检索结果-南通市图书馆

Acta Mechanica Solida Sinica 2016年第4期29卷 391-406页

作者： Linlin Sun miao zhang Weiping Hu Qingchun Meng Institute of Solid Mechanics School of Aeronautic Science and Engineering Beihang University Institute of Manned Space System Engineering China Academy of Space Technology

To consider the anisotropic damage in fatigue, an improved boom-panel model is presented to simulate a representative volume element (RVE) in the framework of continuum damage mechanics. The anisotropic damage state of the RVE is described by the continuity extents of booms and panels, whose damage evolutions are assumed to be isotropic. The numerical implementation is proposed on the basis of damage mechanics and the finite element method. Finally, the approach is applied to the fatigue life prediction of 2A12-T4 aluminium alloy specimen under cyclic loading of tension-torsion. The results indicate a good agreement with the experimental data.

关键词： boom-panel model anisotropic damage fatigue tension-torsion life prediction

A Two-Stage Genetic Algorithm for the Truck-Door Assignment Problem with Limited Capacity Vehicles and Storage Area

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science and Systems Engineering 2019年第3期28卷 285-298页

作者： Zhaowei miao Jie zhang Yongquan Lan Ruize Su School of Management Xiamen UniversityXiamen 361005China School of Business Administration Guangdong University of Finance and EconomicsGuangzhou 510320China

In this paper,we investigate a kind of truck-door assignment problem in a *** related realistic constraints such as the capacity of trucks,the capacity of temporary storage area,the time windows of trucks as well as the operational time inside the crossdock are considered and therefore,make the assignment problem strongly NP-hard and very challenging.A two-stage genetic algorithm is proposed to solve this problem and the experimental results show the superiority of this approach in comparison to CPLEX solver in terms of effectiveness and efficiency especially for the large-scale *** is,the decision making process can speed up and a near optimal truck-door assignment scheme can be obtained within a relatively short time by applying this two-stage approach in practice.

关键词： Truck-door assignment genetic algorithm two-stage approach crossdock

Developing silicon-based photocathodes for CO_(2) conversion

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第6期67卷 1904-1921页

作者： Weijie Zhuang miao Kan Tao Meng Jinlong zhang Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering Feringa Nobel Prize Scientist Joint Research CenterSchool of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai200237China Shanghai Engineering Research Center for Multimedia Environmental Catalysis and Resource Utilization East China University of Science and TechnologyShanghai200237China

Photoelectrochemical(PEC)conversion of CO_(2) presents a promising avenue for solar-driven chemical fuel production,with silicon emerging as a cost-effective and high-light-absorbing material pivotal to this *** at exploring opportunities for industrializing PEC CO_(2) reduction(PEC-CO_(2)R)by minimizing reaction energy consumption,enhancing reaction efficiency and selectivity,this review summarizes recent advancements in developing Si-based photocathodes for PEC-CO_(2)*** outlines the fundamental principles,advantages,and limitations of Si photocathodes with key performance *** on this understanding,the strategies to enhance the performance of the PEC-CO_(2)R system,including light absorption,charge separation,and catalytic reactions are categorized as the interfacial modification,active site decoration,and protective layer *** design ideas of this advantageous three-layer structure in promoting the efficiency,stability,and selectivity have been ***,this review scrutinizes the influence of the photocathodic chemical *** review consolidates the mechanism insights and notable breakthroughs of various fuel generation processes within Si-based PEC-CO_(2)R *** this wealth of information offers an up-to-date perspective on the dynamic developments in silicon-based PEC-CO_(2) conversion and underscores the promising pathways toward the sustainable fuel synthesis from pollutant CO_(2).

关键词： photoelectrochemistry solar fuels silicon photocathodes carbon dioxide reduction microenvironment

Pulsed Nd:YAG laser cladding of high silicon content coating on low silicon steel

在线全文

学校读者我要写书评

暂无评论

Journal of University of Science and Technology Beijing 2007年第4期14卷 321-326页

作者： Danyang Dong Changsheng Liu Bin zhang Jun miao Key Laboratory of the Ministry of Education of China for Anisotropy and Texture of Materials Northeastern University Shenyang 110004 China

A pulsed Nd：YAG （yttrium aluminum garnet） laser-based technique was employed to clad low silicon steel with preplaced Si and Fe mixed powders for high Si content. The surface morphology, microstructural evolution, phase composition, and Si distribution, within the obtained cladding coatings, were characterized by optical microscopy （OM）, field emission scanning electron microscopy （FE-SEM）, with associated energy dispersive spectroscopy （EDS）, transmission electron microscopy （TEM）, and X-ray diffraction （XRD）. The microhardness was also measured along the depth direction of the specimens, A crack- and pore-free cladding coating through excellent metallurgical bonding with the substrate was successfully prepared on low silicon steel by means of optimized single-track and multi-track laser cladding. The phases of the coating are a-Fe, T-Fe, and FeSi. The high microhardness of the lasercladding zone is considered as an increase in Si content and as the refined microstructure produced by the laser treatment. The Si contents of the cladding coatings were about 5.8wt% in the single-track cladding and 6.5wt% in the multi-track cladding, respectively.

关键词： silicon steel pulsed Nd:YAG laser cladding high silicon content coating microstructure microhardness

Fabrication of nano-grained negative temperature coefficient thermistors with high electrical stability

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2021年第4期40卷 1014-1019页

作者： miao-miao Cui Xiao zhang Kuan-Guan Liu Hai-Bo Li Mang-Mang Gao Sen Liang Ningxia Key Laboratory of Photovoltaic Materials Ningxia UniversityYinchuan 750021China School of Materials Science and Engineering North Minzu UniversityYinchuan 750021China

Dense nano-grained Ni_(0.7)Mn_(2.3O4) negative temperature coefficient(NTC) thermistors were fabricated by a novel two-step sintering approach that combines rapid sintering and principle of conventional two-step sintering *** were sintered at 1042℃ for 30 s in the first rapid step and then at 850-950℃ for 20 h in the second soaking *** phase,microstructure and electrical properties of sintered samples were studied by X-ray diffraction(XRD),scanning electron microscopy(SEM),resistance temperature relationship and aging *** samples show a single-phase cubic spinel structure and indicate a high relative density ranging from 84% to 91% of the theoretical ***,average grain sizes of sintered samples under SEM are distributed between 254 and 570 ***,the resistivity and the aging coefficient significantly decrease when soaking sintering temperature *** addition,the obtained material constant(B) ranges from 3931 to 3981 ***_(0.7)Mn_(2.3)O_(4)-3(soaking at 900℃) and Ni_(0.7)Mn_(2.3O4)-4(soaking at 950℃) present little aging behavior,implying great electrical stability.

关键词： Negative temperature coefficient thermistor Sintering Nano-grain Aging

CATH: an effective method for detecting denial-of-service attacks in software defined networks

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2019年第3期62卷 75-89页

作者： Yi GUO Fu miao Liancheng zhang Yu WANG State Key Laboratory of Mathematical Engineering and Advanced Computing Institute for Network Science and Cyberspace Tsinghua University School of Computer Science Henan University of Engineering

Software defined networks(SDNs) are innovative network frameworks that have recently received wide attention. Their programming flexibility facilitates automatic network management and control, thus mitigating existing issues in the traditional network architecture. However, SDNs face several security risks,in particular denial-of-service(DoS) attacks, the most common and serious network attacks. To address such a threat, an SDN-DoS attack detection method is proposed based on fusing multiple flow features for describing the network catastrophe between the normal and the attack state. Several statistic attributes of SDN flow information are first chosen as detection features; subsequently, the cusp model is used to establish a catastrophe equilibrium surface for SDN states. After being trained, the cusp catastrophe model can be utilized to infer whether an SDN is under DoS attack. The experimental results demonstrate that the method can effectively and timely perceive SDN-DoS attacks, not only in simple networks but also in larger enterprise networks.

关键词： DoS attacks software defined network flow features cusp model equilibrium surface

TD-DFT Study on Pyrazoline Derivatives

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Structural Chemistry 2005年第10期24卷 1169-1175页

作者： miao Ti-Fang zhang Jian-Fu LI Shuang Department of Chemistry Huaibei Coal Teachers College Huaibei 235000 China Department of Chemistry Zhoukou Teachers College Zhoukou 466000 China

The molecular structures of ground state and first single excited state for pyrazoline derivatives are optimized with DFT B3LYP method and ab initio “configuration interaction with single excitations”（CIS） method, respectively. The frontier molecular orbital characteristics have been analyzed systematically, and the electronic transition mechanism has been discussed. Electronic spectra are calculated by using TD-DFT method. These results are consistent with those from the experiment.

关键词： pyrazoline derivatives electron transfer time-dependent density functional theory (TD-DFT) electronic spectrum

Revised damage evolution equation for high cycle fatigue life prediction of aluminum alloy LC4 under uniaxial loading

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2015年第9期36卷 1185-1196页

作者： Zhixin ZHAN Weiping HU miao zhang Qingchun MENG Institute of Solid Mechanics School of Aeronautics Science and EngineeringBeiHang University China Academy of Space Technology

The fatigue life prediction for components is a difficult task since many factors can affect the final fatigue life. Based on the damage evolution equation of Lemaitre and Desmorat, a revised two-scale damage evolution equation for high cycle fatigue is presented according to the experimental data, in which factors such as the stress amplitude and mean stress are taken into account. Then, a method is proposed to obtain the material parameters of the revised equation from the present fatigue experimental data. Finally, with the utilization of the ANSYS parametric design language （APDL） on the ANSYS platform, the coupling effect between the fatigue damage of materials and the stress distribution in structures is taken into account, and the fatigue life of specimens is predicted. The outcome shows that the numerical prediction is in accord with the experimental results, indicating that the revised two-scale damage evolution model can be well applied for the high cycle fatigue life prediction under uniaxial loading.

关键词： fatigue damage model continuum damage mechanics fatigue life highcycle fatigue finite element method

A NEW DAMAGE MECHANICS BASED APPROACH TO FATIGUE LIFE PREDICTION AND ITS ENGINEERING APPLICATION

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2015年第5期28卷 510-520页

作者： Fei Shen Weiping Hu Qingchun Meng miao zhang Institute of Solid Mechanics School of Aeronautics Science and Engineering Beihang University Institute of Manned Space System Engineering China Academy of Space Technology

An approach based on continuum damage mechanics to fatigue life prediction for structures is proposed. A new fatigue damage evolution equation is developed, in which the pa- rameters are obtained in a simple way with reference to the experimental results of fatigue tests on standard specimens. With the utilization of APDL language on the ANSYS platform, a finite element implementation is presented to perform coupling operation on damage evolution of mate- rial and stress redistribution. The fatigue lives of some notched specimens and a Pitch-change-link are predicted by using the above approach. The calculated results are validated with experimental data.

关键词： fatigue damage model damage mechanics fatigue life finite element method

Mechanical analysis of effective pressure relief protection range of upper protective seam mining

在线全文

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2017年第3期27卷 537-543页

作者： Yin Wei miao Xiexing zhang Jixiong Zhong Sijian School of Mines Key Laboratory of Deep Coal Resource Ministry of Education China University of Mining & Technology Xuzhou 221116 China State Key Laboratory for Geomechanics & Deep Underground Engineering China University of Mining & Technology Xuzhou 221116 China

This paper analyzes the control mechanism of coal and gas outbursts and proposes the concept of an effective pressure relief protection range, based on the stress relief of the underlying coal-rock mass and the development of a plastic zone. Also this study developed a stress change and fracture development model of the underlying coal-rock mass. In addition, the stress and depth of fracture of any point in the floor were deduced with the application of Maple Calculation Software. The specific engineering parameters of the Pingdingshan No. 12 colliery were applied to determine the relationship between the depth of fracture in the floor and the mining height. The pressure-relief principle of the underlying coal-rock mass was analyzed while varying the mining height of the upper protective seam. The findings indicate that as the depth of fracture in the floor increases, the underlying coal-rock mass experiences a limited amount of pressure relief, and the pressure relief protection range becomes ***, the stress distribution evolves from a ‘‘U" shape into a ‘‘V" shape. A 2.0 m mining height of protective seam situates the outburst-prone seam, Ji_(15), within the effective pressure relief protection range. The fracture development and stress-relief ratio rises to 88%, ensuring the pressure-relief effect as well as economic benefits. The measurement data show that: after mining the upper protective seam, the gas pressure of Ji_(15) dropped from 1.78 to 0.35 MPa, demonstrating agreement between the engineering application and the theoretical calculation.

关键词： Upper protective seam Principle of pressure relief Effective protection range Gas pressure