The aim of this paper is to present a new method used to calculate the long term stability and drift of a group of standard inductors of the Laboratory of Capacitance and Inductance (Lacin), of the National Institute of Metrology, Normalization and Industrial Quality (Inmetro). Using the concepts of time series and standard error of estimate, we developed an automated system with the objective of determining the drift (tendency), the long term stability and to forecast future values, what constitutes a powerful tool in the control and in the conservation of measurement standards.
The basic information concerning opportunities of doctoral degree study in measurement and instrumentation in the Czech Republic is mentioned in the first part of the paper. The study is running usually as a specialisation of the branch control engineering. The separate study programme "Measurement and Instrumentation" is running at the Czech Technical University in Prague – Faculty of Electrical Engineering, which is described in the second part of paper in detail.
This paper deals with the generation of low-distortion sine wave signal by means of low-cost filter for the purpose of ADC testing at the signal frequency of 20 kHz. The design and manufacture of such a filter is proposed and the functionality of a prototype is verified on a top digitizer.
This paper deals with the assessment of the metrological performance of analog-to-digital converters in order to use them in some metrology applications. Hence, digitizers of a commercial DVM have been characterized under DC voltages, with respect of several parameters such as aperture time, dead time and the autozero function.
In the paper are stated methods of education of electronic measurement circuits at Department of Measurement of FEE CTU in Prague. There are specified typically themes applied in bachelor and master grade of study. The education is supported by the set of electronic function units, universal laboratory units LABORO and simulation program MULTISIM.
Semiconductor heterostructures of nanometric dimensions represent a challenge in Metrology, requiring innovations and new developments. A single quantum well is the simplest structure of this nature, the basis for many optoelectronic devices, like lasers. In this work it is calculated the eigenstates of electrons, light holes and heavy holes of quantum wells of GaAs into Al 0.2 Ga 0.8 As. It was varied the width of these wells by typical monolayer values, and evaluated implications in the electronic transitions from valence band to conduction band. Results demonstrated that uncertainties as...
A new controlled-clearance pressure balance has been developed to improve the hydraulic pressure standard for pressures up to 1 GPa. For several controlled-clearance piston-cylinders, characterization experiments based on the Heydemann-Welch model were performed to estimate the effective area of them. The results for the piston-cylinders of different pressure ranges are exemplified in this paper. Some of the piston-cylinders showed different characteristics from those expected by the model at higher pressures. To change the deformational characteristics in response of the jacket pressure,...
A recent improvement on the ancillary instrumentation and on the acquisition software of the 100 kN and 500 kN INRIM six-component dynamometers makes it possible to measure the parasitic components at static conditions and during the weight transition too, in order to weigh up the influence of the dynamic phenomena on the value of axial load. This paper presents the main results of the evaluation of the parasitic components arising in static and dynamic conditions on the INRIM 1 MN force standard machine by using the INRIM 500 kN six-components dynamometer. It shows that the values of...
When applying digital sampling to high-accuracy electrical measurements, aliasing and quantization errors contribute significantly to increase the incertitude. Fractional delay is a simple technique to reduce both errors, improving the accuracy of electrical digital measurements. In this paper we apply the fractional delay technique to asynchronous data acquisition and harmonic estimation of periodic signals. We also combine the use of the fractional delay technique with Principal Component Analysis. We present simulations and laboratory measurements to illustrate both techniques.
Basis weight of paper web is an important property for quality management, but rather slow and expensive to measure. It is known that light transmittance is related to basis weight and thus a potential means for estimating the basis weight of paper. The basis weight is of interest in quality management from single fibre scale (0.1 mm) to scale of paper machine control effects scale (more than 10 km). This paper studies the relationship between basis weight and light transmittance, and how the relationship changes over the eight orders of spatial scale magnitude. It was noticed that the...