Volume 8 (2008): Issue 2 (January 2008)

The paper suggests algorithms enabling self-calibration of measurement channels with linear as well as nonlinear conversion functions. To approximate conversion characteristics, interpolation methods are used. They are widely known; however, the essence of the suggested self-calibration method is the current modernization of interpolating functions parameters due to a suitable procedure. It enables correction of the two essential error components which may appear in the measurement channel by means of evaluating the current value of the real slope of the conversion characteristic as well as of the components describing nonlinearity generated by disturbing factors. The methods of self-calibration for measurement channels cooperating with non-electrical quantities sensors are compared. Interpolation of conversion functions is assumed as linear in intervals and polynomial.

The main purpose of this paper is to present the external correction of analog to digital converters (ADC) integral nonlinearity and quantization noise based on the look up table method (LUT) combined with the averaging and Wiener filtering and dithering method. The LUT compression and LUT precision effect are also studied.

The realization, maintenance and dissemination of the SI base unit, the kilogram, is one of the tasks of the NMI's mass laboratory and is assured by means of reference standards which are traceable to the International Kilogram Prototype through the mass of the National Prototypes. This paper describes the dissemination of mass scale from 1 kg reference standard to weights of E1 class between (1…10) kg, using one of the two methods of calibration: subdivision or multiplication. The paper compares the variance of each weight obtained by both methods. The presented subdivision method deals with a link of standards following the example of Mihailov - Romanowski where the measurements start downwards from 10 kg to 1 kg. The multiplication method is the one usually used in many calibration laboratories and starts from 1 kg to 10 kg. The paper also presents an example of calibration and uncertainty calculations.

An optical structured illumination of 3D object as a light band method for automatic noncontact wear measurement and defects detection of a contact wire network is presented. The experimental device can extract main technological wire parameters like remaining height with RMS value down to 0.15 mm. Also the cross-sectional area of the wire can be measured with RMS area noise value of 1.5 mm2, which is sufficient for a confident decision-making related to the automatic wire wears and defects on railways, tram and trolleybus lines, and similar systems of vehicles electro-supply.

This paper deals with signal processing for vibration analysis of the gear transmission. The main goal was localization of the best measuring point on the gearbox housing, which could provide the highest sensitivity to gearwheels vibration. Vibration measured at some selected points on the gearbox housing was analysed using methods of spectral analysis. The important frequencies in the vibration spectra and a value of their importance were estimated using Group of Adaptive Models Evolution. This work was done within the framework of experimental research concerned with testing and lifetime estimation of new designs of gearwheels. The lifetime of an examined gearwheel, which is mainly related to rise of pitting faults, was assessed by monitoring of a gearwheel vibration level.

At the end of 2007, the world's largest particle accelerator, the LHC (Large Hadron Collider), will be ready to collide first particles. Protons will be accelerated in a ring of 27 km circumference, contained inside an evacuated pipe of 60mm diameter. At four interaction points, where the large particle detectors are placed, this beampipe is made from beryllium in order to limit the multiple scattering of particles on their way from the interaction point to the detector. In order to keep the sag in the pipe to acceptable levels, accurate monitoring of the forces in the cables, which hold the beryllium beampipe in place, is required. The beampipe is installed in an environment of 0.5 T magnetic field and is expected to absorb a dose of 1 Mrad in ten years. These special constraints and the lack of accessibility preclude most standard monitoring systems. Previous work has shown that strain gauge based systems work well under the described conditions. This report shows that the monitoring system for the ALICE beryllium beampipe requires a minimum sensor size which results in μ V effective range for the signal. The device provides the requested resolution of 1 N.