Errors in near-field radioholography

Formulae are given for the aperture plane phase errors which are incurred in near-field radioholography of reflector antennas when a simple Fresnel correction is used. Approximate analytic expressions are derived for circular data windows and antennas with parabolic illumination taper. Infocus and defocused cases are treated. Numerical simulations are used for estimating errors for square data windows     

Errors in dynamic force measurement

Loadcells for materials testing machines are calibrated statically by comparison with a transfer standard, traceable to the National Physical Laboratory. There is evidence to suggest that, under certain conditions, this static calibration may be insufficient for dynamic testing. The possibility of an error being generated by the inertia of the mass between the loadcell and the specimen is discussed and the results of experiments to measure this error are presented. For the case chosen it is shown that the inertia error may be predicted by calculation. Errors may also arise from the method of dynamic force measurement. The conventional DVM and the analogue peak hold voltmeter are widely used but are subject to errors in a practical machine situation due to their method of operation. Bandwidth limitations are also illustrated for a number of instruments with different sampling rates. A better, although more expensive and complicated solution is to digitise the signal and to use some form of spectral analysis such as the Fast Fourier Transform or the Cross Correlation Integral. The theory for the latter is presented and its merits discussed.     

Errors of Measurement in Statistics

In this review of some of the recent work in the study of errora of measurement, attention is centered on the type of mathematical model used to represent errom of measurement, on the extent to which standard techniques of analysis become erroneous and misleading if certain types of errors are present (and the possible remedial procedures), and the techniques that are available for the numerical study of errors of measurement.     

Errors in cubic spline interpolation

Summary This paper deals with the problem of finding error bounds for cubic spline interpolation of functions of the classC ⁴[a, b], andC ⁵[a, b], by examining a relationship between cubic spline interpolation and piecewise cubic Hermitian interpolation.The method also gives an indication of what happens, in the case of almost uniform meshes, especially if the approximated function is in the classC ⁵[a, b].Comparison is made with recent work carried out by K. E. Atkinson [3], in dealing with natural cubic spline interpolation.     

Errors of multipliers

Conclusions The errors of a multiplier depend not only on the errors of the units but also on the magnitudes of the quantities to be multiplied.If the inputs vary widely, a squaring multiplier has twice the error of a logarithmic one. If the inputs are similar in magnitude, a squaring multiplier has less error than a logarithmic one.Translated from Izmeritel'naya Tekhnika, No. 5, pp. 10–13, May, 1971.     

Errors in Results and Measurement Provisions

The relative and reduced errors of measurement provisions and the relative errors of measurements are considered. Analytical expressions are provided that make it possible to evaluate the errors in question. Conclusions and practical recommendations are given.Translated from Izmeritel’naya Tekhnika, No. 3, pp. 71–72, March, 2005.