Subdivision based isogeometric analysis for geometric flows

We present a new isogeometric analysis (IGA) approach based on extended Loop subdivision scheme for solving various geometric flows defined on subdivision surfaces. The studied flows include the second-order, fourth-order, and sixth-order geometric flows, such as averaged mean curvature flow, constant mean curvature flow, and minimal mean-curvature-variation flow, which are generally derived by minimizing the associate energy functionals with $L^2$-gradient flow respectively. The geometric flows are discretized by means of subdivision based IGA, where the finite element space is formulated by the limit form of the extended Loop subdivision for different initial control meshes. The basis functions, consisting of quartic box-splines corresponding to each subdivided control mesh, are utilized to represent the geometry exactly. For the cases of the evolution of open surfaces with any shape boundary, high-order continuous boundary conditions derived from the mixed variational forms of the geometric flows should be implemented to be consistent with the isogeometric concept. For time discretization, we adopt an adaptive semi-implicit Euler scheme. By several numerical experiments, we study the convergence behaviors of the proposed approach for solving the geometric flows with high-order boundary conditions. Moreover, the numerical results also show the accuracy and efficiency of the proposed method.     

慢刀伺服车削刀具半径定向补偿的分段逼近求解

复杂曲面的慢刀伺服车削加工过程中，采用刀具法向补偿算法会在各个直线轴产生补偿量，加工法向矢量突变的曲面时，这种算法并非最优，将补偿量只应用于负载较低的直线轴却是更优的选择。提出一种基于线段逼近的刀具半径定向补偿数值求解算法来求解定向刀位点，通过半径细分的策略使法向误差收敛。算法实例验证及与相关算法的对比结果显示，该算法适用于点云构成的曲面或分段曲面的刀具半径补偿。     

第二代小波降噪法在故障诊断中的应用

介绍了基于插值细分法的第二代小波变换的基本原理和变换过程,给出了小波降噪的阈值选取方法。用仿真信号进行验证,并将该算法应用于矿用通风机振动信号的降噪处理中,提高故障诊断的准确率。     

JTK-1.2型提升绞车滚筒剖分设计

JTK -1 2型提升绞车的滚筒原为整体结构 ,不便于在特殊环境下运输和安装。为满足上述要求 ,对滚筒进行了剖分设计。剖分后的滚筒在结构尺寸上、强度上及使用性能上达到了原来的要求 ,能够满足安全提升的需要     

溢洪道开挖边坡三维地质建模与稳定性分析及应用

溢洪道的开挖边坡,与一般的自然边坡不同,属于人工开挖边坡,有着施工区内山高坡陡的特点,其边坡稳定性通常采用极限平衡法进行分析,但由于所建立的三维地质模型不够精确,剖分过程可视化的缺失以及稳定性分析计算界面的不够友好,很难做到直观性和清晰性的统一。运用NURBS技术建立研究区域的三维地质模型,并对 VisualGeo 三维地质软件进行二次开发,实现三维边坡体的自动剖分和数据提取,同时采用改进的三维可视化模拟分析系统VisualSlope进行稳定性计算、参数敏感性分析和支护措施研究。该方法可实现边坡稳定性的可视化分析与直观演示,开辟了基于三维地质模型的边坡稳定性与可视化分析的新途径。     

渤海Q油田层间干扰定量表征技术及应用

针对渤海Q油田北区块油井多层合采导致的含水上升快、采油速度低、采出程度差异大等问题,对不同含水阶段的层间干扰现象进行分析,建立了层间干扰定量表征技术,并结合Q油田油藏类型和储层纵向非均质性,研究了底水关闭前后不同含水阶段的层间干扰规律,提出了高含水期细分层系开发的技术对策:对北区块进行调整,将原来的一套开发层系细分为三套开发层系,采用水平井开发,同时对老井进行关层。调整后全区含水率下降了10%,采油速度提高了0.5%,采收率提高了10.6%。     

基于复合砂体构型样式的河流相储层细分对比方法

根据"依据标志、旋回对比、分级控制、地震约束"的储层细分和对比方法,可以对含油储集层逐级细分为含油层系、油层组、砂层组和单油层等4个级次。由于河流相沉积储层缺少可依据的细分和对比标志层,从而导致了细分对比的不确定性。根据复合砂体构型分类体系将河流相砂体构型样式细分为4大类7亚类,实践证明该方法准确有效。     

A novel mesh subdivision algorithm for dense reconstruction from multi-image based on preliminary model

To solve the disadvantages of the recent three-dimensional (3D) reconstruction methods, this paper presents a dense reconstruction algorithm which incorporates image features into the mesh subdivision. A preliminary model is deformed from statistical deformation model (SDM) to catch the roughest features, and later densified under a multi-resolution frame to achieve a dense model until all image features are used. In every round of this framework, the image features are detected, and then cut into planar points. At the same time, the transitional model is re-projected into views, and all images are segmented to triangles. So the planar points are constrained by these triangles, and the corresponding relations among these triangles are certain. Then some new spatial points are generated from these planar points and subdivide the transitional model. Later, the transitional model is re-arranged to get a right topology, and becomes denser. This method contributes three novelties: (1) there is an inherited relationship between the later points and the early points; (2) if the hierarchy of multi-resolution frame and the number of new spatial points at every round are set appropriately, the transitional model evolves with a correct topology; (3) the density of the final model is proportional to the information account of views. The experiment validates these virtues.     

采出井6段以上细分配产技术

为了提高油层的动用程度,实现油层的精细划分,研究出一种采出井6段以上细分层产量控制工艺。通过油管和套管之间的环形空间下入电控式测调仪,与井下可调式分层配产器进行对接,依据监测数据对高产液层段状态进行直观分析判断,实现一次下井完成各层段产液量的合理控制,使各层段均保持合理流压,充分发挥产油潜力。通过配套细分工艺的研究,满足了采出井6段以上的细分控制,达到了剩余油深度挖潜的目的。     

复杂断块油藏三级细分技术的研究与应用——以永安镇油田永3-1断块沙二段7-9层系为例

复杂断块油藏由于层间、层内非均质性以及开发非均质性的存在,导致开发不均衡.随着开发的不断深入,层间干扰矛盾越来越突出,多次细分后再进行层系分段细分经济效益变差.减缓干扰、均衡注采、扩大水驱波及体积,是大幅度提高这类油藏水驱采收率的关键.以永安镇油田永3-1断块沙二段7-9层系为例,采用层系重组、油井分层采油、水井分层注...