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Hitting Probabilities and the Hausdorff Dimension of the Inverse Images of a Class of Anisotropic Random Fields

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Acta Mathematica Sinica,English Series 2015年第12期31卷 1895-1922页

作者： zhen long CHEN Quan ZHOU School of Statistics and Mathematics Zhejiang Gongshang University

Let X = {X（t）：t ∈ R^N} be an anisotropic random field with values in R^*** certain conditions on X,we establish upper and lower bounds on the hitting probabilities of X in terms of respectively Hausdorff measure and Bessel-Riesz *** also obtain the Hausdorff dimension of its inverse image,and the Hausdorff and packing dimensions of its level *** results are applicable to non-linear solutions of stochastic heat equations driven by a white in time and spatially homogeneous Gaussian noise and anisotropic Guassian random fields.

关键词： Anisotropic random field non-linear stochastic heat equations spatially homogeneous Gaussian noise hitting probabilities Hausdorff dimension inverse image

Privacy-Preserving Public Auditing Scheme for Data Confidentiality and Accountability in Cloud Storage

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Chinese Journal of Electronics 2019年第1期28卷 179-187页

作者： YANG zhen WANG Wenyu HUANG Yongfeng LI xing Department of Electronic Engineering Tsinghua University Tsinghua National Laboratory for Information Science and Technology Information Networking Institute Carnegie Mellon University

Cloud data confidentiality need to be audited for the data owner’s concern. Confidentiality auditing is usually based on logging schemes, whereas cloud data dynamics and sharing group dynamics result in massive logs, which makes confidentiality auditing a formidable task for user with limited resources. So we propose a public auditing scheme for data confidentiality,in which user resorts to a Third-party auditor(TPA)for auditing. Our scheme design a special log called attestation in which hash user pseudonym is used to preserve user privacy. Attestation-based data access identifying is presented in our scheme which brings no new vulnerabilities toward data confidentiality and no extra online burden for user. We further support accountability of responsible user for data leakage based on user pseudonym. Extensive security and performance analysis compare our scheme with existing auditing *** indicate that the proposed scheme is provably secure and highly efficient.

关键词： Data confidentiality Public auditability Privacy preserving Cloud storage User accountability

Effect of energy density on defect evolution in 3D printed Zr-based metallic glasses by selective laser melting

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Science China(Physics,Mechanics & Astronomy) 2020年第2期63卷 104-110页

作者： Wei xing Di Ouyang zhen Chen Lin Liu School of Materials Science and Engineering and State Key Lab for Materials Processing and Die&Mould TechnologyHuazhong University of Science and TechnologyWuhan 430074China State Key Lab for Manufacturing Systems Engineering Xi’an Jiaotong UniversityXi’an 710049China

In this study, the defects in 3D printed Zr-based bulk metallic glasses(BMGs) fabricated by selective laser melting(SLM) under different energy densities have been investigated via both experimental and simulation approaches. Different defects, including balling, interlayer pores, open pores and metallurgical pores, are detected in the 3D-printed Zr-based MGs depending on the energy inputs. Balling mainly occurs at a relatively low energy density(E<8.33 J/mm^3) due to the incomplete melting of particles, while interlayer pores and open pores are formed at modest energy densities(E=13.89-16.67 J/mm^3) because of incomplete welding and insufficient filling of molten liquid between layers. Fine metallurgical pores appear on the upper surface at relatively high energy densities(E=20.83-27.78 J/mm^3), which originate from gas escaping from molten pools during rapid solidification of the melt. Computational fluid dynamics(CFD) simulations are carried out to verify the experimental observations. The CFD simulations reveal that the various defects formed in the 3D-printed Zr-based BMG are related to the melt flow behaviours in the molten pools under different energy densities. The present work provides in-depth understandings of defect formation in the SLM process and provides methods for eliminating these defects in order to enhance the mechanical performance of 3D printed BMGs.

关键词： metallic glass selective laser melting defect formation mesoscopic simulation

Estimation of soil organic carbon stock and its controlling factors in cropland of Yunnan Province,China

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Journal of Integrative Agriculture 2022年第5期21卷 1475-1487页

作者： SUN Tao TONG Wen-jie CHANG Nai-jie DENG Ai-xing LIN Zhong-long FENG xing-bing LI Jun-ying SONG zhen-wei Institute of Crop Sciences Chinese Academy of Agricultural Sciences/Key Laboratory of Crop Physiology and EcologyMinistry of Agriculture and Rural AffairsBeijing 100081P.R.China Yunnan Academy of Tobacco Agricultural Sciences Kunming 650021P.R.China Institute of Agricultural Resources and Regional Planning Chinese Academy of Agricultural SciencesBeijing 100081P.R.China China Tobacco Company Yunnan Branch Kunming 650011P.R.China

Soil organic carbon(SOC)is the most important indicators of soil quality and *** the spatial distribution of SOC and its influencing factors in cropland is crucial to understand the terrestrial carbon cycle and optimize agronomic *** Province,characterized by mountainous topography and varied elevation,is one of the highest SOC regions in *** its SOC stock of cropland and influencing factors has not been fully studied due to the lack of adequate soil *** this study,the digital mapping of SOC at 1 km resolution and the estimation of total SOC stock in cropland of Yunnan Province was undertaken using 8637 topsoil(0-20 cm)samples and a series of spatial data through Random Forest(RF)*** was showed that across the cropland of Yunnan Province,the mean SOC density and total stock were 4.84 kg m^(-2) and 337.5 Mt,*** spatial distribution indicated that relatively high SOC density regions resided in the northwest and northeast parts of Yunnan ***(19.5%),temperature(17.3%),rainfall(14.5%),and Topographic wetness index(9.9%)were the most important factors which controlled spatial variability of SOC *** practices(e.g.,crop straw treatments,fertilizer management)should be optimized for the sustainable development of crop production with high SOC sequestration capacity in Yunnan Province.

关键词： cultivated land soil organic carbon spatial distribution driving factors Random Forest

Improved Fractional-order Damping Method for Voltage-controlled DFIG System Under Weak Grid

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Journal of Modern Power Systems and Clean Energy 2022年第6期10卷 1531-1541页

作者： zhen Xie Xiang Gao Shuying Yang xing Zhang School of Electrical Engineering and Automation Hefei University of TechnologyHefeiChina

When a doubly-fed induction generator(DFIG)is connected to a weak grid,the coupling between the grid and the DFIG itself will increase,which will cause stability *** is difficult to maintain the tracking accuracy and robustness of the phase-locked loop(PLL)in the weak grid,and the risk of instability of the current-controlled DFIG(CC-DFIG)system will *** this paper,a new type of voltage-controlled DFIG(VC-DFIG)mode is adopted,which is a grid-forming structure that can independently support the voltage and frequency with a certain adaptability in the weak grid.A small-signal impedance model of the VC-DFIG system is also *** impedance of DFIG inevitably generates coupling with the grid impedance in the weak grid,especially in parallel compensation grids,and results in *** the basis of the VC-DFIG,impedance stability analysis is performed to study the influences of the control structure and short-circuit ***,a feedforward damping method is proposed to modify the impedance of the VC-DFIG system at resonance *** proposed fractional order damping is utilized,which can enhance the robustness and rapidity of resonance suppression under parameter ***,the experimental results are presented to validate the effectiveness of the proposed control strategy.

关键词： Weak grid voltage-controlled doubly-fed induction generator(DFIG) resonance feedforward damping fractional-order damping

Enhanced electrode kinetics and properties via anionic regulation in polyanionic Na_(3+x)V_(2)(PO_(4))_(3-x)(P_(2)O_(7))_(x) cathode material

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Green Energy & Environment 2022年第4期7卷 763-771页

作者： Mei-Yi Wang Xin-Xin Zhao Jin-Zhi Guo Xue-Jiao Nie zhen-Yi Gu Xu Yang xing-long Wu National&Local United Engineering Laboratory for Power Batteries Faculty of ChemistryNortheast Normal UniversityChangchunJilin130024China Key Laboratory for UV Light-Emitting Materials and Technology of Ministry of Education Northeast Normal UniversityChangchunJilin130024China

Mixing polyanion cathode materials are promising candidates for the development of next-generation batteries, owing to their structural robustness and low-volume changes, yet low conductivity of polyanion hinders their practical capacity. Herein, the anion-site regulation is proposed to elevate the electrode kinetics and properties of polyanionic cathode. Multivalent anion P_(2)O_(7)^(4-) is selected to substitute the PO_(4)^(3-) in Na_(3)V_(2)(PO_(4))_(3) (NVP) lattice and regulate the ratio of polyanion groups to prepare Na_(3+x)V_(2)(PO_(4))_(3-x)(P_(2)O_(7))_(x)(NVPP_(x), 0 ≤ x ≤ 0.15) *** optimal Na_(3.1)V_(2)(PO_(4))_(2.9)(P_(2)O_(7))_(0.1) (NVPP_(0.1)) material can deliver remarkably elevated specific capacity(104 mAh g^(-1) at 0.1 C, 60 mAh g^(-1) at 20 C, respectively), which is higher than those of NVP. Moreover, NVPP_(0.1) exhibits outstanding cyclic stability(91% capacity retention after 300 cycles at 1 C). Experimental analyses reveal that the regulation of anions improves the structure stability, increases the active Na occupancy in the lattice and accelerates the Na+migration kinetics. The strategy of anion-site regulation provides the researchers a reference for the design of new high-performance polyanionic materials.

关键词： Sodium-ion batteries Cathode Polyanion materials Anionic substitution Electrode kinetics

Comparison of gut-associated and nest-associated microbial communities of a fungus-growing termite （Odontotermes yunnanensis）

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Insect Science 2010年第3期17卷 265-276页

作者： Yan-Hua long Lei Xie Ning Liu xing Yan Ming-Hui Li Mei-zhen Fan Qian Wang Provincial Key Laboratory of Microbial Pest Control Anhui Agricultural University Hefei Institute of Plant Physiology and Ecology Shanghai Institutes for Biological Sciences Chinese Academy of Sciences Shanghai China

The digestion of cellulose by fungus-growing termites involves a complex of different organisms, such as the termites themselves, fungi and bacteria. To further investigate the symbiotic relationships of fungus-growing termites, the microbial communities of the termite gut and fungus combs of Odontotermes yunnanensis were examined. The major fungus species was identified as Termitomyces sp. To compare the micro-organism diversity between the digestive tract of termites and fungus combs, four polymerase chain reaction clone libraries were created （two fungus-targeted internal transcribed spacer [ITS] - ribosomal DNA [rDNA] libraries and two bacteria-targeted 16S rDNA libraries）, and one library of each type was produced for the host termite gut and the symbiotic fimgus comb. Results of the fungal clone libraries revealed that only Termitomyces sp. was detected on the fungus comb; no non-Termitomyces fungi were detected. Meanwhile, the same fungus was also found in the termite gut. The bacterial clone libraries showed higher numbers and greater diversity of bacteria in the termite gut than in the fungus comb. Both bacterial clone libraries from the insect gut included Firmicutes, Bacteroidetes, Proteobacteria, Spirochaetes, Nitrospira, Deferribacteres, and Fibrobacteres, whereas the bacterial clone libraries from the fungal comb only contained Firmicutes, Bacteroidetes, Proteobacteria, and Acidobacteris.

关键词： fungus comb gut ITS phylotype termite Termitomyces

Validity of Parametrized Quark Propagator

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Communications in Theoretical Physics 2005年第1X期44卷 117-122页

作者： ZHUJi-zhen ZHOULi-Juan MAWei-xing DepartmentofInformationandComputingScience GuangxiUniversityofTechnologyLiuzhou545006China DepartmentofInformationandComputingScience GuangxiUniversityofTechnologyLiuzhou545006China//CollegeofPhysicalScienceandEngineeringTechnologyGuangxiUniversityNanning530004China DepartmentofInformationandComputingScience GuangxiUniversityofTechnologyLiuzhou545006China//InstituteofHighEnergyPhysicstheChineseAcademyofSciencesP.O.Box918Beijing100039China

Based on an extensively study of the Dyson-Schwinger equations for a fully dressed quark propagator in the "rainbow" approximation, a parametrized fully dressed quark propagator is proposed in this paper. The parametrized propagator describes a confining quark propagator in hadron since it is analytic everywhere in complex p2-plane and has no Lemmann representation. The validity of the new propagator is discussed by comparing its predictions on selfenergy functions Af(p2), Bf(p2) and effective mass Mf(p2) of quark with flavor f to their corresponding theoretical results produced by Dyson-Schwinger equations. Our comparison shows that the parametrized quark propagator is a good approximation to the fully dressed quark propagator given by the solutions of Dyson-Schwinger equations in the rainbow approximation and is convenient to use in any theoretical calculations.

关键词：夸克传播 Dyson-Schwinger方程非干涉QCD 参数表示高能物理

Ruin Probabilities in the Risk Process with Random Income

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Acta Mathematicae Applicatae Sinica 2008年第2期24卷 195-202页

作者： zhen-hua Bao Zhong-xing Ye School of Mathematics Liaoning Normal University Dalian 116029 China Department of mathematics Shanghai Jiaotong University Shanghai 200240 China

We extend the classical risk model to the case in which the premium income process, modelled as a Poisson process, is no longer a linear function. We derive an analog of the Beekman convolution formula for the ultimate ruin probability when the inter-claim times are exponentially distributed. A defective renewal equation satisfied by the ultimate ruin probability is then given. For the general inter-claim times with zero-truncated geometrically distributed claim sizes, the explicit expression for the ultimate ruin probability is derived.

关键词： Beekman convolution formula Defective renewal equation Ruin probability Zero-truncated geo-metric distribution