大口径管道带水抢修

包头地区1996年5月3日发生6.4级强烈地震,给包钢生产造成重大损失,地震发生后,包钢生产用动力系统发生多起事故.本文针对4#高炉工业回水管道(φ1220×10)震后发生断裂,如何在保证不停止生产的前提下,采取什么措施进行管道带水抢修进行了阐述,本文是经过现场抢修过程总结而来,对今后大口径管道带水抢修提供了宝贵的经验.     

3DFD Simulation of Asymmetric Wave Field by Side-wall Acoustic Tool in Open and Cased Wells

1. Introduction Side-wall acoustic logging tools, such as the Segmented Bond Tool (SBT) from Baker Atlas and the tools for open hole measurements, utilize acoustic transducers mounted on six pads to make compensated acoustic velocity and attenuation measurements which are not affected by mud weight, gas cut, fast formation effects, casing surface conditions or reasonable tool de- centralizing. Studies on the wave fields generated by these tools are very important to tool design and data int…     

The optimal diamond wheels for grinding diamond tools

Grinding is the most suitable process for manufacturing good quality diamond tools. In this paper, diamond wheels have been studied. From the grinding of polycrystalline diamond (PCD) insets, the effects of certain factors such as the bonding material, the grit size and structure of a diamond wheel have been investigated. It is concluded that vitrified bond diamond wheels are the most suitable for grinding PCDs and the recommended grit size is mesh number 1000, which can get a good surface quality within an appropriate time. The wheel structure is another important factor. Rougher wheels (mesh #800, #1000) with the softer grade scale P yield a higher material removal rate (MRR) than scale Q. However, a finer wheel (mesh #1200) needs a tougher structure to promote its grinding ability and to have a higher MRR.     

轮式工程机械轮边减速器优化模型与方法

论述了重构轮式工程机械轮边减速器优化设计数学模型的必要性,给出了精确化的目标函数,全面化和准确化的设计变量、基于并行设计的约束条件;介绍了对优化解适用性评价的方法和手段。巧妙地解决了优化解中离散变量的圆整问题,提供了基于MATLAB的求解反渐开线函数的M文件。     

S28-248型偏心BDC钻头的研制与应用

为了提高中原油田沙3中至沙4段四开小井眼的钻井速度,有效地解决易卡钻、钻速低、成本高以及小间隙井眼固井质量差等问题,中原油田与川石·克里斯坦森金刚石钻头有限公司合作,研制开发了用于深部小井眼钻井的149.2mm的S28-248型偏心BDC钻头。详细介绍了该钻头的设计特点及现场应用情况。     

SGW-420/30型刮板输送机的研制与应用

针对煤矿中小型开采工作面的运输,研制出介于22型和40T型之间的一种新型刮板 输送机,时它的结构组成、功能特点、技术参数等作以简介和阐述,使其得以推广使用。     

静止和旋转孤立车轮局部流场的评价

为研究车轮周围流场特征,分别对某孤立车轮静止和旋转工况下周围流场进行数值研究,并给予试验验证.计算采用定常雷诺时均纳维斯托克斯方程.在1∶15的模型风洞中进行试验.数值模拟结果与试验数据吻合.针对数值模拟结果,详细分析静止和旋转孤立车轮周围流场的流动情况、表面压力因数、气动阻力因数和气动升力因数等,得到孤立车轮旋转对车轮附近局部流场的影响以及形成机理.车轮的转动使总体压差减小,降低气动阻力和升力,改善气动性能。     

Modelling of the mist formation in a segmented grinding wheel system

It has been found that using a segmented grinding wheel with a fluid chamber can significantly minimise the quantity of coolant while improving the ground surface integrity. The present investigation aims to explore the fluid flow mechanism in such a wheel system. To this end, the Weber theory for Newtonian jet instability was applied to quantitatively determine the contribution of coolant flow rate to mist and ligament modes. A semi-analytical model was then developed to predict the mist flow rate by taking into account both the grinding parameters and fluid properties. It was shown that the model prediction was in good agreement with experimental measurements. Because of the comprehensive integration of variables in the formulation, the model provides a good fundamental understanding of the mist formation and offers a practical guideline for the selection and use coolant in minimising the mist flow rate.     

再生砖混骨料混凝土柱的小偏心受压性能

通过小偏心受压性能试验对比研究3根的天然骨料混凝土柱和3根同强度全再生砖混骨料混凝土柱,强度分别为C25、C30和C35. 对6根柱进行加载试验,分析再生砖混骨料混凝土柱相比于同强度天然骨料混凝土柱在受力过程、破坏特征、变形能力与承载力等方面的差异. 试验发现,再生砖混骨料混凝土柱在小偏心加载至破坏的过程中,具有与天然骨料混凝土柱相似的3个受力阶段,且符合平截面假定. 与同强度的天然骨料混凝土柱相比,变形较大,但再生砖混骨料混凝土柱的极限承载力略高,原因可能在于两者轴心抗压强度的差异.     

一种评价二尖瓣偏心返流严重程度的修正PISA算法

基于彩色多普勒成像的近测等速面(PISA)算法是临床评价二尖瓣中心返流严重程度的一种常用方法,但对于偏心返流却存在极大低估。针对这一现状,从返流角度和湍流强度两个方面,对传统PISA算法的有效返流瓣口面积(EROA)进行修正。为比较首先用传统PISA算法的EROA对具有不同程度偏心返流的20例患者进行分级,结果误差较大;用改进PISA算法的EROA分级效果良好。对比实时三维超声测得的数据表明修改后的PISA算法相关性更好。