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Multimedia model of atrazine in plant-soil-groundwater system with a fugacity approach

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j.urnal of Environmental Sciences 2001年第4期13卷 466-471页

作者： Ye, c.-m. Lei, Z.-f. wang, X.-j. Gong, A.-j. Zheng, H.-h. Res. cntr. Eco-Environmental Sci. Chinese Academy of Sciences Beijing 100085 China

The application of atrazine in china during the last ten years has led to some environmental problems. In this paper, the multimedia model of atrazine in soil-plant-groundwater system at Baiyangdian Lake area in Northern china was established using a fugacity approach, and verified with observed values. The model involved 7 environmental compartments which are air, groundwater, soil, corn roots, corn stem, corn leaf and kernel of corn. The results showed that the relative errors between calculated and observed values have a mean value of 24.7%, the highest value is 48% and the lowest value is 1.4%. All these values indicated that this multimedia model can be used to simulate the environmental fate of atrazine. Both the calculated and observed values of concentrations of atrazine in plant compartments are in the following order: in corn roots > in corn stem > in kernel of corn > in corn leaf, it exhibited a good regularity. The prediction results indicated that concentrations of atrazine in the groundwater and kernel of corn will override the limitation of 3 μg/L and 0.05 mg/kg respectively.

关键词： concentration (process) Error detection Groundwater Lakes Plants (botany) Soils

Stresses State and Mechanical Behaviors of the Green Body During Die compaction and Ej.ction Process

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Acta Metallurgica Sinica(English Letters) 2020年第4期33卷 605-614页

作者： S.M.wang Y.wang Y.X.wang f.P.liu j.cao Department of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China State Key Laboratory of Advanced Welding and j.ining Harbin Institute of TechnologyHarbin 15001China

finite element simulations for metal powder compaction of a clutch plate were performed to examine the stresses during compaction,unloading,and *** describe the mechanical behavior of compacted green body,a modified densitydependent Drucker-Prager cap model was utilized to predict the stress and density distribution of the compacted clutch plate during loading and ej.ction *** results indicate that maximum tensile principal stress was a main driving force for the tensile crack initiation during ej.ction stage,and shear stress may be another driving force in both compaction and ej.ction stages for shear crack *** were peak value of the stresses during ej.ction stage,and the stresses are in compressive state only during compaction ***,the tensile crack initiation is not possible during compaction except shear *** stress in the clutch plate is of less contribution to the crack initiation during compaction,unloading and *** of criteria of the crack initiation and fracture is necessary in order to obtain uniform density and crackfree components in the manufacturing of metal powder compaction.

关键词： Powder compaction finite element simulation Stress history cap model Green body

Boosting bidirectional sulfur conversion enabled by introducing boron-doped atoms and phosphorus vacancies in Ni2P for lithium-sulfur batteries

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j.urnal of Energy chemistry 2025年第1期100卷 760-769页

作者： Lin Peng Yu Bai Hang Li Meixiu Qu Zhenhua wang Kening Sun Advanced Research Institute of Multidisciplinary Science Beijing Institute of Technology Beij.ng Key Laboratory of chemical Power Source and Green catalysis School of Chemistry and Chemical Engineering Beijing Institute of Technology

Lithium-sulfur （Li-S） batteries have gained great attention due to the high theoretical energy density and low cost,yet their further commercialization has been obstructed by the notorious shuttle effect and sluggish redox ***,we supply a strategy to optimize the electron structure of Ni2P by concurrently introducing B-doped atoms and P vacancies in Ni2P （Vp-B-Ni2P）,thereby enhancing the bidirectional sulfur *** study indicates that the simultaneous introduction of B-doped atoms and P vacancies in Ni2P causes the redistribution of electron around Ni atoms,bringing about the upward shift of d-band center of Ni atoms and effective d-p orbital hybridization between Ni atoms and sulfur species,thus strengthening the chemical anchoring for lithium polysulfides （LiPSs） as well as expediting the bidirectional conversion kinetics of sulfur ***,theoretical calculations reveal that the incorporation of B-doped atoms and P vacancies in Ni2P selectively promotes Li2S dissolution and nucleation ***,the Li-S batteries with Vp-B-Ni2P-separators present outstanding rate ability of 777 m A h g-1at 5 c and high areal capacity of 8.03 mA h cm-2under E/S of 5μL mg-1and sulfur loading of 7.20 mg *** work elucidates that introducing heteroatom and vacancy in metal phosphide collaboratively regulates the electron structure to accelerate bidirectional sulfur conversion.

关键词： Lithium sulfur batteries

Precipitation on stacking faults in Mg–9.8wt%Sn alloy

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j.urnal of Materials Science & Technology 2020年第10期42卷 230-240页

作者： c.Q.liu c.He H.W.chen j.f.Nie International j.int Laboratory for Light Alloys(Ministry of Education) College of Materials Science and EngineeringChongqing UniversityChongqing400044China Department of Materials Science and Engineering Monash UniversityVictoria3800Australia Electron Microscopy center Chongqing UniversityChongqing400044PR China

In this work,we have systematically investigated precipitation ofβ’-Mg3Sn phase on intrinsic stacking faults I1 and I2 in a Mg-9.8 wt%Sn alloy using aberration-corrected scanning transmission electron *** observed I1 faults are generated by the dissociation of c+a perfect dislocations and bounded by frank partial dislocations having a Shockley *** ofβ’on I1 involves a shear of 1/3α,similar to its formation directly from theα-Mg ***β’phase often nucleates at one end of an I1 fault due to the interaction between shear strain fields ofβ’and the Shockley component of the frank partial at that end,and subsequently grows towards the other end of the *** theβ’reaches to the other end,the Shockley partial bounding the lengthening end of theβ’reacts with the frank partial bounding the fault,generating an a perfect dislocation that can glide away from the precipitate and the *** observed I2 faults are generated by the dissociation of a perfect dislocations and bounded by Shockley *** ofβ’on I2 does not need a shear of 1/3α,since the pre-existing I2 fault already provides an ABcA four-layer structure ofβ’.Thickening of theβ’that has already formed on the I2 involves the successive occurrence of three crystallographically equivalent shears of 1/3αon every second(0002)αplane of theα-Mg *** this thickening mechanism is similar to that of theβ’formed directly from theα-Mg matrix,an a perfect dislocation will be produced when theβ’is thickened to eight layers,and it can again glide away from the precipitate and the fault.

关键词： Heterogeneous precipitation HAADf-STEM Shockley partial dislocation frank partial dislocation Dislocation reaction

computerized control and Operation of Rutherford Backscattering/channeling for an in situ Ion Beam System and Its Application for Measurement of Si（001） and ZnO（001）

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chinese Physics Letters 2011年第1期28卷 66-69页

作者： HE j.n j. c. LEE LI Ming wang Ze-Song liu chuan-Sheng fU De-j.n Accelerator Laboratory Wuhan University Wuhan 430072 Quantum-functional Semiconductor Research center Dongguk University 3-26 Pildong Seoul 100-715 Korea

A computer-automated Rutherford backscattering/channeling （RBS/c） system is developed to provide in situ ion beam analysis of the accelerator-TEM system in Wuhan University. The basic system components are a Pc equipped with a multichannel analyzer data acquisition board, motion control hardware including the Panmure stepping motor controller and integrated circuit modules, and a Labview programmed operating system with associated electronics. Single crystalline Si（001） and ZnO（001） implanted with Mn ions were characterized with this computerized setup. The crystalline quality Xmin and channeling half angle of Si（O01） were measured to be 4.65% and 0.52%, respectively, which are comparable to theoretical values 4.2% and 0.32%. The ion implantation induced damage depth profile derived from channeling and random spectrum is in reasonable agreement with the result calculated by the SRIM Monte-carlo simulation code.

关键词： Surfaces interfaces and thin films condensed matter: structural mechanical & thermal

Propagation behavior of elastic waves in one-dimensional piezoelectric/piezomagnetic phononic crystal with line defects

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Acta Mechanica Sinica 2014年第5期30卷 703-713页

作者： Y.Pang f.-Y.j.ao j.-X.liu Department of Engineering Mechanics Shijiazhuang Tie Dao University School of Mathematics and Physics University of Science and Technology Beijing

Using a stiffness matrix method, we in- vestigate the propagation behaviors of elastic waves in one-dimensional （1D） piezoelectric/piezomagnetic （PE/PM） phononic crystals （Pcs） with line defects by calculating energy reflection/transmittion coefficients of quasi-pressure and quasi-shear waves. Line defects are created by the re- placement of PE or PM constituent layer. The defect modes existing in the first gap are considered and the influences on defect modes of the material properties and volume fraction of the defect layers, the type of incident waves, the location of defect layer and the number of structural layers are discussed in detail. Numerical results indicate that defect modes are the most obvious when the defect layers are inserted in the middle of the perfect Pcs; the types of incidence wave and material properties of the defect layers have important effects on the numbers, the location of frequencies and the peaks of defect modes, and the defect modes are strongly de- pendent on volume fraction of the defect layers. We hope this paper will be found useful for the design of PE/PM acoustic filters or acoustic transducer with Pcs structures.

关键词： 1D phononic crystal Piezoelectric/piezomag- netic. Elastic wave Line defect Stiffness matrix method

Unsteady flow and heat transfer of porous media sandwiched between viscous fluids

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Applied Mathematics and Mechanics(English Edition) 2010年第12期31卷 1497-1516页

作者： j. c. UMAVATHI I. c. liu j. PRATHAP-KUMAR D. SHAIK-MEERA Department of Mathematics Gulbarga University Gulbarga 585106 Karnaktaka India Department of civil Engineering National Chi Nan University University Road Puli Nantou Hsien 54561 Taiwan China

The problem of unsteady oscillatory flow and heat transfer of porous medin sandwiched between viscous fluids has been considered through a horizontal channel with isothermal wall temperatures. The flow in the porous medium is modeled using the Brinkman equation. The governing partial differential equations are transformed to ordinary differential equations by collecting the non-periodic and periodic terms. closed-form solutions for each region are found after applying the boundary and interface conditions. The influence of physical parameters, such as the porous parameter, the frequency parameter, the periodic frequency parameter, the viscosity ratios, the conductivity ratios, and the Prandtl number, on the velocity and temperature fields is computed numerically and presented graphically. In addition, the numerical values of the Nusselt number at the top and bottom walls are derived and tabulated.

关键词： unsteady porous medium immiscible fluid horizontal channel analyticalsolution

Interactive buckling of an inflated envelope under mechanical and thermal loads

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Acta Mechanica Sinica 2017年第1期33卷 159-172页

作者： c. G. wang M. X. liu H. f. Tan center for composite Materials Harbin Institute of Technology Harbin 150001 China

This paper elucidates the interactive buckling behaviors of an inflated envelope under coupled mechanical and thermal loads, especially the longitudinal wrinkling bifurcation and hoop ovalization buckling. The longitudinal bending buckling process of the inflated envelope can be divided into three continuous stages, which are global buckling, interactive global-local buckling, and kink. A variety of hoop ovalization buckling modes are observed under coupled mechanical-thermal load. Unlike the mechanical case, thermal load leads to a hoop negative ovalization buckling. In addition, it can accelerate the longitudinal coupled bifurcation and resist the hoop coupled ovalization buckling. Moreover, the bending resistance of the inflated envelope will be improved when the length of the structure is increased, resulting in the difficulty of it to become wrinkled. These results provide a new insight into the buckling behaviors of an inflated envelope under coupled external loads, and give a reference for the design of the inflated envelope.

关键词： Mechanical and thermal buckling Bifurcation Ovalization coupled buckling

Unsteady mixed convective heat transfer of two immiscible fluids confined between long vertical wavy wall and parallel flat wall

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Applied Mathematics and Mechanics(English Edition) 2012年第7期33卷 931-950页

作者： j. c. UMAVATHI I. c. liu M. SHEKAR Department of Mathematics Gulbarga University Department of civil Engineering National Chi Nan University

The combined effects of thermal and mass convection of viscous incom- pressible and immiscible fluids through a vertical wavy wall and a smooth flat wall are analyzed. The dimensionless governing equations are perturbed into a mean part （the zeroth-order） and a perturbed part （the first-order）. The first-order quantities are ob- tained by the perturbation series expansion for short wavelength, in which the terms of the exponential order arise. The analytical expressions for the zeroth-order, the first-order, and the total solutions are obtained. The numerical computations are presented graph- ically to show the salient features of the fluid flow and the heat transfer characteristics. Separate solutions are matched at the interface by using suitable matching conditions. The shear stress and the Nusselt number are also analyzed for variations of the governing parameters. It is observed that the Grashof number, the viscosity ratio, the width ratio, and the conductivity ratio promote the velocity parallel to the flow direction. A reversal effect is observed for the velocity perpendicular to the flow direction.

关键词： mixed convection wavy wall immiscible fluid perturbation method