检索结果-南通市图书馆

A Simplified Algorithm of PLS Regression

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Systems science and Systems engineering 2000年第4期10卷 414-419页

作者： ZHU Yun\|hua,\ WANG Hui\|wen,\ YANG Xiang\|long school of Management, beijing university of aeronautics and astronautics, beijing 100083,{3.

This paper describes a simplified algorithm of PLS regression, which can obviously reduce the computation of some parameters and simplify the computing procedure. Moreover, the new optimistic rule of this method provi... 详细信息

关键词： PLS regression simplified algorithm

Effect of Continuous Cooling Conditions on Microstructure and Mechanical Properties of High Carbon Steel Rod

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and materials 1999年第4期13卷 277-280页

作者： QingWu Cai1 Yumei Pu2 Di Tang1 Zhenli Mi1 Yuzhou Zhu2(l material science and engineering {3., university of science and Technology beijing, beijing 100083, china2 Maanshan iron and Steel Co. Ltd., Maanshan 243.00, china) Univ Sci & Technol beijing Sch Mat Sci & Engn Beijing 100083 Peoples R China Maanshan Iron & Steel Co Ltd Maanshan 243000 Peoples R China

The effect of cooling rate and austenitizing condition on the mechanical properties of high carbon steel (SWRH82B) has beeninvestigated. Specimens were made of high carbon steel rod and heat-treated by Gleeble-2000 to produce a wide variation in prior austenite size. Different cooling rates were carried out, and then pearlite interlaminar spacing and mechanical properties were measured andtested respectively. According to the results, it could be found that under the continuous cooling with the increase of cooling rate, tensilestrength greatly increases and reduction in area exhibits a slightly increase for an equivalent value of prior austenite grain size. Whenprior austenite size increases, reduction in area decreases, and tensile strength increases slightly for an equivalent value of pearlite interlaminar spacing. It is concluded that prior austenite size primarily controls ductility and pearlite interlaminar spacing controls tensilestrength. Mathematical formulae are given for these relations.

关键词： high carbon steel continuous cooling, interlaminar spacing ofpearlite, austenite grain size.

MICROSTRUCTURE EVALUATION OF SEMI-SOLID STEEL materialS IN ROLLING PROCESS AND THE RESULTING MECHANICAL PROPERTIES

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2001年第5期14卷 347-351页

作者： R.B. Song, Y.L. Kang, J.L. Sun, A.M. Zhao and W.M. Mao school of materials science & {3., university of science & Technology beijing, beijing 100083,china Sch. of Mat. Sci. and Eng. Univ. of Sci. and Technol. Beijing Beijing 100083 China

The experimental study on the familiar 60Si2Mn and 1Cr18Ni9Ti materials rolled in the semi-solid state was carried out. Experimental results show that the segregation of liquid occurs when the semi-solid slurry is rolled, which influences the microstructure and mechanics performance of workpiece under room temperature. The globular solid particles can not present plastic deformation unless high solid fraction. At the same time, the mechanics property of workpiece is pretty good while the semi-solid slurry of 1Cr18Ni9Ti material is rolled by a pass and no other treatment.

关键词： Mechanical properties Microstructure Performance Rolling

Characterization of the negative thermal expansion material Zr_(1-x)Hf_xW_2O_8

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2003年第2期22卷 107-111页

作者： SHENRong WANGCong WANGTianmin DONGCheng CHENHong LIANGJingkui schoolofMatgfialsandMetallurgicalengineering KunmingUniversityofScienceandTechnologyKunming650093China CenterofmaterialPhysicsandChemistry SchoolofSciencesBeijingUniversityofAeronauticsandAstronauticsBeijing100083China InstituteofPhysics ChineseAcademyofScienceBeijing100080China

The oxide ZrW_2O_8 displays unusual property of isotropic negative thermalexpansion in a large wide temperature range, which makes it have a number of important potentialapplications. The cubic Zr_(1-x)Hf_xW_2O_8 (x velence 0,0.3. 0.5, 0.7, and 1.0) were synthesized bystandard solid state reaction technique. The high and low temperature X-ray diffraction analysisindicate that the substitution of the Hf^(4+) for Zr^(4+) only leads to reducing the latticeconstants, and the changes of negative thermal expansion coefficients are not obvious. The linearexpansion coefficients of Zr_(1-x)Hf_xW_2O_8 (x velence 0,0.3. 0.5, 0.7, and 1.0) are about -6 X 10^(-6) K^(-1) in the temperature range of 298 to 973.K, while that of Zr_(0.5)Hf_(0.5)W_2O_8 is -9.6X 10^(-6) K_(-1) from 83.to 298 K. The phase transition temperatures from alpha-ZrW_2O_8 tobeta-ZrW_2O_8 structure were also determined by X-ray diffraction method. Thermogravimetric analysis(TGA) exhibits that Zr_(1-x)Hf_xW_2O_8 is not hygroscopic in air.

关键词： inorganic non-metallic materials negative thermal expansion X-raydiffraction Zr_(1-x)Hf_xW_2O_8

Crystallographic Texture of MgO and its effect on the growth of BaTiO3.thin films by RF sputtering

在线全文

学校读者我要写书评

暂无评论

Crystallographic Texture of MgO and its effect on the growth...

Physical analysis and numerical simulation for the dynamic behaviour of vehicles in pitching oscillations or rocking motions

International Conference on Superconducting materials(ICSM 2006)

作者： Liang Qiao and Xiaofang Bi school of material science and {3., beijing university of aeronautics and astronautics, beijing 100083, china

In this work, MgO thin films were prepared by rf magnetron sputtering technique on two different substrates of Si (100) wafers and amorphous glasses. The influence of different deposition conditions such as substrate temperature, Ar pressure, film thicknesses on the crystal structure of MgO thin films were studied. BaTiO3.ferroelectric thin films were subsequently deposited on the MgO films. The XRD results showed that the orientation of MgO films was dependent greatly on the substrate temperature. A highly (100) oriented MgO thin films were obtained at the temperature of 800℃. The crystallographic texture has been deteriorated rapidly as the argon pressure decreased to 1.0 Pa. It has been also found that the film thickness has a great influence on the film orientation. High substrate temperature, high argon pressure and a certain thickness appear to be favorable for formation of a good texture for the MgO films. The structure and microstructure of the BaTiO3.films were various both with deposition conditions and with the crystallographic texture of the MgO. A highly (001) oriented ferroelectric BTO film was obtained on the MgO films with an optimized deposition conditions.

关键词： MgO films BTO films highly-orientation RF sputtering

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

science china(Technological sciences) 2007年第4期50卷 385-401页

作者： ZHANG HanXin1,2,3. ZHANG Zhao1,3. YUAN XianXu1,2, LIU Wei1, XIE YuFei1,2 & YE YouDa1,2 1 china Aerodynamics Research and Development Center, Mianyang 621000, china 2 National Laboratory for Computational Fluid Dynamics, beijing university of aeronautics and astronautics,{3., china 3.school of Aerospace, Tsinghua university, beijing 100084, china 1. china Aerodynamics Research and Development Center Mianyan 621000 China 2. National Laboratory for Computational Fluid Dynamics Beijing University of Aeronautics and Astronautics Beijing 100083 China 3. school of Aerospace Tsinghua University Beijing 100084 China

Analytical methods of nonlinear dynamics and numerical simulations for the cou-pling equations of Navier-Stokes and flight mechanics are used to study the dynamic behaviour of pitching motions of reentry capsules with the variation of Mach number, and rocking motions of swept wings with the variation of angle of attack. Conditions under which the dynamic instability, Hopf bifurcation and saddle-node bifurcation occur are obtained. The node-saddle-node topological structure in the phase portrait, i.e. the state of bi-attractors (attracting basins) is described. The evolving process of dynamic behaviour and flow fields are given. The theories are compared with some numerical simulations conducted by the authors. Besides, some verifiable experi-mental results are cited. The agreement between them is very well.

关键词： physical analysis numerical simulation pitching oscillation rocking motion bifurcation

An Improved Distortion Operator for Insurance Risks

在线全文

学校读者我要写书评

暂无评论

Systems science and Systems engineering 2002年第3期11卷 296-301页

作者： GAO Jian-wei, QIU Wan-huaschool of Economics & Management, beijing university of aeronautics and astronautics, beijing 100083,{3. school of Economics & Management Beijing University of Aeronautics and Astronautics Beijing 100083 China

This paper reviews the distortion function approach developed in the actuarial literature for insurance risks. The main aim of this paper is to derive an extensive distortion operator, and to propose a new premium principle based on this extensive distortion operator. Furthermore, the non-robustness of general distortion operator is also discussed. Examples are provided using Bernoulli, Pareto, Lognormal and Gamma distribution assumptions.

关键词： proportional hazards transform distortion operator non-robustness

Ultralight X-type lattice sandwich structure (Ⅱ):Micromechanics modeling and finite element analysis

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2009年第9期52卷 2670-2680页

作者： ZHANG QianCheng1,CHEN AiPing 2,CHEN ChangQing2,3.& LU TianJian2 1 State Key Laboratory for Mechanical Behavior of materials,school of material {3. and engineering,Xi’an Jiaotong university,Xi’an 710049,china 2 MOE Key Laboratory for Strength and Vibration,school of Aerospace,Xi’an Jiaotong university,Xi’an 710049,china 3.Department of engineering Mechanics,AML,Tsinghua university,beijing 100084,china State Key Laboratory for Mechanical Behavior of materials School of Material Science and Engineering Xi’an Jiaotong University Xi’an China MOE Key Laboratory for Strength and Vibration School of Aerospace Xi’an Jiaotong University Xi’an China Department of engineering Mechanics AML Tsinghua University Beijing China

The methods of homogenization and finite elements are employed to predict the effective elastic constants and stress-strain responses of a new type of lattice structure,the X-structure proposed by the authors in a companion paper. It is shown that in most cases the predictions by the equivalent homogenization theory agree well with the experimental and 3.dimensional finite element calculated results. The theoretical and numerical study supports the argument that the X-structure is superior to the pyramid lattice structure in terms of mechanical strength.

关键词： sandwich panel lattice structure equivalent homogenization finite element model

Effect of particle size on the microstructure and thermal conductivity of Al/diamond composites prepared by spark plasma sintering

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2009年第6期28卷 646-650页

作者： CHU Ke JIA Chengchang LIANG Xuebing CHEN Hui GAO Wenji school of material science and {3. University of Science and Technology Beijing Beijing 100083 China

Spark plasma sintering （SPS） was used to fabricate Al/diamond composites. The influence of diamond particle size on the microstructure and thermal conductivity （TC） of composites was investigated by combining experimental results with model prediction. The results show that both composites with 40 pan particles and 70 μm particles exhibit high density and good TC, and the composite with 70 μm particles indicates an excellent TC of 3.5 W.m^-1.K^-1. Their TCs lay between the theoretical estimated bounds. In contrast, the composite with 100 lain particles demonstrates low density as well as poor TC due to its high porosity and weak interfacial bonding. Its TC is even considerably less than the lower bound of the predicted value. Using larger diamond particles can further enhance thermal conductive performance only based on the premise that highly dense composites of strong interfacial bonding can be obtained.

关键词： metal matrix composites thermal properties sintering particle size