单片机控制的数字式闭环直流调速系统

本文在实验的基础上,探讨了实现一种价廉的MCS-51单片机控制的数字式闭环直流调速系统。重点对数字系统的硬件和软件进行了设计。文中还给出了试验特性曲线及数字仿真结果。     

Applications of Digital Correlation Method to Structure Inspection

In structure inspections, applications of optical techniques are rare, but the advantages of a non-contact, full field technique using a simple apparatus are attractive. The main requirements for structure in- spection are the full-field strain measurement with the required precision and on-site measurement ability. The digital correlation method (DCM), a new optical deformation measurement tool, can satisfy all of the re-quirements for structure inspection. A smoothing algorithm which can greatly improve the strain measure-ment precision, and a 3-D DCM have been developed in this paper. For verifying this improvement, a com-parison of strain measurements by computer-simulated speckle images has been carried out. Additionally, three structure inspection examples that cover typical materials and structure styles are presented: the inter-face shear stress distribution for reinforced concrete piles bedded on rock, the 3-D strain distribution of a composite vessel structure, and stresses in a hookup that connects two steel bridge structures. All the ex- amples show that the new structural inspection tool is exemplary and illustrates the obvious advantages of this optical non-destructive technique.     

材料微观结构表征的数据规范模型(英文)

介绍了文章提出的数据规范微结构模型(DCM)在确定材料孔隙及物相分布方面的应用.多光谱X光CT数据约束下的DCM模型,是一种南CPU计算效率的线性及非线性最优化途径.DCM模型的非线性最优化途径允许把对材料的前期了解或其他实验测试结果植入其中,从而使得对材料的微观结构表征更加精确.文章通过与油气资源相关的具体实例展示了DCM模型的应用.对材料组分三维分布的精确表征有助于更加准确地表征及计算包括渗透性在内的材料其他物理性质.     

有源功率因数校正(APFC)技术综述

本文介绍了有源功率因数校正技术的基本原理、分类和控制方法,并概括了其发展趋势。     

劲性搅拌桩单桩工作特性

劲性搅拌桩是1种用于处理软土地基的新型桩,是在水泥土搅拌桩中即时插入高强度的内芯桩形成的复合桩,对劲性搅拌桩荷载传递特性进行了分析;并结合劲性搅拌桩的成桩特点,通过原位试验的研究,对该桩的几种破坏模式进行了研究、分析．     

混凝土芯水泥土搅拌桩群桩复合地基承载特性分析

为了探讨混凝土芯水泥土搅拌桩群桩基础在软土地基中的受力特征,以及褥垫层的移动趋势,进行混凝土芯水泥土搅拌桩群桩复合地基加固软土地基的室内模型试验。通过监测分级荷载作用下复合地基的沉降和桩顶、桩底以及桩间土不同位置的应力分布的变化来探讨复合地基承载特性。对桩顶平面处A桩周围土层表面埋设标志物,分析了褥垫层材料的移动态势和桩间土体的沉降量的规律。试验结果表明:复合地基在上部荷载作用下,加载初期是由桩来承担大部分上部荷载;由于褥垫层的调节作用,桩顶面处的桩土应力比逐渐增大,达到峰值后比值有所减小直到趋于稳定。混凝土芯水泥土搅拌桩群桩复合地基在上部荷载作用下的沉降曲线(P-S曲线)为缓变型;褥垫层向群桩所围成几何图形的中心移动,桩周土的水平位移和竖向沉降都以桩为中心呈现由近及远不断减少的趋势。研究结果为工程实践提供了有益的参考。