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Key engineering materials
Trans Tech Publications Ltd.
Key engineering materials

Trans Tech Publications Ltd.

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1013-9826

Key engineering materials/Journal Key engineering materials
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    Optical Hilbert Diagnostics of the Vortical Structures Induced by the Pressure Front on an Aperture

    Vitaly A. ArbuzovYury N. DubnishchevNikolay A. DvornikovViktor G. Nechaev...
    P.208-211页
    查看更多>>摘要：The methods of Hilbert optics widely use in tasks of visualization and measurement of phase optical density in fluids. In this work, the problem of vortex rings generation upon sudden opening of a cylindrical chamber containing a gas at elevated pressure is considered. At diffraction of pressure front on an aperture in a wall the vortical rings propagated in the opposite directions from the wall have been detected by optical Hilbert methods.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Uncertainty Analysis of Helical Deviation Measurements

    Shi ZhaoyaoLin JiachunMichael Krystek
    P.212-216页
    查看更多>>摘要：The helix is a complex geometrical element. During the process of a dynamical measurement of the helical deviations, many factors, including the machine and the environment, lead to measurement errors. Although ISO as well as national standards stipulate the tolerances and assessment methods for helical deviations, these standards contribute little to the uncertainty calculations concerning such measurements. According to the Guide to the Expression of Uncertainty in Measurement (GUM), all measurement results must have a stated uncertainty associated to them. But in most cases of helical deviation measurements, no uncertainty value is given, simply because no measurement uncertainty calculation procedure exists. For the case of helical deviation measurements on a Computer Numeric Control (CNC) polar coordinate machine, this paper analyses in detail all kinds of factors contributing to the measurement uncertainty, and gives the calculation procedure of the measurement uncertainty of helical deviation. As an example, the calculation of the measurement uncertainty of the helical deviations of a worm is presented.
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    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Uncertainty Calculation of Roundness by Automatic Differentiation

    Lin JiachunMichael KrystekShi Zhaoyao
    P.217-221页
    查看更多>>摘要：According to the Guide to the Expression of Uncertainty in Measurement (GUM), all measurement results must have a stated uncertainty associated to them. But in most cases of roundness measurement either no uncertainty value is given, or the calculation is not based on the model of the respective association criterion for the geometrical feature, because no suitable measurement uncertainty calculation procedure does exist. For the case of roundness measurement in coordinate metrology, this paper will suggest algorithms for the calculation of the measurement uncertainty of the roundness deviation based on the two mainly used association criteria LSC and MZC. The calculation of the sensitivity coefficients for the uncertainty calculation can be done by automatic differentiation, in order to avoid introducing additional errors by the traditional difference quotient approximations. The proposed methods are exact and need as input data only the measured co-ordinates of the data points and their associated uncertainties.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Least Squares Association of Geometrical Features by Automatic Differentiation

    Michael KrystekShi ZhaoyaoLin Jiachun
    P.222-226页
    查看更多>>摘要：Least squares association of geometrical features plays an important role in geometrical product specification and verification. Most existing algorithms for the least squares association today usually do not give the covariance matrix associated with the parameters of the respective geometrical feature. The reason is that the complexity of these algorithms can be very high, because partial differential quotients are needed. If the necessary partial difference quotients are calculated by hand and subsequently coded into an algorithm, there is a high risk to introduce unwillingly errors. This paper shows how the least squares algorithm can automatically be generated solely from the equation specifying the distance function of the measured points from the geometrical feature.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Study and Improvement of a Destructive 3D Digitizer Based on Grinding Technique

    Wei-chen LeePo-Kai Hsu
    P.227-231页
    查看更多>>摘要：The objective of this research was to study and improve the destructive 3D digitizer based on grinding technique that was developed previously. It is shown that the grinding technique used in the 3D digitizer generates better surface condition than the milling technique commonly used in other 3D digitizers, and this is beneficial to the subsequent image processing to obtain the profiles of the cross-sectional images. To increase the overall image resolution, an image-merging method was employed by putting a fiducial on top of the object to allow us to merge partial images into a full image. One of the key factors for the success of image processing is to have good contrast between the object and the background material, and we developed a program with a controllable power supply to automatically adjust the illumination based on the histograms of the images to obtain the maximum contrast. At the end, we performed an experiment by using Taguchi method and found out that the grinding depth is the most significant factor that can be controlled on the destructive 3D digitizer for burr length reduction.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Error Modeling and Compensation for High-precision Non-contact Four Coordinate Measuring System

    Fei ZhangZhuangde JiangBing LiJianjun Ding...
    P.232-236页
    查看更多>>摘要：The error compensation technique is used to improve the accuracy of non-contact high-precision measuring system. To ensure the accuracy of the high-precision non-contact four-coordinate blade profile measuring system, the geometric and thermal error compensation model is proposed in this paper. The system is composed of three orthogonal coordinate axes (X, Y and Z) and a rotation axis R. The coordinate transformation matrix can be calculated by the mathematical model of rigid body which is established according to the related theoretical analysis. Three-beam interferometer and standard gauge block are adopted to verify the geometric error of the system. In the thermal deformation error compensation, wavelet neural network model is established. The thermal and geometric error compensation methods are analyzed and the experimental results are given.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Inner-Base Optoelectronic System for the Control of Linear Displacements

    Konstantin G. ArakantsevIgor A. KonyakhinAleksandr N. Timofeev
    P.237-241页
    查看更多>>摘要：The principle of inner-base optoelectronic system for the control of objects linear displacements is considered. The ways for improvement of measurements accuracy are pointed out.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    A Study of Key Optical Profiler Parameters for Form Error Measurement

    X. HuangY. Gao
    P.242-246页
    查看更多>>摘要：Optical profiler is a typical modern device for precision form error measurement. In our use of the equipment, we found that the surface form profile after stitching is ambiguous if the lens magnification is changed. The error in terms of PV value can be up to 3200% when the lens magnification changes from 2.5 times to 30 times. This has been confirmed by the equipment supplier. It is worthwhile to offer a comprehensive study as many users may use the instrument of the kind straightforward without detailed investigation of the performance. We found that, among the 6 key parameters studied, 3 independent parameters are more important. For the 3 independent parameters, we recommend to set the magnification A=2.5 times, the resolution r=0.5, and the overlap p=20%. With the recommended settings, the measurement error can be less than 0.5%. Backscan and length for scanning in the vertical direction, and cut off frequency for delivering form profile are less critical compared with the three independent parameters.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Laser Doppler Visualization of 2D Velocity Fields with Minimization Dependence from Multi-Particle Scattering

    Yu.N. DubnishchevYu.V. ChuguiJurgen Kompenhans
    P.247-252页
    查看更多>>摘要：The method of laser Doppler visualization and measurement of 2D velocity vector field in flows with minimization of influence of a multi-particle scattering is discussed. The investigated section in the flow is illuminated with a laser sheet. Our approach is based on reception of a pair wise difference of normalized frequency-demodulated images of a laser sheet in light beams scattered in various directions. The 2D velocities field is formed from linear combinations of images of the laser sheet in frequency-demodulated light scattered in directions orthogonal to it.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Estimation of Uncertainty of Coordinate Measurements According to the Type B Method

    Wladyslaw Jakubiec
    P.253-257页
    查看更多>>摘要：The paper describes a new method for analytical estimation of the uncertainty component introduced by the CMM, including temperature influence. The uncertainty is estimated separately for each characteristic (dimension or geometrical deviation) given in the geometrical specification. The uncertainty is calculated directly, i.e. no analysis of the accuracy of determination of particular geometrical elements is performed. The fundamental condition enabling analytical estimation of the uncertainty is assumption that uncertainty of coordinate measurement depends on the differences of coordinates of characteristic points used to calculate particular deviation.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd