Statistical characteristics of phase measurement errors caused by harmonic noise

1992 ◽  
Vol 35 (2) ◽  
pp. 207-210
Author(s):  
A. M. Gladkin
Keyword(s):  
Measurement Errors ◽  
Phase Measurement ◽  
Statistical Characteristics ◽  
Harmonic Noise

Interferometry-based measurements of oil-film thickness

2001 ◽  
Vol 215 (3) ◽  
pp. 243-259 ◽  
Author(s):  
O Marklund ◽  
L Gustafsson
Keyword(s):  
Film Thickness ◽  
Measurement Errors ◽  
Phase Measurement ◽  
Elastohydrodynamic Lubrication ◽  
Oil Film ◽  
Interferometric Phase ◽  
Experimental Apparatus ◽  
Colour Parameters ◽  
Computer Based ◽  
The Absolute

Measurement of the thickness of thin lubricant films separating rotating surfaces in elastohydrodynamic experiments presents some challenging problems. The nature of the experimental apparatus inhibits the use of most commonly applied interferometric phase measurement methods. Also the absolute thickness of the separating film must be determined, as opposed to relative distances that would be sufficient in most other measurement scenarios where interferometry methods are used. In this paper, computer-based analysis of interferograms recorded using an elastohydrodynamic lubrication Fitzeu interferometer (a so-called ball-and-disc apparatus) is discussed, the main objective being to extract the absolute oil-film thickness. Intensity based methods (most importantly, calibration look-up procedures where colour parameters from recorded dynamic interferograms are compared with table values corresponding to known film thicknesses, but also a phase measurement approach based on multi-channel interferometry using trichromatic light) are described. A discussion regarding compensation for measurement errors due to the pressure dependence of the refractive index of the lubricant is also included.

scholarly journals Measurement errors of electromagnetic fields of industrial frequency in urban areas

2018 ◽  
Vol 170 ◽  
pp. 02020 ◽  
Author(s):  
Mariya Amirkhanyan ◽  
Fedor Bryukhan
Keyword(s):  
Electromagnetic Fields ◽  
Urban Areas ◽  
Measurement Errors ◽  
Large Scale ◽  
Negative Influence ◽  
Statistical Characteristics ◽  
Emf Measurements ◽  
Electrical Grid ◽  
North East ◽  
Industrial Frequency

The universal development of electrical grid infrastructure of the cities leads to an increase in the level of electromagnetic pollution of residential and especially industrial areas. Concern of the urban population about human exposure to potential danger of negative influence of electromagnetic fields (EMF) causes the need for large-scale EMF research in urban areas. To conduct this type of study, the estimates of measurement errors of intensities of the electrical and magnetic components of the EMF should be performed. The goal of this research is to assess the EMF measurement errors of the industrial frequency in urban areas. The error estimation of EMF measurements generated by power line communication was performed using the section of the territory of Moscow’s North East, as an example. The main statistical characteristics of measurement errors were determined. It is found that, when performing 3 series of measuring, the errors reduce by 1.5-3 times. When strong EMF intensities exist, it is recommended to carry out not one but a series of measurements with subsequent averaging of the results in each investigated point of the area.

Surface Topography Measurement Using Digital Moirè Contouring—Errors and Limitations

1995 ◽  
Vol 209 (4) ◽  
pp. 317-325 ◽  
Author(s):  
C Wykes ◽  
R Morshedizadeh
Keyword(s):  
Surface Topography ◽  
Measurement Errors ◽  
Phase Measurement ◽  
Single View ◽  
Maximum Accuracy ◽  
Wide Range ◽  
Optical Magnification ◽  
Potential Applications ◽  
Digital Moiré

Moiré contouring is a technique that enables the surface topography of an object to be measured in a single view and has a wide range of potential applications in manufacturing. However, to be useful, it is necessary to be able to calibrate the system and establish the traceability of the calibration. In this paper, the factors that determine the accuracy of the technique are identified, methods of calibration proposed and attainable accuracies estimated. These include the optical magnification, phase measurement and sensitivity, all of which contribute to measurement errors in the technique. The methods are illustrated with results from a digital moiré system, and the improvements required to obtain maximum accuracy are outlined.

scholarly journals A New Stochastic Model Updating Method Based on Improved Cross-Model Cross-Mode Technique

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 3290
Author(s):  
Hui Chen ◽  
Bin Huang ◽  
Kong Fah Tee ◽  
Bo Lu
Keyword(s):  
Stochastic Model ◽  
Galerkin Method ◽  
Measurement Errors ◽  
Model Updating ◽  
Measurement Data ◽  
New Method ◽  
Statistical Characteristics ◽  
Practical Significance ◽  
Cross Model ◽  
Coefficient Vector

This paper proposes a new stochastic model updating method to update structural models based on the improved cross-model cross-mode (ICMCM) technique. This new method combines the stochastic hybrid perturbation-Galerkin method with the ICMCM method to solve the model updating problems with limited measurement data and uncertain measurement errors. First, using the ICMCM technique, a new stochastic model updating equation with an updated coefficient vector is established by considering the uncertain measured modal data. Then, the stochastic model updating equation is solved by the stochastic hybrid perturbation-Galerkin method so as to obtain the random updated coefficient vector. Following that, the statistical characteristics of the updated coefficients can be determined. Numerical results of a continuous beam show that the proposed method can effectively cope with relatively large uncertainty in measured data, and the computational efficiency of this new method is several orders of magnitude higher than that of the Monte Carlo simulation method. When considering the rank deficiency, the proposed stochastic ICMCM method can achieve more accurate updating results compared with the cross-model cross-mode (CMCM) method. An experimental example shows that the new method can effectively update the structural stiffness and mass, and the statistics of the frequencies of the updated model are consistent with the measured results, which ensures that the updated coefficients are of practical significance.

scholarly journals Phase measurement errors due to holographic interferograms compression

2007 ◽  
Author(s):  
Emmanouil Darakis ◽  
Vijay Raj Singh ◽  
Anand K. Asundi ◽  
John J. Soraghan
Keyword(s):  
Measurement Errors ◽  
Phase Measurement

scholarly journals Analysis of Phase Evaluation Algorithms in an Interferometric Method for Static Deformation Measurement

10.14311/372 ◽  
2002 ◽  
Vol 42 (4) ◽  
Author(s):  
J. Novák
Keyword(s):  
Measurement Errors ◽  
Complex Analysis ◽  
Phase Measurement ◽  
Evaluation Process ◽  
Surface Shape ◽  
Interferometric Method ◽  
Phase Calculation ◽  
Calculation Algorithms ◽  
Negative Effect ◽  
Measurement And Evaluation

This article describes and analyses an interferometric method for measuring displacements and deformation. The method can be used for a very accurate evaluation of the change in the surface shape of structures used in industry. The paper proposes several multistep phase calculation algorithms and describes an automatic evaluation process using the measurement technique. A complex analysis is also performed of various factors that can have a negative effect on the practical measurement and evaluation process. An analysis is made of the proposed multistep phase calculation algorithms using the proposed error model. It is shown that the resulting phase measurement errors can be effectively reduced by using suitable phase calculation algorithms. The analysis can be applied for a complex comparison of the accuracy and stability of such algorithms.

Sign in / Sign up

Export Citation Format

Share Document