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Variations in aeolian landform patterns in the Gonghe Basin over the last 30 years

Journal of Mountain Science 2021年第8期18卷 2034-2047页

作者： QI Yu-han PAN Mei-hui HAO Ze-wen YANG An-na XUE wen-xuan College of Geography and Environment Science Northwest Normal UniversityLanzhou730070China

Wind erosion,or the transportation and deposition of sand into desert dunes and aeolian loess,is one of the most important aeolian *** progression of aeolian landforms expands arid and barren landscapes,leading to the degradation of adjacent *** Gonghe Basin,as a typical plateau with abundant sand sources,is highly sensitive to changes in the local climate *** order to quantify the spatial-temporal variations in the aeolian landforms in the Gonghe Basin,we conducted field surveys and also analyzed twelve remote sensing(Landsat5 TM and Landsat8 OLI)images that sample the Gonghe Basin from 1989 to *** the Gonghe Basin,we identified aeolian landforms such as climbing dunes on the windward slopes of the foothills,checkerboard dunes in the southeastern part of the basin,flat dunes,parabolic dunes and crescent dunes on the east and west sides of Longyangxia Reservoir,shrubby sandbanks on the valley slope in Shazhuyu,Tanggemu,and Indel,and sandy thickets at the bottom of the valley near the Dalian Sea,the Longyangxia Reservoir,and the tributaries of the Yellow *** 1989 to 2005,the area of the aeolian regions expanded by 816.7 km2,with an annual conversion rate of 0.05%.From 2015 to 2019,the area of the aeolian regions shrunk by 2411.9 km2,with an annual conversion rate of−0.15%.The number and size of the fixed and semi-fixed dunes(*** shrubby sandbanks on the valley slope and the sandy thickets at the bottom of the valley)were more stable than those of the mobile dunes(*** checkerboard dunes,the flat dunes,the crescent dunes,the parabolic dunes,and the climbing dunes).The fixed and semi-fixed dunes were arranged in an irregular ring shape,and the location of the center of gravity of this ring did not change significantly from 1989 to 2019;in this time,the mobile dunes migrated to the northwest.

关键词： Gonghe Basin Spatial-temporal variation Aeolian processes Remote sensing interpretation

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Experimental Investigation of Reflectometry as a Density Fluctuation Diagnostic

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Chinese Physics Letters 1996年第5期13卷 374-377页

作者： XU Hong-liang cao Jin-xiang DING Wei-xing YU Chang-xuan Department of Modem Physics University of Science and Technology of ChinaHefei 230026

In this paper,a controlled laboratory experiment to investigate the response properties of reflec-tometry to the density fluctuations is *** reflectometer signal is observed to be highly spatially localized in the *** quantitative measurement has demonstrated that the signal originates about one free space wavelength of the probe•wave in front of the critical layer and this position is independent of the fluctuation *** is also found that the sensitivity of transverse response to wavenumbers is different from that of longitudinal response.

关键词： number. wave spatially

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Formation and Evolution of Non-dendritic Microstructures of Semisolid Alloys Prepared by Shearing/Cooling Roll Process

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Journal of Materials Science & Technology 2006年第2期22卷 195-199页

作者： Shuncheng WANG Furong cao Renguo GUAN Jinglin wen School of Materials and Metallurgy Northeastern University Shenyang 110004 China

The shearing/cooling roll （SCR） process was adopted to prepare semi-solid A2017 alloy. The formation and evolution of non-dendritic microstructures in semi-solid A2017 alloy were studied. It is shown that the microstructures of semi-solid billets transform from coarse dendrites into fine equiaxed grains as the pouring temperature of molten alloy decreases o.r roll-shoe cavity height is reduced. From the inlet to the exit of roll-shoe cavity, microstructure of semi-solid slurry near the shoe surface is in the order of coarse dendrites, degenerated dendrites or equiaxed grains, but fine equiaxed grains are near the roll surface. Microstructural evolution of semi-solid slurry prepared by SCR process is that the molten alloy nucleates and grows into dendrite firstly on the roll and shoe＇s surface. Under the shearing and stirring given by the rotating roll, the dendrites crush off and disperse into the melt. Under the shearing and stirring on semi-solid slurry with high volume fraction of solid, the dendrite arms fracture and form equiaxed grain microstructures.

关键词： Semi-solid metal processing Non-dendrite Microstructural evolution Shearing and stirring Aluminum alloy

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Lax Pairs for Discrete Integrable Equations via Darboux Transformations

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Chinese Physics Letters 2012年第5期29卷 5-6页

作者： cao Ce-wen ZHANG Guang-Yao Department of Mathematics Zhengzhou UniversityZhengzhou 450001

A method is developed to construct discrete Lax pairs using Darboux *** kinds of Lax pairs are found for some newly appeared discrete integrable equations,including the H1,the special H3 and the Q1 models in the Adler... 详细信息

关键词： equations. Transformation Darboux

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Phonon relaxation and heat conduction in one-dimensional Fermi Pasta Ulam β lattices by molecular dynamics simulations

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Chinese Physics B 2012年第1期21卷 279-283页

作者： Hou Quan-wen cao Bing-Yang Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering MechanicsTsinghua UniversityBeijing 100084China Key Laboratory of Space Applied Physics and Chemistry of Ministry of Education Department of Applied PhysicsNorthwestern Polytechnical UniversityXi’an 710072China

The phonon relaxation and heat conduction in one-dimensional Fermi Pasta-Ulam （FPU） β lattices are studied by using molecular dynamics simulations. The phonon relaxation rate, which dominates the length dependence of the FPU β lattice, is first calculated from the energy autoeorrelation function for different modes at various temperatures through equilibrium molecular dynamics simulations. We find that the relaxation rate as a function of wave number k is proportional to k^1.688, which leads to a N^0.41 divergence of the thermal conductivity in the framework of Green-Kubo relation. This is also in good agreement with the data obtained by non-equilibrium molecular dynamics simulations which estimate the length dependence exponent of the thermal conductivity as 0.415. Our results confirm the N^2/5 divergence in one-dimensional FPU β lattices. The effects of the heat flux on the thermal conductivity are also studied by imposing different temperature differences on the two ends of the lattices. We find that the thermal conductivity is insensitive to the heat flux under our simulation conditions. It implies that the linear response theory is applicable towards the heat conduction in one-dimensional FPU β lattices.

关键词： thermal conductivity phonon relaxation low-dimensional heat conduction FermiPasta Ulam (FPU) Key Laboratory of Space Applied Physics and Chemistry of Ministry of Education Department of Applied Physics Northwestern Polytechnical University Xi'an 710072 China lattice

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Mechanical Behaviour and Microstructure Evolution of Superplastic Mg-8.4 wt pct Li Alloy and Effect of Grain Size and Phase Ratio on Its Elongation

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Journal of Materials Science & Technology 2000年第1期16卷 55-58页

作者： cao, FR Cui, JZ wen, JL Lei, F Northeastern Univ Sch Met & Mat Dept Mat & Forming Control Shenyang 110006 Peoples R China

Mechanical properties and microstructure evolution of Mg-8.4 wt pet Li alloy have been investigated. The superplastic elongation-to-failure 920% at 573 K and initial strain rate of 5 x 10(-4) s(-1) at low nominal stress 2 MPa has been demonstrated. It was shown through optical microstructure that the average grain sizes at gauge length section before and after superplastic tension and at grip section were 7.5 mu m, 31.7 mu m and 20 mu m respectively, indicating significant deformation induced grain growth and static grain growth. Comparison of experiment data with published data for superplastic Mg-Li alloys shows that fine grain size and about 50 to 50 phase ratio contribute to achieving the largest superplasticity. Some related research works in other alloys are compiled and further evidences to such theoretic argument are provided.

关键词： Magnesium alloys

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Molecular mechanosensors in osteocytes

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Bone Research 2020年第2期8卷 115-138页

作者： Lei Qin wen Liu Huiling cao Guozhi Xiao Guangdong Provincial Key Laboratory of Cell Microenvironment and Disease Research Shenzhen Key Laboratory of Cell Microenvironmentand School of MedicineSouthern University of Science and TechnologyShenzhen 518055China

Osteocytes, the most abundant and long-lived cells in bone, are the master regulators of bone remodeling. In addition to their functions in endocrine regulation and calcium and phosphate metabolism, osteocytes are the major responsive cells in force adaptation due to mechanical stimulation. Mechanically induced bone formation and adaptation, disuse-induced bone loss and skeletal fragility are mediated by osteocytes, which sense local mechanical cues and respond to these cues in both direct and indirect ways. The mechanotransduction process in osteocytes is a complex but exquisite regulatory process between cells and their environment, between neighboring cells, and between different functional mechanosensors in individual cells. Over the past two decades, great efforts have focused on finding various mechanosensors in osteocytes that transmit extracellular mechanical signals into osteocytes and regulate responsive gene expression. The osteocyte cytoskeleton, dendritic processes, Integrin-based focal adhesions, connexin-based intercellular junctions, primary cilium, ion channels, and extracellular matrix are the major mechanosensors in osteocytes reported so far with evidence from both in vitro and in vitro studies. This review aims to give a systematic introduction to osteocyte mechanobiology, provide details of osteocyte mechanosensors, and discuss the roles of osteocyte mechanosensitive signaling pathways in the regulation of bone homeostasis.

关键词： cytes mec metabolism

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Recyclable thiol-modified Zr-based MOFs/hydrogel composite beads for effective removal of Hg(Ⅱ)

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Progress in Natural Science:Materials International 2023年第5期33卷 644-651页

作者： Xuechun Wang Zeming Dai xuan Zhou Hao Chen Yu cao Jianhua Hou Xiaozhi Wang College of Environmental Science and Engineering Yangzhou University Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization Institutes of Agricultural Science and Technology Development

In general, majority of MOFs are powder, which limit their applications. In this study, the highly stable Zr-based MOF-808 and its thiol-modified MOF-808-SH were selected as precursors, and then they were wrapped by sodium alginate hydrogel via a dripping strategy. Based on these, MOF/hydrogel composite beads(Alg-MOF-808, AlgMOF-808-SH) with 3D network structure were prepared successfully. Due to its excellent adsorption properties and easy recovery, they were employed as effective environmental functional materials for the adsorption of Hg(Ⅱ). The adsorption capacities of Hg(Ⅱ) were 170.52 mg·g-1and 221.73 mg·g-1respectively and they can achieve adsorption equilibrium in a short time. The adsorption stability of Alg-MOF-808-SH was studied at different p H as well. In addition, the removal efficiency of composite beads for Hg(Ⅱ) was almost unaffected by other coexisting ions, displaying good adsorption selectivity. Furthermore, the removal efficiency only decreased by 10.4% after 5 cycles, indicating that the as-prepared materials have high recycling efficiency. The results demonstrated that the MOF/hydrogel composite beads have a certain application potential for mercury removal in actual wastewater.

关键词： Environmental functional material Hg (II) adsorption MOF-808 thiol groups Beads

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Bounded Evaluation:Querying Big Data with Bounded Resources

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International Journal of Automation and computing 2020年第4期17卷 502-526页

作者： Yang cao wen-Fei Fan Teng-Fei Yuan University of Edinburgh Edinburg EH89ABUKUniversity of EdinburghEdinburg EH89ABUK Shenzhen Institute of Computing Sciences Shenzhen UniversityShenzhen 518060China Beijing Advanced Innovation Center for Big Data and Brain Computing Beihang UniversityBeijing 100191China

This work aims to reduce queries on big data to computations on small data,and hence make querying big data possible under bounded resources.A query Q is boundedly evaluable when posed on any big dataset D,there exists a fraction DQ of D such that Q(D)=Q(DQ),and the cost of identifying DQ is independent of the size of *** has been shown that with an auxiliary structure known as access schema,many queries in relational algebra(RA)are boundedly evaluable under the set semantics of *** paper extends the theory of bounded evaluation to RAaggr,i.e.,RA extended with aggregation,under the bag semantics.(1)We extend access schema to bag access schema,to help us identify DQ for RAaggr queries Q.(2)While it is undecidable to determine whether an RAaggr query is boundedly evaluable under a bag access schema,we identify special cases that are decidable and practical.(3)In addition,we develop an effective syntax for bounded RAaggr queries,i.e.,a core subclass of boundedly evaluable RAaggr queries without sacrificing their expressive power.(4)Based on the effective syntax,we provide efficient algorithms to check the bounded evaluability of RAaggr queries and to generate query plans for bounded RAaggr queries.(5)As proof of concept,we extend PostgreSQL to support bounded *** experimentally verify that the extended system improves performance by orders of magnitude.

关键词： Bounded evaluation resource-bounded query processing effective syntax access schema boundedness

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Unique polysulfide reaction on VO_(2) for restraining shuttle effect in soft-packaged Li-S pouch cells

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Rare Metals 2024年第6期43卷 2842-2850页

作者： Ruo-xuan Yang Qing-Chun Zhang Jing-Sheng Cai xuan cao Qin Yang Ying-Ze Song Wei Zhang State Key Laboratory of Environment-Friendly Energy Materials Tianfu Institute of Research and InnovationSchool of Materials and ChemistrySouthwest University of Science and TechnologyMianyang 621010China School of Materials Engineering Changshu Institute of TechnologyChangshu 215500China Chongqing Institute of Green and Intelligent Technology Chinese Academy of SciencesChongqing 400714China

The shuttle phenomenon and retarded conversion kinetics of lithium poly sulfides(LiPSs)are relatively severe in lithium-sulfur(Li-S)pouch *** to their redox potential in the sulfur working window,VO_(2)nanobelts show ... 详细信息

关键词： mechanism sulfide lithium

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