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On Some Model Equations of Euler and Navier-Stokes Equations

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Chinese Annals of Mathematics,Series B 2021年第2期42卷 281-290页

作者： Dapeng du Department of Mathematics and statistics Northeast Normal UniversityChangchun 130024China

The author proposes a two-dimensional generalization of Constantin-Lax-Majda model. Some results about singular solutions are given. This model might be the first step toward the singular solutions of the Euler equations. Along the same line(vorticity formulation), the author presents some further model equations. He possibly models various aspects of difficulties related with the singular solutions of the Euler and Navier-Stokes equations. Some discussions on the possible connection between turbulence and the singular solutions of the Navier-Stokes equations are made.

关键词： Euler equations Navier-Stokes equations Singular solutions Turbulence

Higher order Poisson kernels and L^p polyharmonic boundary value problems in Lipschitz domains

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Science China Mathematics 2020年第6期63卷 1065-1106页

作者： Zhihua du Department of Mathematics Jinan UniversityGuangzhou 510632China

In this article, we introduce higher order conjugate Poisson and Poisson kernels, which are higher order analogues of the classical conjugate Poisson and Poisson kernels, as well as the polyharmonic fundamental solutions, and define multi-layer potentials in terms of the Poisson field and the polyharmonic fundamental solutions, in which the former is formed by the higher order conjugate Poisson and the Poisson kernels. Then by the multi-layer potentials, we solve three classes of boundary value problems(i.e., Dirichlet, Neumann and regularity problems) with L^p boundary data for polyharmonic equations in Lipschitz domains and give integral representation(or potential) solutions of these problems.

关键词： polyharmonic equation boundary value problem higher order Poisson and conjugate Poisson kernel integral representation

Recent Advances in Electrode Design Based on One-Dimensional Nanostructure Arrays for Proton Exchange Membrane Fuel Cell Applications

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Engineering 2021年第1期7卷 33-49页

作者： Shangfeng du School of Chemical Engineering University of BirminghamBirmingham B152TTUK

One-dimensional(1D)Pt-based electrocatalysts demonstrate outstanding catalytic activities and stability toward the oxygen reduction reaction(ORR).Advances in three-dimensional(3D)ordered electrodes based on 1D Pt-based nanostructure arrays have revealed great potential for developing highperformance proton exchange membrane fuel cells(PEMFCs),in particular for addressing the mass transfer and durability challenges of Pt/C nanoparticle *** paper reviews recent progress in the field,with a focus on the 3D ordered electrodes based on self-standing Pt nanowire *** thin-film(NSTF)catalysts are discussed along with electrodes made from Pt-based nanoparticles deposited on arrays of polymer nanowires,and carbon and TiO2 *** on electrodes from Pt-based nanotube arrays are also *** importance of size,surface properties,and the distribution control of 1D catalyst nanostructures is ***,challenges and future development opportunities are addressed regarding increasing electrochemical surface area(ECSA)and quantifying oxygen mass transport resistance for 1D nanostructure array electrodes.

关键词： Proton exchange membrane fuel cell (PEMFC) Electrode One-dimensional(1D) Oxygen reduction reaction(ORR) Catalyst Ordered

Anisotropic Rock Poroelasticity Evolution in Ultra-low Permeability Sandstones under Pore Pressure,Confining Pressure,and Temperature:Experiments with Biot's Coefficient

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Acta Geologica Sinica(English Edition) 2021年第3期95卷 937-945页

作者： du Shuheng State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China

This study aimed to show anisotropic poroelasticity evolution in ultra-low permeability reservoirs under pore pressure,confining pressure,and *** groups of experiments examining Biot's coefficient under different conditions were carried *** showed that Biot's coefficient decreased with increased pore pressure,and the variation trend is linear,but the decreasing rate is variable between ***'s coefficient increased with increased confining pressure;the variation trend is linear,but the increasing rate varies by material as ***,Biot's coefficient remains stable with increased ***,clay mineral content,particle arrangement,and pore arrangement showed impacts on Biot's *** strong hydrophilic clay minerals,expansion in water could result in a strong surface adsorption reaction,which could result in an increased fluid bulk modulus and higher Biot's *** skeleton minerals with strong lipophilicity,such as quartz and feldspar,increased oil saturation will also result in an adsorption reaction,leading to increased fluid bulk modulus and a higher Biot's *** study's conclusions provide evidence of poroelasticity evolution of ultra-low permeability and help the enhancing oil recovery(EOR)process.

关键词： Biot's coefficient ultra-low permeability pore pressure confining pressure temperature

An Alternative Way of Utilizing Fixed Point Theory

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Chinese Annals of Mathematics,Series B 2020年第6期41卷 861-872页

作者： Dapeng du Department of Mathematics and Statistics Northeast Normal UniversityChangchun 130024China

The author proposes an alternative way of using fixed point theory to get the existence for semilinear *** an example,a nonlocal ordinary differential equation is *** idea is to solve homogeneous equations in the *** feature of this method is that it does not need the equation to have special structures,for instance,variational structures,maximum principle,*** speaking,the existence comes from good properties of the suitably linearized *** idea may have wider application.

关键词： Existence Semi-linear equations Fixed point theory Homogeneous linearization

A Practical Regular LDPC Coded Scheme for Physical-Layer Information Security

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China Communications 2024年第5期21卷 190-201页

作者： du Junyi CETC Key Laboratory of Avionic Information System Southwest China Institute of Electronic TechnologyChengdu 610036China

In this paper,we aim to design a practical low complexity low-density parity-check(LDPC)coded scheme to build a secure open channel and protect information from *** this end,we first propose a punctured LDPC coded scheme,where the information bits in a codeword are punctured and only the parity check bits are transmitted to the *** further propose a notion of check node type distribution and derive multi-edge type extrinsic information transfer functions to estimate the security performance,instead of the well-known weak metric bit error *** optimize the check node type distribution in terms of the signal-to-noise ratio(SNR)gap and modify the progressive edge growth algorithm to design finite-length *** results show that our proposed scheme can achieve a lower computational complexity and a smaller security gap,compared to the existing scrambling and puncturing schemes.

关键词： extrinsic information transfer function physical layer scheme secure open channel security gap

Co-incorporation of Chinese milk vetch(Astragalus sinicus L.)and chemical fertilizers alters microbial functional genes supporting short-time scale positive nitrogen priming effects in paddy soils

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Pedosphere 2024年第3期34卷 567-576页

作者： Limin WANG Chunmei HE Dongfeng HUANG Juhua YU cailing LIU Qinghua LI Yibin HUANG Juan LI Fei WANG Institute of Resources Environment and Soil FertilizerSoil and Fertilizer InstituteFujian Academy of Agricultural SciencesFuzhou 350012(China) School of Resources and Environment Engineering Anhui UniversityHefei 230601(China)

Nitrogen(N)priming is a microbially mediated biochemical process as affected by different incorporation ***,little information is known about the microbial mechanisms driving the response of N priming to co-operation of Chinese milk vetch(CMV,Astragalus sinicus L.)and different rates of chemical fertilizers in paddy soils in South ***,an anaerobic incubation experiment was conducted to study N priming effects(PE)and their relationships with soil microbial functional genes after CMV incorporation alone(M),co-incorporation of CMV with 100%(normal dosage)chemical fertilizers(MC100),and co-incorporation of CMV with 80% chemical fertilizers(MC80).Co-incorporation of CMV and chemical fertilizers enhanced the short-time scale(the first 20 d of incubation)positive PE of N,while no significant differences existed among the three treatments on day 60 or 90 of incubation(P>0.05).Compared with the M treatment,gross priming effect(GPE)in the MC100 and MC80 treatments significantly increased by 34.0% and 31.3%,respectively,and net priming effect(NPE)increased by 47.7% and 47.8%,respectively,during the first 20 d of incubation(Pduction(nasB),and nitrification(amoB)were significantly correlated with N priming under different incorporation practices during the incubation period(Pduction and inhibit

关键词： green manure gross priming effect incorporation practice microbial mechanism net priming effect rice field soil

Modeling of Fatigue Crack Growth Closure Considering the Integrative Effect of Cyclic Stress Ratio,Specimen Thickness and Poisson's Ratio

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Chinese Journal of Mechanical Engineering 2012年第4期25卷 816-825页

作者： LIU Jiantao du Pingan LIU Xiaobao du Qiang College of Mechanical and Electronic Engineering University of Electronic Science and Technology of China Chengdu 611731 China

Key components of large structures in aeronautics industry are required to be made light and have long enough fatigue *** is of vital importance to estimate the fatigue life of these structures *** the FCG process is affected by various factors,no universal model exists due to the complexity of the *** of the existing models are obtained by fitting the experimental data and could hardly describe the integrative effect of most existing factors *** order to account for the integrative effect of specimen parameters,material property and loading conditions on FCG process,a new model named integrative influence factor model（IIF） is proposed based on the plasticity-induced crack closure *** to the predictions of crack opening ratio（γ） and effective stress intensity factor range ratio（U） with different material under various loading conditions,predictions of γ and U by the IIF model are completely identical to the theoretical results from the plane stress state to the plane strain state when Poisson＇s ratio equals 1/*** Poisson＇s ratio equals 0.3,predictions of γ and U by the IIF model are larger than the predictions by the existing model,and more close to the theoretical *** addition,it describes the influence of R ratios on γ and U effectively in the whole region from-1.0 to ***,several sets of test data of FCG rates in 5 kinds of aluminum alloys with various specimen thicknesses under different loading conditions are used to validate the IIF model,most of the test data are situated on the predicted curves or between the two curves that represent the specimen with different thicknesses under the same stress *** of the test data slightly departure from the predictions by the IIF model due to the surface roughness and errors in ***,based on the analysis of the physical rule of crack opening ratios,a relative thickness of specimen is defined to describe the influence of mate

关键词： fatigue crack growth crack opening stress cyclic stress ratio constraint factor Poisson's ratio stress intensity factor

A nonenzymatic electrochemical sensor for the detection of hydrogen peroxide in vitro and in vivo fibrosis models

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Chinese Chemical Letters 2024年第3期35卷 394-398页

作者： Hongyao Liu Yan Yu Taixiong Xue cailing Gan Yuting Xie Doudou Wang Peilin Li Zhiyong Qian Tinghong Ye Department of Gastroenterology and Hepatology Sichuan University-University of Oxford Huaxi Joint Centre for Gastrointestinal Cancer and Frontiers Science Center for Disease-Related Molecular NetworkState Key Laboratory of BiotherapyWest China HospitalSichuan UniversityChengdu 610041China Department of Biotherapy Cancer Center and State Key Laboratory of BiotherapyWest China HospitalSichuan UniversityChengdu 610041China

Fibrosis occurs due to the excessive deposition of extracellular matrix caused by cell *** various types of tissue injury,the dysregulation of the internal response can eventually lead to the destruction of organ structure and *** is increasing evidence that oxidative stress,which is characterized by excessive production of hydrogen peroxide(H_(2)O_(2)),is an important cause of ***,we synthesized a biosensitive and efficient electrochemical H_(2)O_(2)sensor based on PtNi nanoparticle-doped N-reduced graphene oxide(PtNi-N-rGO)to detect H_(2)O_(2)released from transforming growth factorβ1(TGFβ1)-induced *** addition,the sensor could easily detect changes in H_(2)O_(2)in the lung and bronchoalveolar lavage fluid(BALF)of mice with pulmonary ***,the sensor could also detect H_(2)O_(2)in activated hepatic stellate cells and the liver of carbon tetrachloride(CCl_(4))-induced liver ***,the alterations in H_(2)O_(2)detected by the sensor were consistent with nicotinamide adenine dinucleotide phosphate oxidase 4(NOX4)protein expression and the staining results of pathological *** together,these results highlight the use of H_(2)O_(2)sensors for the rapid detection of fibrosis and facilitate the rapid evaluation of antifibrotic drug candidates.

关键词： Fibrosis H_(2)O_(2) Electrochemical sensor NOX4 Nintedanib