In wind tunnels, aerospace vehicle models are tested in order to analyze their performance in real flight situations. The forces and moments exerted by the airflow on the surface of the test article are measured using multi-component balances. The balance measures the aerodynamic loads by using strain-gages. It is calibrated prior to the tests, resulting in the estimation of the parameters of the polynomial mathematical modelling relating the strain-gage readings to the aerodynamic loads. This paper presents the aerodynamic load values acting on a sounding rocket vehicle under test in a...
The special compact transducer has been developed – to be better known the force's and pressure's effects by transporting the loose materials. The projects of these transporting devices often demand to know not only the normal force's effect, but the effect of the lateral forces "the shearing or slip forces", too. The transducer creates two parts. First one is calibrated as Vector signal analyser – to be caught the elementary forces F x , F y , F z (Cartesian system). The strain gauges are used on the special deformation "S–shape" element. Worth seeing - the second part of transducer - what...
In recent decades the ethanol metrology has became of significant importance, particularly in the area of individual's blood alcohol control. Portuguese Institute for Quality is responsible for the calibration and metrological control of breath analyzers. This is done by means of comparison with mixtures of certified reference materials, which are traceable to IPQ and NMi primary standards. This work aims to demonstrate the importance that the operations of calibration and metrological control of breath analyzers has in our society today, and also to present the calibration and verification...
The random noise test of analogue to digital converters (ADCs) recommended by the IEEE 1057 Standard for Digitizing Waveform Recorders recommends the use of a triangular signal to stimulate the ADC under test. Here it will be shown that a sinusoidal stimulus signal can be used instead. This gives greater flexibility when carrying out the test and allows sine fitting algorithms to be employed to determine the initial phase of the two data records that need to be acquired. The knowledge of this initial phase can be used to align the two records and reduce the errors introduced by additive...
The random noise test of analogue to digital converters recommended by the IEEE 1057-2007 Standard for Digitizing Waveform Recorders is studied highlighting the estimation error and the influence of stimulus signal offset and amplitude on the estimation.
The Histogram Method of analogue to digital converter testing can be used to estimate their gain and offset error. There are two commonly used definitions for these parameters, namely "Terminal Based" and "Independently Based". In this paper the precision of those two different estimators is compared with the goal of assessing which one is more precise for the same number of samples and the same amount of additive noise.
It is demonstrated that, when using the Histogram Test Method to test an analogue to digital converter, the presence of additive noise in the test setup or in the converter itself causes a bias in the terminal based estimation of the gain but not in the estimation of the offset. This will be demonstrated here by analytically determining the estimation error as a function of the sinusoidal stimulus signal amplitude and the noise standard deviation. A closed form approximate expression will be proposed for the computation of the bias of terminal based gain. The results presented are...
A tool that could improve the quality of the assistance perceived by the visually impaired students, during a PC laboratory teaching session, is presented in this paper. The work of qualified supporting teachers could be highly improved by the use of suitable software and hardware facilities allowing for remote monitoring of students' physical and working condition. This could highly reduce the need for a continuous presence of a tutor, that might downgrade students' self estimate.
Present work is devoted to the experimental determination of the non-steady aerodynamic forces acting on the flapping wings of the micro air vehicles (MAVs). At the National Institute for Aerospace Research from Bucharest, Romania, a multidisciplinary collective of scientists performed both theoretical and experimental research on flapping flight. In this work we present some aspects concerning the force measurement procedure in the range of small forces. The moment components given by the forces acting in two directions (perpendicular and parallel to the wing plane) are tensometrically...
The paper deals with the measurement of software quality in frameworks for automatic test systems. In particular, the quality characterization of software components inside the Flexible Framework for Magnetic Measurements, developed at the European Organization for Nuclear Research (CERN), is illustrated with respect to the ISO 9126 reference model through the introduction of suitable metrics. Experimental results for code quality assessment are finally reported.