EWB在拉压测试仪误差分析中的应用

Electronics Workbench(EWB)软件是加拿大Interactive Image Technology公司推出的用于电子电路仿真的虚拟电子工作台软件。它可以对模拟、数字或混合电路进行仿真。本文在分析了整个系统的误差分配情况后,着重介绍如何利用ElectronicsWorkbench对拉压测试仪各主要功能模块进行误差分析,实现了对仪器的准确评估及进一步优化设计。

齿轮径向综合误差检测分析

被测齿轮的径向综合误差包含有用来作为测量齿轮的理想精确齿轮的误差,这一现象可在对齿轮加工后出现的径向综合误差进行分析时发现。而理想精确齿轮的误差与被测齿轮径向综合误差之间可能存在叠加和抵消,从而导致被测齿轮误收或误判。定性分析了两种误差之间的关系以避免误收或误判,并提出了为避免这些情况发生而在检测时应重视和考虑的问题。

矩阵扰动分析方法及对三维重构误差分析的应用

三维重构问题是一个由二维图像获取三维信息的逆问题，由成像模型的复杂性所决定，其数据很容易受到各方面因素的影响，本文是利用矩阵扰动理论来研究研究矩阵元素的变化对于矩阵间题的解的影响。由于在测量数据处理中，经常要利用矩阵方法对测量观测数据进行分析和解算，因此我们便可通过矩阵扰动分析的方法分析其解算结果，从而对成像的数据进行处理并有效的评价。

关于冬测成果与工程规划设计误差的探讨

本文通过对寒区地面冻胀引起冬测成果误差的分析及利用冬测成果进行工程规划设计出现的问题,提出了相应的对策,对提高工程规划设计的质量具有一定的实际意义。

纳米三坐标测量机不确定度分析与精度设计

利用现代精度设计理念设计纳米三坐标测量机的结构,选用高精度的零部件进行组装,解决了传统阿贝误差问题,通过研究现代精度保障理论和技术,进行纳米级水平的误差源全面分析,推导各个不确定度分量的计算公式,根据给定的精度指标设计合理的精度,提出所需检定仪器的具体技术指标,精度设计的结果满足了纳米三坐标测量机的测量精度要求.

Error Analysis and Compensation of Strapdown Inertial Navigation System

Based on error analysis, the influence of error sources on strapdown inertial navigation systems is discussed. And the maximum permissible component tolerances are established. In order to achieve the desired accuracy (defined by circular error probability), the types of appropriate sensors are chosen. The inertial measurement unit (IMU) is composed of those sensors. It is necessary to calibrate the sensors to obtain their error model coefficients of IMU. After calibration tests, the accuracy is calculated by uniform design method and it is proved that the accuracy of IMU is satisfied for the desired goal.

3-D fracture network dynamic simulation based on error analysis in rock mass of dam foundation

Accurate 3-D fracture network model for rock mass in dam foundation is of vital importance for stability,grouting and seepage analysis of dam foundation.With the aim of reducing deviation between fracture network model and measured data,a 3-D fracture network dynamic modeling method based on error analysis was proposed.Firstly,errors of four fracture volume density estimation methods(proposed by ODA,KULATILAKE,MAULDON,and SONG)and that of four fracture size estimation methods(proposed by EINSTEIN,SONG and TONON)were respectively compared,and the optimal methods were determined.Additionally,error index representing the deviation between fracture network model and measured data was established with integrated use of fractal dimension and relative absolute error(RAE).On this basis,the downhill simplex method was used to build the dynamic modeling method,which takes the minimum of error index as objective function and dynamically adjusts the fracture density and size parameters to correct the error index.Finally,the 3-D fracture network model could be obtained which meets the requirements.The proposed method was applied for 3-D fractures simulation in Miao Wei hydropower project in China for feasibility verification and the error index reduced from 2.618 to 0.337.

Development of analysis model for geometric error in turning processes

A finite element model was established for analyzing the geometric errors in turning operations and a two-step analyzing process was proposed. In the first analyzing step, the cutting force and the cutting heat for the cutting conditions were obtained using the AdvantEdge. Also, the deformation of a workpiece was estimated in the second step using the ANSYS. The deformation was analyzed for a 150 mm-long workpiece at three different measuring points, such as 10, 70 and 130 mm from a reference point, and the amounts of the deformation were compared through experiments. /n the results of the comparison and analysis, the values obtained from these comparison and analysis represent similar tendencies. Also, it is verified that their geometric errors increase with the increase in temperature. In addition, regarding the factors that affect the deformation of a workpiecc, it can be seen that the geometric error in the lathe is about 15%, the error caused by the cutting force is about 10%, and the deformation caused by the heat is about 75%.

Analysis of Error for a Rotating Strap-down Inertial Navigation System with Fibro Gyro

The error equation of a rotating inertial navigation system was introduced. The effect of the system's main error source (constant drift of gyro and zero bias of accelerometer) under rotating conditions for the system was analyzed. Validity of theoretical analysis was shown via simulation, and that provides a theoretical foundation for a rotating strap-down inertial navigation system during actual experimentation and application.

Geometric Approximation Technique for Minimum Zone Sphericity Error

The mathematical modeling for evaluation of the sphericity error is proposed with minimum radial separation center. To obtain the minimum sphericity error from the form data, a geometric approximation technique was devised. The technique regarded the least square sphere center as the initial center of the concentric spheres containing all measurement points, and then the center was moved gradually to reduce the radial separation till the minimum radial separation center was got where the constructed concentric spheres conformed to the minimum zone condition. The method was modeled firstly, then the geometric approximation process was analyzed, and finally,the software for data processing was programmed. As evaluation example, five steel balls were measured and the measurement data were processed with the developed program. The average iteration times of the approximation technique is 4.2, and on average the obtained sphericity error is 0. 529μm smaller than the least square solution,with accuracy increased by 7. 696%.

Remedial Learning： A CALL Approach

Computer Assisted Language Learning （CALL） has been in use as a learner centered method since 1960. In this paper an attempt is made to evolve a Remedial Grammar （RG） which enables the teacher to develop a repertoire of remedial activities based on the errors identified following Error Analysis （EA） for repeated presentation. The error types are considered as teaching/learning points. The present paper argues that CALL is the right model for effective remedial learning. Remedial Gmaster （RGm）, an authoring package is introduced. This is an exclusive mode of error correction in which interlingual, intralingual, developmental, and global errors are dealt with. The syntactical problems due to the subtle difference between simple past and perfect tenses in English language use are discussed and CALL authoring package presented.

Error Analysis of Robotic Assembly System Based on Screw Theory

Assembly errors have great influence on assembly quality in robotic assembly systems. Error analysis is directed to the propagations and accumula-tions of various errors and their effect on assembly success.Using the screw coordinates, assembly errors are represented as 'error twist', the extremely compact expression. According to the law of screw composition, relative position and orientation errors of mating parts are computed and the necessary condition of assembly success is concluded. A new simple method for measuring assembly errors is also proposed based on the transformation law of a screw.Because of the compact representation of error, the model presented for error analysis can be applied to various part- mating types and especially useful for error analysis of complexity assembly.

A new a priori error estimate of nonconforming finite element methods

This paper is devoted to a new error analysis of nonconforming finite element methods.Compared with the classic error analysis in literature,only weak continuity,the F-E-M-Test for nonconforming finite element spaces,and basic Hm regularity for exact solutions of 2m-th order elliptic problems under consideration are assumed.The analysis is motivated by ideas from a posteriori error estimates and projection average operators.One main ingredient is a novel decomposition for some key average terms on(n.1)-dimensional faces by introducing a piecewise constant projection,which defines the generalization to more general nonconforming finite elements of the results in literature.The analysis and results herein are conjectured to apply for all nonconforming finite elements in literature.

Forecast scheme and strategy for extended-range predictable components

Although extended-range forecasting has exceeded the limit of daily predictability of weather,there are still partially predictable characteristics of meteorological fields in such forecasts.A targeted forecast scheme and strategy for extended-range predictable components is proposed.Based on chaotic characteristics of the atmosphere,predictable components and unpredictable random components are separated by using the standpoint of error growth in a numerical model.The predictable components are defined as those with slow error growth at a given range,which are not sensitive to small errors in initial conditions. A numerical model for predictable components(NMPC)is established,by filtering random components with poor predictability.The aim is to maintain predictable components and avoid the influence of rapidly growing forecast errors on small scales. Meanwhile,the analogue-dynamical approach(ADA)is used to correct forecast errors of predictable components,to decrease model error and statistically take into account the influence of random components.The scheme is applied to operational dynamical extended-range forecast(DERF)model of the National Climate Center of China Meteorological Administration (NCC/CMA).Prediction results show that the scheme can improve forecast skill of predictable components to some extent, especially in high predictability regions.Forecast skill at zonal wave zero is improved more than for ultra-long waves and synoptic-scale waves.Results show good agreement with predictability of spatial scale.As a result,the scheme can reduce forecast errors and improve forecast skill,which favors operational use.

Large-scale spatial angle measurement and the pointing error analysis

A large-scale spatial angle measurement method is proposed based on inertial reference. Common measurement reter- ence is established in inertial space, and the spatial vector coordinates of each measured axis in inertial space are measured by using autocollimation tracking and inertial measurement technology. According to the spatial coordinates of each test vector axis, the measurement of large-scale spatial angle is easily realized. The pointing error of tracking device based on the two mirrors in the measurement system is studied, and the influence of different installation errors to the pointing error is analyzed. This research can lay a foundation for error allocation, calibration and compensation for the measurement system.

Upper spectral bounds and a posteriori error analysis of several mixed finite element approximations for the Stokes eigenvalue problem

This paper discusses conforming mixed finite element approximations for the Stokes eigenvalue problem. Firstly, several mixed finite element identities are proved. Based on these identities, the following new results are given： （1） It is proved that the numerical eigenvalues obtained by mini-element, P1-P1 element and Q1-Q1 element approximate the exact eigenvalues from above. （2） As for the P1-P1, Q1-Q1 and Q1-Po element eigenvalues, the asymptotically exact a posteriori error indicators are presented. （3） The reliable and efficient a posteriori error estimator proposed by Verfiirth is applied to mini-element eigenfunctions. Finally, numerical experiments are carried out to verify the theoretical analysis.

A POSTERIORI ERROR ANALYSIS OF NONCONFORMING METHODS FOR THE EIGENVALUE PROBLEM

This paper extends the unifying theory for a posteriori error analysis of the nonconformingfinite element methods to the second order elliptic eigenvalue problem.In particular,the authorproposes the a posteriori error estimator for nonconforming methods of the eigenvalue problems andprove its reliability and efficiency based on two assumptions concerning both the weak continuity andthe weak orthogonality of the nonconforming finite element spaces,respectively.In addition,the authorexamines these two assumptions for those nonconforming methods checked in literature for the Laplace,Stokes,and the linear elasticity problems.

Analysis of effective capacity for free-space optical communication systems over gamma-gamma turbulence channels with pointing errors

To facilitate the efficient support of quality-of-service(Qo S)for promising free-space optical(FSO)communication systems,it is essential to model and analyze FSO channels in terms of delay Qo S.However,most existing works focus on the average capacity and outage capacity for FSO,which are not enough to characterize the effective transmission data rate when delay-sensitive service is applied.In this paper,the effective capacity of FSO communication systems under statistical Qo S provisioning constraints is investigated to meet heterogeneous traffic demands.A novel closed-form expression for effective capacity is derived under the combined effects of atmospheric turbulence conditions,pointing errors,beam widths,detector sizes and Qo S exponents.The obtained results reveal the effects of some significant parameters on effective capacity,which can be used for the design of FSO systems carrying a wide range of services with diverse Qo S requirements.