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Experimental study on fire extinguishing with a newly prepared multi-component compressed air foam

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Chinese Science Bulletin 2009年第3期54卷 492-496页

作者： WANG XiShi liao YaoJian lin lin State Key Laboratory of Fire Science University of Science and Technology of China Hefei 230026 China

A multi-component compressed air foam system (MCAFS) was developed with newly prepared multi-component foaming agents. Extinguishing of wood crib and oil pool fires was performed under different conditions, such as foam concentration, mixing chamber forepart structure and working pressure. It was found that the foam concentration had sufficient effects on fire extinguishing efficiency, and an optimized concentration value exists. For instance, for diesel oil pool fires, this value is about 2.2% while it is about 4.0% for wood crib fires. The results also show that the system with a coaxial mixing chamber has greater efficiency than a T-shape. The effects of working pressure on fire extin- guishing are evident in experiments, i.e., the higher the working pressure is, the more readily the fire is extinguished.

关键词：木材失火油库失火灭火方式泡沫灭火器

Appraising the potential of calcium sulfoaluminate cement-based grouts in simulated permafrost environments

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Frontiers of Structural and Civil Engineering 2023年第5期17卷 722-731页

作者： Jian ZHAO Guangping HUANG lin liao Wei Victor LIU Department of Civil and Environmental Engineering University of AlbertaEdmonton T6G 1H9Canada College of Mining Engineering Taiyuan University of TechnologyTaiyuan 030024China

The aim of this study is to appraise the potential of calcium sulfoaluminate(CSA)cement-based grouts in simulated permafrost *** hydration and performance of CSA cement-based grouts cured in cold environments(10,0,and−10℃)are investigated using a combination of tests,including temperature recording,X-ray diffraction(XRD)tests,thermogravimetric analysis(TGA),and unconfined compressive strength(UCS)*** recorded temperature shows a rapid increase in temperature at the early stage in all the ***,results of the TGA and XRD tests show the generation of a significant quantity of hydration products,which indicates the rapid hydration of CSA cement-based grouts at the early stage at low ***,the CSA cement-based grouts exhibit remarkably high early *** UCS values of the samples cured for 2 h at−10,0,and 10℃ are 6.5,12.0,and 12.3 MPa,*** UCS of the grouts cured at−10,0,and 10℃ increases continuously with age and ultimately reached 14.9,19.0,and 30.6 MPa at 28 d,*** findings show that the strength of grouts fabricated using CSA cement can develop rapidly in cold environments,thus rendering them promising for permafrost applications.

关键词： permafrost low temperatures calcium sulfoaluminate cement-based grouts hydration reaction compressive strength

The Variable-Step L1 Scheme Preserving a Compatible Energy Law for Time-Fractional Allen-Cahn Equation

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Numerical Mathematics(Theory,Methods and Applications) 2022年第4期15卷 1128-1146页

作者： Hong-lin liao Xiaohan Zhu Jindi Wang MIIT Key Laboratory of Mathematical Modelling and High Performance Computing of Air Vehicles Nanjing 211106P.R.China School of Mathematics Nanjing University of Aeronautics and Astronautics211106P.R.China School of Mathematics and Computational Science Xiangtan UniversityXiangtan 411105P.R.China

In this work,we revisit the adaptive L1 time-stepping scheme for solving the time-fractional Allen-Cahn equation in the Caputo’s *** L1 implicit scheme is shown to preserve a variational energy dissipation law on arbitrary nonuniform time meshes by using the recent discrete analysis tools,i.e.,the discrete orthogonal convolution kernels and discrete complementary convolution *** the discrete embedding techniques and the fractional Gronwall inequality are applied to establish an L^(2)norm error estimate on nonuniform time *** adaptive time-stepping strategy according to the dynamical feature of the system is presented to capture the multi-scale behaviors and to improve the computational performance.

关键词： Time-fractional Allen-Cahn equation adaptive L1 scheme variational energy dissipation law orthogonal convolution kernels complementary convolution kernels

Positive definiteness of real quadratic forms resulting from the variable-step L1-type approximations of convolution operators

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Science China Mathematics 2024年第2期67卷 237-252页

作者： Hong-lin liao Tao Tang Tao Zhou School of Mathematics Nanjing University of Aeronautics and AstronauticsNanjing 211106China Division of Science and Technology BNU-HKBU United International CollegeZhuhai 519087China SUSTech International Center for Mathematics Shenzhen 518055China NCMIS&LSEC Institute of Computational Mathematics and Scientific/Engineering ComputingAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China

The positive definiteness of real quadratic forms with convolution structures plays an important rolein stability analysis for time-stepping schemes for nonlocal operators. In this work, we present a novel analysistool to handle discrete convolution kernels resulting from variable-step approximations for convolution *** precisely, for a class of discrete convolution kernels relevant to variable-step L1-type time discretizations, weshow that the associated quadratic form is positive definite under some easy-to-check algebraic conditions. Ourproof is based on an elementary constructing strategy by using the properties of discrete orthogonal convolutionkernels and discrete complementary convolution kernels. To our knowledge, this is the first general result onsimple algebraic conditions for the positive definiteness of variable-step discrete convolution kernels. Using theunified theory, we obtain the stability for some simple nonuniform time-stepping schemes straightforwardly.

关键词： discrete convolution kernels positive definiteness variable time-stepping orthogonal convolution kernels complementary convolution kernels

An Energy Stable Filtered Backward Euler Scheme for the MBE Equation with Slope Selection

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Numerical Mathematics(Theory,Methods and Applications) 2023年第1期16卷 165-181页

作者： Jiexin Wang Hong-lin liao Ying Zhao School of Mathematics Nanjing University of Aeronautics and AstronauticsNanjing 211106China Key Laboratory of Mathematical Modelling and High Performance Computing of Air Vehicles(NUAA) MIITNanjing 211106China

As a promising strategy to adjust the order in the variable-order BDF algorithm,a time filtered backward Euler scheme is investigated for the molecular beam epitaxial equation with slope *** temporal second-order convergence in the L^(2)norm is established under a convergence-solvability-stability(CSS)-consistent time-step *** CSS-consistent condition means that the maximum stepsize limit required for convergence is of the same order to that for solvability and stability(in certain norms)as the small interface parameterε→0^(+).Similar to the backward Euler scheme,the time filtered backward Euler scheme preserves some physical properties of the original problem at the discrete levels,including the volume conservation,the energy dissipation law and L^(2)norm *** tests are included to support the theoretical results.

关键词： MBE model time filter energy dissipation law error estimate

Analysis of the second-order BDF scheme with variable steps for the molecular beam epitaxial model without slope selection

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Science China Mathematics 2021年第5期64卷 887-902页

作者： Hong-lin liao Xuehua Song Tao Tang Tao Zhou Department of Mathematics Nanjing University of Aeronautics and AstronauticsNanjing 211101China Department of Mathematics and International Center for Mathematics Southern University of Science and TechnologyShenzhen 518055China Division of Science and Technology BNU-HKBU United International CollegeZhuhai 519087China NCMIS&LSEC Institute of Computational Mathematics and Scientific Engineering ComputingAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China

In this work,we are concerned with the stability and convergence analysis of the second-order backward difference formula(BDF2)with variable steps for the molecular beam epitaxial model without slope *** first show that the variable-step BDF2 scheme is convex and uniquely solvable under a weak time-step *** we show that it preserves an energy dissipation law if the adjacent time-step ratios satisfy r_(k):=τ_(k)/τ_(k-1)<***,with a novel discrete orthogonal convolution kernels argument and some new estimates on the corresponding positive definite quadratic forms,the L^(2)norm stability and rigorous error estimates are established,under the same step-ratio constraint that ensures the energy stability,i.e.,0

关键词： molecular beam epitaxial growth variable-step BDF2 scheme discrete orthogonal convolution kernels energy stability convergence analysis

ZM1 magnesium alloy reinforced by carbon nanotubes using an improved casting process

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Rare Metals 2021年第5期40卷 1275-1283页

作者： Qiu-Hong Yuan lin liao Guo-Hua Zhou Zheng-Yun Liu Physical Science and Technology College Yichun UniversityYichun 336000China Department of Materials Processing Engineering Nanchang UniversityNanchang 330031China

Melt processing is a promising process to fabricate Mg-CNTs(carbon nanotubes)composites with high performance and large *** this work,the liquidmixing technique and ball-milling processes as well as the stirring casting method were used to prepare ZM1-1.0 CNTs-L and ZM1-1.0 CNTs-B composites,*** composites were studied using optical microscopy(OM),Raman spectroscopy,scanning electron microscope(SEM),transmission electron microscope(TEM)and room-temperature tensile *** results show that the yield strength(YS),ultimate tensile strength(UTS),elongation and microhardness values of the ***-L composite are improved by 37.3%,29.6%,37.0%and33.3%,respectively,compared with those of ZM1 *** uniform dispersion of CNTs as well as the strong interfacial bonds with the Mg matrix is the main reason for the significant improvement in mechanical properties of the as-cast *** mixing combined with the stirring casting method is favorable to fabricate Mg-CNTs composite with high mechanical properties.

关键词： ZM1 alloy Carbon nanotubes(CNTs) Composites Microstructure Mechanical properties

A review on high power SOFC electrolyte layer manufacturing using thermal spray and physical vapour deposition technologies

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Advances in Manufacturing 2014年第3期2卷 212-221页

作者： Pierre Coddet Han-lin liao Christian Coddet IRTES-LERMPS/UTBM Site de Sevenans90010 Belfort CedexFrance

Manufacturing of solid oxide fuel cell （SOFC） components remains nowadays a key point for the indus- trial development of this technology. Especially, the deposition of the dense electrolyte layer which is sand- wiched between the porous anode and the porous cathode is of paramount importance and thus focuses a lot of attention. Therefore, this paper considers and reviews recent developments concerning solid electrolyte layers manufacturing using thermal spray （TS） and physical vapour deposition （PVD） technologies.

关键词： Solid oxide fuel cell (SOFC) Solidelectrolytes Thermal spray (TS) Physical vapourdeposition (PVD)

Preparation of ZnO_(1-x) by peroxide thermal decomposition and its room temperature gas sensing properties

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Rare Metals 2022年第3期41卷 871-876页

作者： Chao Zhang Ying Li Gui-Fang Liu Han-lin liao College of Mechanical Engineering Yangzhou UniversityYangzhou 225127China ICB UMR 6303 CNRSUniversity Bourgogne Franche-ComtéUTBMBelfort 90010France

The excessive concentration of NO_(2) in the atmosphere has gained considerable attention due to its damage to the environment and human health. Gas sensor technology has important application prospects in detecting atmospheric NO_(2) concentration. Restricted by its wide bandgap, pristine ZnO needs additional energy to power the electronic transition as a gas sensing material.

关键词： Restricted gained damage