Effect of a direct magnetic field on the interfacial microstructure between molten aluminium and solid iron

Many processing techniques, such as hot dip aluminizing, bimetal formation, liquid metal corrosion, cementing, welding and diffusion bonding, are basically dependent on interfacial reactions [1-3]. It is therefore important to investigate the formation and growth of intermetallic layers at the interface. There have been several studies carried out to examine chemical compositions and growth kinetics of intermetallic layers in the Al-Fe system [4-9]. Most authors have come to an agreement that…     

铸造车间树脂砂有害气体祛除的研究

在铸造车间内,针对局部通风系统不能有效消除有机污染物的特点,介绍一种新型铸造生产净化装置。它采用臭氧的超臭氧化技术,净化车间内由酚醛树脂所带来的污染物,并利用臭氧发生器改进吸收塔。结果表明：空气净化装置采用臭氧发生器的在净化系统中可以高效净化和祛除车间空气中的甲醛,酚,甲醇,碳氢化合物等有机物质。     

腔内流动对储罐机械清洗泵性能影响研究

选取储罐机械清洗成套设备中的清洗泵作为研究对象,并且流场的确定包含了前后腔区域的整体流场,研究结果更加准确。通过Pro/E建立叶轮、蜗壳以及前后腔耦合的三维计算模型,利用FLUENT计算清洗泵流场,研究清洗泵三维湍流流场的流动规律,揭示内部流场的流动特征,着重分析流场中的前后腔内的流体流动对泵的流量和扬程等外特性的影响。对比包含腔体与不包含腔体的两种计算模型的数值计算结果之间的差异,根据数值计算的流动信息,分析外特性发生变化的原因。     

Modeling and optimizing of steel and mushy Al-28Pb alloy bonding

1　ＩＮＴＲＯＤＵＣＴＩＯＮＡｔｐｒｅｓｅｎｔ,ｔｈｅｔｙｐｉｃａｌｍａｔｅｒｉａｌｏｆｎｅｏｔｙｐｅｂｅａｒ ｉｎｇｉｓｓｔｅｅｌ ｂａｃｋｅｄＡｌ 2 0Ｓｎａｌｌｏｙｂｏｎｄｉｎｇ ｐｌａｔｅ[1 ] .Ｆｏｒｓｔｅｅｌ ｂａｃｋｅｄＡｌ 2 0Ｓｎａｌｌｏｙｂｏｎｄｉｎｇｐｌａｔｅ ,ｓｔｅｅｌｂａｃｋｈａｓｈｉｇｈｓｔｒｅｎｇｔｈｗｈｉｃｈｃａｎｂｅａｒｔｈｅｅｘｔｅｒｎａｌｌｏａｄ ,ａｎｄＡｌ 2 0ＳｎａｌｌｏｙｌａｙｅｒｉｓａｌｕｂｒｉｃａｔｉｎｇｏｎｅｉｎｗｈｉｃｈＡｌｓｕｂｓｔｒａｔｅｈａｓｅｘｃｅｌ…     

基于有限元技术实现工程机械料斗的结构分析与优化

料斗是一种薄壁类型的力学模型,利用一般材料力学校核方法是难以精确校核计算。因此本文采用有限元技术对一款料斗进行了精确的结构分析,发现其具有强度和刚度不足的问题。通过针对性的改进措施实现结构优化,并再次通过有限元分析验证以确保产品的安全性能。     

四辊轧机轧辊弹性变形解析模块的开发

采用影响函数方法开发了四辊轧机轧辊弹性变形解析模块，完善了辊间压扁和工作辊压扁影响函数计算模型，克服了轧辊压扁影响函数计算过程浮点数被零除的缺陷，提出了平滑指数和收敛指标取值的处理方法，有效地解决了四辊轧机辊系弹性变形计算精度及收敛问题。该模块适应于普通四辊轧机、PC轧机和CVC轧机轧辊弹性变形计算，为热轧带钢板形控制提供了解析工具。     

基于Logistic回归模型的TC4零件激光熔化沉积工艺参数分析（英文）

In this paper, laser melting deposition(LMD), a new advanced manufacture technology. While manufacturing a metal part by LMD process, if we could control the energy distribution in internal different areas such as cladding layer or that between cladding layer and the substrate with optimal process parameters, the probability of internal defects of parts can be reduced, and the mechanical properties of parts will be greatly improved. To address the problem that whether the part made by LMD has internal defects, in this paper we designed the orthogonal rotation experiments through selecting different process parameters. Then a Logistic Regression model was built based on the experiments data. The calculation result of the regression model was in good agreement with the result of authentication test. Therefore, this Logistic Regression model has important reference for selecting LMD process parameters.     

CVT中阻尼器的研究

阐述了电容式电压互感器的各种阻尼器的优缺点,并对速饱和阻尼器设计进行了详述,提出了CVT设计速饱和阻尼器应注意的事项。     

Changes in human immunodeficiency virus type 1 envelope glycoproteins responsible for the pathogenicity of a multiply passaged simian-human immunodeficiency virus (SHIV-HXBc2)

In vivo passage of a poorly replicating, nonpathogenic simian-human immunodeficiency virus (SHIV-HXBc2) generated an efficiently replicating virus, KU-1, that caused rapid CD4(+) T-lymphocyte depletion and AIDS-like illness in monkeys (S. V. Joag, Z. Li, L. Foresman, E. B. Stephens, L.-J. Zhao, I. Adany, D. M. Pinson, H. M. McClure, and O. Narayan, J. Virol. 70:3189-3197, 1996). The env gene of the KU-1 virus was used to create a molecularly cloned virus, SHIV-HXBc2P 3.2, that differed from a nonpathogenic SHIV-HXBc2 virus in only 12 envelope glycoprotein residues. SHIV-HXBc2P 3.2 replicated efficiently and caused rapid and persistent CD4(+) T-lymphocyte depletion in inoculated rhesus macaques. Compared with the envelope glycoproteins of the parental SHIV-HXBc2, the SHIV-HXBc2P 3.2 envelope glycoproteins supported more efficient infection of rhesus monkey peripheral blood mononuclear cells. Both the parental SHIV-HXBc2 and the pathogenic SHIV-HXBc2P 3.2 used CXCR4 but none of the other seven transmembrane segment receptors tested as a second receptor. Compared with the parental virus, viruses with the SHIV-HXBc2P 3.2 envelope glycoproteins were more resistant to neutralization by soluble CD4 and antibodies. Thus, changes in the envelope glycoproteins account for the ability of the passaged virus to deplete CD4(+) T lymphocytes rapidly and specify increased replicative capacity and resistance to neutralization.     

Effects of non-conservative changes to tyrosine 76, a key DNA binding residue of DNase I, on phosphodiester bond cleavage and DNA hydrolysis selectivity

Non-conservative changes, consisting of Y76E, Y76L, Y76Q and Y76W, have been made to tyrosine 76, one of the key DNA binding residues in DNase I. Normally Y76 inserts into the minor groove of DNA and makes an unusual, hydrophobic, stacking interaction with one of the sugars. All four mutants bind to DNA more tightly than the wild type, but cut it more slowly as assessed by Kunitz assays. This gives a rather small decrease in the specificity constants (Vmax/K(m)) for the hydrolysis of DNA, which is roughly paralleled by the loss of activity towards the non-DNA small chromophoric substrate, thymidine-3',5'-di(p- nitrophenyl)phosphate. These non-conservative mutants, therefore, show different behaviour to Y76A and Y76G, studied previously [Doherty A.J., Worrall A.F. and Connolly B.A. (1995) J: Mol. Biol., 251, 366-377]. These two mutants both bind to and cut DNA poorly, resulting in large decreases in Vmax/K(m) values. However, they showed little reduction in rates with the chromophoric substrate. It is likely that the altered side chains in the non-conservative mutants are still able to interact productively with the DNA and contribute to the observed DNA distortion that is essential for efficient catalysis. However, these mutations disrupt the active site, most probably by interference with the hydrogen bonded Y76-E78-H134 triad. H134 is a critical hydrolytic residue of DNase I that is essential for catalysis. The DNA cleavage selectivity of the Y76E, Y76L, Y76Q and Y76W mutants were little altered as compared with the wild-type enzyme as measured using the cutting patterns of a 160 base-pair Escherichia coli Tyr T promoter DNA fragment. This confirms earlier observations, with Y76F, Y76A and Y76G, that showed that this tyrosine has little role in DNA cleavage specificity.