Search

华北克拉通中西部中生代晚期早白垩世是否存在岩石圈减薄是地学界普遍关注的重大地质问题。本文在作者多年来对鄂尔多斯盆地构造热演化史研究的基础上，充分收集了近年来前人研究的成果及进展，对鄂尔多斯盆地现今地温场、地壳结构、构造热事件、深部热岩石圈厚度、早白垩世火成岩活动期次、构造热事件形成机理及构造热事件与多种矿产成藏成矿关系方面进行探讨。鄂尔多斯盆地现今地温梯度及大地热流中等，属中温型盆地，现今地温场受现今地壳、岩石圈厚度较厚控制。通过对构造背景、古地温恢复、火成岩活动及热岩石圈厚度恢复等资料分析发现早白垩世太行山以西的山西地块及鄂尔多斯盆地处于拉张背景，早白垩世地温梯度高，存在古地温异常及热事件。早白垩世鄂尔多斯盆地热岩石圈厚度明显较现今岩石圈厚度薄，表明华北克拉通中生代晚期以来岩石圈减薄的西界可推到鄂尔多斯盆地。华北克拉通中西部鄂尔多斯盆地周缘、华北克拉通中部山西地块、华北克拉通中西部南缘早白垩世火成岩形成时间相同，岩浆侵入和喷出的时代主要集中在138~108Ma，反映在燕山晚期早白垩世华北克拉通中西部存在一期较为强烈的热事件。火成岩地球化学分析表明火成岩来源为地幔，反映岩石圈处于拉张背景。早白垩世热事件发生的时间与华北克拉通岩石圈减薄的峰期年龄相一致，表明华北克拉通岩石圈减薄作用在华北克拉通中西部广泛存在。早白垩世构造热事件发生的根本原因在于鄂尔多斯盆地岩石圈深部热活动增强，深部软流圈物质上涌，岩石圈厚度减薄。通过对油气、煤、铀等金属矿产成矿（藏）时代与热事件的对应关系分析发现鄂尔多斯盆地油气、煤、铀矿产及华北克拉通中西部金属矿产的形成受控于早白垩世构造热事件及岩石圈拉张减薄的深部热背景，主要成藏（矿）期均为早白垩世，成藏、成矿具有爆发式及同时性特点。

基于三维地震、测井、岩矿测试等资料，分析了镇泾地区中生界断裂体系特征与成因，结合源岩热演化与储层物性反演结果，恢复了长8段油气成藏的动态演化过程，探讨了中生代以来构造活动对长8段油气成藏的影响作用。研究认为鄂尔多斯盆地内部镇泾构造转折区构造变形受盆地边缘影响明显，发育复杂断裂体系，构造特征及演化对油气藏的形成与分布有重要控制作用。结果表明：（1）中生界北西向、北东东向、近东西向3组断裂发育，平面上呈雁列式带状展布，剖面上为高陡产状且小断距错动。印支期北西向主断裂走滑明显，中、晚燕山期北东向断裂活动加强，喜山期北东东向次级断裂密度增大，并派生大量剪切裂隙。（2）长8段油藏经历了晚三叠世储集层、烃源岩层初始沉积形成，早白垩世初期少量低熟油近源充注形成岩性油藏，早白垩世末成熟油快速输导形成受断层及裂缝控制的构造-岩性油气藏，晚白垩世以来早期油藏调整等4个阶段。（3）印支运动控制了烃源岩及储层展布范围，Ⅰ类北西向走滑断裂控制了镇泾地区中生界构造格局；中、晚燕山运动加速烃源岩热演化进程，并改善储层物性，Ⅱ类断裂活动，为烃类输导提供垂向通道；喜山运动使先存中生界断裂活动，控制油气调整范围及油藏差异富集；其中北东东向Ⅱ类张性或张扭性断裂导流性能好，是最为有效的富油断层。

The purpose of this research is to present a grasping force model for a soft robotic gripper with variable stiffness. The soft robotic gripper was made of shape memory alloys (SMAs) with contraction and variable stiffness properties. A variable stiffness mechanism with embedded sets of SMA fibers was developed; however, the response characteristics of its backbone did not comply with the constant-curvature model when it was subjected to complex forces/torques, such as gravity, grasping forces and driving torques. In this case, the Cosserat theory was used to implement real-time computations of the grasping force of the soft robotic gripper that was subjected to complex forces. Finally, a series of tests were conducted on the grasping force of the soft finger and the gripper. The elicited results showed that the grasping force is related to the stiffness and to the object's offset and friction coefficient. Moreover, experimental results showed that the grasping force of the soft robotic gripper increased by 48.7% when the Young's modulus of the SMA-2 wires increased from 25 GPa to 48 GPa.

This paper presents a new method for large range and high resolution force measurement. Unlike conventional strain-gauge-based force measurement, our method measures an external force through measuring the displacement of a movable member suspended by a compliant mechanism. The compliant mechanism is specially design to have two different stiffness values in its workspace. The low stiffness is used for small force measurement while the high stiffness is used for larger force measurement. A grating scale is attached on the movable member to measure the displacement. The major advantage of this method is that it can measure both micro and macro forces with different scales in one setup, and the output signals are digital. A force sensor prototype has been developed and applied for wire-bond pull tests.

This paper presents the design of a novel 4-DOF (x-y-θ x -θ y ) flexure-based system used for coaxial alignment. The movable head (a rigid rod) of the system is suspended with two monolithic flexural mechanisms constructed with leaf flexures. To achieve the required x-y-θ x -θ y motion, the leaf-type flexures are specially arranged in such a configuration that is compliant in the specified axes but stiff in other axes. The leaf flexures are initially designed based on the linear models of the flexible beam deflection and then improved through FEA simulations. A system prototype was built with the flexural mechanisms. It demonstrates superior motion performances in the x and y axes as well as the angular axes. The prototype has been successfully applied in the coaxial alignment of the capillary machining.

The velocity and the axial dispersion of solids within a bed (50 mm in inner diameter, 3600 mm in height) with high gas velocity were analyzed by impulse response of tracer particles. FCC-particles (“group A” powder according to Geldart classification) were employed for the present investigation.Local particle velocity at the axis of the bed increased with increased gas velocity, while the fraction of solids decreased. The axial dispersion coefficient within the bed ranged from 1 to 900 cm2/s. This result suggested unsteady and random behaviour of solids within the fast fluidized bed. Local slip velocity at the axis of the bed was mostly larger than the terminal velocity of a single particle.

Experimental results obtained in a circulating fluidized bed with a diameter of 115mm, show that the minimum fluidization velocity of coarse particles can be reduced by circulating fine particles around them. An empirical correlation based on experiments with seven kinds of coarse particles and two kinds of fine particles has been derived.