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Journal of Materials Science & Technology 2023年第7期138卷 17-28页

作者： Xuewei Zhang Bixue Wang Hua Hong Ying Wang Jiashang liu Changsheng liu Xi Chen Key Laboratory for Ultrafine Materials of Ministry of Education Frontiers Science Center for Materiobiology and Dynamic ChemistryEngineering Research Center for Biomaterials of Ministry of EducationSchool of Materials Science and EngineeringEast China University of Science and TechnologyShanghai 200237China

Damaged neurons and harsh microenvironments contribute to the injury cascades following traumatic brain injury(TBI).Mesenchymal stem cell(MSC)therapy is considered a viable choice for brain in-jury treatment;however,its clinical use is hindered by limited engraftment,low survival ratio,and uncontrolled ***,the decellularized brain extracellular matrix(dBECM)was prepared through a new method as a delivery system for ***-based hydrogel with favorable biochem-ical and biomechanical features provides a microenvironment for MSCs in nerve *** MSCs-encapsulated dBECM-based hydrogel is shown to improve neuron compensation and structural regen-eration,alleviate neuroinflammation,and promote M1-to-M2 polarization of *** results first demonstrate that the combination of dBECM and MSCs is a critical vehicle to promote TBI repair from neurogenesis and immunoregulation,showing promise for the physiological recovery of neurogenic dis-eases and injuries.

关键词： ECM Stem cells Brain injury Neurogenesis Neuroinflammation

A three-dimensional solid-liquid two-phase turbulence model with the effect of vegetation in non-orthogonal curvilinear coordinates

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Science China(Physics,Mechanics & Astronomy) 2009年第7期52卷 1062-1073页

作者： liu Cheng SHEN YongMing Coastal&Estuary Dynamics Section Pearl River Hydraulic Research InstituteGuangzhou 510611China State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116023China

A three-dimensional k-ε-Ap solid-liquid two-phase two-fluid model with the effect of vegetation is solved numerically with a finite-volume method on an adaptive grid to study water-sediment movements and bed evolution in vegetated channels. The additional drag force and additional turbulence generation due to vegetation are added to the relevant control equations for simulating the interaction between vegetation and flow. The flow structure and the bed-topography changes in a 60° partly vegetated channel bend are calculated by the model. The numerical results agree well with the measured ones. Calculated and measured results show that the primary flow velocity reduces much in the vegetation zone and increases in the non-vegetation zone, the secondary flow velocity weakens in the vegetation zone and strengthens in the non-vegetation zone, the sediment movement and bed-topography change also weaken in the vegetation zone and strengthen in the non-vegetation zone, a well-planed vegetation arrangement can improve bank stabilization program, and the k-ε-Ap model can deal with bed-load transport with a more reasonable method than the one-fluid model.

关键词： adaptive grid three dimensional k-ε-A_(p)model solid-liquid two-phase turbulence model vegetation channel bend sediment transport bed-topography change

On Non-commuting Sets in Certain Finite p-Groups

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Algebra Colloquium 2015年第4期22卷 555-560页

作者： Heguo liu Yulei Wang Department of Mathematics Hubei University Wuhan 430062 China vDepartment of Mathematics Henan University of Technology Zhengzhou 450001 China

Let G be a group. A subset X of G is said to be non-commuting if xy ≠ yx for any x, y ∈ X with x ≠ y. If {X}≥ IYI for any other non-commuting set Y in G, then X is said to be a maximal non-commuting set. In this paper, the bound for the cardinality of a maximal non-commuting set in a finite p-group G is determined, where G is a non-abelian p-group given by a central extension as1 → Zp→ G →Zp ×→ × Zp →1 and its derivedsubgroup has order p.

关键词： generalized extraspecial p-group central product non-commuting set

SLIDING MODE CONTROL FOR ACTIVE AUTOMOBILE SUSPENSIONS

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Chinese Journal of Mechanical Engineering 1998年第1期11卷 12-19页

作者： Zhang, Jianwu liu, Xinliang Shanghai Jiaotong Univ Shanghai China

Nonlinear control methods are presented based on theory of sliding mode control (SMC) or variable structure control (VSC) for application to active automobile suspensions. Requirements of reducing manufacturing cost and energy consumption of the active suspension system may be satisfied by reasonable design of the sliding surface and hydraulic servo system. Emphasis is placed on the study of the discrete sliding mode control method (DSMC) applicable for a new sort of speed on off solenoid valves of anti dust capability and low price. Robustness and effectiveness of the feedback linearized controller in typical road conditions are demonstrated by numerical results for a quarter car suspension model.

关键词： Automobile suspension Siding mode control Nonlinear dynamics

PLDMLT:Multi-Task Learning of Diabetic Retinopathy Using the Pixel-Level Labeled Fundus Images

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Computers, Materials & Continua 2023年第8期76卷 1745-1761页

作者： Hengyang liu Chuncheng Huang Department of Computer Science and Engineering Chongqing University of TechnologyChongqing400054China

In the field of medical images,pixel-level labels are time-consuming and expensive to acquire,while image-level labels are relatively easier to ***,it makes sense to learn more information(knowledge)from a small number of hard-to-get pixel-level annotated images to apply to different tasks to maximize their usefulness and save time and training *** this paper,using Pixel-Level Labeled Images forMulti-Task Learning(PLDMLT),we focus on grading the severity of fundus images for Diabetic Retinopathy(DR).This is because,for the segmentation task,there is a finely labeled mask,while the severity grading task is without classification *** this end,we propose a two-stage multi-label learning weakly supervised algorithm,which generates initial classification pseudo labels in the first stage and visualizes heat maps at all levels of severity using Grad-Cam to further provide medical interpretability for the classification task.A multitask model framework with U-net as the baseline is proposed in the second stage.A label update network is designed to alleviate the gradient balance between the classification and segmentation *** experimental results show that our PLDMLTmethod significantly outperforms other stateof-the-art methods in DR segmentation on two public datasets,achieving up to 98.897%segmentation *** addition,our method achieves comparable competitiveness with single-task fully supervised learning in the DR severity grading task.

关键词： DR lesion segmentation pseudo labels grading task class activation heat map update label network

Continuum description for the characteristic resistance sensed by a cylinder colliding against granular medium

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Science China(Physics,Mechanics & Astronomy) 2013年第8期56卷 1428-1436页

作者： PANG Yong liu CaiShan State Key Laboratory for Turbulence and Complex Systems College of EngineeringPeking University

In this paper, we experimentally and theoretically study the resistance force that develops when a cylinder with a flat face colliding against dry quartzite sand. Observations from experimental data clearly show that the acceleration curves are characterized by a double-peak structure. The first agitated peak can be attributed to a shock process where sand responds elastically, and the valley bottom in the double-peak structure is related to a limited plastic load when a fully plastic region is formed in the sand, while the second agitated peak corresponds to a the occurrence of the maximum of viscous force in a homogeneous developed bulk flow. We use slip line theory (SL) developed in plastic mechanics to capture the value at the valley bottom, adopt the double shearing theory (DS), together with a Local Rheological Constitutive Law (LRCL) suggested in this paper, to capture the drag force generated in a homogeneous bulk flow. Good agreements in the comparisons between numerical and experimental results support the characteristic resistance by the cylinder to predict granular states.

关键词： granular material penetrating dynamics rheological property

Effect of ultrasonic peening treatment on the fatigue behaviors of a magnesium alloy up to very high cycle regime

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Journal of Magnesium and Alloys 2022年第3期10卷 659-673页

作者： Yao Chen Fulin liu Chao He Lang Li Chong Wang Yongjie liu Qingyuan Wang Failure Mechanics and Engineering Disaster Prevention and Mitigation Key Laboratory of Sichuan Province Sichuan UniversityChengdu 610065China MOE Key Laboratory of Deep Earth Science and Engineering College of Architecture and EnvironmentSichuan UniversityChengdu 610065China Institute for Advanced Study Chengdu UniversityChengdu 610106China

Ultrasonic fatigue tests are performed on a magnesium alloy with and without ultrasonic peening treatment(UPT).Surface enhancement layer leads to the complete change of crack initiation ***,crack initiation mechanism keeps the same and results in a single-faceted morphology at crack initiation *** initiate as Mode Ⅱ crack within the original grain,but deflect to Mode I crack outside of the original cracked grain.A threshold SIF value is proposed to evaluate the retarding effect of grain boundary on microcrack *** of the original cracked grain,Mode I crack propagation below the threshold ΔK_(σ-th) is responsible for the formation of fine granular area(FGA,a nano-grain layer).Based on the Numerous Cyclic Pressing(NCP) model,it is proposed that crack type should be another necessary condition for the formation of FGA.

关键词： Ultrasonic peening treatment Very-high-cycle fatigue Crack initiation mechanism Fine granular area Nanograins.

Pseudo core-shell LaCoO3@MgO perovskite oxides for high performance methane catalytic oxidation

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Journal of Rare Earths 2021年第1期39卷 51-57,I0002页

作者： Saifei Wang Jie liu Yiyuan Zhang Peiqi Chu Haobin liu Man Wang Erhong Duan School of Environmental Science and Engineering Hebei University of Science and TechnologyShijiazhuang 050018China

Magnesia modified LaCoO3 was prepared by a facile one-step sol-gel method and used for removal of dilute *** with the conventional doping technique,the obtained LaCoO3@MgO-x exhibits pseudo core-shell structure and shows superior catalytic *** methane conversion exceeds90%at 532℃on LaCoO3@MgO-0.1,while only 60%of methane is conversed using the doped perovskite *** high catalytic performance of LaCoO3@MgO-0.1 is mainly attributed to the adjustment of surface acid-base properties by the MgO shell *** to density functional theory(DFT)calculation,the methane is more likely to be adsorbed and cracked on LaCoO3@*** in situ DRIFTS shows that CH3-O-CH3 intermediate specie is *** pseudo core-shell structure also enhances the stability and the LaCoO3@MgO-0.1 maintains high activity after working for 100 *** above results demonstrate that surface modification by magnesia is an effective strategy for improving LaCoO3 catalytic performance.

关键词： Perovskite oxides Core-shell structure Surface acid-base properties Methane catalytic oxidation Rare earths

Flame-retardant and antibacterial flexible polyurethane foams with high resilience based on a P/N/Si-containing system

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Journal of Materials Science & Technology 2024年第15期182卷 141-151页

作者： Ping Li Hui liu Ying-Jun Xu De-Yi Wang Yun liu Ping Zhu College of Textiles&Clothing Institute of Functional Textiles and Advanced MaterialsNational Engineering Research Center for Advanced Fire-Safety Materials D&A(Shandong)Qingdao Key Laboratory of Flame Retardant Textile MaterialsState Key Laboratory of Bio-Fibers and Eco-TextilesQingdao UniversityQingdao 266071China IMDEA Materials Institute C/Eric Kandel 2GetafeMadrid 28906Spain

In this work,the coatings used phosphorylated chitosan(PCS)and GP-108 via the dip-coating method presented exceptional flame retardancy and antibacterial properties for flexible polyurethane foams(FPUF).PCS/GP@FPUF with 35%weight gain of PCS/GP can receive the UL-94 V-0 rating and obtain a 32%reduction of peak heat release rate value compared with that of FPUF,and it remains relatively dense char *** effective heat of combustion of PCS/GP@FPUF is 21.6 kJ/g,presenting a 22%decrease compared with that of ***,the PCS/GP coatings mainly have the condensed-phase flame-retardant mechanism associated with the analysis of char residues and the volatile products released through the thermal degradation process.X-ray photoelectron spectroscopy results confirm that the char residues of PCS/GP@FPUF consist of highly-graphitized carbon and it formed P-N-Si synergistic char *** addition,the antibacterial rates of PCS/GP@FPUF against Escherichia coli(***)and Staphylococcus aureus(***)are 99.99%,and the incorporation of GP-108 does not influence the antibacterial proper-ties of ***,the resiliency of FPUFs has been slightly ***,the flame-retardant and antibacterial FPUFs with wonderful resiliency are hopeful to be applied as filler materials for vehicle seats and obtain longer service lives.

关键词： Environmental organic-inorganic coatings FPUF Flame retardancy Antibacterial properties

An Inverse Problem of Identifying the Radiative Coefficient in a Degenerate Parabolic Equation

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Chinese Annals of Mathematics,Series B 2014年第3期35卷 355-382页

作者： Zuicha DENG liu YANG Department of Mathematics Lanzhou Jiaotong University School of Mathematics and Statistics Lanzhou University

The authors investigate an inverse problem of determining the radiative coefficient in a degenerate parabolic equation from the final overspecified data. Being different from other inverse coefficient problems in which the principle coefficients are assumed to be strictly positive definite, the mathematical model discussed in this paper belongs to the second order parabolic equations with non-negative characteristic form, namely, there exists a degeneracy on the lateral boundaries of the domain. Based on the optimal control framework, the problem is transformed into an optimization problem and the existence of the minimizer is established. After the necessary conditions which must be satisfied by the minimizer are deduced, the uniqueness and stability of the minimizer are proved. By minor modification of the cost functional and some a priori regularity conditions imposed on the forward operator, the convergence of the minimizer for the noisy input data is obtained in this paper. The results can be extended to more general degenerate parabolic equations.

关键词： Inverse problem Degenerate parabolic equation Optimal control Exis-tence Uniqueness Stability Convergence