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Journal of Computational Mathematics 2024年第1期42卷 71-110页

作者： Shipeng Mao Jiaao sun Wendong Xue NCMIS LSECInstitute of Computational Mathematics and Scientific/Enginnering ComputingAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China

In this paper,we consider the initial-boundary value problem(IBVP)for the micropolar Naviers-Stokes equations(MNSE)and analyze a first order fully discrete mixed finite element *** first establish some regularity results for the solution of MNSE,which seem to be not available in the ***,we study a semi-implicit time-discrete scheme for the MNSE and prove L2-h1 error estimates for the time discrete ***,certain regularity results for the time discrete solution are establishes *** on these regularity results,we prove the unconditional L2-h1 error estimates for the finite element solution of ***,some numerical examples are carried out to demonstrate both accuracy and efficiency of the fully discrete finite element scheme.

关键词： Micropolar fluids Regularity estimates Euler semi-implicit scheme Mixed finite element methods Unconditional convergence

Synthesis of multifunctional additives for solid propellants:Structure,properties and mechanism

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Defence Technology（防务技术） 2024年第3期33卷 308-316页

作者： Pingan Zhang Lina sun Jianmin Yuan Jianru Deng College of Chemistry and Chemical Engineering Hunan UniversityChangsha 410082PR China College of Material Science and Engineering Hunan UniversityChangsha 410082PR China hu Bei Sanjiang Aerospace Jianghe Chemical Technology Co. LtdYichang 444200PR China

To simplify the composite propellant formulation and address the current issue of the single-functionality present in existing additives,the multi-cyano,amine-based polybutadiene(AEhTPB-CN)was prepared based on AEhTPB by adopting appropriate synthesis *** replacing 10% of hTPB binder in the propellant formulation,it can effectively enhance the interfacial bond strength between the propellant binder matrix and solid fillers(AP(ammonium perchlorate)and RDX(cyclotrimethylene-trinitramine)),the mechanical properties of the hTPB/AP/RDX/Al propellant were superior to blank control propellant with an improvement of 35.4% in tensile strength,62.0% enhancement in elongation at break,and reduce the propellant burn rate by 10.7% with any energy *** function mechanism of AEhTPB-CN was systematically elucidated through experiments and computer simulation *** results show that the tertiary amine group in AEhTPB-CN can react with AP to form ammonium ionic bonds,and the hydroxyl and cyano groups can form hydrogen bonding interactions with AP,which enables AEhTPB-CN to be firmly adsorbed on the AP surface through chemical and physical *** RDX,the interfacial bonding effect of AEhTPB-CN is attributed to their ability to form C-h···N≡C weak hydrogen bonding interaction between the cyano group and RDX methylene group.

关键词： hydroxyl-terminated polybutadiene(hTPB) hTPB propellant Chemical modification Bonding agent Mechanism

Achieving Negatively Charged Pt Single Atoms on Amorphous Ni(Oh)_(2)Nanosheets with Promoted hydrogen Absorption in hydrogen Evolution

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Nano-Micro Letters 2024年第10期16卷 213-224页

作者： Yue Liu Gui Liu Xiangyu Chen Chuang Xue Mingke sun Yifei Liu Jianxin Kang Xiujuan sun Lin Guo School of Chemistry Beijing Advanced Innovation Center for Biomedical EngineeringKey Laboratory of Bio-inspired Smart Interfacial Science and TechnologyBeihang UniversityBeijing 100191People's Republic of China School of Chemistry Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of EducationXiangtan UniversityXiangtan 411105HunanPeople'Republic of China

Single-atom(SA)catalysts with nearly 100%atom utilization have been widely employed in electrolysis for decades,due to the outperforming catalytic activity and ***,most of the reported SA catalysts are fixed through the strong bonding between the dispersed single metallic atoms with nonmetallic atoms of the substrates,which greatly limits the controllable regulation of electrocatalytic activity of SA *** this work,Pt-Ni bonded Pt SA catalyst with adjustable electronic states was successfully constructed through a controllable electrochemical reduction on the coordination unsaturated amorphous Ni(Oh)_(2)nanosheet *** on the X-ray absorption fine structure analysis and first-principles calculations,Pt SA was bonded with Ni sites of amorphous Ni(Oh)_(2),rather than conventional O sites,resulting in negatively charged Pt^(δ-).In situ Raman spectroscopy revealed that the changed configuration and electronic states greatly enhanced absorbability for activated hydrogen atoms,which were the essential intermediate for alkaline hydrogen evolution *** hydrogen spillover process was revealed from amorphous Ni(Oh)_(2)that effectively cleave the h-O-h bond of h_(2)O and produce h atom to the Pt SA sites,leading to a low overpotential of 48 mV in alkaline electrolyte at-1000 mA cm^(-2)mg^(-1)_(Pt),evidently better than commercial Pt/C *** work provided new strategy for the control-lable modulation of the local structure of SA catalysts and the systematic regulation of the electronic states.

关键词： hydrogen evolution reaction Amorphous Pt single atoms hydrogen spillover

Passivation remediation of weakly alkaline Cd-contaminated soils using combined treatments of biochar and sepiolite

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Ecological Processes 2024年第1期13卷 40-52页

作者： Yuxin Zhang Shan Gao hongtao Jia Tao sun Shunan Zheng Shihang Wu Yuebing sun Key Laboratory of Original AgroEnvironmental Pollution Prevention and Control Ministry of Agriculture and Rural Affairs (MARA)/Tianjin Key Laboratory of Agro-Environment and Agro-Product Safety Agro–Environmental Protection InstituteMARA College of Resources and Environment Sciences Xinjiang Agricultural University Rural Energy and Environment Agency Ministry of Agriculture and Rural Affairs

Background Cadmium(Cd) pollution in agricultural soils has become a priority environmental concern globally. A reasonable application of passivators is critical to address the problem. In this study, we examined the remediation effects of rice husk biochar(r BC) and sepiolite(Sep) as single and combined(r BC + Sep) treatments on Cd pollution in a weakly alkaline soil using three maize cultivars(Liyu 16, Zhengdan 958, and Sanbei 218) as test crops. We also explained the mechanisms involved in the remediation *** The pseudo-second-order kinetic equation and Langmuir model could well describe the adsorption process of r BC + Sep for Cd2+. Compared with the control treatment(CK), soil available Cd concentration decreased by 29.51–36.34% under r BC + Sep treatment(phe Cd concentrations in maize grains of Liyu 16, Zhengdan 958, and Sanbei 218 decreased by 38.08–47.85%, 37.25–45.61%, and 33.96–46.15%, respectively(phanged from the exchangeable and carbonate binding forms to the Fe/Mn oxide and residual forms. The bioconcentration factors of Liyu 16(0.05–0.09) and Sanbei 218(0.05–0.09) were lower than those of Zhengdan 958(0.07–0.13). In addition, r BC +Sep treatment increased soil p h and soil electrical conductivity, but the differences were not significant(p> 0.05).Conclusions The application of 0.2% r BC + 0.5% Sep composite passivation material to weakly alkaline Cd-contaminated soil can effectively reduce the Cd concentration of soil and maize.

关键词： Cd Rice husk biochar Sepiolite Passivation restoration Weakly alkaline soil Maize

Microstructures and mechanical properties of laser-directed energy deposited CrCoNi medium-entropy alloy

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Rare Metals 2024年第7期43卷 3286-3300页

作者： Wen-Jie Zhao Chang-Yu Liu Peng-Cheng Che Zhi-Liang Ning hong-Bo Fan Jian-Fei sun Yong-Jiang huang Alfonso h.W.Ngan National Key Laboratory for Precision hot Processing of Metals Harbin Institute of TechnologyHarbin 150001China Space Environment Simulation Research Infrastructure Harbin Institute of TechnologyHarbin 150001China Department of Mechanical Engineering The University of Hong KongHong Kong 999077China

The distinctive intrinsic heat treatment(IhT)originating from cyclic reheating in the laser-directed energy deposition(LDED) has attracted growing attention in recent *** this investigation,simulations and experimental characterizations were performed to examine the impact of IhT on the micros true ture and mechanical properties of LDED-fabricated CrCoNi medium-entropy alloy(MEA).The results show that the intensity of the IhT is proportional to the utilized laser energy density(LED).As the LED increased,significant dynamic recrystallization and grain refinement occurred within the alloy due to the enhanced intensity of ***,the high LED leads to severe hot cracking within the as-built MEA,resulting in inferior *** decreasing LED,the hot cracking was effectively ***,low LED weakened the intensity of IhT and consequently inhibited kinetic conditions of dynamic recrystallization,resulting in a heterogeneous grain structure characterized by multi-scale-sized *** structure provides significant hetero-deformation-induced hardening during plastic deformation,enabling the alloy to have a sustainable work-hardening *** expect that this work will have implications in taking full advantage of the unique IhT of the LDED process to fabricate ME As with excellent metallurgical quality and mechanical performance.

关键词： Intrinsic heat treatment Laser-directed energy deposition CrCoNi MEA Dynamic recrystallization heterogeneous grain structure

A Note of the Interpolating Sequence in Qp∩h~∞

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Wuhan University Journal of Natural Sciences 2024年第1期29卷 1-6页

作者： ZhOU Jizhen sun hejie School of Mathematics and Big Data Anhui University of Science and Technology

In this paper,{zn}n=1~∞ acts as an interpolating sequence for Qp∩h~∞.An analytic function f is constructed,and f(zn)=∑jλjfzj(zn)=λn,n=1,2,…for any {λn}∈l~∞,wheref and ■ belong to Qp∩h~∞.As a result,the st... 详细信息

关键词： Q_p space h∞ space F (p,p - 2,s) ∩h~∞ interpolating sequence

Stem cell-based ischemic stroke therapy:Novel modifications and clinical challenges

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Asian Journal of Pharmaceutical Sciences 2024年第1期19卷 18-34页

作者： Yuankai sun Xinchi Jiang Jianqing Gao Institute of Pharmaceutics College of Pharmaceutical SciencesZhejiang UniversityHangzhou 310058China hangzhou Institute of Innovative Medicine College of Pharmaceutical SciencesZhejiang UniversityHangzhou 310058China Dr.Li Dak Sum&Yip Yio Chin Center for Stem Cell and Regenerative Medicine Zhejiang UniversityHangzhou 310058China Department of Pharmacy The Second Affiliated HospitalZhejiang University School of MedicineHangzhou 310009China

Ischemic stroke(IS)causes severe disability and high mortality *** cell(SC)therapy exhibits unique therapeutic potential for IS that differs from current ***’s cell homing,differentiation and paracrine abilities give hope for *** studies on SC modification have enhanced therapeutic effects for IS,including gene transfection,nanoparticle modification,biomaterial modification and *** improve survival rate,homing,neural differentiation,and paracrine abilities in ischemic ***,many problems must be resolved before SC therapy can be clinically *** issues include production quality and quantity,stability during transportation and storage,as well as usage ***,we reviewed the brief pathogenesis of IS,the“multi-mechanism”advantages of SCs for treating IS,various SC modification methods,and SC therapy *** aim to uncover the potential and overcome the challenges of using SCs for treating IS and convey innovative ideas for modifying SCs.

关键词： Ischemic stroke Stem cell therapy Stem cell modification Cell therapy challenge

Stability and Time-Step Constraints of Implicit-Explicit Runge-Kutta Methods for the Linearized Korteweg-de Vries Equation

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Communications on Applied Mathematics and Computation 2024年第1期6卷 658-687页

作者： Joseph hunter Zheng sun Yulong Xing Department of Mathematics The Ohio State UniversityColumbusOH43210USA Department of Mathematics The University of AlabamaTuscaloosaAL35487USA

This paper provides a study on the stability and time-step constraints of solving the linearized Korteweg-de Vries(KdV)equation,using implicit-explicit(IMEX)Runge-Kutta(RK)time integration methods combined with either finite difference(FD)or local discontinuous Galerkin(DG)spatial *** analyze the stability of the fully discrete scheme,on a uniform mesh with periodic boundary conditions,using the Fourier *** the linearized KdV equation,the IMEX schemes are stable under the standard Courant-Friedrichs-Lewy(CFL)conditionτ≤λ***,λis the CFL number,τis the time-step size,and h is the spatial mesh *** study several IMEX schemes and characterize their CFL number as a function ofθ=d/h^(2)with d being the dispersion coefficient,which leads to several interesting *** also investigate the asymptotic behaviors of the CFL number for sufficiently refined meshes and derive the necessary conditions for the asymptotic stability of the IMEX-RK *** numerical experiments are provided in the paper to illustrate the performance of IMEX methods under different time-step constraints.

关键词： Linearized Korteweg-de Vries(KdV)equation Implicit-explicit(IMEX)Runge-Kutta(RK)method Stability Courant-Friedrichs-Lewy(CFL)condition Finite difference(FD)method Local discontinuous Galerkin(DG)method

Reduced-order modeling and vibration transfer analysis of a fluid-delivering branch pipeline that consider fluid–solid interactions

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Frontiers of Mechanical Engineering 2024年第2期19卷 75-97页

作者： Wenhao JI hongwei MA Wei sun Yinhang CAO School of Mechanical Engineering and Automation Northeastern UniversityShenyang 110819China Key Laboratory of Vibration and Control of Aero-Propulsion Systems(Ministry of Education) Northeastern UniversityShenyang 110819China College of Power and Energy Engineering Harbin Engineering UniversityHarbin 150001China

The efficient dynamic modeling and vibration transfer analysis of a fluid-delivering branch pipeline(FDBP)are essential for analyzing vibration coupling effects and implementing vibration reduction ***,this study proposes a reduced-order dynamic modeling method suitable for FDBPs and then analyzes the vibration transfer *** the modeling method,the finite element method and absorbing transfer matrix method(ATMM)are integrated,considering the fluid–structure coupling effect and fluid *** dual-domain dynamic substructure method is developed to perform the reduced-order modeling of FDBP,and ATMM is adopted to reduce the matrix order when solving fluid ***,the modeling method is validated by experiments on an h-shaped branch ***,transient and steady-state vibration transfer analyses of FDBP are performed,and the effects of branch locations on natural characteristics and vibration transfer behavior are *** show that transient vibration transfer represents the transfer and conversion of the kinematic,strain,and damping energies,while steady-state vibration transfer characteristics are related to the vibration *** addition,multiple-order mode exchanges are triggered when branch locations vary in frequency-shift regions,and the mode-exchange regions are also the transformation ones for vibration transfer patterns.

关键词： fluid-delivering branch pipeline vibration transfer analysis reduced-order modeling fluid-solid interactions finite element method absorbing transfer matrix method

An ensemble learning method to retrieve sea ice roughness from Sentinel-1 SAR images

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Acta Oceanologica Sinica 2024年第5期43卷 78-90页

作者： Pengyi Chen Zhongbiao Chen Runxia sun Yijun he School of Marine Sciences Nanjing University of Information Science&TechnologyNanjing 210044China East Sea Information Center of State Oceanic Administration Shanghai 200136China

Sea ice surface roughness(SIR)affects the energy transfer between the atmosphere and the ocean,and it is also an important indicator for sea ice *** obtain a small-scale SIR with high spatial resolution,a novel method is proposed to retrieve SIR from Sentinel-1 synthetic aperture radar(SAR)images,utilizing an ensemble learning ***,the two-dimensional continuous wavelet transform is applied to obtain the spatial information of sea ice,including the scale and direction of ice ***,a model is developed using the Adaboost Regression model to establish a relationship among SIR,radar backscatter and the spatial information of sea *** proposed method is validated by using the SIR retrieved from SAR images and comparing it to the measurements obtained by the Airborne Topographic Mapper(ATM)in the summer Beaufort *** determination of coefficient,mean absolute error,root-mean-square error and mean absolute percentage error of the testing data are 0.91,1.71 cm,2.82 cm,and 36.37%,respectively,which are ***,K-fold cross-validation and learning curves are analyzed,which also demonstrate the method’s applicability in retrieving SIR from SAR images.

关键词： 2-D Cauchy continuous wavelet transform(CWT) Adaboost Regression sea ice sea ice surface roughness