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ANALYTICAL TREATMENT OF BOUNDARY INTEGRALS IN DIRECT BOUNDARY ELEMENT ANALYSIS OF PLAN POTENTIAL AND ELASTICITY PROBLEMS

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Applied Mathematics and Mechanics(English Edition) 2001年第6期22卷 664-673页

作者： ZHANG yao-ming(张耀明) SUN Huan-chun(孙焕纯) Department of Mathematics and Physics Shandong Institute of Engineering Zibo 255012 P R China Department of Mechanics Dalian University of Technology Dalian 116023 P R China

An analytical scheme, which avoids using the standard Gaussian approximate quadrature to treat the boundary integrals in direct boundary element method (DBEM) of two-dimensional potential and elastic problems, is established. With some numerical results, it is shown that the better precision and high computational efficiency, especially in the band of the domain near boundary, can be derived by the present scheme.

关键词： potential/elasticity problems analytical method boundary element

Arabidopsis AtADF1 is Functionally Affected by Mutations on Actin Binding Sites

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Journal of Integrative Plant Biology 2013年第3期55卷 250-261页

作者： chun-Hai Dong Wei-Ping Tang Jia-yao Liu College of Life Sciences Qingdao Agricultural University

The plant actin depolymerizing factor （ADF） binds to both monomeric and filamentous actin, and is directly involved in the depolymerization of actin filaments. To better understand the actin binding sites of the Arabidopsis thaliana L. AtADF1, we generated mutants of AtADF1 and investigated their functions in vitro and in vivo. Analysis of mutants harboring amino acid substitutions revealed that charged residues （Arg98 and Lys100） located at the α-helix 3 and forming an actin binding site together with the N-terminus are essential for both G- and F-actin binding. The basic residues on the β-strand 5 （K82/A） and the α-helix 4 （R135/A, R137/A） form another actin binding site that is important for F-actin binding. Using transient expression of CFP-tagged AtADF1 mutant proteins in onion （Allium cepa） peel epidermal cells and transgenic Arabidopsis thaliana L. plants overexpressing these mutants, we analyzed how these mutant proteins regulate actin organization and affect seedling growth. Our results show that the ADF mutants with a lower affinity for actin filament binding can still be functional, unless the affinity for actin monomers is also affected. The G-actin binding activity of the ADF plays an essential role in actin binding, depolymerization of actin polymers, and therefore in the control of actin organization.

关键词： Actin binding site actin depolymerizing factor Arabidopsis thaliana mutation.

SCENARIOS SIMULATION OF COUPLING SYSTEM BETWEEN URBANIZATION AND ECO-ENVIRONMENT IN JIANGSU PROVINCE BASED ON SYSTEM DYNAMICS MODEL

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Chinese Geographical Science 2005年第3期15卷 219-226页

作者： LIU yao-bin LI Ren-dong LI chun-hua School of Management China University of Mining and Technology Xuzhou 221008 P. R. China Institute of Geodesy and Geophysics Research Chinese Academy of Sciences Wuhan 430077 P. R. China Institute of Resource Beijing Normal University Beijing 100875 P. R. China

By means of ISM (Interpretative Structural Modeling) and SD (System Dynamics) methods, this paper made a system dynamics model of urbanization and eco-environment coupling in Jiangsu Province according to the implication and PSR (Pressure State Response) framework of urbanization and eco-environment coupling. Moreover, five typical scenarios during 2000-2015 have been simulated and analyzed based on the time serial statistical data during 1990-2003 in Jiangsu, which indicates: firstly, there are significant differences between the results and the scenarios, and the five coupling models all have comparative advantages and drawbacks; secondly, in terms of the characteristics and regional development disparities of Jiangsu and the general rule of world urbanization process, this paper reveals that only when either population urbanization model or social urbanization model to be correspondingly adopted, the sustainable development among population, economy, urbanization and eco-environment can be realized.

关键词： urbanization eco-environment system dynamics model simulation Jiangsu Province

Contribution of winter fluxes to the annual CH_4, CO_2 and N_2O emissions from fres hwater marshes in the Sanjiang Plain

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Journal of Environmental Sciences 2006年第2期18卷 270-275页

作者： HAO Qing-ju WANG Yue-si SONG Chang-chun HUANG yao Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China Northeast Institute of Geography and Agricultural Ecology Chinese Academy of Sciences Changchun 130012 China Graduate School of the Chinese Academy of Sciences Beijing 100049 China

Wetlands at the interface of the terrestrial and aquatic ecosystems are intensive sites for mineralization of organic matter, but the contribution of winter season fluxes of CH4, CO2 and N2O from wetland ecosystems to annual budgets is poorly known. By using the static opaque chamber and GC techniques, fluxes of CH4, CO2 and N2O at two freshwater marshes in the Sanjiang Plain were measured during the winter seasons of 2002/2003 and 2003/2004 with contrasting snow conditions and flooding regimes. The results showed that there were significant interannual and spatial differences in CH4, CO2 and N2O fluxes. The Carex lasiocarpa marsh emitted more CH4 and CO2 while absorbed less N2O than the Deyeuxia angustifolia marsh during the winter seasons. Over the winter season, emissions of CH4, CO2 and N2O ranged from 0.42 to 2.41 gC/m^2, from 24.13 to 50.16 gC/m^2, and from -25,20 to -148.96 mgN/m^2, respectively. The contributions of winter season CH4 and CO2 emission to the annual budgets were 2.32% 4.62% and 22.17%- 27.97%, respectively. Marshes uptake N2O during the freezing period, while release N2O during the thawing period. The winter uptake equaled to 13.70%-86.69% of the growing-season loss. We conclude that gas exchange between soil/snow and the atmosphere in the winter season contributed greatly to the annual budgets and cannot be ignored in a cool temperate freshwater marsh in Northeast China.

关键词： freshwater marsh winter flux greenhouse gas emission Sanjiang Plain

A Brief Summary of Current Therapeutic Strategies for Spinal Cord Injury

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Engineering 2022年第6期8卷 46-52页

作者： chun yao Xin Tang Yuqi Cao Xuhua Wang Bin Yu Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education&NMPA Key Laboratory for the Research and Evaluation of Tissue Engineering Technology Products Co-Innovation Center of NeuroregenerationNantong UniversityNantong 226001China NHC and CAMS Key Laboratory of Medical Neurobiology MOE Frontier Science Center for Brain Science and Brain-Machine IntegrationSchool of Brain Science and Brain MedicineZhejiang UniversityHangzhou 310003China Jiangsu Clinical Medicine Center of Tissue Engineering and Nerve Injury Repair Affiliated Hospital of Nantong UniversityNantong UniversityNantong 226001China

Spinal cord injury(SCI)is a tremendous disaster in a person’s *** interrupts the brain-body neuronal circuits,resulting in functional *** of SCI is a progressive and comprehensive *** clinical trials,attempts to promote nerve regeneration and functional recovery after SCI have met with ***,with the development of transcriptome sequencing and biomaterials,researchers have struggled to explore novel efficient therapeutic treatments for ***,we summarize the recent pro-gress that has been made in SCI repair based on the lesion microenvironment,neural circuits,and bioma-terial *** also propose several important directions for future research,including targeted-microRNA therapy,blood vessel interventions,and multiple treatment *** short,we hope this review will enlighten researchers in the field and pave the way for SCI therapy.

关键词： Spinal cord injury Microenvironment Neural circuits Biomaterial scaffolds

Design of an innovative multi-stage forming process for a complex aeronautical thin-walled part with very small radii

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Chinese Journal of Aeronautics 2018年第11期31卷 2165-2175页

作者： yao WANG Lihui LANG Ehsan SHERKATGHANAD Karl Brian NIELSEN chun ZHANG School of Mechanical Engineering and Automation Beihang University Department of Materials and Production Aalborg University Tianjin Tianduan Press Co. LTD

In this paper, an aeronautical thin-walled part with a complex geometry which has several sharp bends and curvatures in different directions was investigated. This kind of part is difficult to be manufactured only in one stage. Therefore, an innovative multi-stage active hydroforming process assisted by the rigid forming method was designed. In addition, an optimized blank geometry is obtained. In fact, the main focused point of this paper is to propose a new small radius rounded corner forming technique and analyze the mechanism. Two kinds of forming modes of changing a big rounded corner into a small one, which are related to different tangential positions of the die in the process of calibration, are analyzed theoretically. Meanwhile, the stress and strain states of the deformation region are compared. The relationships between the minimum relative radii of rounded corners I and II in the first stage and the hydraulic pressure are calculated by the bending theory. Finally, the influences of the tensile-bulging effect and the interface condition of the double-layer sheet on the forming quality of the specimen are investigated. The achieved results can make a foundation for utilizing the proposed method in forming of thin-walled parts with very small radii.

关键词： Double-layer sheet Hydroforming Multi-stage forming Small rounded corner Tensile-bulging effect

Decomposition behavior of titanium hydride treated by surface oxidation

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Rare Metals 2015年第1期34卷 28-33页

作者： Hong-Jie Luo Hao Lin Pei-Hong Chen Guang-chun yao School of Materials and Metallurgy Northeastern University Engineering Technology Research Centre of Ministry of Education for Materials Advanced Preparation

Titanium hydride attracts more attention as foaming agent in the fabrication of cellular metal materials. In order to meet most aluminum casting alloy＇s melting properties, the heat treatment processes for Till2 particles were investigated in a rotating device. In the present work, the most two important dynamic parameters, the treating temperature and oxidation interval, were taken under consideration. The decomposition behavior of titanium hydride was measured by differential scanning calorimetry （DSC） and the residual hydrogen content, morphologies and phase conversion were also characterized by hydrogen determinator, scanning electron microscopy （SEM）, and X-ray diffractometer （XRD）, respectively. The results show that the effect of temperature on the formation of oxidation film and decomposition behavior of Till2 is more significant than that of oxidation time. The onset temper- ature and peak value of Till2 decomposition shift from left to right through elevating temperature and extending time. Heat treatment process for Till2 at 500 ℃ between 1 and 5 h in air is favorable for preparing aluminum foam.

关键词： Titanium hydride Oxidation treatment Thermal decomposition Aluminum foam

Numerical analysis of hydraulic fracture propagation in deep shale reservoir with different injection strategies

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第9期16卷 3558-3574页

作者： Yingjie Xia Mingyu yao Tianjiao Li Hai Yang chun'an Tang School of Civil Engineering Dalian University of TechnologyDalian116024China Deep Underground Engineering Research Center Dalian University of TechnologyDalian116024China CNPC Chuanqing Drilling Engineering Company Limited Chengdu610051China

Deep shale reservoirs are characterized by elevated breakdown pressures,diminished fracture complexity,and reduced modified volumes compared to medium and shallow ***,it is urgent to investigate particular injection strategies that can optimize breakdown pressure and fracturing efficiency to address the increasing demands for deep shale reservoir *** this study,the efficiency of various stimulation strategies,including multi-cluster simultaneous fracturing,modified alternating fracturing,alternating shut-in fracturing,and cyclic alternating fracturing,was ***,the sensitivity of factors such as the cycle index,shut-in time,cluster spacing,and horizontal permeability was ***,the flow distribution effect within the wellbore was *** results indicate that relative to multi-cluster simultaneous fracturing,modified alternating fracturing exhibits reduced susceptibility to the stress shadow effect,which results in earlier breakdown,extended hydraulic fracture lengths,and more consistent propagation despite an increase in breakdown *** alternating shut-in fracturing benefits the increase of fracture length,which is closely related to the shut-in ***,cyclic alternating fracturing markedly lowers breakdown pressure and contributes to uniform fracture propagation,in which the cycle count plays an important *** alternating fracturing demonstrates insensitivity to variations in cluster spacing,whereas horizontal permeability is a critical factor affecting fracture *** wellbore effect restrains the accumulation of pressure and flow near the perforation,delaying the initiation of hydraulic *** simulation results can provide valuable numerical insights for optimizing injection strategies for deep shale hydraulic fracturing.

关键词： Fracture propagation Numerical simulation Hydraulic fracturing Rock failure process analysis(RFPA) Injection strategy

Hydrodynamics of a dual-module pontoon-net floating breakwater system:Numerical simulations and prototype tests

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Journal of Hydrodynamics 2021年第5期33卷 915-927页

作者： Yong Cheng chun-yan Ji Xue-kang Gu fa-liHuo Jie Cui Zhi-Ming Yuan School of Naval Architecture and Ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China China ship Scientific Research Center Wuxi 214082China Department of Naval Architecture Ocean and Marine EngineeringUniversity of StrathclydeGlasgowUK

Floating breakwaters with a mooring system have been widely applied to protect marine infrastructures(e.g.,artificial beach or island,aquaculture farm or marine vessels in harbors)from being destroyed by severe *** this paper,an innovative cylindrical dual pontoon-net floating breakwater was developed to enhance the wave attenuation *** dual-module floating breakwater system was constructed as the prototype for on-site testing.A fully nonlinear time-domain model based on the coupled iterative solutions of the fluid integral equation and the pontoon-net dynamic equations was proposed to simulate the interactions between waves and the floating breakwater *** flow field around the nets was simulated by introducing a porous-media model with Darcy’s law,while the deformation of the flexible nets was solved by using the lumped mass *** instantaneous free surface was captured using the mixed Eulerian-Lagrangian(MEL)approach which employs an improved moving-grid technique based on the spring analysis to re-mesh the instantaneous water surface and the body wetted ***-site tests were also conducted to evaluate wave transmission performance of the floating breakwater system and to validate the numerical *** comparisons show that the numerical solutions are in good agreement with the measured *** effects of incident wave direction,wave period,wave height,net height,net number and net porosity on the hydrodynamic performance of the floating breakwater system were emphatically examined.

关键词： Floating breakwater fully nonlinear simulations on-site tests flexible net wave attenuation moving-grid technique