检索结果-南通市图书馆

TESTING SERIAL CORRELATION IN SEMIPARAMETRIC VARYING COEFFICIENT PARTIALLY LINEAR ERRORS-IN-VARIABLES MODEL

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2009年第3期22卷 483-494页

作者： Xuemei HU Feng LIU Zhizhong WANG Mathematics and statistics College Chongqing Technology and Business University Chongqing 400067 China. School of Mathematics and Physics Chongqing InsLitu$e of Technology Chongqing 400050 China. School of Mathematics and Computing technology Central South University Changsha 410075 China.

The authors propose a V_(N,p) test statistic for testing finite-order serial correlation in asemiparametric varying coefficient partially linear errors-in-variables *** test statistic is shownto have asymptotic normal distribution under the null hypothesis of no serial *** MonteCarlo experiments are conducted to examine the finite sample performance of the proposed V_(N,p) *** results confirm that the proposed test performs satisfactorily in estimated sizeand power.

关键词： Asymptotic normality local linear regression measurement error modified profile leastsquares estimation partial linear model testing serial correlation varying coefficient model.

THE GENERALIZED REFLEXIVE SOLUTION FOR A CLASS OF MATRIX EQUATIONS (AX-B,XC=D)

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2008年第1期28卷 185-193页

作者：李范良胡锡炎张磊 institute of Mathematics and Physics School of SciencesCentral South University of Forestry and Technology College of Mathematics and Econometrics Hunan University

In this article, the generalized reflexive solution of matrix equations （AX = B, XC = D） is considered. With special properties of generalized reflexive matrices, the necessary and sufficient conditions for the solvability and the general expression of the solution are obtained. Moreover, the related optimal approximation problem to a given matrix over the solution set is solved.

关键词： Matrix equations generalized reflexive matrix optimal approximation

Finite Element Analysis of Die Geometry and Process Conditions Effects on Equal Channel Angular Extrusion for β-Titanium Alloy

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10期19卷 54-58页

作者： SI Jia-yong1,2. GAO Fan3, ZHANG Ji3 (1. State Key Laboratory of Powder Metallurgy, Central south university, {2. 410083, Hunan, china.2. College of Mechanical and Electrical Engineering, Central south university of forestry and technology, changsha 410004, Hunan, china.3. High Temperature Material Research Division, Central Iron and Steel Research institute, Beijing 100081, china. [a] State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 Hunan China [b] College of Mechanical and Electrical Engineering Central South University of Forestry and Technology Changsha 410004 Hunan China [c] High Temperature Material Research Division Central Iron and Steel Research Institute Beijing 100081 China

The finite element analysis was applied to evaluate the respective influences of die geometry and process conditions on plastic strain distribution for β-titanium (Ti-13V11Cr3Al) alloy during the equal channel angular extrusion (ECAE). It was found that optimum equal channel angular extrusion die geometry is strongly material dependent. Optimal strain homogeneity in the Ti-13V11Cr3Al alloy may be achieved at r (inner radius)=5 mm, R (outer radius)=3 mm. The equivalent plastic strain increases with increasing friction coefficient. And the better homogeneity of the equivalent plastic strain distribution can be achieved when friction coefficient value is lower. The faster the ram speed is, the lower the homogeneity of the equivalent plastic strain distribution is and the influence is slight. The back-pressure does not help to improve the plastic strain homogeneity, and the increasing temperature has a slightly favourable effect on the plastic strain homogeneity between 400 and 600 ℃.

关键词： equal channel angular extrusion finite element analysis die geometry β-titanium

Molecular dynamics simulation of kink in 〈100〉 edge dislocation in body centred cubic iron

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2007年第16期52卷 2291-2296页

作者： CHEN LiQun1,2.WANG ChongYu2.3,4 & YU Tao2.1 College of Sciences,Central south university of {2. & technology,changsha 410004,china.2.Central Iron and Steel Research institute,Beijing 100081,china.3 Department of Physics,Tsinghua university,Beijing 100084,china.4 International Center for Materials Physics,Chinese Academy of Sciences,Shenyang 110016,china College of Sciences Central South University of Forestry and Technology Changsha 410004 China

Using the molecular dynamics method,we have constructed two kink models corresponding to the 〈100〉{010} and 〈100〉{011} edge dislocations (EDs) in body centred cubic (bcc) Fe. It is found that the geometric structure of a kink depends on the type of edge dislocation and the structural energies of the atoms sites in the dislocation core region. The formation energies,migration energies and widths of the kinks in different types of EDs are calculated. The results show that formation and migration of the kink in the 〈100〉{010} edge dislocation are difficult. The 〈100〉{011} edge dislocation moves primarily through kink nucleation,rather than kink migration.

关键词：分子动力学边缘位移铁纽结结构

Energetics and electronic structure of refractory elements in the dislocation of NiAl

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2012年第8期21卷 402-408页

作者：陈丽群彭小方于涛 College of Sciences Central South University of Forestry&Technology Central Iron and Steel Research institute

Using DMol and the discrete variational method within the framework of the density functional theory, we study the alloying effects of Nb, Ti, and V in the [100] （010） edge dislocation core of NiAl. We find that when Nb （Ti, V） is substituted for Al in the center-Al, the binding energy of the system reduces 3.00 eV （2.98 eV, 2.66 eV）. When Nb （Ti, V） is substituted for Ni in the center-Ni, the binding energy of the system reduces only 0.47 eV （0.16 eV, 0.09 eV）. This shows that Nb （Ti, V） exhibits a strong Al site preference, which agrees with the experimental and other theoretical results. The analyses of the charge distribution, the interatomic energy and the partial density of states show that some charge accumulations appear between the impurity atom and Ni atoms, and the strong bonding states are formed between impurity atom and neighbouring host atoms due mainly to the hybridization of 4d5s（3d4s） orbitals of impurity atoms and 3d4s4p orbitals of host Ni atoms. The impurity induces a strong pinning effect on the [100] （010） edge dislocation motion in NiAl, which is related to the mechanical properties of the NiAl alloy.

关键词： electronic structure dislocation intermetallic compounds impurity

The effect of hydrogen on the electronic structure of kink in bcc iron

在线全文

学校读者我要写书评

暂无评论

Science china.Technological Sciences) 2009年第5期52卷 1212-1218页

作者： CHEN LiQun1,QIU ZhengChen1,YU Tao2.& WANG ChongYu2.3,4 1 College of Sciences,Central south university of {2. and technology,changsha 410004,china.2.Central Iron and Steel Research institute,Beijing 100081,china.3 Department of Physics,Tsinghua university,Beijing 100084,china.4 International Center for Materials Physics,Chinese Academy of Sciences,Shenyang 110016,china 1. College of Sciences Central South University of Forestry and Technology Changsha 410004 China 2. Central Iron and Steel Research institute Beijing 100081 China 3. Department of Physics Tsinghua University Beijing 100084 China 4. International Center for Materials Physics Chinese Academy of Sciences Shenyang 110016 China

The electronic structures of kinks in the [100](010) and 1/2.111](-110) edge dislocations in bcc iron containing hydrogen are investigated by means of the first-principles DMol method and the discrete variational *** effects of hydrogen on the kinks are *** results show that hydro-gen forms weak bonding states with its neighboring host atoms,and since hydrogen draws charge from its neighboring host atoms,the interactions between most of the host atoms are weakened com-pared with those of the corresponding atomic pairs in the clean *** indicates that the migration of kink,*** motion of dislocation,is easier in the doping hydrogen kink than in the clean kink,which may be the solid solution softening effect resulting from the impurity hydrogen.

关键词： electronic structure dislocation kink impurity

Phylogenetic diversity of bacteria associated with the marine sponge Agelas robusta from south china.Sea

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2010年第5期29卷 65-73页

作者： SUN We DAI Shikun WANG Guanghua XIE Lianwu JIANG Shumei LI Xiang Key Laboratory of Marine Bio-resources Sustainable Utilization （LMB-CAS） Guangdong Key Laboratory of Marine Materia Mediea （LMMM-GD） South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou 510301 China Graduate university of the Chinese Academy of Sciences Beijing 100049 China Central south university of {2. and technology Changsha 410004 China

It is well known that marine sponges harbor large numbers of bacteria,some of which have been proved to be *** diversity of bacteria in marine sponges distributed along the coast of south china.Sea has been previously studied but that of bacteria in sponges inhabiting the open sea has been rarely *** this report,the diversity of bacteria associated with the marine sponge Agelas robusta from a remote coral reef in the south china.Sea was documented employing 16S rDNA library construction,amplified ribosomal DNA restriction analysis（ARDRA） and phylogenetic analysis.A total of 32.phylotypes were finally categorized in nine phyla including Cyanobacteria,Proteobacteria,Chloroflexi,Firmicutes,Actinobacteria,Acidobacteria,Planctomycetes,Bacteroidetes and *** dominant phylum was Proteobacteria whereas the dominant genus was Synechococcus in *** spongespecific bacteria were also found in the bacteria population,but the proportion（5 OTUs/32.OTUs） was much lower than other *** study reveals the phylogenetic diversity of bacteria in *** and confirms the presence of some sponge-specific bacteria in the south china.*** the diversity of sponge-associated bacteria in china.assists to exploit the bacteria resources for biotechnology.

关键词： south china.Sea Agelas robusta phylogenetic diversity sponge-specific bacteria

Analysis of Road Base Uniformity via the Deviation of Modulus of Asphalt Mixtures

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan university of technology(Materials Science) 2007年第2期22卷 367-370页

作者：职雨风 Road Research institute South China University of Technology

The modulus deviation of base material calculated from the data of falling weight deflectometer （FWD） was used to evaluate the uniformity of road base so as to reflect the construction quality. Four parameters,the repeatability standard deviation of the data in the same driveway, the reproducibility standard deviation of the data in the different driveway, the consistency statistics value of the data in the different driveway, and the consistency statistics value of the data in the same driveway, were introduced for the construction uniformity analysis. The experimental result shows that the materials modulus calculated from FWD has a highly correlative relationship with the uniformity of road base.

关键词： road base material modulus falling weight deflectometer (FWD)

RESEARCH OF THE MEAN COOK DISTANCE AND THE ROBUST ESTIMATE OF SCALE PARAMETER

在线全文

学校读者我要写书评

暂无评论

Journal of Central south university 1997年第1期9卷 61-64页

作者： Wang Zhizhong(institute of Surverying Engineering and Land Information, Central south{2. of technology, changsha 410083, china. institute of Surverying Engineering and Land Information Central South University of Technology Changsha 410083 China

Based on the principle of statistics and the research results by Zhu Jianjun, the paper establishesthe mean Cook distance of scale parameter and studies its properties. The paper still presents the robust estimate of scale parameter with minimum mean Cook distance and theoretically shows that scale parameter isnot "nuisance parameter" and it determined by the plus weight squared sums of the residuals of observations.A simple numerical example is given.

关键词： Cook distance robust estimate scale parameter