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排序方式: 共有6351条查询结果,搜索用时 93 毫秒
81.
Di-feng Wu) Shu-sen Cheng) Zi-jian Cheng) ) School of Metallurgical Ecological Engineering University of Science Technology Beijing Beijing China ) Steelmaking Plant Jiuquan Iron Steel Co. Ltd. Jiayuguan China 《北京科技大学学报(英文版)》2009,16(1):25-31
The key to reduce shell breakout in the continuous casting process is to control shell thickness in the mold.A numerical simulation on the turbulent flow and heat transfer coupled with solidification in the slab mold using the volume of fluid (VOF) model and the enthalpy-porosity scheme was conducted and the emphasis was put upon the flow effect on the shell thickness profiles in longitudinal and transverse directions.The results show that the jet acts a stronger impingement on the shell of narrow face,which causes a zero-increase of shell thickness in a certain range near the impingement point.The thinnest shell on the slab cross-section locates primarily in the center of the narrow face,and secondly near the comer of the wide face.Nozzle optimization can obviously increase the shell thickness and make it more uniform. 相似文献
82.
Ji-ping Chen) Yong-lin Kang ) Ying-min Hao) Guang-ming Liu) Ai-ming Xiong) ) School of Materials Science Engineering University of Science Technology Beijing Beijing China ) The State Key Laboratory for Advanced Metals Materials China ) Steel Research Institute of Shougang Beijing China 《北京科技大学学报(英文版)》2009,16(5):540-548
A Ti+Nb bearing ultra-low carbon bake hardening sheet steel hot-rolled in the conventional austenite region and in the ferrite region with lubrication was experimentally studied.Subsequent cold rolling and continuous annealing processes were also conducted.The results show that microstructures of ultra-low carbon bake hardening hot strips at room temperature are basically irregular polygonal ferrites.The yield strength,ultimate tensile strength,n value,and r value of the No.2 specimen hot-rolled in the ferr... 相似文献
83.
Ultralight X-type lattice sandwich structure (I): Concept,fabrication and experimental characterization 总被引:1,自引:1,他引:0
ZHANG QianCheng HAN YunJie CHEN ChangQing & LU TianJian State Key Laboratory for Mechanical Behavior of Materials School of Material Science Engineering Xi’an Jiaotong University Xi’an China MOE Key Laboratory for Strength Vibration School of Aerospace Department of Engineering Mechanics AML Tsinghua University Beijing 《中国科学E辑(英文版)》2009,52(8):2147-2154
A new type of ultra-lightweight metallic lattice structure (named as the X-type structure) is reported. This periodic structure
was formed by two groups of staggered struts in the traditional pyramid structure, and fabricated by folding expanded metal
sheet along rows of offset nodes and then brazing the folded structure (as the core) with top and bottom facesheets to form
sandwich panels. The out-of-plane compressive and shear properties of the X-type lattice sandwich structure were investigated
experimentally and compared to those of the sandwich having a pyramidal truss core. It is found that the formation of the
2-dimensional staggered nodes can effectively make the X-type structure more resistant to inelastic and plastic buckling under
both compression and shear loading than the pyramidal lattice truss. Obtained results show that the compressive and shear
peak strengths of the X-type lattice structure are about 30% higher than those of the pyramidal lattice truss having the same
relative density.
Supported by the National Basic Research Program of China (“973” Project) (Grant No. 2006CB601202), the National Natural Science
Foundation of China (Grant Nos. 10632060,10825210), the National “111” Project of China (Grant No. B06024) and the National
High-Tech Research and Development Program of China (“863” Project) (Grant No. 2006AA03Z519) 相似文献
84.
XU Bin WU ZhenSen WU Jian & XUE Kun School of Science Xidian University Xi’an China State Key Laboratory of Electromagnetic Environment China Research Institute of Radiowave Propagation Beijing 《中国科学E辑(英文版)》2009,52(4):1112-1116
The electron velocity distribution function and the incoherent scatter spectra during ionospheric heating in low ionosphere
region are presented with consideration of the elastic collision between electrons and neural particles and the excitation
of rotation energy level. The effects of pump frequency and electric fields on the spectra are discussed. With the increase
of electric field, the non-Maxwellian feature is enhanced, and with the increase of heating frequency, the non-Maxwellian
feature is weakened. The non-Maxwellian factor will bring a large error in ionosphere parameters, which must be considered
in the inversion.
Supported by the National Natural Science Foundation of China (Grant No. 40310223), the National Key Laboratory of Electromagnetic
Environment (LEME), and National Key Technologies R&D Program of China (Grant No. 2006BAB18B06) 相似文献
85.
GUAN Ping LIU ChangChun & Lü HeXiang College of Architectural Engineering Dalian University Dalian China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 《中国科学E辑(英文版)》2009,52(5):1248-1253
The traditional unified viscoplasticity constitutive model can be only applied to metal materials. The study of the unified
constitutive theory for metal materials has discovered the correlation between the classical plasticity theory and the unified
viscoplasticity constitutive model, thus leading to the concepts of the classic plastic potential and yield surface in the
unified constitutive model. Moreover, this research has given the continuous expression of the classical plastic multiplier
and presented the corresponding constructive method, which extends its physical significance and lays down a good foundation
for the application of the unified constitutive theory to the material analysis in more fields. This paper also introduces
the unified constitutive model for metal materials and geo-materials. The numerical simulation indicates that the construction
should be both reasonable and practical.
Supported by the National Natural Science Foundation of China (Grant No. 90410012) 相似文献
86.
Research on indoor experimentation of range SAL imaging system 总被引:1,自引:0,他引:1
GUO Liang XING MengDao ZHANG Long TANG Yu & BAO Zheng State Key Laboratory of Radar Signal Processing Xidian University Xi’an China Xi’an Polytechnic University Xi’an 《中国科学E辑(英文版)》2009,52(10):3098-3104
By means of advantages of both SAR and lidar, the combination of the techniques of (inverse) synthetic aperture and lidar makes it possible to obtain high resolution 2-D image. In this paper, an indoor experimental system of inverse synthetic aperture lidar imaging is given and a processing approach is presented. The given system is in the mode of lidar system with separated receiver and transmitter, which can effectively eliminate the jamming from the lens or/and the intersection between two optic fibers. ... 相似文献
87.
YUAN Jing HE ZhengJia ZI YanYang & LIU Han State Key Laboratory for Manufacturing Systems Engineering School of Mechanical Engineering Xi’an Jiaotong University Xi’an China Shanghai Baosteel Industry Inspection Corporation Baosteel Group Corporation Shanghai 《中国科学E辑(英文版)》2009,52(10):2801-2809
Fault diagnosis of rolling mills, especially the main drive gearbox, is of great importance to the high quality products and long-term safe operation. However, the useful fault information is usually submerged in heavy background noise under the severe condition. Thereby, a novel method based on multiwavelet sliding window neighboring coefficient denoising and optimal blind deconvolution is proposed for gearbox fault diagnosis in rolling mills. The emerging multiwavelets can seize the important signal proce... 相似文献
88.
为揭示车辆荷载作用下公路隧道复合式路面结构力学响应,依托实体工程开展现场试验,采用有限元软件建立三维有限元模型并进行模型精度验证,分析车辆荷载、路面结构尺寸以及材料参数对有仰拱和无仰拱的隧道复合式路面动力响应的影响。结果表明:隧道复合式路面混凝土面层最不利荷载位置为纵缝边缘中部,轴载和混凝土面层厚度对混凝土面层板板底拉应力、沥青层层底拉应变以及层间剪应力的影响较大,水平荷载和混凝土面层模量对各项动力响应指标的影响较小;普通复合式路面沥青面层动力响应隧道路面相差较小,混凝土面层板底拉应力分别为有仰拱的 5.99倍、无仰拱的 1.74倍。研究结果可为隧道复合式路面结构设计方法研究提供参考。 相似文献
89.
传统的位移监测方案通常以对单一点位的监测数据为基础。在对测量结果的评估中,也只考虑单一点位的数据变化情况,而忽略各监测点间监测数据的空间效应。以南京地区某边坡的自动化位移监测数据为依托,通过引入普通克里金(O-K)空间插值技术,运用 Matlab平台自主研发了边坡位移时空演化规律分析模块,实现了对目标边坡位移时空演化过程的分析。该模块可以将位移插值误差控制在 5%范围之内,在部分监测数据缺失的情况下,解决了基于实测数据的边坡位移时空演化规律分析问题。 相似文献
90.
边坡岩土与支护结构长期耐久性能弱化对边坡变形及安全稳定性产生影响,开展定量化研究以指导边坡耐久性设计和评估分析具有重要意义。以锚喷支护边坡为例,通过几何相似比为 1∶50的模型试验探讨不同弱化程度的边坡受耐久性因素影响的效果。首先基于正交设计试验确定模型边坡岩层以及喷射混凝土层相似材料配合比,进一步设计单槽尺寸 0.75m×1.5m×1.1m的双模型槽对比试验系统,模拟正常工况,以及降雨(7d)+风干(7d)、酸雨/盐雾(7d)+风干(7d)等边坡耐久性影响工况,基于 DIC仪器测试不同工况条件下坡顶分次堆载对坡面位移变化影响。研究表明:支护结构材料耐久性能退化对边坡变形位移产生一定量影响,可为长期复杂环境影响下的边坡耐久性稳定性设计评估提供参照。 相似文献