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Mapping critical loads of Acid Deposition for Soils in China

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Tsinghua Science and Technology 2000年第3期5卷 270-278页

作者：段雷郝吉明 Alan Jenkins' Rob Collins Chris Evans 谢绍东 Department of Environmental Science and Engineering Tsinghua University Beijing 100084 Institute of Hydrology. Wallingford Oxfordshire OXIO 8BB UK Center of Environmental Sciences Peking University Beijing 100871 China

A method described is to produce critical load maps of acid deposition for soils in China. critical loads were assigned to the most sensitive soil in each 0.1°×0.1° grid square of China based on the Skokloster classification [1] and adjusted for temperature and land use. The map shows that soils with small critical load (critical load maps at 1°×1° scale were compiled for integrated assessments, as well as a critical load map using the minimum critical load for each grid. Comparison of critical loads with sulphur deposition in 1995 led to the critical load exceedance maps for sulphur deposition, which show that high exceedance areas do not correlate well with the low critical load areas, and almost one fourth of the land area, mainly in the southeast, is subject to the risk of acidification. 

关键词： critical load acid deposition soil sensitivity

critical transitions in the shape morphing of kirigami metallic glass

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Journal of Materials Science & Technology 2021年第2期61卷 204-212页

作者： D.X.Han L.Zhao S.H.Chen G.Wang K.C.Chan Advanced Manufacturing Technology Research Center Department of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityHung HornKowloonHong KongChina School of Mechanical Engineering Hefei University of TechnologyHefei230009China Laboratory for Microstructures Institute of MaterialsShanghai UniversityShanghai200444China

Kirigami, the ancient Japanese paper cutting technique, has been applied to achieve high stretchability and low energy loss of designed metallic glass. Despite the exploration of the underlying deformation mechanism of kirigami-inspired structures from the energy point of view, the morphable responses of the kirigami patterns and the origin of the kirigami response are yet to be fully understood. This study reveals the mechanical driven-forms of the kirigami structure with the corresponding deformation stages. Based on the beam deflection theory, the elastic buckling behavior of kirigami metallic glass is manifested and a critical force prediction model is developed. Moreover, a force concentration parameter is introduced in the rigid-plastic deformation stage, predicting the nominal ultimate force. The kirigami-inspired facture force is firstly proposed. The findings of these models are in good agreement with the experimental sizedependent kirigami responses, and expected to provide significant insights into the understanding of the deformation behavior and the design of kirigami metallic glasses.

关键词： Metamaterial Kirigami metallic glass critical load Size effect Beam deflection

Nonlinear stability of sensor elastic element--corrugated shallow spherical shell in coupled multi-field

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Applied Mathematics and Mechanics(English Edition) 2017年第6期38卷 877-888页

作者： Yongan ZHU Fan WANG Renhuai LIU Institute of Applied Mechanics Jinan University Guangzhou 510632 China Key Laboratory of Disaster Forecast and Control in Engineering of Ministry of Education Jinan University Guangzhou 510632 China

Nonlinear stability of sensor elastic element- corrugated shallow spherical shell in coupled multi-field is studied. With the equivalent orthotropic parameter obtairled by the author, the corrugated shallow spherical shell is considered as an orthotropic shallow spherical shell, and geometrical nonlinearity and transverse shear deformation are taken into account. Nonlinear governing equations are obtained. The critical load is obtained using a modified iteration method. The effect of temperature variation and shear rigidity variation on stability is analyzed.

关键词： modified iteration method corrugated shallow spherical shell multi-field,stability critical load temperature variation

Effects of acid deposition control in China:a review based on responses of subtropical forests

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Frontiers of Environmental Science & Engineering 2024年第6期18卷 115-126页

作者： Danni Xie Xiaodong Ge Lei Duan Jan Mulder School of Land Engineering Chang’an UniversityXi’an 710064China State Key Laboratory of Environmental Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex Beijing 100084China Faculty of Environmental Sciences and Natural Resource Management Norwegian University of Life SciencesBox 5003NO-1432ÅsNorway

For many decades,acid deposition used to pose a significant regional air pollution challenge in *** substantial emission control of anthropogenically derived sulfur and nitrogen containing gasses,both sulfur and nitrogen deposition,as well as the acid rain-affected area,have significantly decreased compared to their peak ***,particularly in the humid subtropics,are sensitive to acid deposition,as evidenced by soil acidification,sulfate and nitrate leaching in stream water,and elevated soil nitrous oxide *** in the total deposition of sulfur and nitrogen,caused a significant decline in sulfate and nitrate leaching from subtropical forest and subsequently in sulfate and nitrate concentrations in stream water,although there was about a 5-year *** delay may be attributed to the desorption of accumulated sulfate and continued elevated mineralization of accumulated nitrogen *** of nitrous oxide,a potent greenhouse gas,also declined in nitrogen-saturated subtropical forest soils,as soil water nitrate concentration ***,subtropical forests in China suffering from elevated acid deposition have begun to ***,the current levels of sulfur and nitrogen deposition continue to exceed the critical loads,i.e.,the assigned threshold levels in accordance with emission control policies,in more than 10%of the country’s land area,respectively,indicating remaining risks of acidification and ***,further emission reductions are urgently needed,also because they will help achieving goals related to air quality and nitrous oxide emissions.

关键词： Acidification critical load Nitrous oxide Surface water chemistry Recovery

CLASSICAL AND HOMOGENIZED EXPRESSIONS FOR BUCKLING SOLUTIONS OF FUNCTIONALLY GRADED MATERIAL LEVINSON BEAMS

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Acta Mechanica Solida Sinica 2015年第5期28卷 592-604页

作者： Shirong Li Xuan Wang Zeqing Wan Department of Civil Engineering Yangzhou University

The relationship between the critical buckling loads of functionally graded material （FGM） Levinson beams （LBs） and those of the corresponding homogeneous Euler-Bernoulli beams （HEBBs） is investigated. Properties of the beam are assumed to vary continuously in the depth direction. The governing equations of the FGM beam are derived based on the Levinson beam theory, in which a quadratic variation of the transverse shear strain through the depth is included. By eliminating the axial displacement as well as the rotational angle in the governing equations, an ordinary differential equation in terms of the deflection of the FGM LBs is derived, the form of which is the same as that of HEBBs except for the definition of the load parameter. By solving the eigenvalue problem of ordinary differential equations under different boundary conditions clamped （C）, simply-supported （S）, roller （R） and free （F） edges combined, a uniform analytical formulation of buckling loads of FGM LBs with S-S, C-C, C-F, C-R and S-R edges is presented for those of HEBBs with the same boundary conditions. For the C-S beam the above-mentioned equation does not hold. Instead, a transcendental equation is derived to find the critical buckling load for the FGM LB which is similar to that for HEBB with the same ends. The significance of this work lies in that the solution of the critical buckling load of a FGM LB can be reduced to that of the HEBB and calculation of three constants whose values only depend upon the through- the-depth gradient of the material properties and the geometry of the beam. So, a homogeneous and classical expression for the buckling solution of FGM LBs is accomplished.

关键词： FCM beam Levinson beam theory buckling critical load Euler-Bernoulli beam

Local Strain Energy Density Applied to Bainitic Functionally Graded Steels Plates Under Mixed-Mode(Ⅰ+Ⅱ) loading

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Acta Metallurgica Sinica(English Letters) 2015年第2期28卷 164-172页

作者： H.Salavati Y.Alizadeh F.Berto Department of Mechanical Engineering Amirkabir University of Technology Department of Management and Engineering University of Padova

In this paper, the averaged value of the strain energy density （SED） over a control volume is used to predict the critical load of V-notched specimens made of functionally graded steels （FGSs） under mixed-mode loading. The studied FGSs contain ferritic and austenite phases in addition to bainitic layer produced by electroslag remelting. The mechanism- based strain gradient plasticity theory is used to determine the flow stress （yield stress or ultimate stress） of each layer. The Young＇s modulus and the Poisson＇s ratio have been assumed to be constant, while other mechanical properties vary exponentially along the specimen width. The control volume is centered in relation to the maximum principal stress present on the notch edge and assumes a crescent shape. The points belonging to the volume perimeter are obtained numerically. In the present contribution, the effects of notch radius and notch depth on the SED and the critical load are studied. The notch radius varies from 0.2 to 2.0 mm, and the notch depth varies from 5 to 7 ram. By using the SED approach and finite element simulations, the critical load is determined, and the obtained results show a sound agreement with the experimental results.

关键词： Functionally bainitic graded steel Strain energy density Mechanism-based strain gradientplasticity theory critical load Notch radius Notch depth

Co-based Amorphous/Nanocrystalline Composite Coatings Deposited by Arc Ion Plating

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Journal of Materials Science & Technology 2013年第9期29卷 806-812页

作者： Zhengkai Chang Jun Gong Chao Sun State Key Laboratory for Corrosion and Protection Institute of Metal ResearchChinese Academy of Sciences

Cobalt-based amorphous/nanocrystalline composite coatings have been grown by arc ion plating together with a specimen cooling system. With decreasing substrate temperature, the coatings undergo significant structure evolution. The degree of crystallization first decreases and subsequently increases as confirmed by X-ray diffraction. The cluster size first decreases and then remains constant as confirmed by transmission electron microscopy. The effect of substrate temperature on the evolution of the structure has been studied as a result of a competition between nucleation thermodynamics and kinetics of crystalline growth. With decreasing the substrate temperature, the microhardness and the critical load of the composite coatings firstly increased, and then remained almost constant. And the saturation magnetization revealed the opposite trend over the same range. The essence of these phenomena was ascribed to the microstructural variations caused by the decrease of the substrate temperature.

关键词： Amorphous/nanocrystalline composite coatings Arc ion plating Thermodynamics Kinetics Microhardness critical load

Dynamical response of hyper-elastic cylindrical shells under periodic load

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Applied Mathematics and Mechanics(English Edition) 2008年第10期29卷 1319-1327页

作者：任九生 Department of Mechanics Shanghai Institute of Applied Mathematics and Mechanics Shanghai University

Dynamical responses, such as motion and destruction of hyper-elastic cylindrical shells subject to periodic or suddenly applied constant load on the inner surface, are studied within a framework of finite elasto-dynamics. By numerical computation and dynamic qualitative analysis of the nonlinear differential equation, it is shown that there exists a certain critical value for the internal load describing motion of the inner surface of the shell. Motion of the shell is nonlinear periodic or quasi-periodic oscillation when the average load of the periodic load or the constant load is less than its critical value. However, the shell will be destroyed when the load exceeds the critical value. Solution to the static equilibrium problem is a fixed point for the dynamical response of the corresponding system under a suddenly applied constant load. The property of fixed point is related to the property of the dynamical solution and motion of the shell. The effects of thickness and load parameters on the critical value and oscillation of the shell are discussed.

关键词： hyper-elastic cylindrical shells nonlinear differential equation periodic oscillation quasi-periodic oscillation critical load

NONLINEAR VIBRATION OF CIRCULAR SANDWICH PLATES UNDER CIRCUMJACENT load

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Applied Mathematics and Mechanics(English Edition) 2006年第10期27卷 1417-1424页

作者：杜国君马建青 Yanshan University Qinhuangdao 066004Hebei ProvinceP.R.China

Based on von Karman plate theory, the issue about nonlinear vibration for circular sandwich plates under circumjacent load with the loosely clamped boundary condition was researched. Nonlinear differential eigenvalue equations and boundary conditions of the problem were formulated by variational method and then their exact static solution can be got. The solution was derived by modified iteration method, so the analytic relations between amplitude and nonlinear oscillating frequency for circular sandwich plates were obtained. When circumjacent load makes the lowest natural frequency zero, critical load is obtained.

关键词： sandwich plate nonlinear vibration critical load buckling amplitude frequency-load characteristic relation