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Method for Predicting the Fatigue Life of Geometrically Discontinuous Structures Under Combined Bending and Torsion

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Acta Mechanica Solida Sinica 2019年第3期32卷 367-377页

作者： Jianhui Liu Xuemei Pan Yaobing Wei Youliang Wang School of Mechanical and Electronical Engineering Lanzhou University of Technology Lanzhou 730050 China

The fatigue damage model based on theory of damage mechanics is capable of predicting the fatigue life under multiaxial loading. Meanwhile, the application of critical plane method in the prediction of multiaxial fatigue life has made certain progress. According to the law of thermodynamics, a new damage evolution equation is developed in the present study to predict the fatigue life of geometrically discontinuous structure under tension-torsion loading based on damage mechanics and the critical plane method. The essence of this approach is tha t the st rain parame ter of the uniaxial nonlinear fatigue damage model is replaced with the equivalent strain, which consists of the releva nt parame ters of the critical plane. However, it is difficult to calculate the stress-strain status and the critical plane position of geometrically dis? continuous structure by theoretical methods because of the existence of stress concentration and the multiaxial nonproportional characteristics. Therefore, a new numerical simulation method is proposed to determine the critical plane of geometrically discontinuous structure under multiaxial loading by means of the finite element method and MATLAB software. The fatigue life of notched specimens subjected to combined bending and torsion is predicted using the proposed met hod, and the result is compared with t hose from the experimen ts and the Manson-Cfiffin law. The comparisons show that the proposed method is superior to the Manson-Coffin law and is capable of reproducing the experimental results reasonably when the geometry of the structure is complex. It completely meets the needs of engineering practice.

关键词： Damage mechanics Critical plane method Geometrically discontinuous structure Finite element method

Semi-Varying Coefficient panel Data Model with Technical Indicators Predicts Stock Returns in Financial Market

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Journal of Systems Science & Complexity 2024年第4期37卷 1638-1652页

作者： HU xuemei pan Ying LI Xiang School of Mathematics and Statistics Chongqing Technology and Business University Chongqing Key Laboratory of Social Economy and Applied Statistics Research Center for Economy of Upper Reaches of the Yangtse River Chongqing Technology and Business University

Accurately predicting stock returns is a conundrum in financial market. Solving this conundrum can bring huge economic benefits for investors and also attract the attention of all circles of people. In this paper the authors combine semi-varying coefficient model with technical analysis and statistical learning, and propose semi-varying coefficient panel data model with individual effects to explore the dynamic relations between the stock returns from five companies: CVX, DFS, EMN, LYB,and MET and five technical indicators: CCI, EMV, MOM, ln ATR, ln RSI as well as closing price(ln CP), combine semi-parametric fixed effects estimator, semi-parametric random effects estimator with the testing procedure to distinguish fixed effects(FE) from random effects(RE), and finally apply the estimated dynamic relations and the testing set to predict stock returns in December 2020 for the five companies. The proposed method can accommodate the varying relationship and the interactive relationship between the different technical indicators, and further enhance the prediction accuracy to stock returns.

关键词： Fixed effects random effects semi-varying coefficient panel data model stock returns technical indicators

Catalytic hydrogenation performance of ZIF-8 carbide for electrochemical reduction of carbon dioxide

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Chinese Journal of Chemical Engineering 2021年第11期34卷 144-153页

作者： Shuai Fan Huiyuan Cheng Manman Feng xuemei Wu Zihao Fan Dongwei pan Gaohong He State Key Laboratory of Fine Chemicals Research and Development Center of Membrane Science and TechnologySchool of Chemical EngineeringDalian University of TechnologyDalian 116024China

The conversion of CO_(2) electrocatalytic hydrogenation into energy-rich fuel is considered to be the most effective way to carbon recycle.Nitrogen-doping carbonized ZIF-8 is proposed as carrier of the earth-rich Sn catalyst to overcome the limit of electron transfer and CO_(2) adsorption capacity of Sn.Hierarchically porous structure of Sn doped carbonized ZIF-8 is controlled by hydrothermal and carbonization conditions,which induces much higher specific surface area than that of the commercial Sn nanoparticle(1003.174 vs.7.410 m^(2)·g^(-1)).The shift of nitrogen peaks in X-ray Photoelectron Spectroscopy spectra indicates interaction between ZIF-8 and Sn,which induces the shift of electron cloud from Sn to the chemical nitrogen to enhance conductivity and regulate electron transfer from catalyst to CO_(2).Lower mass transfer resistance and Warburg resistance are investigated through EIS,which significantly improves the catalytic activity for CO_(2) reduction reaction(CO_(2)RR).Onset potential of the reaction is reduced from-0.74 V to less than-0.54 V vs.RHE.The total Faraday efficiency of HCOOH and CO reaches 68.9%at-1.14 V vs.RHE,which is much higher than that of the commercial Sn(45.0%)and some other Sn-based catalyst reported in the literature.

关键词： Carbon dioxide Electrochemistry Selective catalytic reduction Electrochemical hydrogen pump Nitrogen-doping carbonized ZIF-8

SMC for Rudder/Fin Joint Roll Stabilization Based on Input-output Feedback Linearization

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SMC for Rudder/Fin Joint Roll Stabilization Based on Input-o...

A system dynamics approach for water resources policy analysis in arid land:a model for Manas River Basin

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作者： Hui Li Xuemei Pan Chen Guo Information Science and Technology College Dalian Maritime University Automation and Electrical Engineering College Linyi University

ISBN: (纸本)9781538629185

In order to ensure the accuracy of course control and achieve good performance on roll stabilization, this paper designs rudder/fin joint SMC system, thereby improving ship’s course stability, security and comfort of crew and passenger. Aiming at ship motion with the features of nonlinearity, strong coupling, multivariable and complex sea condition, this paper establishes the ship motion mathematical model of 4 degrees of freedom, which can more fully reflect the nonlinear essence of ship motion. On this basis, in view of the features of sliding mode variable structure control which is to insensitive in disturbance and model error, combining the theory of nonlinear differential geometry, the sliding mode controller based on the input-output feedback linearization is designed and applied to rudder/fin joint roll stabilization control system. The simulation results show that the controller has good robustness, and the control system can achieve better performance on roll stabilization while maintaining the accuracy of course control.

关键词： Rudder/Fin Joint Roll Stabilization SMC Feedback Linearization

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Journal of Arid Land 2013年第1期5卷 118-131页

作者： ShanShan DAI LanHai LI HongGang XU XiangLiang pan xuemei LI Faculty of Hospitality and Tourism Management Macao University of Science and Technology Macao 999078 China State Key Laboratory of Desert and Oasis Ecology Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Urumqi 830011 China Xinjiang Key Lab of Water Cycle and Utilization in Arid Zone Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Urumqi 830011 China School of Tourism Management Sun Yat-sen University Guangzhou 510275 China

The Manas River Basin in Xinjiang Uygur autonomous region, similar to other arid regions, is facing water constraints which challenge decision-makers as to how to rationally allocate the available water resources to meet the demands from industries and natural ecosystems. Policies which integrate the supply and demand are needed to address the water stress issues. An object-oriented system dynamics model was developed to capture the interrelationships between water availability and increasing water demands from the growth of industries, agri- cultural production and the population through modeling the decision-making process of the water exploration ex- plicitly, in which water stress is used as a major indicator. The model is composed of four sectors： 1 ） natural surface and groundwater resources; 2） water demand; 3） the water exploitation process, including the decision to build reservoirs, canals and pumps; 4） water stress to which political and social systems respond through increasing the supply, limiting the growth or improving the water use efficiency. The model was calibrated using data from 1949 to 2009 for population growth, irrigated land area, industry output, perceived water stress, groundwater resources availability and the drying-out process of Manas River; and simulations were carried out from 2010 to 2050 on an annual time step. The comparison of results from calibration and observation showed that the model corresponds to observed behavior, and the simulated values fit the observed data and trends accurately. Sensitivity analysis showed that the model is robust to changes in model parameters related to population growth, land reclamation, pumping capacity and capital contribution to industry development capacity. Six scenarios were designed to inves- tigate the effectiveness of policy options in the area of reservoir relocation, urban water recycling, water demand control and groundwater pumping control. The simulation runs demonstrated that the technical solutions for im- proving water availabi

关键词： water resources management sustainable development system dynamics modeling water stress arid river basin

Two-dimensional molecular crystalline semiconductors towards advanced organic optoelectronics

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Nano Research 2022年第10期15卷 9554-9572页

作者： xuemei Dong Heshan Zhang Yinxiang Li Bin Liu Keyuan pan Yijie Nie Mengna Yu Mustafa Eginligil Juqing Liu Wei Huang Key Laboratory of Flexible Electronics(KLOFE)&Institute of Advanced Materials(IAM) Nanjing Tech University(Nanjing Tech)Nanjing 211816China Center for Molecular Systems and Organic Devices(CMSOD) State Key Laboratory of Organic Electronics and Information Displays&Institute of Advanced Materials(IAM)Nanjing University of Posts&TelecommunicationsNanjing 210023China Frontiers Science Center for Flexible Electronics Xi’an Institute of Flexible Electronics(IFE)and Xi’an Institute of Biomedical Materials&EngineeringNorthwestern Polytechnical UniversityXi’an 710072China

The compelling demand for higher performance and lower cost in the optoelectronics industry has driven the development of organic semiconductors.Molecular crystalline semiconductors(MCSs),especially two-dimensional MCSs(2D-MCSs),possess intrinsic ordered structure,quantum confinement effect,high mobility,unique optical and electrical properties,and more ecological and cheaper production,which make great promises in high-performance optoelectronic applications.Here we provide a review of design principles and synthetic strategies for 2D-MCS materials,exploiting their potential as a revolution option in associated optoelectronic devices.The merits and limitations of each strategy are presented,and these molecular crystals are considered as a competitive choice for emerging semiconducting materials in information science.Finally,the current challenges and future perspectives in this field are also elaborated.

关键词： two-dimensional molecular crystalline semiconductors(2D-MCSs) molecular design strategies preparation techniques photoelectronic applications

The control and optimization of macro/micro-structure of ion conductive membranes for energy conversion and storage

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Chinese Journal of Chemical Engineering 2016年第5期24卷 558-571页

作者： Xiaoming Yan Wenji Zheng Xuehua Ruan Yu pan xuemei Wu Gaohong He State Key Laboratory of Fine Chemicals School of Petroleum and Chemical EngineeringDalian University of Technology Research and Development Center of Membrane Science and Technology School of Chemical EngineeringDalian University of Technology

Ion conductive membranes(ICMs)are frequently used as separators for energy conversion and storage technologies of fuel cells,flow battery,and hydrogen pump,because of their good ion-selective conduction and low electronic conductivity.Firstly,this feature article reviews the recent studies on the development of new nonfluorinated ICMs with low cost and their macro/micro-structure control.In general,these new nonfluorinated ICMs have lower conductivity than commercial perfluorinated ones,due to their poor ion transport channels.Increasing ion exchange capacity(IEC)would create more continuous hydrophilic channels,thus enhancing the conductivity.However,high IEC also expands the overall hydrophilic domains,weakens the interaction between polymer chains,enhances the mobility of polymer chains,and eventually induces larger swelling.The micro-scale expansion and macro-scale swelling of the ICMs with high IEC could be controlled by limiting the mobility of polymer chains.Based on this strategy,some ef ficient techniques have been developed,including covalent crosslinking,semi-interpenatrating polymer network,and blending.Secondly,this review introduces the optimization of macro/microstructure of both perfluorinated and nonfluorinated ICMs to improve the performance.Macro-scale multilayer composite is an ef ficient way to enhance the mechanical strength and the dimensional stability of the ICMs,and could also decrease the content of per fluorosulfonic acid resin in the membrane,thereby reducing the cost of the perfluorinated ICMs.Long side chain,multiple functionalization,small molecule inducing micro-phase separation,electrospun nano fiber,and organic–inorganic hybrid could construct more ef ficient ion transport channels,improving the ion conductivity of ICMs.

关键词：离子传导存储技术能量转换导电膜宏观控制优化微结构

miR319-TCPs-TGA9/TGA10/ROXY2 regulatory module controls cell fate specification in early anther development in Arabidopsis

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Science China(Life Sciences) 2024年第4期67卷 839-842页

作者： Jinyuan Tao Zijie pan Wenwen Kong Beixin Mo xuemei Chen Yu Yu Guangdong Provincial Key Laboratory for Plant Epigenetics Longhua Bioindustry and Innovation Research InstituteCollege of Life Sciences and OceanographyShenzhen UniversityShenzhen 518060China Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Optoelectronic EngineeringShenzhen UniversityShenzhen 518060China School of Life Sciences Peking-Tsinghua Joint Center for Life SciencesPeking UniversityBeijing 100871China

Dear Editor,The process of anther development is generally conserved across plant species(Ma,2005).Many protein-coding genes and noncoding RNAs have been identified to participate in early anther development in Arabidopsis(Walbot and Egger,2016).mi R319 is one of the most ancient and conserved mi RNA families in land plants(Chávez Montes et al.,2014).

关键词： Arabidopsis miR319 ancient

A 1G-cell floating-gate NOR flash memory in 65 nm technology with 100 ns random access time

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Science China(Information Sciences) 2015年第4期58卷 158-165页

作者： LIU LiFang WU Dong LIU xuemei HUO ZongLiang LIU Ming pan LiYang Institute of Microelectronics University of Tsinghua Tsinghua National Laboratory for Information Science and Technology Laboratory of Nano-Fabrication and Novel Devices Integrated Technology Institute of MicroelectronicsChinese Academy of Sciences

A 1G-cell NOR flash memory chip has been designed and fabricated successfully with 65 nm technology. To compromise the array efficiency and chip speed, the paper establishes an array model including parasitics of the whole array, and optimizes the sector structure as 512 wordlines(WLs) and 4096 bitlines(BLs).Furthermore, by adding other models of long and thin metal lines, we have analyzed the speed of critical circuit nodes. As a result, the agreement of WL delay between simulation and measurement verifies the accuracy of the array model and lines models. The test results indicate that the chip achieves random access time of 100 ns and page read time of 25 ns under 3.3 V voltage supply.

关键词： NOR flash memory giga-level 65 nm technology array efficiency high speed