengjie Li Zheng'an Chen Xuelian Lai Xiaokang Ma | 2022 | Journal of Earth Science2022，33，2： | 2 |
| 8 | Effects of local biotic neighbors and habitat heterogeneity on tree and shrub seedling survival in an old-growth temperate forest显示文摘 | Xuejiao Bai Simon A. Queenborough Xugao Wang Jian Zhang Buhang Li Zuoqiang Yuan Dingliang Xing Fei Lin Ji Ye Zhanqing Hao | 2012 | Oecologia2012，，3： | 1 |
| 9 | Adaptive Data Analysis via Sparse Time-frequency Representation显示文摘 | Hou T Y Shi Zuoqiang | 2011 | Ad- vances in Adaptive Data Analysis2011，3，12： | 1 |
| 10 | Adaptive data analysis via sparse time-frequency representation 显示文摘 | Thomas Y H Shi Zuoqiang | 2011 | Ad vances in Adaptive I)ata Analysis2011，3，12： | 1 |
| 11 | Non-line-of-sight reconstruction with signal–object collaborative regularization显示文摘Non-line-of-sight imaging aims at recovering obscured objects from multiple scattered lights.It has recently received widespread attention due to its potential applications,such as autonomous driving,rescue operations,and remote sensing.However,in cases with high measurement noise,obtaining high-quality reconstructions remains a challenging task.In this work,we establish a unified regularization framework,which can be tailored for different scenarios,including indoor and outdoor scenes with substantial background noise under both confocal and non-confocal settings.The proposed regularization framework incorporates sparseness and non-local self-similarity of the hidden objects as well as the smoothness of the signals.We show that the estimated signals,albedo,and surface normal of the hidden objects can be reconstructed robustly even with high measurement noise under the proposed framework.Reconstruction results on synthetic and experimental data show that our approach recovers the hidden objects faithfully and outperforms state-of-the-art reconstruction algorithms in terms of both quantitative criteria and visual quality. | Xintong Liu Jianyu Wang Zhupeng Li Zuoqiang Shi Xing Fu Lingyun Qiu | 2021 | Light(Science & Applications)2021，10，10： | 1 |
| 12 | Powerful supercontinuum vortices generated by femtosecond vortex beams with thin plates显示文摘We demonstrate numerically and experimentally the generation of powerful supercontinuum vortices from femtosecond vortex beams by using multiple thin fused silica plates.The supercontinuum vortices are shown to preserve the vortex phase profile of the initial beam for spectral components ranging from 500 nm to 1200 nm.The transfer of the vortex phase profile results from the inhibition of multiple filamentation and the preservation of the vortex ring with relatively uniform intensity distribution by means of the thin-plate scheme,where the supercontinuum is mainly generated from the self-phase modulation and self-steepening effects.Our scheme works for vortex beams with different topological charges,which provides a simple and effective method to generate supercontinuum vortices with high power. | Litong Xu Dongwei Li Junwei Chang Deming Li Tingting Xi Zuoqiang Hao | 2022 | Photonics Research2022，10，3： | 1 |
| 13 | Similarity between seed rain and neighbouring mature tree communities in an old-growth temperate forest显示文摘Seed distribution and deposition patterns around parent trees are strongly aff ected by functional traits and therefore infl uence the development of plant communities.To assess the limitations of seed dispersal and the extent to which diaspore and neighbouring parental traits explain seed rain,we used a 9-year seed data set based on 150 seed traps in a 25-ha area of a temperate forest in the Changbai Mountain.Among 480,598 seeds belonging to 12 families,17 genera,and 26 species were identifi ed,only 54%of the species with mature trees in the community were represented in seeds collected over the 9 years,indicating a limitation in seed dispersal.Understory species were most limited;overstory species were least limited.Species with wind-dispersed seed had the least limitation,while the lowest similarity in species richness was for animal-dispersed species followed by gravity-dispersed species;fl eshy-fruited species had stronger dispersal limitations than dry-fruited species.Generalized linear mixed models showed that relative basal area had a signifi cant positive eff ect on seed abundance in traps,while the contribution of diaspore traits was low for nearly all groups.These results suggest that tree traits had the strongest contribution to seed dispersal and deposition for all functional groups examined here.These fi ndings strengthen the knowledge that tree traits are key in explaining seed deposition patterns,at least at the primary dispersal stage.This improved knowledge of sources of seeds that are dispersed could facilitate greater understanding of seedling and community dynamics in temperate forests. | Yunyun Wang Jalene M.La.Montagne Fei Lin Zuoqiang Yuan Ji Ye Xugao Wang Zhanqing Hao | 2020 | Journal of Forestry Research2020，31，6： | 1 |
| 14 | Characteristics of multiple filaments generated by femtosecond laser pulses in air: Prefoeused versus free propagation显示文摘 | Zuoqiang Hao Jie Zhang Zhe Zhang | 2006 | Phys Rev E2006，，： | 1 |
| 15 | Multiple filamentation of non-uniformly focused ultrashort laser pulses显示文摘 | Hao Zuoqiang Salame R Lascoux N | 2009 | Applied Physics B:Lasers and Optics2009，94，2： | 1 |
| 16 | Adaptive Data Analysis Via Sparse Time - frequency Representation 显示文摘 | Hou T Y Shi Zuoqiang | 2011 | Advances in Adaptive Data Analysis2011，3，12： | 1 |
| 17 | guanyu yan huanghe yan jiaotong ganxian jingjidai zhongdian gongye yuanqu kaifaqu changye fazhan de jige wenti (Several Issues Related to Industrial Development in the Key Industrial Park of Economic Zone along the Yellow River and the Key Transportation 显示文摘 | Wang Zuoqiang | | 0，，07： | 1 |
| 18 | CONVERGENCE OF THE WEIGHTED NONLOCAL LAPLACIAN ON RANDOM POINT CLOUD显示文摘We analyze the convergence of the weighted nonlocal Laplacian(WNLL)on the high dimensional randomly distributed point cloud.Our analysis reveals the importance of the scaling weight,µ∼|P|/|S|with|P|and|S|being the number of entire and labeled data,respectively,in WNLL.The established result gives a theoretical foundation of the WNLL for high dimensional data interpolation. | Zuoqiang Shi Bao Wang | 2021 | Journal of Computational Mathematics2021，39，6： | 0 |
| 19 | Powerful supercontinuum vortices generated by femtosecond vortex beams with thin plates: publisher’s note显示文摘 | Litong Xu Dongwei Li Junwei Chang Deming Li Tingting Xi Zuoqiang Hao | 2022 | Photonics Research2022，10，4： | 0 |
| 20 | A two-level method for sparse time-frequency representation of multiscale data Dedicated to Professor LI TaTsien on the Occasion of His 80th Birthday显示文摘Based on the recently developed data-driven time-frequency analysis(Hou and Shi, 2013), we propose a two-level method to look for the sparse time-frequency decomposition of multiscale data. In the two-level method, we first run a local algorithm to get a good approximation of the instantaneous frequency. We then pass this instantaneous frequency to the global algorithm to get an accurate global intrinsic mode function(IMF)and instantaneous frequency. The two-level method alleviates the difficulty of the mode mixing to some extent.We also present a method to reduce the end effects. | LIU ChunGuang SHI ZuoQiang HOU Thomas Yizhao | 2017 | Science China Mathematics2017，60，10： | 0 |
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