检索结果-南通市图书馆

A load simulation method of piezoelectric actuator in FEM for smart structures

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2009年第9期52卷 2576-2584页

作者： LI min CHEN Weimin WANG mingChun JIA LiJie School of Aeronautics Science and Engineering Beihang UniversityBeijing 100191China Division of Engineering Science Research Institute of MechanicsChinese Academy of SciencesBeijing 100190China

More and more piezoelectric materials and structures have been used for structure control in aviation and aerospace industry. More efficient and convenient computation method for large complex structure with piezoelectric actuation devices is required. A load simulation method of piezoelectric actuation is presented in this paper. By this method, the freedom degree of finite element simulation is significantly reduced, the difficulty in defining in-plane voltage for multi-layers piezoelectric composite is overcome and the transfer computation between material main direction and the element main direction is simplified. The concept of simulation load is comprehensible and suitable for engineers of structure strength in shape and vibration control, thereby is valuable for promoting the application of piezoelectric material and structures in practical aviation and aerospace fields.

关键词： piezoelectric actuator piezoelectric fiber composite shape control vibration control drive characteristic

Precipitation of AlN and MnS in Low Carbon Aluminium-Killed Steel

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2012年第4期19卷 51-56页

作者： CHEN Yin-li WANG Yan ZHAO Ai-min (Engineering Research Institute University of Science and Technology Beijing Beijing 100083 China)

The precipitation kinetics of AlN and MnS in low carbon aluminium-killed steel was *** electron microscopy（TEM）,energy disperse spectroscopy（EDS） and phase analyses have been used to investigate the morphology,compositions and particle size distribution of AlN and MnS precipitates in three positions of the *** particles of AlN and MnS precipitates in the ferrite region after coiling and distributes along and adjacent to the ferrite grain *** shapes of AlN are plate-like,the precipitates size is about 10 to 60 nm;the shapes of MnS are spherical,the precipitates size is about 200 to 600 *** precipitation behavior of AlN is sensitive to the isothermal temperature and holding time,the precipitation quantity and particle size distribution of AlN in different positions of coil are unequal

关键词： precipitation kinetics morphology low carbon steel AIN MnS

The contribution of bacteria to organic matter in coal-measure source rocks

在线全文

学校读者我要写书评

暂无评论

Acta Geochimica 2019年第3期38卷 364-375页

作者： Qingsong Cheng min Zhang Guanghui Huang Wenjun Zhang College of Resources and Environment Yangtze University Key Laboratory of Exploration Technology for Oil & Gas Research (Yangtze University) Ministry of Education Bohai Petroleum Research Institute CNOOC (China) Co.Ltd.Tianjin Branch

On the basis of GC–MS analysis, a suite of nine coal-measure source rocks(Ro 0.51%–0.63%) from the southern margin of Junggar basin was found to contain many biomarkers for bacterially-generated hydrocarbons:hopane, sesquiterpene, C_(23)+ monomethyl alkanes(even carbon predominance), and C_(24)+ alkyl ***–eval and microscope analysis indicate that vitrinite(especially desmocollinite and homocollinite) plays a significant role in the generation of hydrocarbons in coalmeasure source rocks. Vitrinite performs this role by absorbing ultramicroscopic organic matter, generally in the form of resins or bacterial plastids. C_(23)+ monomethyl alkanes(even carbon predominance) and C_(24)+ alkyl cyclohexane series compounds are derived from bacterial metabolites of higher plants. The ultramicro organic matter adsorbed by vitrinite source rocks in the study area is probably ultramicro bacterial plastids. Because the organic matter of higher plants with low hydrogen content has been transformed into organic matter rich in hydrogen by bacteria, the hydrocarbon generation capacity of source rocks is greatly improved. In other words, in coal-measure source rocks, bacteria play an important role in hydrocarbon generation.

关键词： Coal-measure source rocks Organic matter type Bacteria Monomethyl alkanes Alkyl cyclohexane

Activation of the Brain to Postpone Dementia: A Concept Originating from Postmortem Human Brain Studies

在线全文

学校读者我要写书评

暂无评论

Neuroscience Bulletin 2019年第2期35卷 253-266页

作者： Qiong-Bin Zhu Ai-min Bao Dick Swaab Department of Neurology Sir Run Run Shaw HospitalZhejiang University School of Medicine Department of Neurobiology Key Laboratory of Medical Neurobiology of the Ministry of Health of China Zhejiang Province Key Laboratory of Neurobiology Zhejiang University School of Medicine Netherlands Institute for Neuroscience Institute of the Royal Netherlands Academy of Arts and Sciences

Alzheimer's disease(AD) is characterized by decreased neuronal activity and atrophy, while hyperactivity of neurons seems to make them resistant to aging and neurodegeneration, a phenomenon which we have paraphrased as ‘use it or lose it'. Our hypothesis proposes that(1) during their functioning, neurons are damaged;(2)accumulation of damage that is not repaired is the basis of aging;(3) the vulnerability to AD is determined by the genetic background and the balance between the amount of damage and the efficiency of repair, and(4) by stimulating the brain, repair mechanisms are stimulated and cognitive reserve is increased, resulting in a decreased rate of aging and risk for AD. Environmental stimulating factors such as bilingualism/multilingualism, education, occupation, musical experience, physical exercise, and leisure activities have been reported to reduce the risk of dementia and decrease the rate of cognitive decline, although methodological problems are present.

关键词： Dementia Genes Environmental stimulation Brain activation Cognitive reserve Use it or lose it

Exact Solutions of One-Dimensional N-Component Bariev Model with General Boundary Conditions

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2006年第4X期46卷 755-760页

作者： KE San-min WANG Chun YUE Rui-Hong Institute of Modern Physics Northwest University Xi'an 710069 China College of Science Xi'an Shiyou University Xi'an 710065 China

The N-component Bariev model for correlated hopping with open boundary conditions in one dimension is studied in the framework of coordinate Bethe ansatz method. The energy spectrum, integrable boundary conditions and... 详细信息

关键词： coordinate Bethe ansatz open-boundary conditions N-component Bariev model

Influence of molecular weight of modified ultrahigh-molecular-weight polyethylene with Cu(II) chelate of bissalicylaldehyde-ethylenediamine on wear-resistant materials

在线全文

学校读者我要写书评

暂无评论

Friction 2016年第2期4卷 116-123页

作者： min LIU Li WU Fuqing ZHANG Jing FU School of Chemistry and Environmental Engineering Wuhan Institute of Technology Wuhan 430073 China

Reciprocating friction and wear performances of pure ultrahigh-molecular-weight polyethylenes (UHMWPEs) with molecular weights (MWs) of 2, 3, 5, and 9 million and their modified UHMWPEs with 15 wt.% Cu(II) chelate of bissalicylaldehyde-ethylenediamine (add1) against titanium alloy (Ti6Al4V) were investigated under boundary lubrication with 25 vol.% calf serum deionized water solution. Differential scanning calorimetry (DSC) of purchased UHMWPE powders was performed. The enthalpy changed with an increase in MW. UH300 had the lowest temperature of an extrapolated peak and the best peak symmetry in DSC analysis. The friction coefficient curves of molded pure and modified UHMWPEs/Ti6Al4V were compared, and the volume loss by the wear of polymers was measured. 3D topographies of the worn surfaces of polymers and images of the worn surfaces of polymers and titanium alloy against polymers were analyzed by confocal white light microscopy and scanning electron microscopy, respectively. Results showed that the influence of MW of UHMWPE was obvious on the friction and wear characteristics of pure UHMWPEs and 15% add1 UHMWPEs. An MW of 3 million was the best to reduce the friction of rubbing pairs, enhance the wear resistance of pure UHMWPEs and 15% add1-UHMWPEs, and improve the mating properties of Ti6Al4V.

关键词： ultrahigh-molecular-weight polyethylene reciprocating friction and wear boundary lubrication molecular weight Cu(Ⅱ) chelate of bissalicylaldehyde-ethylenediamine

On the Fourth Power Moment of Fourier Coefficients of Cusp Form

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

Acta Mathematica Sinica,English Series 2018年第6期34卷 1050-1058页

作者： Jin Jiang LI Pan Wang WANG min ZHANG Department of Mathematics China University of Mining and Technology

Let a（n） be the Fourier coefficients of a holomorphic cusp form of weight κ = 2n ≥ 12 for the full modular group and A（x） =∑n≤xa（n）.In this paper, we establish an asymptotic formula of tile fourth power moment of A（x） and prove that ∫1^TA^4（x）dx=3/64κπ^4s4;2（a^~）T^2κ＋O（T^2a-δ4＋t） with δ4 = 1/8, which improves the previous result.

关键词： Cusp form Fourier coefficient mean value asymptotic formula

A novel method for discovering spatio-temporal clusters of different sizes, shapes, and densities in the presence of noise

在线全文

学校读者我要写书评

暂无评论

International Journal of Digital Earth 2014年第2期7卷 138-157页

作者： Qiliang Liu min Deng Jiantao Bi Wentao Yang Department of Surveying and Geo-informatics Central South UniversityChangshaChina Department of Land Surveying and Geo-Informatics Hong Kong Polytechnic UniversityHong Kong Center for Earth Observation and Digital Earth Chinese Academy of SciencesBeijingChina

The discovery of spatio-temporal clusters in complex spatio-temporal data-sets has been a challenging issue in the domain of spatio-temporal data mining and knowledge *** this paper,a novel spatio-temporal clustering method based on spatio-temporal shared nearest neighbors(STSNN)is proposed to detect spatio-temporal clusters of different sizes,shapes,and densities in spatiotemporal databases with a large amount of *** concepts of windowed distance and shared nearest neighbor are utilized to define a novel spatiotemporal density for a spatio-temporal entity with definite mathematical ***,the density-based clustering strategy is employed to uncover spatio-temporal *** spatio-temporal clustering algorithm developed in this paper is easily implemented and less sensitive to density variation among spatio-temporal *** are undertaken on several simulated datasets to demonstrate the effectiveness and advantage of the STSNN ***,the real-world applications on two seismic databases show that the STSNN algorithm has the ability to uncover foreshocks and aftershocks effectively.

关键词： spatio-temporal clustering shared nearest neighbor windowed distance spatio-temporal density foreshocks and aftershocks data mining Digital Earth geo-spatial science geospatial data integration

Analysis of Microstructure Characteristics and Precipitation Behavior of Automobile Beam Steels Produced by Compact Strip Production

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

Journal of Iron and Steel Research International 2010年第3期17卷 56-61页

作者： ZHAO Zheng-zhi LIU Jie ZHAO Ai-min Metallurgical Engineering Research Institute University of Science and Technology Beijing Beijing 100083 China Shougang Research Institute of Technology Beijing 100041 China School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

The microstructure characteristics and precipitation behavior of automobile beam steels produced by compact strip production （CSP） were investigated by use of scanning electron microscopy （SEM） transmission electron microscopy （TEM） and X-ray energy dispersive spectroscopy. The result shows that the final microstructure is mainly composed of polygonal ferrite and small amount of pearlite, and the average ferrite grain size is about 3-6μm. Small amount addition Ti to aluminium-killed steel can help to refine the microstructure and improve the mechanical properties. A large number of fine precipitates have been observed in automobile beam steels. The mean particle size is about 10-30 nm. Remarkable strengthening and grain refinement can be obtained by these nano-particles.

关键词： compact strip production microstructure precipitation behavior