一种双通道测角系统的设计

本文介绍一种由旋转变压器和感应同步器作敏感元件组成的双通道采样测角系统。该测角系统采用双相激磁，单相输出鉴相工作方式，具有精度高、可靠性好、易实现、温度鲁棒性好等优点，能满足高精度惯导测试的要求，是高精度转台的重要组成部分。     

感应同步器测角系统误差分析及补偿

本文讨论了提高感应同步器精度的硬件方法和软件方法。硬件方法即根据误差来源，针对不同谐波成分误差，用电路调节的方法消除误差。软件方法就是采用计算机通过误差曲线拟合来减小误差。     

旋转变压器-感应同步器双通道测角系统一次谐波误差补偿

由旋转变压器和感应同步器组成的精粗双通道测角系统可达到较高的精度。但由于感应同步器安装、布线等原因会造成一次谐波误差。要提高测角精度，必须对一次谐波误差进行补偿。本文对一次谐波误差进行了定量分析，并提出了一种有效的补偿方法     

精密测角系统的幅相变换与误差补偿

本文重点介绍ＳＪ－１型测角系统幅相变换部分的工作原理、误差分析及误差补偿。该系统的主要特点是：采用单相激磁的双通道工作方式，在幅相变换和误差补偿方面，突破了一次谐波和二次谐波误差补偿的技术关键，具有较高的抗干扰能力及长期工作的稳定、可靠。     

感应同步器鉴幅测角系统静态误差分析及关键电路设计

本文系统论述了采用感应同步器进行角位置测量的连续绕组激磁，分段绕组输出的鉴幅方案，对这个方案的工作原理进行介绍，并对此方案产生的静态误差进行分析，给出减小误差的方法，最后得出相关结论。     

大型精密离心机光栅测角系统的设计与实现

对JML－1大型精密离心机主轴光栅测角系统的关键技术进行了研究,给出了如何解决光栅测角系统的精度问题。抗干扰问题和动态测角问题的设计方法及测试结果。     

基于轴角转换器的一种高精度动态测角系统

设计了一种基于轴角转换器AD2S80的高精度感应同步器动态测角系统，分析了测角误差产生原因，提出了误差调整和补偿措施。通过实例数据表明：用谐波分析的方法对测角误差进行了调整与补偿，从而可大幅度提高测角精度。     

经纬仪测星评估惯导系统姿态角误差方法

针对动态条件航天测量船惯导系统姿态角精度鉴定和评估这个困扰多年的难题,提出一种利用经纬仪观测恒星对惯导姿态角误差进行解算的方法:用短时间(每颗星记录2 s)观测方位角大致均匀分布的多颗恒星数据解算惯导姿态角误差的稳态分量;用较长时间(每颗星记录200 s以上)观测特殊方位角单颗恒星的数据,观察惯导姿态角误差的动态特性,详细介绍了该方法数学模型的推导过程,从理论上分析了该方法各种数据误差源对解算精度的影响,并利用实际观测数据对惯导姿态角误差稳态分量和动态特性进行了解算和观察,结果与航天测量船惯导系统的设计指标基本吻合,表明该方法可以作为评估航天测量船惯导系统姿态角动态精度的一种有效手段.     

基于转台误差分析的高精度惯测组合标定编排改进

转台误差影响高精度惯测组合标定精度。利用姿态转换四元数建立了转台误差模型,分析了转台误差对一种典型惯测组合标定编排方案的影响。在分析转台误差影响规律的基础上,提出了一种标定编排改进方案,可以有效抑制转台误差,提高标定精度。仿真和试验对标定编排改进前后的标定精度和导航性能进行了对比,表明改进编排方案可以提高陀螺和加速度计安装误差角标定精度,改善系统导航性能。     

转台测角系统标定方法的研究

本文提出一种高精度转台测角系统标定的新方法，该方法以光电自准直仪作为标定基准，用齿盘、多面棱镜作角度给定，转台工作在速率状态下，自动完成高精度转台测角系统标定任务，给出标定精度和误差曲线。该方法避免了人为因素造成的测量和计算误差，使标定过程更加快捷、准确、可靠。     

现行扭转角测试误差分析

对现行扭转角测试误差进行了分析计算,给出了直曲误差及综合误差计算公式, 指出了提高测试精度的方法和现行扭转角测试方法的局限性.     

用三线摆方法测试物体转动惯量的误差问题

通过对均质圆盘的转动惯量用实验方法测试的结果和理论精确值的对比,揭示了摆线长度是三线摆方法测试物体转动惯量精度的主要影响因素. 从而对这种方法的等效条件作了进一步的讨论和补充.     

BP混沌混合神经网络在光纤陀螺温度漂移预测中的应用

提出使用BP混沌混合神经网络建立FOG温度漂移模型的方法.该方法在BP算法中采用了改进型Logistic-Map映射生成的混沌变量,能够避免陷入局部最小,可迅速达到全局最优.应用该方法分析某型FOG温度漂移实测数据,结果表明其具有良好的预测效果.     

Improved methods for measuring laminar-turbulent intermittency in boundary layers

The last stage of laminar-turbulent transition in boundary layers is commonly described using the spatial distribution of intermittency. Existing methods for computing this laminar-turbulent intermittency from experimental data involve the use of thresholds that are set by the experimentalist using subjective comparisons to the raw signal. These threshold settings cannot be reproduced by other experimentalists using different equipment, so a precise determination of intermittency is not currently possible. This note reports on a new method of determining boundary-layer intermittency that appears to be objective and reproducible. The wall shear was measured in a flat-plate boundary layer using hot-film sensors. Probability density functions (PDF's) of the calibrated wall shear are remarkably consistent. A correlation to the turbulent portion of these PDF's is given. The consistency observed in these PDF's suggests an objective and reproducible setting for the laminar-turbulent cutoff threshold. Intermittencies determined using this method can be compared quantitatively, with any differences being caused only by experimental error or differences in the flows. The universality of the method can be determined through comparisons to measurements in other flows.     

挠性陀螺系统不对称性误差研究

首先从原理上分析其产生的原因,不对称性误差主要是由于陀螺系统中各环节的输入-输出关系并不是理想的线性特性而引起的;然后对陀螺系统不对称性误差进行定量分析,采用一种寻优的方法估算出不对称性误差值大小,并用实验进行验证;最后提出了一种不对称性误差的补偿方法,即在陀螺角速度模型中增加角速度绝对值项.实验结果证明了其简单有效性.     

Necessary discrete condition for error control of time-domain methods in milling stability prediction

Nonlinear Dynamics - Stability prediction is an efficient way to avoid milling chatter which is one of the major limitations in increasing efficiency of milling operations. Prediction accuracy is...     

Proportional and derivative control for steady-state vibration mitigation in a piecewise linear beam system

A control using Proportional and/or Derivative feedback (PD-control) is applied on a piecewise linear beam system with a flushing one-sided spring element for steady-state vibration amplitude mitigation. Two control objectives are formulated: (1) minimize the transversal vibration amplitude of the midpoint of the beam at the frequency where the first harmonic resonance occurs, (2) achieve this in a larger (low) excitation frequency range, where the lowest nonlinear normal mode dominates the response. Experimentally realizable combinations of PD-control are evaluated for both control objectives. Eventually objective (1) is realized by applying proportional control only, whereas derivative control is selected to realize objective (2). The vibration reduction that is achieved in simulations and validated by experiments is very significant for both objectives. Current results obtained with active PD-control are compared with earlier results obtained using a passive dynamic vibration absorber.     

DVL安装角估计方法在水下组合导航系统中的应用

对于INS/DVL组合导航系统,如何准确估计出DVL与载体之间的安装关系是影响组合导航系统精度的关键因素,针对该问题提出了一种在线迭代递推算法,应用卡尔曼滤波技术,对此安装关系进行估计。并对安装关系中的状态变量的可观性进行分析,给出了满足可观性所需的条件以及舰船运动方式。设计出了估计滤波器,并进行了实际船载实验。实验结果表明:在安装角误差小于10°的情况下,迭代计算两次后误差小于0.1°,估计精度满足要求,算法有效可行。该方法代替了人工光学标定方法,具有很好的工程应用价值。     

Uncertainty quantification in a chemical system using error estimate-based mesh adaption

This paper describes a rigorous a posteriori error analysis for the stochastic solution of non-linear uncertain chemical models. The dual-based a posteriori stochastic error analysis extends the methodology developed in the deterministic finite elements context to stochastic discretization frameworks. It requires the resolution of two additional (dual) problems to yield the local error estimate. The stochastic error estimate can then be used to adapt the stochastic discretization. Different anisotropic refinement strategies are proposed, leading to a cost-efficient tool suitable for multi-dimensional problems of moderate stochastic dimension. The adaptive strategies allow both for refinement and coarsening of the stochastic discretization, as needed to satisfy a prescribed error tolerance. The adaptive strategies were successfully tested on a model for the hydrogen oxidation in supercritical conditions having 8 random parameters. The proposed methodologies are however general enough to be also applicable for a wide class of models such as uncertain fluid flows.