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Transactions of Nanjing University of Aeronautics and Astronautics 2018年第5期35卷 778-788页

作者： zhao liqing Sun Jianhong School of Marine Sciences Nanjing University of Information Science & Technology College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics

A dual-jet consisting of a wall jet and an offset jet has been numerically simulated using lattice Boltzmann method to examine the effects of jet spacing between two jet centerlines,defined as *** Reynolds number based on jet-exit-width dis set to be Re = 56 and the jet spacing is set to be less than or equal 10 times the *** results reveal that the flow field displays periodic vortex shedding when the jet spacing is in the range of 9≤s/d ≤ 10,while it remains steady with two counter-rotating vortices in the converging region when s/d ≤ *** s/d = 9,the power spectral analyses indicate that the vortex shedding phenomenon has specific *** significant oscillation stresses induced by the periodic components of velocities are found to mainly exist in the inner shear layer regions,implying stronger momentum transfer occuring in these regions.

关键词： dual-jet low-Reynolds number lattice Boltzmann method vortex shedding

Constructing ultrafine monodispersed Co_(2)P/(0.59-Cu_(3)P)on Cu doped CoZn-ZIF derived porous N-doped carbon for highly efficient dehydrogenation of ammonia borane

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Nano Research 2023年第5期16卷 6687-6700页

作者： Yinze Yang liqing zhao Xiangyang Gao Yafei zhao School of Chemical Engineering Zhengzhou UniversityZhengzhou 450001China State Key Laboratory of Electroanalytical Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China School of Environmental Engineering and Chemistry Luoyang Institute of Science and TechnologyLuoyang 471023China Key Laboratory of Artificial Micro Nano-structures of Ministry of EducationSchool of Physics and TechnologyWuhan UniversityWuhan 430072China

Rational construction of highly dispersed,small size,low cost catalysts for release of hydrogen from ammonia borane(AB)is regarded as a prospective approach for promoting the development of upcoming hydrogen ***,the high price and scarcity of precious metal catalysts impose restrictions on their large-scale *** this end,with the aid of a Cu doped CoZn-zeolitic imidazolate frameworks(ZIFs)template strategy,we successfully construct ultrafine monodispersed Co_(2)P/(0.59-Cu_(3)P)on CoZn-ZIF derived porous N-doped carbon(Co_(2)P/(0.59-Cu_(3)P)-NC)as an efficient non-noble-metal ***,Co and Cu atoms can be geometrically separated to high degree due to the presence of Zn in the CuCoZn-ZIF precursor,evaporation of Zn during pyrolysis can generate porous structure with the framework well *** results show that porous Co_(2)P/(0.59-Cu_(3)P)-NC bimetallic phosphide exhibits large specific surface area,hierarchical pore structure,well-exposed active *** on the kinetics analyses and ion effects,the catalyst has achieved an unprecedentedly high total turnover frequency(TOF)of 798 mol·molcat^(−1)·min^(−1)in 0.4 M NaOH solution at 298 K,which surpasses all the ever-reported transition-metal phosphides catalysts for hydrogen generation from *** and theoretical studies confirm that the highly porous structure of the support,the ultrafine and high dispersion of nanoparticles,the N/P doping and their synergistic effects(e.g.,M-P,M-N,N-C,M-M',M-support)jointly induce strong electron transfer,which can reduce the reaction energy barrier and enhance their interaction with AB,thus correspondingly obtaining excellent catalytic *** mechanism and strategy presented in this work pave an avenue for the design of non-noble metal catalyst for hydrogen energy system.

关键词： non-noble metal transition-metal phosphides porous N-doped carbon hydrogen evolution ammonia borane catalytic hydrolysis

Flow Characteristics of Flapping Motion of a Plane Water Jet Impinging onto Free Surface

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Advances in Applied Mathematics and Mechanics 2013年第6期5卷 846-856页

作者： liqing zhao Jianhong Sun College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics29 Yudao StreetNanjing 210016JiangsuChina

A submerged turbulent plane jet in shallow water impinging vertically onto the free surface will produce a large-scale flapping motion when the jet exit velocity is larger than a critical *** flapping phenomenon is verified in this paper through a large eddy simulation where the free surface is modeled by volume of fluid *** quantitative results for flapping jet are found to be in good agreement with available experimental data in terms of mean velocity,flapping-induced velocity and turbulence *** show that the flapping motion is a new flow pattern with characteristic flapping frequency for submerged turbulent plane jets,the mean centerline velocity decay is considerably faster than that of the stable impinging jet without flapping motion,and the flapping-induced velocities are as important as the turbulent fluctuations.

关键词： Turbulent plane jet flapping motion volume of fluid large eddy simulation

Experimental and numerical study on the flapping motion of submerged turbulent plane jet

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Science China(Technological Sciences) 2013年第10期56卷 2391-2397页

作者： SUN JianHong zhao liqing HSU ChinTsau College of Aerospace Engineering Nanjing University of Aeronautics & Astronautics Department of Mechanical Engineering Hong Kong University of Science & Technology

A submerged,vertical turbulent plane water jet impinging onto a free surface will be self-excited into a flapping oscillation when the jet velocity,leaving the jet orifice,exceeds a critical *** flapping phenomenon was verified simultaneously in this paper by laser Doppler velocimeter measurement and numerical analyses with volume of fluid approach coupled with a large eddy simulation turbulent *** general agreement of mean velocities between numerical predictions and experimental results in self-similar region is good for two cases:Reynolds numbers 2090 and 2970,which correspond to the stable impinging jet and flapping *** show that the flapping jet is a new flow pattern for submerged turbulent plane jets with characteristic flapping frequency,and that the decay of the mean velocity along the jet centerline is considerably faster than that of the stable impinging state.

关键词： turbulent plane jet flapping motion laser Doppler velocimeter volume of fluid large eddy simulation

Large-eddy simulation of the compressible flow past a tabbed cylinder

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Chinese Science Bulletin 2012年第24期57卷 3203-3210页

作者： XU ChangYue zhao liqing SUN JianHong College of Aerospace Engineering Nanjing University of Aeronautics&Astronautics Nanjing 210016China

The compressible flow past a tabbed cylinder has been studied numerically using large-eddy simulation for a free-stream Mach number M∞=0.75 and a Reynolds number based on the diameter Re=2×105. Because of the passive control of the flow past a tabbed cylinder, the mean drag coefficient of tabbed cylinder is less than that of a corresponding circular cylinder with a drag reduction up to 33%. The fluctuating lift coefficient is greatly suppressed to be nearly zero. Drag reduction due to the shearing process prevails over that due to the compressing process in this flow. Through investigating the mechanisms relevant to passive control of the tab, it is found that suppression of the shear layer instability can lead to a higher-base-pressure distribution, which can reasonably be associated with drag reduction and suppression of the lift fluctuations. The analysis of convective Mach number and self-sustained oscillations phenomenon inside the shear layers indicates that both the compressible effect and high-frequency forcing result in suppression of the shear layer instability of tabbed cylinder.

关键词：可压缩流动大涡模拟标签气缸被动控制剪切层数值研究阻力系数

Assessing the collapse risk of Stipa bungeana grassland in China based on its distribution changes

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Journal of Arid Land 2020年第2期12卷 303-317页

作者： QIAO Xianguo GUO Ke LI Guoqing zhao liqing LI Frank Yonghong GAO Chenguang State Key Laboratory of Vegetation and Environmental Change Institute of BotanyChinese Academy of SciencesBeijing 100093China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Northwest A&F UniversityYangling 712100China Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water ResourcesYangling 712100China Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau&Inner Mongolia Key Laboratory of Grassland Ecology School of Ecology and EnvironmentInner Mongolia UniversityHohhot 010021China

The criteria used by International Union for Conservation of Nature(IUCN) for its Red List of Ecosystems(RLE) are the global standards for ecosystem-level risk assessment, and they have been increasingly used for biodiversity conservation. The changed distribution area of an ecosystem is one of the key criteria in such assessments. The Stipa bungeana grassland is one of the most widely distributed grasslands in the warm-temperate semi-arid regions of China. However, the total distribution area of this grassland was noted to have shrunk and become fragmented because of its conversion to cropland and grazing-induced degradation. Following the IUCN-RLE standards, here we analyzed changes in the geographical distribution of this degraded grassland, to evaluate its degradation and risk of collapse. Past(1950-1980) distribution areas were extracted from the Vegetation Map of China(1:1,000,000). Present realizable distribution areas were equated to these past areas minus any habitat area losses. We then predicted the grassland’s present and future(under the Representative Concentration Pathway 8.5 scenario) potential distribution areas using maximum entropy algorithm(MaxEnt), based on field survey data and nine environmental layers. Our results showed that the S. bungeana grassland was mainly distributed in the Loess Plateau, Hexi Corridor, and low altitudes of the Qilian Mountains and Longshou Mountain. This ecosystem occurred mainly on loess soils, kastanozems, steppe aeolian soils and sierozems. Thermal and edaphic factors were the most important factors limiting the distribution of S. bungeana grassland across China. Since 56.1% of its past distribution area(4.9×10~4 km^2) disappeared in the last 50 a, the present realizable distribution area only amounts to 2.2×10~4 km^2. But only 15.7% of its present potential distribution area(14.0×10~4 km^2) is actually occupied by the S. bungeana grassland. The future potential distribution of S. bungeana grassland was predicted t

关键词： climate change limiting factors maximum entropy algorithm potential distribution realizable distribution Red List of Ecosystems Loess Plateau

Evaluation of Arctic sea ice simulation of CMIP6 models from China

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Advances in Polar Science 2022年第3期33卷 220-234页

作者： LI Jiaqi WANG Xiaochun WANG Ziqi zhao liqing WANG Jin School of Marine Sciences Nanjing University of Information Science and TechnologyNanjing 210014China

Nine coupled climate models from China participating in the Coupled Model Intercomparison Project Phase 6(CMIP6)were evaluated in terms of their capability in ensemble historical Arctic sea ice simulation in the context of 56 CMIP6 *** evaluated these nine models using satellite observations from 1980 to *** evaluation was conducted comprehensively using 12 metrics covering different aspects of the seasonal cycle and long-term trend of sea ice extent(SIE)and sea ice concentration(SIC).The nine Chinese modelstended to overestimate SIE,especially in March,and underestimate its long-term decline *** was less spread in model skill in reproducing the spatial pattern of March SIC than in reproducing the spatial pattern of September *** error of March SIC simulation was distributed at the margins of sea ice cover,such as in the Nordic Seas,the Barents Sea,the Labrador Sea,the Bering Sea,and the Sea of ***,the error of September SIC was distributed both at the margins of sea ice cover and in the central part of the Arctic *** of these nine models had capabilities comparable with the majority of the CMIP6 models in reproducing the seasonal cycle and long-term trend of Arctic sea ice.

关键词： coupled climate model CMIP6 Arctic sea ice

Warming and increased precipitation alter soil carbon cycling in a temperate desert steppe of Inner Mongolia

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Journal of Plant Ecology 2024年第2期17卷 161-172页

作者： Mu Lan Xiao Qiu Wei La Huimin Wang Yahong Liu liqing zhao Hailian Sun Inner Mongolia Key Laboratory of Grassland Ecology and School of Ecology and Environment Inner Mongolia UniversityHohhot 010021China Inner Mongolia Academy of Agricultural and Animal Husbandry Sciences Hohhot 010031China State Key Laboratory of Vegetation and Environmental Change Institute of Botanythe Chinese Academy of SciencesBeijing 100093China College of Resources and Environment Baotou Teachers’CollegeBaotou 014030China

Warming and precipitation are key global change factors driving soil carbon(C)dynamics in terrestrial ***,the effects of warming and altered precipitation on soil microbial diversity and functional genes involved in soil C cycling remain largely *** investigated the effects of warming and increased precipitation on soil C cycling in a temperate desert steppe of Inner Mongolia using metagenomic *** found that warming reduced plant richness,Shannon-Wiener and Simpson *** contrast,increased precipitation signifcantly infuenced Shannon-Wiener and Simpson *** reduced soil microbial species by 5.4%while increased precipitation and warming combined with increased precipitation led to increases in soil microbial species by 23.3%and 2.7%,*** relative abundance of Proteobacteria,which involve C cycling genes,was signifcantly increased by warming and increased *** signifcantly reduced the abundance of GAPDH(Calvin cycle)and celF(cellulose degradation)while it enhanced the abundance of glxR(lignin degradation).Increased precipitation signifcantly enhanced the abundance of pgk(Calvin cycle),coxL(carbon monoxide oxidation),malZ(starch degradation),and mttB(methane production).Moreover,a wide range of correlations among soil properties and C cycling functional genes was detected,suggesting the synergistic and/or antagonistic relationships under scenario of global *** results may suggest that warming is benefcial to soil C storage while increased precipitation negatively affects soil C *** fndings provide a new perspective for understanding the response of microbial communities to warming and increased precipitation in the temperate desert steppe.

关键词： carbon cycling desert steppe functional genes global change soil microbes precipitation warming

Stipa steppes in scantily explored regions of the tibetan Plateau:classification,community characteristics and climatic distribution patterns

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Journal of Plant Ecology 2018年第4期11卷 585-594页

作者： Haiwei zhao Ke Guo Yao Yang Changcheng Liu liqing zhao Xianguo Qiao Dongjie Hou Chenguang Gao State Key Laboratory of Vegetation and Environmental Change Institute of BotanyChinese Academy of SciencesNo.20 NanxincunXiangshanBeijing 100093China College of Life Sciences University of Chinese Academy of SciencesNo.19A Yuquan RoadBeijing 100049China School of Life Sciences Inner Mongolia UniversityNo.235 Daxuexi RoadHohhotInner Mongolia 010021China

Aims As a unique geographical unit of the earth,the tibetan Plateau is extensively covered by various Stipa ***,their vegetation features have not been reported systematically till now,especially in some scantily explored *** this study,we endeavor to reveal the community types,quantitative charac-teristics and climatic distribution patterns of Stipa steppes in these areas based on primary relevés obtained from *** We collected a total of 223 plots in 79 study sites in the Changthang Plateau and the Yarlung Zangbo Valley,ranging from 79°E to 91°*** categories of Stipa formations were identified according to the classification scheme in Vegetation of China and then verified by Nonmetric Multidimensional *** performed detrended correspondence analysis and detrended canonical correspondence analysis to hunt for the alteration of Stipa communities along the precipitation *** characteristics including species richness,coverage,biomass as well as importance values(IV)of dominant species were calcu-lated and visualized,*** Findings Stipa steppes in scantily explored regions of the tibetan Plateau are classified into 11 formations but major formations are rather limited in ***(form.)Stipa purpurea is the most widespread Stipa assemblages not only in scantily explored regions but also across the whole tibetan *** characteristics of Stipa com-munities,including coverage,species richness,productivity and IV of dominant species,demonstrate the features of typical alpine steppes on the tibetan *** proves to be the prime climatic factor controlling the distribution patterns of Stipa *** subsessiliflora *** and *** glareosa normally distribute in arid habitats,but rainfall for the former is of greater *** roborowskyi and *** capillacea favor moderately moist *** purpurea and ***

关键词： stipa steppe community characteristic distribution pattern alpine steppe the tibetan Plateau

Analysis of in situ Reaction and Pressureless Infiltration Process in Fabricating TiC/Mg Composites

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Journal of Materials Science & Technology 2004年第1期20卷 3-7页

作者： Qun DONG, liqing CHEN, Mingjiu zhao and Jing BIInstitute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China Inst. of Metal Res. Chinese Acad. of Sci. Shenyang 110016 China

An innovative processing route, in situ reaction combined with pressureless infiltration, was adopted to fabricate magnesium matrix composites, where the reinforcement TiC formed in situ from elemental Ti and C powders and molten Mg spontaneously infiltrated the preform of Ti and C. The influences of primarily elemental particle sizes, synthesizing temperature, holding time etc on in situ reactive infiltration for Mg-Ti-C system were systematically investigated in order to explore the mechanism of this process. In fabricating TiC/Mg composites, Mg can not only spontaneously infiltrate the preform of reinforcement and thus densify the as fabricated composites as matrix metal, but also it can accelerate the in situ reaction process and lower the synthesizing temperature of Ti and C as well. In situ reaction of Ti and C and Mg infiltration processes are essentially overlapping and interacting during fabrication of TiC/Mg composites. The mechanism proposed in this paper can be used to explain the formation and morphologies of the reinforcement phase TiC.

关键词： Magnesium matrix composite In situ reactive infiltration Titanium carbide Mechanism