Experimental study of the movement of control fluid in compound perforation

The interaction between the high pressure gas and the control fluid and the movement mechanism of the control fluid in compound perforation were studied by a series of large-scale experiments, where the movement behavior of the control fluid was observed. The curves of measured pressure were analyzed, a mathematical model for the rigid movement of the control fluid was established, and the movement velocity of control fluid was analyzed. Moreover, the velocity from experimental results and velocity from an analytical solution were contrasted. The movement of the control fluid in the initial stage was similar to the rigid movement; however, the propagation of the pressure wave in the control fluid should be taken into account. Experimental results are significant for research on the movement mechanism of control fluid in compound perforation.

Research progress and development of deep and ultra-deep drilling fluid technology

The research progress of deep and ultra-deep drilling fluid technology systematically reviewed,the key problems existing are analyzed,and the future development direction is proposed.In view of the high temperature,high pressure and high stress,fracture development,wellbore instability,drilling fluid lost circulation and other problems faced in the process of deep and ultra-deep complex oil and gas drilling,scholars have developed deep and ultra-deep high-temperature and high-salt resistant water-based drilling fluid technology,high-temperature resistant oil-based/synthetic drilling fluid technology,drilling fluid technology for reservoir protection and drilling fluid lost circulation control technology.However,there are still some key problems such as insufficient resistance to high temperature,high pressure and high stress,wellbore instability and serious lost circulation.Therefore,the development direction of deep and ultra-deep drilling fluid technology in the future is proposed:(1)The technology of high-temperature and high-salt resistant water-based drilling fluid should focus on improving high temperature stability,improving rheological properties,strengthening filtration control and improving compatibility with formation.(2)The technology of oil-based/synthetic drilling fluid resistant to high temperature should further study in the aspects of easily degradable environmental protection additives with low toxicity such as high temperature stabilizer,rheological regulator and related supporting technologies.(3)The drilling fluid technology for reservoir protection should be devoted to the development of new high-performance additives and materials,and further improve the real-time monitoring technology by introducing advanced sensor networks and artificial intelligence algorithms.(4)The lost circulation control of drilling fluid should pay more attention to the integration and application of intelligent technology,the research and application of high-performance plugging materials,the exploration of diversified plugging techniques and methods,and the improvement of environmental protection and production safety awareness.

Numerical modelling of structural controls on fluid flow and mineralization

This paper presents the results of a set of numerical models focussing on structural controls on hydrothermal mineralization. We first give an overview of natural phenomena of structurally-controlled ore formation and the background theory and mechanisms for such controls. We then provide the results of a group of simple 2D numerical models validated through comparison with Cu-vein structure observed near the Shilu Copper deposit （Yangchun, Guangdong Province, China） and finally a case study of 3D numerical modelling applied to the Hodgkinson Province in North Queensland （Australia）. Two modelling approaches, discrete deformation modelling and continuum coupled deformation and fluid flow modelling, are involved. The 2D model-derived patterns are remarkably consistent with the Cu-vein structure from the Shilu Copper deposit, and show that both modelling approaches can realistically simulate the mechanical behaviours of shear and dilatant fractures. The continuum coupled deformation and fluid flow model indicates that pattern of the Cu- veins near the Shilu deposit is the result of shear strain localization, development of dilation and fluid focussing into the dilatant fracture segments. The 3D case-study models （with deformation and fluid flow coupling） on the Hodgkinson Province generated a number of potential gold mineralization

Decoupling Control of Fluid Catalytic Cracking Unit

This study presents a decoupling control scheme of fluid catalytic cracking unit to account for the high interaction between two temperature control loops. The feed flow rate load disturbance is introduced to test the proposed decoupling control scheme. Through simulation study shown that the decoupling is effective, stable and it presents advantage over controller without decoupler. Also, this scheme is able to offer good dynamic performance for most disturbances.

Control of facies and fluid potential on hydrocarbon accumulation and prediction of favorable Silurian targets in the Tazhong Uplift,Tarim Basin,China

Exploration practices show that the Silurian hydrocarbon accumulation in the Tazhong Uplift is extremely complicated.Our research indicates that the oil and gas accumulation is controlled by favorable facies and low fluid potential.At the macro level,hydrocarbon distribution in this uplift is controlled by structural zones and sedimentary systems.At the micro level,oil occurrences are dominated by lithofacies and petrophysical facies.The control of facies is embodied in high porosity and permeability controlling hydrocarbon accumulation.Besides,the macro oil and gas distribution in the uplift is also influenced by the relatively low fluid potential at local highs,where most successful wells are located.These wells are also closely related to the adjacent fractures.Therefore,the Silurian hydrocarbon accumulation mechanism in the Tazhong Uplift can be described as follows.Induced by structures,the deep and overpressured fluids migrated through faults into the sand bodies with relatively low potential and high porosity and permeability.The released overpressure expelled the oil and gas into the normal-pressured zones,and the hydrocarbon was preserved by the overlying caprock of poorly compacted Carboniferous and Permian mudstones.Such a mechanism reflects favorable facies and low potential controlling hydrocarbon accumulation.Based on the statistical analysis of the reservoirs and commercial wells in the uplift,a relationship between oil-bearing property in traps and the facies-potential index was established,and a prediction of two favorable targets was made.

Cerebrospinal fluid and neural stem cell niche control

Neurogenesis from inner brain neural stem cells （NSCs） is a process which takes place continuously in mammals through- out their life. However, the main ontogenic difference is the intensity of neurogenesis, which commences as a very intensive and global activity in the early embryonic brain （neural tube）, persists in fetal and newborn stages, and declines significantly in adulthood, becoming restricted to specific places with low neurogenic activity such as the subventricular zone （SVZ） and the subgranular zone （SGZ） in the dentate gyrus （DG） of the hippocampus.

Offshore Structural Control Considering Fluid Structure Interaction

Tuned Mass Damper （TMD） was applied to an offshore structure to control ocean wave-induced vibration, In the analysis of the dynamic response of the offshore structure, fluid-structure interaction is considered and the errors, which occur in the linearization of the interaction, are investigated. For the investigation of the performance of TMD in controlling the vibration, both regular waves with different periods and irregular waves with different significant wave heights are used. Based on the numerical analysis it is concluded that the fluid-structure interaction should be considered in the evaluation of the capability of TMD in vibration control of offshore structures.

Optimizing Control for Rotor Vibration with Magnetorheological Fluid Damper

The aim of this work is to analyze and design a control system for vibration reduction in a rotor system using a shear mode magnetorheological fluid(MRF)damper.A dynamic model of the MRF damper-rotor system was built and simulated in Matlab/Simulink to analyze the rotor vibration characteristics and the vibration reduction effect of the MRF damper.Based on the numerical simulation analysis,an optimizing control strategy using pattern search method was proposed and designed.The control system was constructed on a test rotor bench and experiment validations on the effectiveness of the proposed control strategy were conducted.Experimental results show that rotor vibration caused by unbalance can be well controlled whether in resonance region(70%)or in non-resonance region(30%).An irregular vibration amplitude jump can be suppressed with the optimization strategy.Furthermore,it is found that the rapidity of transient response and efficiency of optimizing technique depend on the pattern search step.The presented strategies and control system can be extended to multi-span(more than two or three spans)rotor system.It provides a powerful technical support for the extension and application in target and control for shafting vibration.

Bifurcation and stability of an improved time-delayed fluid flow model in internet congestion control

Based on the fluid flow time-delayed model proposed by Misra et al in internet congestion control, one modified time-delayed model is presented, where the influence of the communication delay on the router queue length is investigated in detail. The main advantage of the new model is that its stability domain is larger even without an extra controller. By linear stability analysis and numerical simulation, tbe effectiveness and feasibility of the novel model in internet congestion control are verified.

The Sixth International Conference on Fluid Power Transmission and Control(ICFP'2005)

Date: April 12-15, 2005 Venue: Zhejiang University, Hangzhou, P. R. China Organized by Institute of Mechatronic Control Engineering, Zhejiang University

Automotive Ride Comfort Control Using MR Fluid Damper

In this paper, the performance of automotive ride comfort using Bouc-Wen type magneto-rheological (MR) fluid damper is studied using a two degree of freedom quarter car model. The sliding mode control is used to force the MR damper to follow the dynamics of ideal sky-hock model. The model is tested on two excitations, the first is a road hump with severe peak amplitude and the second is a statistical random road. The results are generated and presented in time and frequency domains using Matlab/Simulink software. Comparison with the fully active, ideal semi-active and conventional passive suspension systems are given as a root mean square values. Simulation results, for the designed controller, show that with the controllable MR damper has a significant improvement for the vehicle road holding then its lateral stability as well as road damage in comparison with passive, fully active and ideal semi-active suspension systems.

大跨度公铁双层斜拉桥主梁涡激共振机理与控制

以拟建的某主跨808 m公铁双层斜拉桥为工程依托,采用节段模型风洞试验研究不同攻角下双层桁架梁断面的涡振性能及5种气动控制措施的抑振效果,结合计算流体动力学(CFD)静态绕流模拟,对比分析双层桁架梁断面的涡振机理及控制方法.研究表明:主梁断面原设计方案在+3°和0°风攻角下存在明显的竖向和扭转涡振现象,且振幅超过规范允许值;间隔封闭上层桥面栏杆或增设抑流板可有效抑制主梁扭转涡振,但竖向涡振振幅仍不满足规范要求;上弦杆外侧增设风嘴可有效抑制主梁竖向和扭转涡振,而下弦杆外侧增设风嘴对主梁涡振抑振效果有限.气流经主梁原设计断面上层桥面分离后,在其上下表面形成周期性脱落的大尺度旋涡,并在上层桥面后部再附,这是主梁发生竖向涡振的主要诱因;上弦杆外侧增设风嘴可引导气流平稳通过上层桥面,消除了周期性的旋涡脱落,并在其上表面形成一段狭长“回流区”,从而有效抑制了涡振的发生.

Vibration and Control of Pipes Conveying Fluid

The vibration and control of pipes conveying fluid is studied. The solid-liquid coupling vibration equations of the pipe conveying fluid are deduced by Hamilton principle.The direct velocity feedback is used to control the pipe vibration. The whip response and control are discussed.

控制杆-强制旋转对圆柱涡激振动的抑制作用研究

为实现圆柱涡激振动的高效抑制,本文基于控制杆-强制旋转组合结构讨论圆柱涡激振动的抑制问题。对低雷诺数下的圆柱涡激振动进行数值模拟研究,对比分析不同控制杆数量和圆柱转速比下的流场特性、振动响应和流体力响应等。结果表明:与裸圆柱相比,控制杆具有一定的涡激振动抑制效果;对于三、五控制杆,通过调节转速比,可以实现最高98%的圆柱振幅抑制(对三控制杆,转速比为0.4~0.6;对五控制杆,转速比为0~0.2);圆柱振幅抑制与圆柱减阻区间相同;对于四、六控制杆,旋转对振幅抑制的影响较小;主圆柱表面的漩涡脱落和漩涡的合并会引起流体力系数的高幅波动,导致圆柱高振幅响应;没有漩涡合并和圆柱表面脱涡不明显时,流体力系数则无明显波动,圆柱振幅也显著降低。

船用三通调节阀流-固耦合噪声数值模拟

针对船用PN10DN32三通调节阀噪声声压频谱、声指向性等声学特性规律不明确,噪声声压级是否满足使用要求的问题,基于流-固耦合理论,同时考虑流-固耦合面及流体域内的脉动声学激励源,开展阀门噪声数值模拟研究。分别对三通调节阀在80%及60%开度阀外1 m处的噪声进行数值模拟,分析研究噪声声压频谱特性及声指向性规律。结果表明:80%及60%开度下的噪声声压级分别为49.14 dB(A)、50.79 dB(A),均小于60 dB(A)的噪声限制,满足使用要求。该文为船用三通调节阀噪声数值模拟提供了理论及方法参考。

Controllability Approach for a Fluid Structure Interaction Problem

The present paper presents a new method to solve fluid structure interaction problem. Our computational method is based on controllability approach. Given a target structural displacement we will find a control steering the displacement of the structure u to . We need to define a payoff functional (J): where u solves the structure equation for the control and is a fixed value. Our aim is to find a control which minimizes the payoff criterion. And therefore we find u the beam displacement, v the velocity of the fluid and p the pressure of the fluid.

基于图和流体扰动算法的多无人车编队及避障研究

为解决多无人车编队在存在运动目标、移动威胁与突发威胁等多种情况的复杂环境中的避障问题,设计了一种基于刚性图论和流体扰动算法的多无人车编队避障控制算法。首先,针对编队控制问题,采用图论方法描述多无人车之间的协同关系,利用无人车之间的距离约束,基于反步控制理论设计领航-跟随编队控制器。李雅普诺夫分析表明,期望的编队形状是渐近稳定的。其次,针对复杂动态障碍物环境下的编队避障问题,设计了基于流体扰动算法的避障路径规划方法,由领航无人车规划出编队的行驶路径,实现编队的整体避障。最后,基于MATLAB的仿真结果验证了所提算法的有效性。

中高渗储层乳状液注入参数优化设计方法研究

乳状液作为一种新型的调驱体系,可以通过在多孔介质中的贾敏效应发挥流度控制作用,抑制驱油体系的窜进。在实施乳状液调驱时,不但要考虑体系的调堵能力,同时还需要综合考虑体系的注入性能。乳状液渗流不同于传统的牛顿流体渗流,其在多孔介质中的渗流压力不但受到自身黏度的影响,同时还受到吸附、滞留等作用的影响。本文基于乳状液的等效流动黏度建立了注入压力预测模型,采用Matlab编程软件定量计算了不同注入参数和注入方式下的流动阻力,该计算方法可以根据现场注采设备的基本性能,优选出复合体系的注入速度与注入量,在保证复合体系具有良好的调驱能力下还有良好的注入性,本研究为现场乳状液调驱施工提供了一种可行的定量设计方法。

50000 kN液压支架试验台垂直加载液压缸同步控制

针对超大采高液压支架试验台垂直加载液压缸同步控制问题,提出一种基于模糊进程标识符(PID)相邻交叉耦合同步控制策略,利用Creo-Adams及ANSYS建立液压支架试验台刚柔耦合动力学仿真模型,根据垂直加载实际工况添加约束条件。利用AMEsim及Matlab/Simulink建立垂直加载液压系统控制模型,基于各软件之间的接口技术构建Adams-AMEsim-Simulink机液控一体化的试验台多领域协同仿真模型。仿真得到模糊PID和常规PID下相邻交叉耦合同步控制策略的加载液压缸位移跟踪曲线、负载变化曲线、信号控制曲线、同步误差曲线。研究结果表明,相比于常规PID算法,模糊PID算法下的系统具有响应速度更快、控制精度更高等特点,使液压支架垂直加载四缸同步精度误差小于0.1 mm,满足使用要求。研究结论为液压支架试验台垂直外加载系统设计提供参考。

基于高分子材质的L型城市应急防洪屏受力分析

国内关于高分子材质城市内涝应急防御装备的研究较为少见。采用水槽试验与流固耦合数值仿真相结合的方法,对城市应急防洪屏(以下简称“防洪屏”)的结构受力特性展开研究。结果表明,数值仿真模拟与试验结果吻合较好。随着水深和流速的增大,防洪屏的应力和变形逐渐增大,最大应力位于防洪屏的踵部,最大变形位于挡水面顶部两侧。防洪屏的结构受力系数随着来流弗劳德数的增大快速衰减,当弗劳德数大于0.15后,结构受力系数趋于定值;相对于惯性力,防洪屏承受最大应力的影响因素主要是重力。研究结果可为防洪屏的进一步优化设计提供参考。