不平衡效应对稠油渗流的影响

本文利用稠油的多组分模型，研究了不平衡效应对粘弹性稠油在多孔介质中渗流的影响。通过建交我孔介质中存在不平衡效应的一维有界不稳定直线渗流的数学模型，分别推出了渗流初期和后期的压力分布解析式，并与一般牛顿流体渗流进行了比较。结果表明，不平衡效应使得渗流过程中的压力下降缓慢，在实际的稠油开采中，要合理的利用稠油的粘弹特性。     

基于MATLAB的电力系统继电保护仿真研究

基于MATLAB的仿真技术可以辅助继电保护系统的分析和设计,针对电力系统继电保护领域的核心内容,构建了系统仿真模型,举例说明了电力系统故障、零序电流保护和变压器纵差保护等仿真实例的实现方案。在运行这些仿真实例的基础上,对仿真结果进行了深入分析。通过仿真实例证明了电力系统继电保护仿真的有效性和可行性。     

三乙胺、乙醇和水混合物分离工艺模拟与优化

以化工流程模拟软件Aspen Plus为工具,通过模拟数据与文献数据对比,确定选用SR-POLAR热力学方程模拟研究体系.利用残余曲线、蒸馏边界理论对三乙胺、乙醇和水混合液模拟分析,确定采用变压精馏技术分离共沸混合物设计方案,利用灵敏度分析对流程进行优化设计.结果表明:低压精馏塔理论塔板数为25、回流比为5,原料进料位...     

大连港大窑湾吹填区软基的堆载预压处理研究

结合大连港大窑湾吹填区软土地基处理具体工程,通过现场试验与监测比较详细地介绍了堆载预压方法中关于分级堆载设计、施工及监测等各方面的技术问题。通过对监测结果的综合分析,探讨了堆载预压处理过程中地表沉降、深层沉降等关键参数的变化规律及堆载级数、堆载高度与固结时间等参数之间的依赖关系,为吹填造陆地区软基处理提供了经验和依据。     

工业多糖中苯甲醇的高效液相色谱分析

用液相色谱法测定了工业多糖中的苯甲醇含量,色谱柱为C8柱,流动相为甲醇∶乙腈∶水(体积比为5∶15∶80),流速1.0mL/min,检测波长256nm.直接进样测定.加标回收率为95%～110%,相对标准偏差优于3%.实际样品分析结果令人满意.     

固相萃取净化-气相色谱法同时测定茶叶中16种有机氯、拟除虫菊酯农药残留

对茶叶中多种农药残留气相色谱测定方法做了改进,建立了茶叶中16种农药残留同时测定的新方法.待测组分经提取、净化后进行气相色谱测定.淋洗液为石油醚和乙酸乙酯混合溶液,对两者的比例作了优化(石油醚:乙酸乙酯=7∶3,v/v).16种农药残留组分的标准加入回收率为92.7%～102.9%,检出下限为0.1～3.3μg/kg,相对标准偏差为3.4%～8.9%(0.04～0.2μg/kg,n=5),能满足出口企业对产品质量控制的要求.     

人工砂配制C60超高层泵送混凝土

本文主要研究利用人工砂配制高强度C60超高层(51层232.5m)一次性泵送混凝土,解决人工砂高强度混凝土在高扩展度(600mm)、高温季节3～4小时,离析沉底可泵性差现象;减少管道的摩擦及混凝土自身重力、泵送压力造成的混凝土坍落度损失、粘性增加;有效避免高强度大体积混凝土产生的裂缝。     

High-temperature fatigue behavior of SiC-coated carbon/carbon composites in oxidizing atmosphere

Tensile fatigue-stressed oxidation experiments were conducted at 1300 °C in oxidizing atmosphere to identify the failure modes and degradation mechanism of a SiC-coated carbon/carbon composite. Five peak fatigue stresses were selected between 90 and 150 MPa and the results showed that the higher the applied stress, the shorter the composite life. Electrical resistance of the composite was acquired in real-time. The composite resistance appeared a slight drop in the initial fatigue period and followed by a continuous increase until failure. Both the changes in modulus and resistance revealed the shrinking core mechanism in the fatigue-stressed oxidation experiments. A model was developed based on a half-cylinder oxidation pattern. Simulations were conducted on the basis of this model, and the results agreed with the experimental data fairly well.     

Risk‐sensitive filtering for nonlinear Markov jump systems on the basis of particle approximation

In this paper, the risk‐sensitive filtering method that relaxes the dependence on model accuracy is extended to nonlinear Markov jump systems (MJSs). In the method, the so‐called reference probability technique together with particle approximation is utilized to derive the risk‐sensitive filter in nonlinear non‐Gaussian framework. The novelty of the proposed approach is that a ‘risky’ interacting resampling step is performed to both moderate the modeling uncertainties and to solve the problem of particle explosion. A designer‐chosen parameter named risk‐sensitive parameter allows us to make a trade‐off between the filtering accuracy for the nominal model and the robustness to uncertainties. With a meaningful example, it shows that the developed method can outperform the widely used method‐particle filter and interacting multiple model‐particle filter in nonlinear MJSs with uncertainties. Copyright © 2011 John Wiley & Sons, Ltd.