基坑开挖土体切线模量取值的研究

基坑开挖过程中,土体的应力—应变关系不但具有非线性特点,还受应力路径的影响.今对基坑开挖过程中底部和周边土体这两种不同的卸荷应力路径下的应力应变关系进行了区分研究,并分别推导了其切线弹性模量的表达式,用于基坑工程的数值计算,并和常规加荷算法进行比较,结果表明:用本文建立的模量公式计算出的结果更接近工程实际.     

通过乙醇催化燃烧方法制备碳纳米纤维

介绍了一种用于合成碳纳米纤维的既简单又经济的方法。该方法采用乙醇作为碳源，硝酸镍，硝酸铁和氯化铁分别作为催化剂先体，铜薄片作为基底。通过这种方法，获得了大量丰富的产物。采用场发射扫描电子显微镜、透射电子显微镜、拉曼光谱仪和选区电子衍射光谱分析仪对所制备的碳纳米纤维进行了表征。实验结果表明，催化剂的形貌、尺寸对碳纳米纤维的形貌有影响。此外，通过对样品的拉曼表征，样品的石墨化程度被估算。     

聚乙烯醇/壳聚糖共混膜的制备及表征

用溶液共混法制备聚乙烯醇/壳聚糖(PVA/CS)共混膜,对共混膜进行了IR、DSC表征和吸水率、透光率、力学性能等进行测定.结果表明: PVA与CS分子链间在共混膜中有一定的相互作用,相容性好;CS的引入有利于改善PVA的吸水性、透光率和综合力学性能,但热稳定性有所降低.     

Study of the effect of process parameters for n-heptylamine plasma polymerization on final layer properties

Plasma polymerization processes are widely used to chemically functionalize surfaces, which properties can be tuned by different operating variables. In this study, thin amine-containing polymer layers were produced on solid substrates in a custom-made cylindrical plasma polymerization reactor by radio frequency glow discharges of n-heptylamine vapours. Carefully planned experiments were conducted to evaluate the importance of four different process parameters on the chemical composition and thickness of the resulting films. The parameters investigated were: 1) deposition time, 2) power of the glow discharge, 3) distance between the electrodes, and 4) monomer pressure. Possible interactions between these variables were investigated through the use of statistical analyses (i.e., factorial design). This study reveals that n-heptylamine plasma polymer (HApp) layer thickness is influenced by the power of the glow discharge and the deposition time, as assessed by surface plasmon resonance and atomic force microscopy step height measurements. Also, the atomic ratio of nitrogen to carbon atoms on the treated surfaces is mainly influenced by the power of the glow discharge, as revealed by X-ray photoelectron spectroscopy. Quartz crystal microbalance analysis also confirmed that HApp layers are stable when immersed in aqueous solution.     

乙醇催化燃烧法制备Y形碳纳米纤维

介绍了一种既简单又经济的用于制备Y形结构碳纳米纤维的催化燃烧方法。采用乙醇作为碳源,金属盐溶液作为催化剂先体;同时,基底材料采用铜薄片;实验装置采用酒精灯。实验在常温常压下就可以进行,且不需要引入其他辅助生长Y形结的气体。实验结果表明,该方法具有一定的实用性,可实现大量制备;透射电镜分析结果表明,产物中所含Y形结结构丰富,如螺旋结构、非螺旋结构以及螺旋与非螺旋混合的结构。     

Chemical Vapor Deposition of Silicon Carbide Epitaxial Films and Their Defect Characterization

A chemical vapor deposition (CVD) system was designed and fabricated in our laboratory and SiC homo-epitaxial layers were grown in the CVD process using silicon tetrachloride and propane precursors with hydrogen as a carrier gas. The temperature field was generated using numerical modeling. Gas flow rates, temperature field, and the gradients are found to influence the growth rates of the epitaxial layers. Growth rates were found to increase as the temperature increased at high carrier gas flow rate, while at lower carrier gas flow rate, growth rates were observed to decrease as the temperature increased. Based on the equilibrium model, “thermodynamically controlled growth” accounts for the growth rate reduction. The grown epitaxial layers were characterized using various techniques. Reduction in the threading screw dislocation (SD) density in the epilayers was observed. Suitable models were developed for explaining the reduction in the SD density as well as the conversion of basal plane dislocations (BPDs) into threading edge dislocations (TEDs).     

喷锚(土钉)技术在翻车机室基坑支护中的应用

根据深基坑复杂地质层的工程特性,结合铜陵电厂五期扩建工程翻车机室实际工程,简要介绍喷锚网支护技术的基本原理,支护设计技术及工程效果,并对施工中一些技术问题进行思考,以期不断提高设计水平、改进施工方法,尽可能地为类似工程提供借鉴.     

基于二进小波统计特征的纹理图像检索

二进小波变换利用模局部极大值来提取图像的多尺度边缘信息。该文研究了二进小波系数的统计特性，提出并验证了二进小波系数直方图服从于指数分布。分析了二进小波系数的一阶、二阶统计矩(共生矩阵)特性并将其应用于纹理特征提取。理论分析和实验说明，采用Manjunath方法和二阶统计矩方法的二进小波在纹理图像检索方面优于单小波。     

均匀设计和灰色理论在基坑支护参数分析中的应用

运用均匀设计和灰色理论结合数值模拟技术分析了土钉间距、土钉倾角、土钉长度布置方式的不同对基坑变形的影响,得到了一些对基坑工程设计和施工有工程实际意义的结论。     

固体超强酸催化合成丁酸已酯的研究

针对目前酯化工艺过程中存在的环境污染问题,应用溶胶凝胶法制备了SO42-/TiO2型固体超强酸.利用IR、XRD等分析手段对固体超强酸催化剂进行结构表征,结果表明,该氧化物载体微观结构为锐钛型,并且SO42-/TiO2型固体超强酸在合成丁酸己酯的反应中表现出很强的催化活性及选择性.