Micro-mechanical properties of shale due to water/supercritical carbon dioxide-rock interaction

To investigate the impacts of water/supercritical CO_(2)-rock interaction on the micro-mechanical properties of shale,a series of high-temperature and high-pressure immersion experiments were performed on the calcareous laminated shale samples mined from the lower submember of the third member of Paleogene Shahejie Formation in the Jiyang Depression,Bohai Bay Basin.After that,grid nanoindentation tests were conducted to analyze the influence of immersion time,pressure,and temperature on micro-mechanical parameters.Experimental results show that the damage of shale caused by the water/supercritical CO_(2)-rock interaction was mainly featured by the generation of induced fractures in the clay-rich laminae.In the case of soaking with supercritical CO_(2),the aperture of induced fracture was smaller.Due to the existence of induced fractures,the statistical averages of elastic modulus and hardness both decreased.Meanwhile,compaction and stress-induced tensile fractures could be observed around the laminae.Generally,the longer the soaking time,the higher the soaking pressure and temperature,the more significant the degradation of micro-mechanical parameters is.Compared with water-rock interaction,the supercritical CO_(2)-rock interaction caused a lower degree of mechanical damage on the shale surface.Thus,supercritical CO_(2)can be used as a fracturing fluid to prevent the surface softening of induced fractures in shale reservoirs.

Investigation of Micro-mechanical Response of Asphalt Mixtures by a Three-dimensional Discrete Element Model

The micro-mechanical response of asphalt mixtures was studied using the discrete element method. The discrete element sample of stone mastic asphalt was generated first and the vehicle load was applied to the sample. A user-written program was coded with the FISH language in PFC3 D to extract the contact forces within the sample and the displacements of the particles. Then, the contact forces within the whole sample, in asphalt mastic, in coarse aggregates and between asphalt mastic and coarse aggregates were investigated. Finally, the movement of the particles in the sample was analyzed. The sample was divided into 15 areas and a figure was drawn to show how the balls move in each area according to the displacements of the balls in each area. The displacements of asphalt mastic balls and coarse aggregates were also analyzed. The experimental results explain how the asphalt mixture bears vehicle load and the potential reasons why the rutting forms from a micro-mechanical view.

Micro-mechanical properties of 2219 welded joints with twin wire welding

Nanoindentation method was adopted to investigate the distribution regularities of micro-mechanical properties of 2219 twin wire welded joints, thus providing the necessary theoretical basis and guidance for joint strengthening and improvement of welding procedure. Experimental results show that in weld zone, micro-mechanical properties are seriously uneven. Both hardness and elastic modulus distribute as uneven sandwich layers, while micro-mechanical properties in bond area are much more uniform than weld zone;In heat-affected zone of 2219 twin wire welded joint, distribution regularity of hardness is similar to elastic modulus. The average hardness in quenching zone is higher than softening zone, and the average elastic modulus in solid solution zone is slightly higher than softening zone. As far as the whole welded joint is concerned, metal in weld possesses the lowest hardness. For welded specimens without reinforcement, fracture position is the weld when tensioning. While for welded specimens with reinforcement, bond area is the poorest position with joint strength coefficient of 61%. So, it is necessary to strengthen the poor positions--weld and bond area of 2219 twin wire welded joint in order to solve joint weakening of welding this kind of alloy.

INCREMENTAL MICRO-MECHANICAL MODEL OF PLAIN WOVEN FABRIC

Warp yarns and weft yarns of plain woven fabric are the principal axes of mate- rial of fabric. They are orthogonal in their original con?guration, but are obliquely crisscross in deformed con?guration in general. In this paper the expressions of incremental components of strain tensor are derived, the non-linear model of woven fabric is linearized physically and its geometric non-linearity survives. The convenience of determining the total deformation is shown by the choice of the coordinate system of the principal axes of the material, with the convergence of the incremental methods illustrated by examples. This incremental model furnishes a basis for numerical simulations of fabric draping and wrinkling based on the micro-mechanical model of fabric.

随钻陀螺GyroSphere在渤海油田浅层防碰作业中的应用

随着渤海油田勘探开发的不断深入,平台槽口数量的不断增多,布井密度急剧增加,再加上隔水管及直井段偏斜的影响,大大增加了浅层碰撞套管的风险,防碰形势日益严峻。针对渤海油田某井浅层面临的突出防碰问题,首次引入斯伦贝谢随钻陀螺GyroSphere工具,安全顺利地完成了本井浅层防碰绕障作业。通过对本次施工的作业总结和技术展望,提出了利用随钻陀螺工具更好地解决相关问题的良好做法。

基于电极模态切换的半球谐振陀螺自校准方法

针对因受加工技术、加工条件以及外部环境因素等影响,半球谐振陀螺在力平衡模式下输出零偏稳定性及重复性变化较大的问题,提出一种基于模态切换的陀螺自校准方法。基于半球谐振陀螺二阶振动模态机理,建立理想状态下谐振子运动方程,并分析推导了谐振子在阻尼不均和频率裂解等非理想因素影响下的运动模型和参数控制方程。根据谐振陀螺输出漂移特性,提出了一种基于电极功能切换的半球谐振陀螺自校准方法。通过相关实验,分析比较了电极模态切换前后陀螺输出稳定性及重复性,实验结果表明,陀螺零偏稳定性提升1.8倍以上,陀螺零偏重复性提升90.5%,所提方法能有效估计及补偿陀螺漂移,提高半球谐振陀螺输出的稳定性和重复性。

长寿命半球谐振陀螺惯性姿态敏感器设计与在轨应用

针对未来航天器对惯性姿态敏感器高可靠和长寿命的应用需求,首先设计了一种基于4通道冗余方案的4S半球谐振陀螺惯性姿态敏感器。其次,针对高可靠、长寿命惯性姿态敏感器研制过程中的关键技术开展研究和验证。最后,对所提产品的在轨应用情况进行了评估,评估结果表明设计的半球谐振陀螺惯性姿态敏感器4轴姿态测量功能正常,在轨性能与地面测试性能相当。通过地面验证和在轨应用情况,综合评估所设计产品寿命不低于20年,可靠度不低于0.98。

基于超短脉冲激光刻蚀的双解耦MEMS陀螺仪调频技术研究

以双解耦双质量硅微陀螺仪为主要研究对象,从微观结构入手,分析其工作原理和双解耦运动模型,并提出影响模态特征频率的因素。提出一种改变陀螺仪弹性梁结构厚度来调整其特征频率的方法,建立模型通过Comsol软件仿真陀螺仪梁厚度变化对特征频率的影响关系,并选择皮秒激光刻蚀系统刻蚀陀螺弹性梁厚度,测试其两模态特征频率。测试结果表明:对应频率变化符合理论推导和仿真趋势。

CPSO优化PNN的陀螺故障诊断方法

针对惯性导航系统中的陀螺仪输出信号非线性、故障特征不明显的问题,为提高惯导系统中惯性器件的故障诊断正确率,提出一种基于改进粒子群算法(PSO)优化概率神经网络(PNN)的陀螺信号故障诊断方法。首先,针对光纤陀螺运行过程中常见的四种故障信号,建立数学模型并进行小波变换提取其故障特征系数;其次,使用Cubic混沌映射以及非线性递减的惯性权重系数对粒子群进行粒子更新,并用于概率神经网络的最优平滑因子选择;最后,训练概率神经网络对陀螺仪故障信号进行分类和诊断。离线测试结果表明,CPSO算法优化的PNN网络针对四种故障分类的平均正确率达到95.8%。

G波段二次谐波准光回旋行波管研究

为开展适用于太赫兹频段的大功率回旋放大器研究。对基于准光共焦波导的二次谐波准光回旋行波管进行了研究,理论与仿真结果表明,准光波导具有良好的模型选择性,利用器件的二次谐波工作,其基波与二次谐波的返波振荡可以得到很好的抑制。在理论与仿真研究基础上,设计了一只G波段的二次谐波准光回旋行波管,理论计算结果表明:在65 kV电子束电压、10 A电流、速度横纵比为1、磁场强度为4.19 T时,最大输出功率为90 kW,效率为13.8%,增益为34.8 dB。当输入功率10 W时,-3 dB带宽为2 GHz。

Target Seeker Gyro and Controls

A composite target seeker gyro with dual spectral range infrared rays and millimeter waves, and the associated control methodology are developed. The static pressure air floated ball bearing is used to sustain the outer frame, the optical fiber and wave guide are used to transmit these two kinds of signals to the rear part of the gyro, and the stator coils are used to get non contact angular measurement. Composite guiding, scanning, tracing and controlling can be achieved, the maximum tracing angular velocity can be as high as 16(°)/s.

高精度惯性导航系统的技术预见

面对水下装备无人化/智能化的发展趋势,系统分析国内外知名惯性导航系统生产公司的产品,梳理水下装备的核心设备—惯性导航系统的发展趋势。基于工具检索国内外知名惯性导航系统公司的公开文献、专利以及产品手册等开源信息,提炼关键信息以及参数进行对比分析。目前,光纤陀螺惯性导航系统在国内已成为实现水下装备高精度定位的核心产品,基于谐振陀螺的惯性导航系统尚处于研发阶段。国际市场上,基于激光陀螺的惯性导航产品正逐渐被基于谐振陀螺和光纤陀螺的惯性产品替代。从法国赛峰和Exail这两家顶尖公司的产品指标看,谐振陀螺高精度惯性产品相比光纤陀螺高精度惯性产品而言,无论在体积还是在质量上都有较大优势,后续可能完全替代光纤陀螺系统成为市场主流。

GYRO BIAS ON-ORBIT CALIBRATION FOR MICRO SATELLITES

According to gyro application in micro-satellites, a new gyro bias real-time on-orbit calibration technology is presented and it is independent of any other sensors. The approach relies on gyro on-orbit measurements restricted by satellite attitude dynamics and estimates the gyro bias generated when the gyro is electrified. Observability of the calibration model is analyzed and applicable conditions of the technology are derived. Simulation results indicate that the calibration algorithm is accurate and robust at gyro sampling rate, and its convergence speed is fast. Within the given attitude dynamics model error, the convergence time is less than 100 s and the convergence accuracy is about 1.0 （°）/h. Calibration performance can meet requirements of spacecraft operations.

谐振式光学陀螺噪声抑制技术研究现状(特邀)

谐振式光学陀螺仪利用光学谐振腔在时空上对光波极强的局域增强效应,有望成为兼具高精度和小体积的光学陀螺。然而,谐振式陀螺转动产生的Sagnac效应相对微弱,容易受到陀螺系统内非互易性以及互易性噪声的干扰,成为其精度提升的瓶颈。在陀螺的小型化过程中这一问题更加凸显。因此,对谐振式光学陀螺仪进行噪声抑制显得尤为重要。本文详细综述了谐振式光学陀螺中非互易性和互易性两大类噪声的原理及其抑制方法,总结了该领域近来年的研究现状及未来挑战与发展趋势,为我国谐振式光学陀螺发展提供参考。

Application of wavelet package filtering in the de-noising of fiber optic gyroscopes

To reduce the drift error existing in the output signal of fiber optic gyroscopes （FOG）, a mathematical model of the FOG output signal is set up; the error characteristics of the FOG output signal are analyzed, and semi-soft threshold filtering is chosen based on the comparison of hard threshold and soft threshold filtering. The semi-soft threshold wavelet package filtering method is applied in the filtering of the FOG output signal. Experiments of the stationary and dynamic FOG output signals filtered with the wavelet package analysis are carried out in a lab environment, respectively. Experiments done with the real-time measured FOG signal show that the method of semi-soft threshold wavelet package filtering reduces the mean square error from 5 （°）/h to 1 （°）/h, so it is effective in eliminating the white noises and the fractal noises existing in the FOG. The novel method proposed here is proved valid in reducing the FOG drift error, satisfying the technical demands of high precision and realtime processing.

GYROMAT 2000陀螺经纬仪定向程序探讨

本文对Gyromat 2000高精度自动陀螺经纬仪的定向程序进行了初步的探讨。首先介绍了自动陀螺仪定向的关键技术,如三点法和积分法观测原理,图解了步进测量的原理,这是分析定向程序的理论基础。接着对三个定向程序相关步骤的用时和精度进行了实测,并以测试结果为参照,对各定向程序进行了合理的猜测。本文的成果将对国产陀螺经纬仪的自动化进程起到一定的参考作用。

基于FPGA与AD9786的调制解调电路的设计

谐振式光学陀螺因其高理论精度、小型化以及高稳定性受到了国内外的强烈关注。针对于谐振式光学陀螺检测信号微弱的特点,需要对该信号进行调制解调,以实现陀螺的稳定输出,设计了一种基于FPGA和AD9786的高精度模拟信号源,该信号以FPGA作为核心控制单元,AD9786作为数模转换器,实现16位的高精度DA转换,通过上位机实现指令的通信过程,可实现不同频率的交流信号。该实验结果表明,该系统符合陀螺测试系统调制解调要求,通过上位机对不同输出信号进行测试,且测试结果无纹波时输出噪声Vrms269μV,交流信号精度达到0.01%,最高频率可达到2M,稳定性高。

基于外弹道和姿态陀螺的导弹攻角和侧滑角解算方法

为获取导弹攻角和侧滑角信息,提出一种基于外弹道和姿态陀螺信息的导弹攻角和侧滑角解算方法。通过导弹外弹道计算导弹弹道倾角和弹道偏角,综合弹上姿态陀螺信息,解算出导弹攻角和侧滑角,用于分析导弹受控特性及弹体气动参数辨识,进一步优化导弹控制系统设计参数。结果表明:本方法简单、有效,可推广应用到所有弹上有姿态测量装置,且可实现外弹道测量的制导弹药飞行攻角和侧滑角分析。

An extended micromechanical-based plastic damage model for understanding water effects on quasi-brittle rocks

Water effects on the mechanical properties of rocks have been extensively investigated through experiments and numerical models.However,few studies have established a comprehensive link between the microscopic mechanisms of water-related micro-crack and the constitutive behaviors of rocks.In this work,we shall propose an extended micromechanical-based plastic damage model for understanding weakening effect induced by the presence of water between micro-crack’s surfaces on quasi-brittle rocks,based on the Mori-Tanaka homogenization and irreversible thermodynamics framework.Regarding the physical mechanism,water strengthens micro-crack propagation,which induces damage evolution during the pre-and post-stage,and weakens the elastic effective properties of rock matrix.After proposing a special calibration procedure for the determination of model parameters based on the laboratory compression tests,the proposed micromechanical-based model is verified by comparing the model predictions to the experimental results.The model effectively captures the mechanical behaviors of quasibrittle rocks subjected to the weakening effects of water.

CHZ-Ⅱ海洋重力仪研制与实践

海洋重力仪是获取高精度高分辨率海洋重力场的重要仪器,主要应用于资源勘探、大地水准面精化、海洋科学研究和重力辅助惯性导航等领域。我国现有的海洋重力仪主要依靠国外进口,不仅价格高,而且在仪器的引进、维护等方面存在诸多的不便。在科技部首批重大科学仪器专项的支持下,基于CHZ海洋重力仪成功研制出具有完全自主知识产权的CHZ-Ⅱ弹簧式海洋重力仪。该新型重力仪采用金属零长弹簧作为测量元件,其独特的轴对称垂直悬挂结构可克服交叉耦合效应;高精度伺服控制技术及强阻尼的应用可克服载体扰动的影响,确保仪器在不同海况下保持测量精度;高精度恒温技术及温度补偿技术可消除环境温度波动对仪器测量精度的影响。本文介绍了该仪器的工作原理、系统构成、技术特点及测试结果。静态试验表明其月漂移优于3 mGal;码头系泊试验表明其动态精度达到0.2 mGal,能清晰反映海潮的重力变化特征;总航程超过5万海里船载试验表明其综合测量精度优于1 mGal。仪器在精度和稳定性上达到与国内外同类仪器并跑水平,可替代当前国外进口的海洋重力仪。