小波分层表示技术在逆向工程中的应用

针对逆向工程的自由曲线重构过程中数据存储量和计算量非常大的缺陷,应用小波分层表示技术减少准均匀B样条曲线控制顶点个数,使得压缩后的曲线与原曲线的形状大致相同.实验表明该方法可以实现曲线的分层压缩,简化数据处理,降低重构代价,而且符合工程实际需求.     

采油井液面深度测量准确性评价方法探讨

采用磁性定位、压力、温度组合测井仪在不同工作制度及时间条件下多次测量油井压力剖面,通过压力的变化计算井内介质的平均密度,根据密度的数值确定油井液面深度及泡沫段高度,结合液面监测仪测试的液面资料进行对比分析,根据密度的变化值判断出气段、泡沫段及油段的位置,为油藏动态分析提供定量数据.     

钢丝拉拨变形温度场的计算和分析

本文采用伽辽金法,对钢丝拉拔过程变形区的温度场进行了有限元计算。从而得出了钢丝温度与有关参数之间的定量关系,以及钢丝表面与中心的温差程度,为解决高速拉丝中的温升问题提供了有效的途径和方向。     

大型回转体零件的精加工

本文针对现有大型回转体零件精加工困难的现状，对砂带磨削此类零件的加工机理进行了分析探讨，并以３０万干瓦汽轮机转子主轴为例进行试验，证明了砂带磨削是解决这类零件精加工的有效方法．     

拉丝固体润滑剂的模糊综合评判

本文采用了模糊数学的方法,在大量试验的基础上,建立了拉丝固体润滑中的各种主要润滑因子的隶属函数,并对七种典型润滑剂进行了二级模糊综合评判。     

贮仓自振特性实验研究

通过对多层仓顶室柱承式贮仓的实验研究,得出了贮仓自振特性随贮料员、贮料状态(散体料、固结料)和激振力变化的基本规律。为进一步完善这类贮仓自振特性的计算提供了可靠的依据。     

稀疏脉冲和基于模型反演在王家岗沙四段砂岩油藏精细勘探中的应用

1998年11月,胜利油田王家岗地区的第一口发现井（WX119井）在埋深2500－3000m的沙河街组沙四段砂岩中发现了高产工业油气流,随后如何进一步确定含油砂体展布范围和空间厚度变化成为对油藏作进一步评价和开发的关键。在研究区仅有4口井的情况下,利用基于道的稀疏脉冲三维地震反演方法确定了含油砂体的分布范围及厚度变化,据此部署的3口评价井和1口探井都获得了高产工业油气流。根据与已知含油砂体的波阻抗特征的类比,对没有钻探的高阻抗区进行钻探以使含油气范围不断扩大。钻井数达30口,其中仅2口井失利。为了进一步搞清含油砂体分布范围,我们采用了基于地质模型的三维地震反演,对所钻遇的油层分布进行了预测,分析了失利井的原因,提供了新的钻探目标,并为开发井的部署提供了有利的地质依据。     

地学应用中的便携式微机多道能谱仪

便携式机多道能谱仪以笔记本式计算机的为核心,采用１２位逐次逼近型Ａ／Ｄ转换芯片,研制成软硬件相结合的２０４８道能谱仪,讨论了适用于地学的野外微机多道能谱仪的硬件电路和软件特点,以及在γ能谱测量和Ｘ荧光测量全谱分析中的初步应用情况,该仪器及其研制技术也适用于其他有关核潜测量研究。     

Topological design of freely vibrating continuum structures for maximum values of simple and multiple eigenfrequencies and frequency gaps

A frequent goal of the design of vibrating structures is to avoid resonance of the structure in a given interval for external excitation frequencies. This can be achieved by, e.g., maximizing the fundamental eigenfrequency, an eigenfrequency of higher order, or the gap between two consecutive eigenfrequencies of given order. This problem is often complicated by the fact that the eigenfrequencies in question may be multiple, and this is particularly the case in topology optimization. In the present paper, different approaches are considered and discussed for topology optimization involving simple and multiple eigenfrequencies of linearly elastic structures without damping. The mathematical formulations of these topology optimization problems and several illustrative results are presented. An erratum to this article can be found at     

Construction Control and Pile Body Tensile Stresses Distribution Pattern during Driving

In this paper, the pile body tensile stresses distribution pattern during driving is discussed, based on dynamic piling testing results of 13 driven piles attained by the laboratory and in situ tests. These tests indicate that the maximum driving tensile stresses occur in the upper portion of the pile, especially at the initial stages of driving the pile tip seated on soft soils or if the pile foundation is built on a soft foundation. After serious study, it can be concluded that the maximum driving tensile stress often occurs at (1/4)l (l stands for the length of pile) from pile top with its value accounts for 50% of the driving compressive stresses at the same cross section. This high driving tensile stress would lead to the occurrence of transverse cracks and even the breakage of the pile, which should claim the attention of the engineer. The tests also demonstrate that high driving tensile stresses often occur due to the usage of a conventional pile cap in the driving of a prestressed concrete (tubular) pile. To the contrary, the tensile stresses tend to diminish within the control tensile stresses (5?MPa) due to the usage of a new type of disk spring pile cap during driving. Moreover, this new pile cap can prevent driving deviation from alignment, ensure an even distribution of the hammer blow on pile top, and protect the integrity of the pile body.