系统误差

Furthermore, how to apply the model efficiently in practice is deeply discussed. As the variance produced by the forecasting model as concerned, the real-time revised method of hydrological forecasting is highlighted. Next arranged, the multi-stratum recursive prediction model is put forward to forecast the error series that is a dynamic system. Later, an error selfregressive multi-stratum recursive prediction model is set up as well as a current algorithm offered. Finally, the difference collated model and the gloss control method, which are devoted to updating the mid-long term hydrological forecasting during the meditate period, are put forward.

在综合评述中长期水文预报现有方法和模型的基础上，采用时间序列分析方法，建立中长期水文预报的时间序列组合模型，并对模型如何在实际中有效应用作了较为深入的探讨；针对模型预报所产生的误差，又重点研究了水文预报实时修正方法：提出了采用多层递阶预报方法对误差序列这一动态系统进行预报，建立了误差自回归多层递阶预报模型，并提出了较为通用的解算方法；给出了水文中长期预报中期修正的残差相关模型和总量控制方法。

Retrace error of nonnull aspheric testing is analyzed in detail with conclusions that retrace error has much to do with the aperture, relative aperture and surface shape error of the apsheric under test.

分析了非球面非零位检测系统中的回程误差问题，得出了回程误差与被测非球面口径、相对口径以及非球面本身面形误差均紧密相关的结论。

H. Lan . The position control of electrohydraulic servomechanism via a novel variable structure control.

当误差较大时，控制系统的主要目的是尽快消除误差，此时误差的权重系数应取大些。

The phase mismatch error is the main error source of sound intensity measurement system.

相位失配误差是声强测量系统的主要误差源，仅靠提高仪器的精度很难消除这一误差。

This paper analysed generating mechanism of the dynamic error induced by the model truncation error and presented a method of varying shift matrix to reduce the effect of the model truncation error on system performance.

文中分析了产生动态偏差的机理，提出了一种根据截断误差大小选取不同位移矩阵来校正截断误差的方法，减小了截断误差对系统性能的影响。

While this situation is inadaptable for quantified description of time error in distributed cooperative measurement,this paper,integrat...

基于此，结合误差分析理论和网络被动测量的具体特点，提出了针对单点双信道被动测量系统的一般性时钟误差概率模型，引入误差不确定度来定量描述协调测量结果的精确度和合理性。

In order to reduce the influence of position error in every standstill-position of turntable on north-seeking precision, the work process of the Dynamically Tuned Gyro multi-position north seeker and the principle of the azimuth arithmetic are introduced, and the relation between position error and north-seeking precision is analyzed.

针对实验过程中转台在每个转位处存在的转位误差对系统寻北精度的影响，介绍了动调陀螺多位置寻北仪的工作过程及真北解算原理，进行了转位误差对寻北精度影响的误差分析。

A new technique,"Curvature Method", recognizing edges of gear cutters is introduced, the tracking principle for scanning edge profile of gear cutter is developed and a robust method is proposed to automatically distinguish boundary points of assessing region.

系统地研究了螺旋曲面特征线的测量原理，建立了特征线的误差模型，给出了相应的误差评定方法；并首次将特征线误差划分为三种基本形态，同时给出了各形态的数学模型。

Periodic fluid pulsation in aeroplane hydraulic piping could induce fluid-construction vibration and lead to fatigue damage. It is impossible to find the error sensor's optimization location because of the pressure standing wave, and the pulsation attenuation effect is not perfect when adopting pulsation attenuation at single point. For this reason, a distributed active control method of fluid pulsation was presented. To avoid stationary point in all aviation states, several fluid pulsation actuators and error pressure sensors were placed along the piping. The second fluid pulsation produced by actuators can counteract the primary pulsation brought by aviation piston pump and make the mean pulsation of whole piping minimum when adopting adaptive feed- forward control and the filtered-X least mean square algorithm.

针对飞机液压能源管路系统中的周期性流体脉动诱发流固耦合振动，导致管路疲劳损伤的问题，针对管路中存在压力驻波特性，在采用单点消振时寻找误差传感器最佳布局位置困难而引起脉动抑制效果不理想的缺点，提出了一种分布式流体脉动主动控制方法，即沿管路不同位置布置多个主动消振阀和误差压力传感器，在任意飞行阶段，避开压力驻波点，以误差压力传感器的脉动测量值为控制目标，采用一种针对周期脉动主动控制的自适应前馈控制法和多通道自适应滤波－X LMS算法，调整控制器参数，使主动消振器产生的次级脉动与管路中的初始脉动相互抵消，达到整个管路中的平均流体脉动最小的效果。

Comparison of the synchronous measurement result of this receiver with that of a reference one shows the error trend is the same. The scatter plots of the horizontal error and vertical error distribution show that this measurement system is more stable and can reflect the position information exactly.

该接收机和参考接收机的同步测量结果表明，两个接收机对定位信息获取的误差趋势相同，通过接收机的水平误差散点图和时间序列垂直误差分布图可见，该测量系统较稳定，可准确地反映定位点的位置信息。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。