The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Richard Leach - One of the best experts on this subject based on the ideXlab platform.
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calibration and verification of areal surface texture Measuring Instruments
Cirp Annals-manufacturing Technology, 2015Co-Authors: Richard Leach, Han H Haitjema, Claudiu L Giusca, Christopher J Evans, Xiangqian JiangAbstract:In this paper, the calibration and verification infrastructure to support areal surface texture measurement and characterisation will be reviewed. A short historical overview of the subject will be given, along with a discussion of the most common Instruments and directions of current international standards. Traceability and uncertainty will be discussed, followed by a presentation of the latest developments in software and material measurement standards. The concept and current infrastructure for determining the metrological characteristics of Instruments will be highlighted and future research requirements will be presented.
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calibration of the scales of areal surface topography Measuring Instruments part 3 resolution
Measurement Science and Technology, 2013Co-Authors: Claudiu Giusca, Richard LeachAbstract:Calibration of the scales of areal surface topography Measuring Instruments requires testing of the resolution. Several designs of artefact that allow testing of the resolution of such Instruments are currently available; however, analysis methods need to be developed to provide comparable results. A novel method for determining the lateral resolution of areal surface topography Measuring Instruments is presented. The method uses a type ASP (star-shaped) material measure. To demonstrate the validity of the method, the resolution of a phase shifting interferometer was determined based on the ISO definition of the lateral period limit. Using the proposed method, the type ASP material measure, which is often used to judge qualitatively an instrument's resolution, can be used to quantitatively estimate the resolution of Instruments using the topography data.
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determination of the transfer function for optical surface topography Measuring Instruments a review
Measurement Science and Technology, 2013Co-Authors: Claudiu Giusca, Matthew R Foreman, Jeremy M Coupland, Peter Torok, Richard LeachAbstract:A significant number of areal surface topography Measuring Instruments, largely based on optical techniques, are commercially available. However,implementation of optical instrumentation into production is currently difficult dueto the lack of understanding of the complex interaction between the light and the component surface. Studying the optical transfer function of the instrument can help address this issue. Herea review is given of techniques for the measurement of optical transfer functions. Starting from the basis of a spatially coherent, monochromatic confocal scanning imaging system, the theory of optical transfer functions in three-dimensional (3D) imaging is presented. Further generalizations are reviewed allowing the extension of the theory to the description of conventional and interferometric 3D imaging systems. Polychromatic transfer functions and surface topography measurements are also discussed. Following presentation of theoretical results, experimental methods to measure the optical transfer function of each class of system are presented, with a focus on suitable methods for the establishment of calibration standards in 3D imaging and surface topography measurements.
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calibration of the scales of areal surface topography Measuring Instruments part 2 amplification linearity and squareness
Measurement Science and Technology, 2012Co-Authors: Claudiu L Giusca, Richard Leach, Frank HeleryAbstract:Methods for determining the amplification coefficient, linearity and squareness of the axes of areal surface topography Measuring Instruments are presented. The methods are compliant with draft international specification standards on areal surface texture. A method of calibrating the z-axis scale according to the guidelines given in surface profile specification standards, which is applied to areal measurements, is first presented. Then a method of calibrating the scales of the x and y axes using cross grating artefacts, and which is not based on pitch measurement, is introduced. A method for extending the calibrated range of the z-axis scale, which uses multiple overlapped measurements of a step height artefact, is also discussed.
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calibration of the scales of areal surface topography Measuring Instruments part 1 measurement noise and residual flatness
Measurement Science and Technology, 2012Co-Authors: Richard Leach, Claudiu L Giusca, Franck Helary, Tadas Gutauskas, Lakshmi NimishakaviAbstract:In this paper, we present methods for determining the measurement noise and residual flatness of areal surface topography-Measuring Instruments. The methods are compliant with draft international specification standards on areal surface texture. We first introduce the international standards framework and then present current methods based on averaging and subtraction to isolate the measurement noise and residual flatness from the sample surface topography. These methods are relatively difficult to apply and time consuming in practice. An alternative method is presented based on thresholding and filtering techniques. This method is simple to apply in practice. Traceability and measurement uncertainty are discussed.
Claudiu L Giusca - One of the best experts on this subject based on the ideXlab platform.
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calibration and verification of areal surface texture Measuring Instruments
Cirp Annals-manufacturing Technology, 2015Co-Authors: Richard Leach, Han H Haitjema, Claudiu L Giusca, Christopher J Evans, Xiangqian JiangAbstract:In this paper, the calibration and verification infrastructure to support areal surface texture measurement and characterisation will be reviewed. A short historical overview of the subject will be given, along with a discussion of the most common Instruments and directions of current international standards. Traceability and uncertainty will be discussed, followed by a presentation of the latest developments in software and material measurement standards. The concept and current infrastructure for determining the metrological characteristics of Instruments will be highlighted and future research requirements will be presented.
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calibration of the scales of areal surface topography Measuring Instruments part 2 amplification linearity and squareness
Measurement Science and Technology, 2012Co-Authors: Claudiu L Giusca, Richard Leach, Frank HeleryAbstract:Methods for determining the amplification coefficient, linearity and squareness of the axes of areal surface topography Measuring Instruments are presented. The methods are compliant with draft international specification standards on areal surface texture. A method of calibrating the z-axis scale according to the guidelines given in surface profile specification standards, which is applied to areal measurements, is first presented. Then a method of calibrating the scales of the x and y axes using cross grating artefacts, and which is not based on pitch measurement, is introduced. A method for extending the calibrated range of the z-axis scale, which uses multiple overlapped measurements of a step height artefact, is also discussed.
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calibration of the scales of areal surface topography Measuring Instruments part 1 measurement noise and residual flatness
Measurement Science and Technology, 2012Co-Authors: Richard Leach, Claudiu L Giusca, Franck Helary, Tadas Gutauskas, Lakshmi NimishakaviAbstract:In this paper, we present methods for determining the measurement noise and residual flatness of areal surface topography-Measuring Instruments. The methods are compliant with draft international specification standards on areal surface texture. We first introduce the international standards framework and then present current methods based on averaging and subtraction to isolate the measurement noise and residual flatness from the sample surface topography. These methods are relatively difficult to apply and time consuming in practice. An alternative method is presented based on thresholding and filtering techniques. This method is simple to apply in practice. Traceability and measurement uncertainty are discussed.
Tenko Raykov - One of the best experts on this subject based on the ideXlab platform.
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Strong Convergence of the Coefficient Alpha Estimator for Reliability of Multiple-Component Measuring Instruments
Structural Equation Modeling: A Multidisciplinary Journal, 2018Co-Authors: Tenko RaykovAbstract:It is shown that in general the popular coefficient alpha estimator for reliability of multi-component Measuring Instruments converges almost surely to a quantity that is not equal to the population reliability coefficient. This convergence with probability 1 is a stronger statement than convergence in probability (consistency) and convergence in distribution for the alpha estimator, which have been studied in the past. In the special case of congeneric measures with uncorrelated errors and equal loadings on the common true score, the alpha estimator converges almost surely to the population reliability coefficient that equals population alpha, which implies also its consistency as a reliability estimator. When the loadings are unequal but sufficiently high and similar, the alpha estimator converges almost surely to population alpha that is essentially indistinguishable from the population reliability coefficient, which implies alpha’s approximate consistency then. For the general case, the results entail...
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Studying Latent Criterion Validity for Complex Structure Measuring Instruments Using Latent Variable Modeling
Educational and psychological measurement, 2017Co-Authors: Tenko Raykov, Natalja Menold, George A. MarcoulidesAbstract:Validity coefficients for multicomponent Measuring Instruments are known to be affected by measurement error that attenuates them, affects associated standard errors, and influences results of statistical tests with respect to population parameter values. To account for measurement error, a latent variable modeling approach is discussed that allows point and interval estimation of the relationship of an underlying latent factor to a criterion variable in a setting that is more general than the commonly considered homogeneous psychometric test case. The method is particularly helpful in validity studies for scales with a second-order factorial structure, by allowing evaluation of the relationship between the second-order factor and a criterion variable. The procedure is similarly useful in studies of discriminant, convergent, concurrent, and predictive validity of Measuring Instruments with complex latent structure, and is readily applicable when Measuring interrelated traits that share a common variance source. The outlined approach is illustrated using data from an authoritarianism study.
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can reliability of multiple component Measuring Instruments depend on response option presentation mode
Educational and Psychological Measurement, 2016Co-Authors: Natalja Menold, Tenko RaykovAbstract:This article examines the possible dependency of composite reliability on presentation format of the elements of a multi-item Measuring instrument. Using empirical data and a recent method for interval estimation of group differences in reliability, we demonstrate that the reliability of an instrument need not be the same when polarity of the response options for its individual components differs across administrations of the instrument. Implications for empirical educational, behavioral, and social research are discussed.
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Evaluation of True Criterion Validity for Unidimensional Multicomponent Measuring Instruments in Longitudinal Studies
Structural Equation Modeling, 2016Co-Authors: Tenko Raykov, George A. MarcoulidesAbstract:Longitudinal studies offer unique opportunities to identify the specificity variance in the components of a psychometric scale that is administered repeatedly. This article discusses a procedure for evaluation of the relationship between true scale scores and criterion variables uncorrelated with measurement errors in longitudinally presented measures comprising unidimensional multicomponent Instruments. The approach provides point and interval estimates of the true scale criterion validity with respect to a criterion that is assessed once or repeatedly, as well as a means for testing temporal stability in this validity. The outlined method is based on an application of the latent variable modeling methodology, is readily applicable with popular software, and is illustrated using empirical data.
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maximal reliability and composite reliability examining their difference for multicomponent Measuring Instruments using latent variable modeling
Structural Equation Modeling, 2016Co-Authors: Tenko Raykov, Siegfried Gabler, Dimiter M DimitrovAbstract:A latent variable modeling method for examining the difference between maximal reliability and composite reliability for homogenous multicomponent Measuring Instruments is outlined. The procedure allows point and interval estimation of the discrepancy between the reliability coefficients associated with the optimal linear combination and with the popular unit-weighted sum of the scale components. The approach permits a researcher to make an informed choice if needed between the maximal reliability and composite reliability coefficients and concepts in an empirical setting as indexes of quality of measurement with an instrument under consideration. The discussed method is illustrated using numerical data.
Han H Haitjema - One of the best experts on this subject based on the ideXlab platform.
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calibration and verification of areal surface texture Measuring Instruments
Cirp Annals-manufacturing Technology, 2015Co-Authors: Richard Leach, Han H Haitjema, Claudiu L Giusca, Christopher J Evans, Xiangqian JiangAbstract:In this paper, the calibration and verification infrastructure to support areal surface texture measurement and characterisation will be reviewed. A short historical overview of the subject will be given, along with a discussion of the most common Instruments and directions of current international standards. Traceability and uncertainty will be discussed, followed by a presentation of the latest developments in software and material measurement standards. The concept and current infrastructure for determining the metrological characteristics of Instruments will be highlighted and future research requirements will be presented.
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bandwidth characteristics and comparisons of surface texture Measuring Instruments
Measurement Science and Technology, 2010Co-Authors: Richard Leach, Han H HaitjemaAbstract:In this review we will discuss many of the problems that are encountered when designing and carrying out comparisons of surface texture Measuring Instruments. Previous comparisons are discussed to highlight some of the key issues. The limitations of stylus and optical Instruments are identified with a focus on the spatial bandwidths in which they operate. Guidance is given on how to design comparisons to avoid variations in the results that are due to the operating principles and bandwidth limitations of the Instruments involved. Methods for matching the bandwidths of different Instruments are presented and some examples are given that highlight potential problems. The software aspects of instrument comparisons are also discussed. Finally, some advice is given on how to compare profile and areal surface texture measurements.
Frank Helery - One of the best experts on this subject based on the ideXlab platform.
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calibration of the scales of areal surface topography Measuring Instruments part 2 amplification linearity and squareness
Measurement Science and Technology, 2012Co-Authors: Claudiu L Giusca, Richard Leach, Frank HeleryAbstract:Methods for determining the amplification coefficient, linearity and squareness of the axes of areal surface topography Measuring Instruments are presented. The methods are compliant with draft international specification standards on areal surface texture. A method of calibrating the z-axis scale according to the guidelines given in surface profile specification standards, which is applied to areal measurements, is first presented. Then a method of calibrating the scales of the x and y axes using cross grating artefacts, and which is not based on pitch measurement, is introduced. A method for extending the calibrated range of the z-axis scale, which uses multiple overlapped measurements of a step height artefact, is also discussed.
