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塔克拉玛干沙漠南缘新月形沙丘移动特征

干旱区研究 2024年第4期41卷 661-673页

作者：刘鑫高鑫中国科学院新疆生态与地理研究所国家荒漠-绿洲生态建设工程技术研究中心新疆乌鲁木齐830011 中国科学院大学北京100049

新月形沙丘的移动特征可以反映区域内风沙运移和地貌演化过程,对于科学开展风沙灾害防治具有重要意义。本文利用卫星遥感影像与气象再分析数据,研究了塔克拉玛干沙漠南缘6个新月形沙丘群2012—2022年的形态变化与移动特征。结果表明:(1... 详细信息

新月形沙丘的移动特征可以反映区域内风沙运移和地貌演化过程,对于科学开展风沙灾害防治具有重要意义。本文利用卫星遥感影像与气象再分析数据,研究了塔克拉玛干沙漠南缘6个新月形沙丘群2012—2022年的形态变化与移动特征。结果表明:(1)研究区域内新月形沙丘平均移动速率为6.86 m·a^(-1),移动方向与对应区域内盛行风方向基本一致;(2)不同区域内新月形沙丘形态参数之间的关联性呈现显著差异;(3)沙丘高度、下垫面植被覆盖、年均降雨量以及地表温度与沙丘移动速率呈负相关关系,分区拟合结果有差异;(4)且末西南区域的年平均输沙通量约为77120.5 kg·m^(-1)。研究结果反映了新月形沙丘移动规律的复杂性,不同地理环境因子的影响程度或存在显著差异,需结合实地情况进行具体分析。同时,在沙丘演化过程中,形态参数的动态变化反映了沙丘迁移的内在机理,进一步为新月形沙丘的发育机理提供了实证数据,也为沙丘危害防治和土地规划提供了参考依据。

关键词：新月形沙丘移动速率形态参数风况塔克拉玛干沙漠南缘

Two Nonmonotone Proximal Gradient Methods for Nonsmooth Optimization over the Stiefel Manifold

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Acta Mathematicae Applicatae Sinica 2024年

作者： Jin-chao ZHANG Juan GAO Ya-kui HUANG xin-wei liu School of Artificial Intelligence Hebei University of Technology Institute of Mathematics Hebei University of Technology

We propose two nonmonotone retraction-based proximal gradient methods for solving a class of nonconvex nonsmooth optimization problems over the Stiefel manifold. The proposed methods are equipped with the descent direction obtained by a proximal mapping restricted in tangent space of the manifold and the BarzilaiBorwein stepsizes determined by two recent iteration points and the corresponding descent directions. By employing, respectively, the Grippo-Lampariello-Lucidi nonmonotone line search strategy and the Dai-Fletcher nonmonotone line search strategy, our proposed methods are proved to be globally convergent. Analysis on the iteration complexity of NPGL for obtaining an?-stationary solution is provided. Numerical results on the sparse principle component analysis problems demonstrate the efficiency of our methods.

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VT3D:a visualization toolbox for 3D transcriptomic data

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Journal of Genetics and Genomics 2023年第9期50卷 713-719页

作者： Lidong Guo Yao Li Yanwei Qi Zhi Huang Kai Han Xiaobin liu xin liu Mengyang Xu Guangyi Fan College of Life Sciences University of Chinese Academy of SciencesBeijing 100049China BGI-Qingdao BGI-ShenzhenQingdaoShandong 266555China BGI-Shenzhen ShenzhenGuangdong 518083China State Key Laboratory of Agricultural Genomics BGI-ShenzhenShenzhenGuangdong 518083China

Data visualization empowers researchers to communicate their results that support scientific reasoning in an intuitive way.Three-dimension(3D)spatially resolved transcriptomic atlases constructed from multi-view and high-dimensional data have rapidly emerged as a powerful tool to unravel spatial gene expression patterns and cell type distribution in biological samples,revolutionizing the understanding of gene regulatory interactions and cell niches.However,limited accessible tools for data visualization impede the potential impact and application of this technology.Here we introduce VT3D,a visualization toolbox that allows users to explore 3D transcriptomic data,enabling gene expression projection to any 2D plane of interest,2D virtual slice creation and visualization,and interactive 3D data browsing with surface model plots.In addition,it can either work on personal devices in standalone mode or be hosted as a web-based server.We apply VT3D to multiple datasets produced by the most popular techniques,including both sequencing-based approaches(Stereo-seq,spatial transcriptomics,and Slide-seq)and imaging-based approaches(MERFISH and STARMap),and successfully build a 3D atlas database that allows interactive data browsing.We demonstrate that VT3D bridges the gap between researchers and spatially resolved transcriptomics,thus accelerating related studies such as embryogenesis and organogenesis processes.The source code of VT3D is available at https://***/BGI-Qingdao/VT3D,and the modeled atlas database is available at http://***/vt3d_example.

关键词： Spatially resolved transcriptomics Stereo-seq Spatial transcriptomics MERFISH 3D visualization Data sharing Virtual slice

D-Optimal Designs for Hierarchical Linear Models with Heteroscedastic Errors

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Communications in Mathematics and Statistics 2022年第4期10卷 669-679页

作者： xin liu Rong-Xian Yue Kashinath Chatterjee College of Science Donghua UniversityShanghai 201620People’s Republic of China Department of Mathematics Shanghai Normal UniversityShanghai 200234People’s Republic of China Department of Statistics Visva-Bharati UniversitySantiniketanIndia

This paper investigates the optimal design problem for the prediction of the individual parameters in hierarchical linear models with heteroscedastic errors.An equivalence theorem is established to characterize D-optimality of designs for the prediction based on the mean squared error matrix.The admissibility of designs is also considered and a sufficient condition to simplify the design problem is obtained.The results obtained are illustrated in terms of a simple linear model with random slope and heteroscedastic errors.

关键词： D-optimal design Heteroscedasticity Mean squared error matrix Mixed-effect model Equivalence theorem Admissibility

Novel P2-type layered medium-entropy ceramics oxide as cathode material for sodium-ion batteries

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Journal of Advanced Ceramics 2022年第1期11卷 158-171页

作者： Shengxue YAN Shaohua LUO liu YANG Jian FENG Pengwei LI Qing WANG Yahui ZHANG xin liu School of Materials Science and Engineering Northeastern UniversityShenyang 110819China Key Laboratory of Dielectric and Electrolyte Functional Material Hebei Province School of Resources and MaterialsNortheastern University at QinhuangdaoQinhuangdao 066004China School of Resources and Materials Northeastern University at QinhuangdaoQinhuangdao 066004China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China

High-entropy oxides(HEOs)and medium-entropy oxides(MEOs)are new types of single-phase solid solution materials.MEOs have rarely been reported as positive electrode material for sodium-ion batteries(SIBs).In this study,we first proposed the concept of the application of MEOs in SIBs.P2-type 3-cation oxide Na_(2/3)Ni_(1/3)Mn_(1/3)Fe_(1/3)O_(2)(NaNMF)and 4-cation oxide Na_(2/3)Ni_(1/3)Mn_(1/3)Fe_(1/3-x)Al_(x)O_(2)(NaNMFA)were prepared using the solid-state method,rather than the doping technology.In addition,the importance of the concept of entropy stabilization in material performance and battery cycling was demonstrated by testing 3-cation(NaNMF)and 4-cation(NaNMFA)oxides in the same system.Thus,NaNMFA can provide a reversible capacity of about 125.6 mAh-g”1 in the voltage range of 2-4.2 V,and has enhanced cycle stability.The capacity and decay law of the MEO batteries indicate that the configurational entropy(1.28 R(NaNMFA)>1.10 R(NaNMF))of the cationic system,is the main factor affecting the structural and cycle stability of the electrode material.This work emphasizes that the rational design of MEOs with novel structures and different electrochemically active elements may be the strategy for exploring high-performance SIB cathode materials in next-generation energy storage devices.

关键词： cathode materials medium-entropy oxide(MEO) configuration entropy electrochemical performance sodium-ion batteries(SIBs)

Water-promoted regio-selective trifluoromethylation of vinyl conjugated diazoacetates

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Organic Chemistry Frontiers 2022年第1期9卷 204-209页

作者： xinxin Han xin liu Yueyun Bao Hunahuan Song Yu-Rou Zhao Xiaoying Wang Junjie Zhang Le liu xin-Hua Duan Jinbo Hu Mingyou Hu School of Chemistry Xi’an Key Laboratory of Sustainable Energy Material Chemistryand MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed MatterXi’an Jiaotong UniversityXi’an 710049China Key Laboratory of Organofluorine Chemistry Center for Excellence in Molecular SynthesisShanghai Institute of Organic ChemistryUniversity of Chinese Academy of SciencesChinese Academy of SciencesShanghai 200032China

An efficient trifluoromethylation reaction of vinyldiazoacetates under mild reaction conditions was depicted.Pre-generated CuCF_(3) was used as a trifluoromethylation reagent and water acted as both a promoter and proton source.The reaction is compatible with a broad scope of functional groups and easy to scale-up.The wide functional group tolerance of the reaction enables further synthetic manipulation of the products.

关键词： products vinyl conjugated

A novel non-contact remote interrogate system based on 5G telecommunication technique during cardiac implantable electrical devices implantation against the background of the global COVID-19 pandemic

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Chinese Medical Journal 2023年第5期136卷 623-625页

作者： Hong Zhang Hai Gao xin liu Xijuan Mu Xiaodong Shi Division of Cardiology Beijing Anzhen HospitalCapital Medical UniversityBeijing 100029China Beijing Nuclear Hospital Beijing 100045China.

To the Editor:Cardiac implantable electrical devices(CIEDs)are the most effective method of treating and diagnosing several different kinds of arrhythmia and heart failure.It is necessary for a clinician to evaluate the parameters of the device to ensure safety and efficacy during the procedure.Traditionally,parameter testing and programming are performed by the manufacturer’s clinical service technician on-site in the Cath-lab.However,after the outbreak of the corona virus disease-2019(COVID-19),the manufacturer’s clinical service technicians are not allowed access to the Cath-lab and ward.Solving the problemof parameter testing and programming is crucial.

关键词： electrical programming implantation

Hierarchically porous CMC/rGo/CNFs aerogels for leakage-proof mirabilite phase change materials with superior energy thermal storage

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Frontiers of Materials Science 2022年第4期16卷 49-61页

作者： Fenglan CHEN xin liu Zhengya WANG Shengnian TIE Chang-An WANG New Energy Photovoltaic Industry Research Center Qinghai UniversityXining 810016China School of Chemical Engineering Qinghai UniversityXining 810016China State Key Lab of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

As a kind of essential hydrated salt phase change energy storage materials,mirabilite with high energy storage density and mild phase-transition temperature has excellent application potential in the problems of solar time and space mismatch.However,there are some disadvantages such as supercooling,substantial phase stratification and leakage problem,limiting its further applications.In this work,for the preparation of shaped mirabilite phase change materials(MPcMs),graphene(GO),sodium carboxymethyl cellulose(CMC),and carbon nanofibers(CNFs)were used as starting materials to prepare lightweight CMC/rGO/CNFs carbon aerogel(CGCA)as support with stable shape,high specific surface area,and well-arranged hierarchically porous structure.The results show that CGCA has regular layered plentiful pores and stable foam structure,and the pore and sheet interspersed structure in CGCA stabilizes PcMs via capillary force and surface tension.The hydrophilic aerogels supported MPCMs decrease mirabilite leaking and reduce supercooling to around 0.7-1C.The latent heats of melting and crystallization of CGCA-supported mirabilite phase change materials(CGCA-PCMs)are 157.1 and 114.8 J-g-1,respectively.Furthermore,after 1500 solid-liquid cycles,there is no leakage,and the retention rate of crystallization latent heat is 45.32%,exhibiting remarkable thermal cycling stability.

关键词： carbon aerogel mirabilite phase change material supercooling thermal cycling stability

Effect of gap and overlap on mode Ⅱ interlaminar fracture toughness of automated fiber placement prepreg laminates

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Chinese Journal of Aeronautics 2023年第6期36卷 390-401页

作者： Fan ZHANG xin liu Yaoyao YE Qisen CHEN Qiang XU Yunbo BI China State Key Laboratory of Fluid Power and Mechatronic System School of Mechanical EngineeringZhejiang UniversityHangzhou 310027China Key Laboratory of Advanced Manufacturing Technology of Zhejiang Province School of Mechanical EngineeringZhejiang UniversityHangzhou 310027China

Automated Fiber Placement(AFP)technology facilitates the manufacturing process of composite structures with complex geometry owing to its high efficiency and accuracy.However.the unavoidable imperfections induced by the automated layup method bring challenges to the stability of the final mechanical properties of composites.The influence of AFP-induced gaps and overlaps on the modeⅡinterlaminar fracture process of oven-cured laminates is experimentally investigated and explicitly revealed.End-Notched Flexure(ENF)tests were performed to measure the interlaminar fracture toughness of unidirectional laminates under three different defect configurations,namely"Gap""Overlap"and"Gap&Overlap".A marginal decline(about-1.2%in non-precracked tests,-5.1%in precracked tests)and an obvious increase(about 15.2%in nonprecracked tests,5.2%in precracked tests)in fracture toughness were observed for the"Gap"group and the"Overlap"group,respectively.Fractographic studies which involve the metallographic observation and Scanning Electron Microscopy(SEM)observation revealed that the increases in fracture area and crack length helped improve the fracture toughness of the Overlap"group.However,the resin-rich area with high porosity induced by gaps was detrimental to the delamination resistance.To capture the interlaminar stress distribution local to imperfections,a three-dimensional numerical model was established.Gap defects facilitate the local delamination process,and the overlap defect postpones the damage onset and the propagation.

关键词： Automated Fiber Placement(AFP) Defects Delamination Fracture toughness Laminates