非接触式检测混凝土桥梁裂缝的测距法

传统的混凝土桥梁裂缝检测方法已经不能满足现代桥梁检测的需求。基于数字摄影测量的基本原理,提出了适合于桥梁裂缝非接触检测的测距法。在试验分析基础上,从拍摄角度、环境因素和焦距误差三个方面对系统的误差进行修正。结果表明,误差修正后,检测系统的精度大幅度提高,可以实现桥梁表面裂缝的远距离、非接触测量。     

高精度预埋地脚螺栓安装

沙景5000mm宽厚板轧机成品库柱基础、设备基础工程的工程量大,施工战线长。每个单独基础及设备基础上部均匀设置地脚螺栓,对螺栓位置要求精度较高,一般施工方法很难达到要求。介绍一种施工方法,完满解决这一施工难题。     

地面三维激光扫描仪的检校与精度评估

三维激光扫描技术是一种先进的全自动高精度立体扫描技术。其中,激光扫描测量仪器的精度对工程应用的影响以及对三维点云模型的建立和精度影响至关重要。本文分析了激光扫描仪的主要误差来源,同时介绍了三维激光扫描仪的检校原理和方法,并以Leica公司的HDS3000为例,从测距、测角、大气影响等方面,对激光扫描仪的精度进行测试和评定。     

某单体工程钻孔灌注桩的超声波检测

结合某单体工程中钻孔灌注桩采用的超声波检测,对超声波检测的原理、方法、检测中常见问题及解决办法等进行了较为详细的阐述,指出超声波检测法具有快捷、准确、可靠,能评价钻孔灌注桩的均匀性、完整性及缺陷的位置与性质等优点。     

工程建设档案与现代工程造价管理

阐述了工程建设档案和工程造价管理的含义,分析了我国现行工程造价管理体系的现状,从工程造价确定方法所需资料的情况,提出了工程建设档案资料收集分类和统计分析应注重的几方面要求,从而更好地控制工程造价。     

神经网络组合预测法在软基沉降预测中的应用

通过引入神经网络组合预测模型,对软基沉降序列进行了非线性组合预测。预测结果表明,神经网络组合预测的结果比各单项模型预测的结果都好,提高了软基沉降的预测精度,可进一步推广应用。     

Comments on "Equilibrium studies for the adsorption of acid dye onto modified hectorite"

The present letter discusses the significance of the dimensionless separation factor of solid/liquid adsorption systems. The present letter also explain citing the original paper for using the term separation factor 'R'.     

A rapid and accurate positioning method with linear deceleration in servo system

The positioning accuracy and positioning time of CNC system have recently been the main performance criteria for industrial applications. The acceleration/deceleration modes, especially deceleration mode, have an important effect on them. The linear deceleration mode is a commonly used deceleration mode. In conventional linear deceleration mode, there is a positioning stage at low speed for a long time after decelerating to ensure the positioning accuracy, because of the “dead zone” and the deceleration point error. In this paper, firstly, some problems in the conventional linear deceleration algorithm are analyzed. Then an improved linear acceleration/deceleration is introduced. In this algorithm, the deceleration point is predicted exactly, and then the deceleration point error is compensated for at higher feedrates. Furthermore, a higher resultant maximum acceleration than that in the conventional scheme is selected to shorten the acceleration/deceleration time. Thus, the positioning stage in conventional scheme is almost cancelled. Compared with that of conventional linear acceleration and deceleration algorithm, the system performance has been significantly improved. Finally, it is confirmed by many simulations and experiments.     

基于曹妃甸工业区的坐标转换精度分析

转换精度是在不同坐标系统转换时关系工程应用的关键因素。文章用曹妃甸工业区同期控制点的两套已知坐标数据,利用4参数、7参数的转换模型对求解参数时选用公共点的位置与精度因素对WGS-84坐标系到唐山城市坐标系平面坐标转换精度的影响进行了实例分析,在此基础上得出了一些有益的结论。     

开放式T 靶弹丸斜入射风矢量修正模型

针对开放式T靶的自动报靶存在的问题,提出一种开放式报靶风矢量修正的数学模型.从T靶的实用性和报靶精度出发,重点讨论开放式 T 靶的二维风矢量修正,并通过实际打靶测试验证.结果表明,该方法可大大提高系统报靶精度.