Synthesis of alpha-alumina nanoribbons: characterization and their morphological evolution

Single crystalline α-alumina nanoribbons were synthesized by reacting aluminum with silicon monoxide at high temperature. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), and high-resolution transmission electron microscope (HRTEM). The intense peaks of XRD pattern indicate that the prepared nanoribbons have a high degree of crystallinity. In the present work, silicon monoxide was used as an oxidant and precursor, which served to control the reaction rate. An interesting morphological evolution that nanoribbons resulted from nanosaws was described, and these novel nanosaws were also carefully characterized.     

防渗渠道顶托渗漏量计算方法的理论探讨

针对灌区高地下水位条件,探讨在饱和渗流水顶托条件下,采取防渗衬砌措施前后渠道渗漏量的理论计算方法,分析研究现有解析计算经典公式的特点及其适应性.根据水力学和水动力学原理,推出理论上可行、结构合理和简便适用的解析计算方法,并用数值模拟计算进行了验证,结果表明,本文解析法与数值法的计算结果比较接近.     

溢洪道泄洪冲刷对马崖高边坡稳定性影响的分析

 选取包括溢洪道冲刷坑在内的马崖高边坡的典型地段，为研究溢洪道泄洪冲刷对未整治和削坡整治后的马崖高边坡稳定性的影响，进行了三维弹塑性有限元分析。结果表明泄洪冲刷将引起马崖的上部边坡朝坡外且向下变形，削坡整治后的边坡其变形和塑性屈服区均较未整治时小。     

熟料窑运行状态检测应用研究

阐述了对回转窑运行轴线进行监测的重要性 ;介绍了一种回转窑运行轴线监测的研究成果 ,该方法采用 15°方向键相法测量窑体截面的回转中心 ,通过对窑各挡支承轮带两侧的截面测量而获得运行轴线 ;研制的监测系统结构简单 ,运行可靠 ,监测精度高 ,操作、使用、维护方便 ,并成功地应用于实际生产中     

The L(2,1)-labeling and operations of graphs

Motivated by a variation of the channel assignment problem, a graph labeling analogous to the graph vertex coloring has been presented and is called an L(2,1)-labeling. More precisely, an L(2,1)-labeling of a graph G is a function f from the vertex set V(G) to the set of all nonnegative integers such that |f(x)-f(y)| /spl ges/ 2 if d(x,y)=1 and |f(x)-f(y)| /spl ges/ 1 if d(x,y) = 2. The L(2,1)-labeling number /spl lambda/(G) of G is the smallest number k such that G has an L(2,1)-labeling with max{f(v):v/spl isin/V(G)}=k. A conjecture states that /spl lambda/(G) /spl les/ /spl Delta//sup 2/ for any simple graph with the maximum degree /spl Delta//spl ges/2. This paper considers the graphs formed by the Cartesian product and the composition of two graphs. The new graph satisfies the conjecture above in both cases(with minor exceptions).     

Local Phenomena in Oxides by Advanced Scanning Probe Microscopy

In the last two decades, scanning probe microscopies (SPMs) have become the primary tool for addressing structure and electronic, mechanical, optical, and transport phenomena on the nanometer and atomic scales. Here, we summarize basic principles of SPM as applied for oxide materials characterization and present recent advances in high-resolution imaging and local property measurements. The use of advanced SPM techniques for solutions of material related problems is illustrated on the examples of grain boundary transport in polycrystalline oxides and ferroelectric domain imaging and manipulation. Future prospects for SPM applications in materials science are discussed.     

Experiment and simulation investigations for effects of flow channel patterns on the PEMFC performance

Experiments and simulations are presented in this paper to investigate the effects of flow channel patterns on the performance of proton exchange membrane fuel cell (PEMFC). The experiments are conducted in the Fuel Cell Center of Yuan Ze University and the simulations are performed by way of a three‐dimensional full‐cell computational fluid dynamics model. The flow channel patterns adopted in this study include the parallel and serpentine flow channels with the single path of uniform depth and four paths of step‐wise depth, respectively. Experimental measurements show that the performance (i.e. cell voltage) of PEMFC with the serpentine flow channel is superior to that with the parallel flow channel, which is precisely captured by the present simulation model. For the parallel flow channel, different depth patterns of flow channel have a strong influence on the PEMFC performance. However, this effect is insignificant for the serpentine flow channel. In addition, the calculated results obtained by the present model show satisfactory agreement with the experimental data for the PEMFC performance under different flow channel patterns. These validations reveal that this simulation model can supplement the useful and localized information for the PEMFC with confidence, which cannot be obtained from the experimental data. Copyright © 2007 John Wiley & Sons, Ltd.     

堆焊层中球状碳化物形成机理的研究

通过同时加入球化剂和碳化物形成元素，成功地在堆焊层中形成了球状碳化物，并对这种碳化物的形成过程进行了理论上的探讨。     

模拟二元复合驱采出液破乳研究

用模拟碱／聚合物二元复合驱采出液，以脱出水色为主要评价项目，对新开发的若干系列的破乳剂＋净水剂复配物的破乳性能进行了室内评价。聚丙烯酰胺含量最高达１１６０ｍｇ／ｌ、碳酸钠含量最高达８０００ｍｇ／ｌ的模拟采出液破乳实验结果表明，聚合物含量是影响破乳效果的主要因素。破乳性能最好的破乳剂是ＡＥＤ７８和ＡＥＤ２３（甲苯二异氰酸酯扩链的双嵌段聚醚），净水剂是ＱＢＳ０５（阳离子苄基淀粉）和ＱＳ０６（阳离子淀粉）。     

用多参量法计算薄层和薄互层厚度

薄层、薄互层厚度预测是储层横向预测的一重要环节。常规计算薄层厚度的方法是在时间域或频率域实现，主要使用单参数计算。本文利用对薄层厚度敏感的地震特征参数之间的非线性关系，使用神经网络算法，建立了一套计算薄层及薄互层厚度方法。通过模型的正反演结果表明：该算法对薄层厚度及薄互层累积厚度的预测均有较好的效果，具有一定的抗噪声能力。对塔中ＤＬ９２－０４测线部分剖面的石炭系Ｉ油组薄互层砂岩的累积厚度进行了预测