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A modified algorithm for SAR parallel imaging

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重庆邮电大学学报（自然科学版） 2009年第2期21卷 267-271页

作者： HU Ju-rong WANG fei cao Ning LU Hao Department of Electronic and Information Engineering University of HoHai Nanjing 213022 P. R. China

Synthetic aperture radar can provide two dimension images by converting the acquired echoed SAR signal to target’s coordinate and reflectivity. With the advancement of sophisticated SAR signal processing, more and more SAR imaging methods have been proposed for synthetic aperture radar which works at near field and the Fresnel approximation is not appropriate. Time domain correlation is a kind of digital reconstruction method based on processing the synthetic aperture radar data in the two-dimensional frequency domain via Fourier transform. It reconstructs SAR image via simply correlation without any need for approximation or interpolation. But its high computational cost for correlation makes it unsuitable for real time imaging. In order to reduce the computational burden a modified algorithm about time domain correlation was given in this paper. It also can take full advantage of parallel computations of the imaging processor. Its practical implementation was proposed and the preliminary simulation results were presented. Simulation results show that the proposed algorithm is a computationally efficient way of implementing the reconstruction in real time SAR image processing.

关键词：合成孔径雷达并行算法雷达成像雷达信号处理 SAR图像雷达图像处理二维频域实时成像

On the Optimal Initial Inner-Core Size for Tropical Cyclone Intensification: An Idealized Numerical Study

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Advances in Atmospheric Sciences 2024年第11期41卷 2141-2155页

作者： rong fei Yuqing WANG School of Atmospheric Sciences and Remote Sensing Wuxi UniversityWuxi 214105China State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100081China International Pacific Research Center Department of Atmospheric SciencesSchool of Ocean and Earth Science and TechnologyUniversity of Hawaii at ManoaHonoluluHawaii 96822USA

Recent observational and numerical studies have revealed the dependence of the intensification rate on the inner-core size of tropical cyclones(TCs). In this study, with the initial inner-core size(i.e., the radius of maximum wind—RMW)varied from 20–180 km in idealized simulations using two different numerical models, we found a nonmonotonic dependence of the lifetime maximum intensification rate(LMIR) on the inner-core size. Namely, there is an optimal innercore size for the LMIR of a TC. Tangential wind budget analysis shows that, compared to large TCs, small TCs have large inward flux of absolute vorticity due to large absolute vorticity inside the RMW. However, small TCs also suffer from strong lateral diffusion across the eyewall, which partly offsets the positive contribution from large inward flux of absolute vorticity. These two competing processes ultimately lead to the TC with an intermediate initial inner-core size having the largest LMIR. Results from sensitivity experiments show that the optimal size varies in the range of 40–120 km and increases with higher sea surface temperature, lower latitude, larger horizontal mixing length, and weaker initial TC intensity. The 40–120 km RMW corresponds to the inner-core size most commonly found for intensifying TCs in observations, suggesting the natural selection of initial TC size for intensification. This study highlights the importance of accurate representation of TC inner-core size to TC intensity forecasts by numerical weather prediction models.

关键词： tropical cyclones intensification inner-core size idealized simulations

Pt nanodendrites with a PtIr alloy surface structure exhibit excellent stability toward acidic hydrogen evolution reaction

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Nano Research 2024年第6期17卷 4844-4849页

作者： Chang Liu Zongnan Wei Minna cao rong cao State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China University of Chinese Academy of Sciences Beijing 100049China Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou 350108China

The development of effective and stable electrocatalysts for the hydrogen evolution reaction(HER)in acidic electrolytes is a significant *** this work,homogeneous Pt nanodendrites(Pt NDs)with a PtIr shell were successfully synthesized by a two-step wet chemical *** open three-dimensional(3D)dendritic structure exhibited exceptional electrocatalytic characteristics,exposing as many active sites as ***,by alloying Ir with Pt on the surface,catalytic activity was greatly enhanced while ensuring extremely high *** surface-enriched platinum nanodendritic catalysts(Pt@PtIr NDs)outperformed the control samples and the commercial *** acidic HER test,Pt@PtIr NDs had a lower overpotential(22 mV)than Pt NDs(26 mV)and commercial Pt/C(31 mV)at 10 mA/cm^(2),and the activity of Pt@PtIr NDs remained consistent even after undergoing a continuous durability test for at least 168 h,which was much superior to the performance of commercial Pt/C(10 h)under identical test *** study revealed that the application of 3D Pt dendritic metal alloys may offer a chance for the development of enhanced electrocatalysts in acidic HER.

关键词： Pt nanodendrites iridium high stability hydrogen evolution reaction alloy

The response of Martian photoelectron boundary to the 2018 global dust storm

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Science China Earth Sciences 2024年第9期67卷 2772-2782页

作者： Yuqi WANG Jun CUI Yong WEI Zhaopeng WU Kai FAN Zhaojin rong fei HE Yutian cao Jiawei GAO Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Planetary Environmental and Astrobiological Research Laboratory(PEARL) School of Atmospheric SciencesSun Yat-sen UniversityZhuhai 519082China Center for Excellence in Comparative Planetology Chinese Academy of SciencesHefei 230026China

Extensive research efforts have revealed that the Martian dust storms can perturb the upper atmospheric condition and as a consequence,enhance plasma density and photoelectron flux in the ***,previous observational studies of the Martian dust storm impacts have been restricted to regions below 400 km,which limits our understanding of the Martian dust storm effects in the upper ionosphere and ***,based on the suprathermal electron measurements made by the Solar Wind Electron Analyzer onboard the Mars Atmosphere and Volatile Evolution,we identify with an automatic procedure the occurrences of all photoelectron boundary(PEB)crossings at solar zenith angle below 120°(with a dust-free median altitude of about 600 km).Using the dayside PEB as a proxy of the upper ionospheric and magnetospheric condition,we analyze the variations of the PEB altitude during the 2018 global dust storm(GDS)of Mars Year 34(MY34)and compare them with the period in MY33 when there was no global dust *** conclude that the column dust optical depth(CDOD)emerges as one of the main driving factors for PEB altitude variations during the *** analysis implies that the GDS can affect the Martian upper atmosphere and ionosphere over considerable distances and extended time scales.

关键词： Martian global dust storm Martian photoelectron boundary Upper ionosphere

Taphonomy and Paleoecology of Lycoptera: A Case Study from the Lower Jehol Group in Western Liaoning, Northeastern China

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Journal of Earth Science 2024年第3期35卷 737-746页

作者： Zhongwu Lan rong cao Shujing Zhang State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and PalaeontologyChinese Academy of SciencesNanjing 210008China State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesWuhan 430078China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Department of Geology Trinity CollegeDublin 999015Ireland

Taphonomy and paleoecology(biological behavior)of the Early Cretaceous fish fossils are poorly *** study reports for the first time a detailed taphonomical and paleoecological study on Lycoptera in the Mesozoic strata of western Liaoning Province,NE *** XRD analysis shows that gismondine is the dominant clay minerals that could have contributed to the preservation of Lycoptera fossils and microbial mat fragments in the fossil-bearing *** may have formed under volcanism-related hydrothermal regime that was transformed from crystal and lithic ***μ-XRF imaging analysis shows a dominant chemical composition of Al,Si,P,S,Rh,K,Ca,Ti,C,Cr,Mn,Fe,Ni,among which P,Ca,C and S are enriched in the fish skeleton in comparison to the *** suggests a dominant apatite composition for the fish *** influence did not smear off these organic signals probably because of protection of *** coexistance of C and S with Ni is assumed to represent recovered primary productivity following volcanic explosions and toxic gas *** head of juvenile fish stays close to the body of adult *** further discoveries,such phenomenon is interpreted to suggest that adult fish actively protected juvenile fish in the presence of environmental pressures such as anoxia and deterioration of water quality induced by *** acidification and hypoxia in association with volcanism created a harmful environment causing mass extinction of *** adult Lycoptera protected their juveniles by its body at the moment before *** biological behavior will be increasingly reported given the wide occurrence of Lycoptera in Mesozoic strata.

关键词： Lycoptera taphonomy paleoecology fish Jehol Group NE China.

Impacts of pancreatic exocrine insufficiency on gut microbiota

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2024年第4期25卷 271-279页

作者： Yulin GUO Feng cao fei LI Department of General Surgery Xuanwu Hospital of Capital Medical UniversityBeijing 100053China Acute Pancreatitis Clinical Center of Capital Medical University Beijing 100053China

Pancreatic exocrine insufficiency(PEI)can be induced by various kinds of diseases,including chronic pancreatitis,acute pancreatitis,and *** main pathogenetic mechanism of PEI involves the decline of trypsin synthesis,disorder of pancreatic fluid flow,and imbalance of secretion *** studies have shown that PEI could induce gut bacterial overgrowth and dysbiosis,with the abundance of Lactobacillus and Bifidobacterium increasing the most,which could be partially reversed by pancreatic enzyme replacement *** studies have also confirmed the association between PEI and the dysbiosis of gut *** exocrine secretions and changes in duodenal p H as well as bile salt malabsorption brought about by PEI may affect and shape the abundance and composition of gut *** turn,the gut microbiota may impact the pancreatic exocrine acinus through potential bidirectional *** forward,more and higher-quality studies are needed that focus on the mechanism underlying the impact of PEI on the gut microbiota.

关键词： Pancreatic exocrine insufficiency Gut microbiota Gut microbiome Pancreatic enzyme replacement therapy

Self-adaptive gas flow and phase change behaviors during hydrate exploitation by alternate injection of N_(2) and CO_(2)

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Petroleum Science 2024年第3期21卷 2120-2129页

作者： Bo-Jian cao Yi-fei Sun Hong-Nan Chen Jin-rong Zhong Ming-Long Wang Ming Wang Chang-Yu Sun Guang-Jin Chen State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing102249China School of Chemistry and Chemical Engineering Changsha University of Science&TechnologyChangsha410114HunanChina

Since hydrate resources play a part of the stratigraphic framework structure in sediments,establishing a safe and economic method for hydrates exploitation remains the primary challenge to this *** the proposed methods,the spontaneous displacement of CH_(4) from hydrate cages by CO_(2) seems to be a perfect mechanism to address gas production and CO_(2) storage,especially in today's strong demand for carbon reduction and replacing clean *** extensive lab researches,in the past decade,injecting a mixture of CO_(2) and small molecule gas has become a key means to enhance displacement efficiency and has great potential for ***,there is a lack of in-depth research on gas flow in the reservoir,while the injected gas always passes through low-saturated hydrate areas with high permeability and then occurs gas channel in a short term,finally resulting in the decreases in gas production efficiency and produced gas ***,we explored a new injection-production mode of alternate injection of N2 and CO_(2) in order to fully coordinate the advantages of N_(2) in enhanced hydrate decomposition and CO_(2) in solid storage and heat *** alternate"taking"and"storing"processes perfectly repair the problem of the gas channel,achieving self-regulation effect of CH_(4) recovery and CO_(2) *** 3-D experimental results show that compared to the mixed gas injection,CH_(4) recovery is increased by>50%and CO_(2) storage is increased by>70%.Additionally,this alternate injection mode presented a better performance in CH_(4) concentration of produced gas and showed outstanding N_(2) utilization ***,we analyzed its self-adaptive gas flow mechanism and proposed an application model of"one injection and multiple production".We look forward to this study accelerating the application of CO_(2)-CH_(4) replacement technology.

关键词： Hydrate Replacement CH_(4)recovery CO_(2)storage Reservoir remediation

New quantification of symmetry energy from neutron skin thicknesses of 48Ca and 208Pb

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Nuclear Science and Techniques 2024年第10期35卷 217-225页

作者： rong An Shuai Sun Li-Gang cao Feng-Shou Zhang School of Physics Ningxia University Key Laboratory of Beam Technology of the Ministry of Education College of Nuclear Science and TechnologyBeijing Normal University Key Laboratory of Beam Technology of the Ministry of Education Institute of Radiation TechnologyBeijing Academy of Science and Technology Center of Theoretical Nuclear Physics National Laboratory of the Heavy Ion Accelerator of Lanzhou

Precise knowledge of the nuclear symmetry energy can be tentatively calibrated using multimessenger *** neutron skin thickness of a heavy nucleus is one of the most sensitive indicators for probing the isovector components of effective interactions in asymmetric nuclear *** studies have suggested that the experimental data from the CREX and PREX2 collaborations are not mutually compatible with existing nuclear *** this study,we review the quantification of the slope parameter of the symmetry energy L from the neutron skin thicknesses of48Ca *** energy density functionals classified by various isoscalar incompressibility coefficients K were employed to evaluate the bulk properties of finite *** calculated results suggest that the slope parameter L deduced from208Pb is sensitive to the compression modulus of symmetric nuclear matter,but not that *** effective parameter sets classified by K=220 MeV can provide an almost overlapping range of L from48Ca and208Pb.

关键词： Energy density functional Neutron skin thickness Nuclear symmetry energy

Correlation between the charge radii difference in mirror partner nuclei and thesymmetry energy slope

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Chinese Physics C 2024年第8期48卷 177-184页

作者： Xiao-rong Ma Shuai Sun rong An Li-Gang cao School of Physics Ningxia UniversityYinchuan 750021China Key Laboratory of Beam Technology of Ministry of Education College of Nuclear Science and TechnologyBeijing Normal UniversityBeijing 100875China Key Laboratory of Beam Technology of Ministry of Education Institute of Radiation TechnologyBeijing Academy of Science and TechnologyBeijing 100875China

A correlation between the charge radii difference of mirror partner nucleiΔR_(ch) and the slope parameter L of symmetry energy has been built to ascertain the equation of state of isospin asymmetric nuclear *** this work,the influences of pairing correlations and isoscalar compression modulus on theΔRch are systematically investigated based on the Skyrme energy density functional *** calculated results suggest that the linear correlation betweenΔR_(ch) and L is decreased by the surface pairing *** slope parameter deduced from the difference of charge radii of mirror-pair nuclei ^(32)Ar-^(32)Si,^(36)Ca-^(36)S,^(38)Ca-^(38)Ar,and ^(54)Ni-^(54)Fe falls into the range of L=42.57−50.64 MeV,that is,the rather soft equation of state of asymmetric nuclear ***,the range of the slope parameter can also be influenced by the effective forces classified by various isoscalar incompressibility coefficients.

关键词： symmetry energy charge radius mirror-pair nuclei slope parameter