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Soil quality assessment for desertification based on multi-indicators with the best-worst method in a semi-arid ecosystem

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Journal of Arid Land 2023年第7期15卷 779-796页

作者： Orhan dengİz İnci DEMİRAĞTURAN Department of Soil Science and Plant Nutrition Faculty of AgricultureOndokuz Mayıs UniversitySamsun-55139Turkey Department of Geography Faculty of EconomicAdministrative and Social SciencesSamsun UniversitySamsun-55030Turkey

Since there are some signs of land degradation and desertification showing how soil sustainability is threatened, it is crucial to create a soil quality index(SQI) model in the semi-arid ?orum Basin, situated between the Black Sea and Anatolia Region, Central Turkey. The primary aims of the study are:(1) to determine SQI values of the micro-basin in terms of land degradation and ***, the best-worst method(BWM) was used to determine the weighting score for each parameter;(2) to produce the soils' spatial distribution by utilizing different geostatistical models and GIS(geographic information system) techniques;and(3) to validate the obtained SQI values with biomass reflectance values. Therefore, the relationship of RE-OSAVI(red-edge optimized soil-adjusted vegetation index) and NDVI(normalized difference vegetation index) generated from Sentinel-2A satellite images at different time series with soil quality was examined. Results showed that SQI values were high in the areas that had almost a flat and slight slope. Moreover, the areas with high clay content and thick soil depth did not have salinity problems, and were generally distributed in the middle parts of the basin. However, the areas with a high slope, poor vegetation, high sand content, and low water holding capacity had low SQI ***, a statistically high positive correlation of RE-OSAVI and NDVI indices with soil quality was found, and NDVI had the highest correlative value for June(R~2=0.802) compared with RE-OSAVI.

关键词： soil quality land degradation desertification best-worst method remote sensing

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Snap-through of an elastica under bilateral displacement control at a material point

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Acta Mechanica Sinica 2020年第3期36卷 727-734页

作者： Q.Wang H.L.zou z.C.deng Department of Engineering Mechanics Northwestern Polytechnical UniversityXi'an 710072China

Snap-through phenomenon widely occurs for elastic systems,where the systems lose stability at critical *** snapthrough of an elastica under bilateral displacement control at a material point is studied,by regarding the whole elastica as two components,i.e.,pinned-clamped ***,stiffness-curvature curves of two pinned-clamped elasticas are firstly efficiently located based on the second-order mode,which are used to determine the shapes of two *** transformations are used to assemble two components together to form the whole elastica,which reveals four kinds of *** advantage of this way compared with other methods such as the shooting method is that multiple coexisting solutions can be located accurately.O n the load-deflection curves,four branches correspond to four kinds of shapes and first two branches are symmetrical to the last two branches relative to the original *** the bilateral displacement control,the critical points can only appear at saddle-node bifurcations,which is different to that for the unilateral displacement ***,one critical point is found on the first branch and two critical points are found on the secondary *** addition,the snap-through among different branches can be well explained with these critical points.

关键词： Elastica Snap-through Critical points Buckling Displacement control

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Structural modeling of sandwich structures with lightweight cellular cores

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Acta Mechanica Sinica 2007年第5期23卷 545-559页

作者： T.Liu z.C.deng T.J.Lu Department of Engineering Mechanics Northwestern Polytechnical UniversityXi'an 710072China MOE Key Laboratory of Strength and Vibration School of AerospaceXi'an Jiaotong UniversityXi'an 710049China

An effective single layered finite element （FE） computational model is proposed to predict the structural behavior of lightweight sandwich panels having two dimensional （2D） prismatic or three dimensional （3D） truss cores. Three different types of cellular core topology are considered： pyramidal truss core （3D）, Kagome truss core （3D） and corrugated core （2D）, representing three kinds of material anisotropy： orthotropic, monoclinic and general anisotropic. A homogenization technique is developed to obtain the homogenized macroscopic stiffness properties of the cellular core. In comparison with the results obtained by using detailed FE model, the single layered computational model can give acceptable predictions for both the static and dynamic behaviors of orthotropic truss core sandwich panels. However, for non-orthotropic 3D truss cores, the predictions are not so well. For both static and dynamic behaviors of a 2D corrugated core sandwich panel, the predictions derived by the single layered computational model is generally acceptable when the size of the unit cell varies within a certain range, with the predictions for moderately strong or strong corrugated cores more accurate than those for weak cores.

关键词： Cellular material Sandwich panel Homogenization Finite element

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Photoluminescence from Silicon Nanocrystals in Encapsulating Materials

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Journal of Materials Science & Technology 2013年第3期29卷 221-224页

作者： z.deng X.D.Pi J.J.zhao D.Yang State Key Laboratory of Silicon Materials and Department of Materials Science and Engineering Zhejiang University

Naturally oxidized freestanding silicon nanocrystals （Si NCs） are incorporated in commonly used encapsulating materials to explore the photoluminescent application of Si NCs in device structures such as solid-state lighting light-emitting diodes （LEDs） and solar cells. The quantum yield of Si NCs before the incorporation has reached about 45% at the excitation wavelength of 370 nm without any special surface modification. It is found that medium Ioadings, e.g., 5 wt% of Si NCs in encapsulating materials help to obtain high external quantum efficiency （EQE） of the mixtures of Si NCs and encapsulating materials. The curing of encapsulating materials significantly reduces EQE. Among all the encapsulating materials investigated in this work, silicone- OE6551 enables the highest EQE （21% at excitation wavelength λex = 370 nm） after curing. Based on current findings, we have discussed the continuous efforts to advance the photoluminescent application of Si NCs.

关键词： Photoluminescence Silicon nanocrystals Epoxy Silicone Quantum yield External quantum efficiency

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CORROSION INHIBITION OF X70 STEEL IN SALINE SOLUTION SATURATED WITH CO_2 BY THIOUREA

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Acta Metallurgica Sinica(English Letters) 2008年第1期21卷 65-71页

作者： X. Y. He H. Y. deng R. Li X.D. Fei H.Y.Wang z. Y. deng College of Chemistry and Chemical Engineering China West Normal University Nanchong 637002 China

Corrosion monitoring techniques were performed on X7O steel in saline solution saturated with CO2 with and without thiourea additives within the concentration range 5-25 mg/L. It was found that when the concentration of the inhibitors were increased, the inhibitor efficiencies（IE） of thiourea varied with solution temperature and immersion time. The results indicated that thiourea had the highest inhibition efficiency. The potentiondynamic polarization studies revealed that thiourea are mixed-type inhibitor that mainly restrains the anodic process.

关键词： Corrosion Inhibition Thiourea XTO steel

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Nodal superconducting gap in LiFeP revealed by NMR:Contrast with LiFeAs

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Chinese Physics B 2021年第4期30卷 113-118页

作者： A F Fang R zhou H Tukada J Yang z deng X C Wang C Q Jin Guo-Qing zheng Department of Physics Beijing Normal UniversityBeijing 100875China Institute of Physics Chinese Academy of Sciencesand Beijing National Laboratory for Condensed Matter PhysicsBeijing 100190China Songshan Lake Materials Laboratory Dongguan 523808China Department of Physics Okayama UniversityOkayama 700-8530Japan

Identifying the uniqueness of FeP-based superconductors may shed new lights on the mechanism of superconductivity in ***,we report nuclear magnetic resonance(NMR) studies on LiFeP and LiFeAs which have the same crystal structure but different pnictogen *** NMR spectrum is sensitive to inhomogeneous magnetic fields in the vortex state and can provide the information on the superconducting pairing symmetry through the temperature dependence of London penetration depth λ_(L).We find that λ_(L) saturates below T~0.2 T_(C) in LiFeAs,where T_(C) is the superconducting transition temperature,indicating nodeless superconducting ***,by using a two-gaps model,we simulate the temperature dependence of λ_(L) and obtain the superconducting gaps of LiFeAs,as Δ_(1)=1.2 kB T_(C) and Δ_(2)=2.8 k_(B)T_(C),in agreement with previous result from spin-lattice *** LiFeP,in contrast,λ_(L) does not show any saturation down to T~0.03 T_(C),indicating nodes in the superconducting gap ***,we demonstrate that strong spin fluctuations with diffusive characteristics exist in LiFeP,as in some cuprate high temperature superconductors.

关键词： iron-based superconductor nuclear magnetic resonance superconducting pairing symmetry spin fluctuations

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EFFECT OF SPECIMEN SIzE ON J_R RESISTANCE CURVE

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Acta Metallurgica Sinica(English Letters) 1996年第5期9卷 350-354页

作者： H.P. Chen and z.J. deng (State Key Lab. for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China)

The effect of specimen thinkness on JR resistance curve has been investigated using low and middle strength steels. As the J dominance regime is reached, the initial J-integral values, J(i), are definite even if the elastic component Ji(e) and plastic component Ji(p)vary with the thinkness of specimen. The wider the specimen width, the larger the Ji(e)/Ji and the smaller the Ji(p)/Ji. The crack propagation resistance, dJR/da and dJp/da, decreases, while dJe/da increases linearly with increasing specimen *** on the above experimental results, an empirical formula dJ/da = α+β. B is given, which can be used to evaluate the safety of practical structural components.A modified J-integral is presented, upon which a new view is Put forward that the increase in crack growth resistance is induced mainly by the increase in the plastic J-integral component with the crack propagation,

关键词： fracture mechanics J-R curve modified J elastic-plastic fracture

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Effects of chemical pressure on diluted magneticsemiconductor(Ba,K)(zn,Mn)_2As_2

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Chinese Physics B 2019年第5期28卷 288-292页

作者： Y Peng S Yu G Q zhao W M Li J F zhao L P Cao X C Wang Q Q Liu S J zhang R z Yu z deng X H zhu C Q Jin College of Materials Science & Engineering Sichuan University Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences School of Physics University of Chinese Academy of Sciences Collaborative Innovation Center of Quantum Matter

Chemical pressure induced by iso-valent doping has been widely employed to tune physical properties of materials. In this work, we report effects of chemical pressure by substitution of Sb or P into As on a recently discovered diluted magnetic semiconductor(Ba,K)(zn,Mn)_2 As_2, which has the record of reliable Curie temperature of 230 K due to independent charge and spin doping. Sb and P are substituted into As-site to produce negative and positive chemical pressures, respectively.X-ray diffraction results demonstrate the successful chemical solution of dopants. Magnetic properties of both K-underdoped and K-optimal-doped samples are effectively tuned by Sb-and P-doping. The Hall effect measurements do not show decrease in carrier concentrations upon Sb-and P-doping. Impressively, magnetoresistance is significantly improved from7% to 27% by only 10% P-doping, successfully extending potential application of(Ba,K)(zn,Mn)_2 As_2.

关键词： chemical pressure (Ba,K)(zn,Mn)2As2 diluted magnetic semiconductor iso-valent doping

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保持良好

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服装设计师 2015年第4期 166-169页

作者： Coco z Grace deng

华灯初上，何必匆忙的走八人群，不如开启一场充满梦幻的游乐园之梦。这不是午夜场，而是在北京长安街W酒店W Lounge上演的Grace deng春夏女装成衣发布会。镁光灯下的气氛有点特别，似乎所有人都感受到了除了时尚情结之外，这里又增添... 详细信息

华灯初上，何必匆忙的走八人群，不如开启一场充满梦幻的游乐园之梦。这不是午夜场，而是在北京长安街W酒店W Lounge上演的Grace deng春夏女装成衣发布会。镁光灯下的气氛有点特别，似乎所有人都感受到了除了时尚情结之外，这里又增添了些许浪漫的气息。

关键词： Grace 游乐园长安街成衣女装春夏时尚

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All-optical μ^- acceleration in the laser wakefield

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High Power Laser Science and Engineering 2018年第4期6卷 119-124页

作者： F.zhang z.G.deng L.Q.Shan z.M.zhang B.Bi D.X.Liu W.W.Wang z.Q.Yuan C.Tian S.Q.Yang B.zhang Y.Q.Gu Science and Technology on Plasma Physics Laboratory Laser Fusion Research CenterChina Academy of Engineering Physics IFSA Collaborative Innovation Center Shanghai Jiao Tong University

Muons produced by the Bethe–Heitler process from laser wakefield accelerated electrons interacting with high z materials have velocities close to the laser wakefield. It is possible to accelerate those muons with laser wakefield *** for the first time we propose an all-optical ‘Generator and Booster’ scheme to accelerate the produced muons by another laser wakefield to supply a prompt, compact, low cost and controllable muon source in laser laboratories. The trapping and acceleration of muons are analyzed by one-dimensional analytic model and verified by two-dimensional particle-in-cell(PIC) simulation. It is shown that muons can be trapped in a broad energy range and accelerated to higher energy than that of electrons for longer dephasing length. We further extrapolate the dependence of the maximum acceleration energy of muons with the laser wakefield relativistic factor γ and the relevant initial energy E_0. It is shown that a maximum energy up to 15.2 GeV is promising with γ = 46 and E_0= 1.45 Ge V on the existing short pulse laser facilities.

关键词： laser wakefield acceleration muon source

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