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Bogdan Blagojevic, Ivan Bajsic
DETERMINATION OF THE EFFECTIVE AREA OF A GAS-PRESSURE BALANCE FOR LOW PRESSURES

This paper describes our attempts to determine the effective area of a pressure balance (Type V1600/4D, manufactured by Pressurements, Ltd.) that is used in our pressure-calibration laboratory as a standard pressure balance for gauge and differential pressure measurements. The gauge measuring range of this gasoperated balance extends from a nominal pressure of 20 Pa up to 16 kPa, and its minimum differential pressure measurement is 5 Pa. This pressure balance is a "discrete" system, and therefore it has several pistons and weights. In the measuring range from a nominal pressure of 400 Pa up to 16 kPa only two different pistons are used. From the calibration results relating to pressure and mass provided by the calibration laboratories of the NPL and Lm (Mass Laboratory of the MIRS) we derived an approximate formula for the effective area. This equation shows the nonlinearity of the pistons’ effective area. Good agreement between the indirectly measured and the approximated values of the effective area was obtained, and their deviations are more than four times smaller than the accuracy of this balance. Knowing the effective area of the piston will reduce the number of discrete calibration points that are required.

G. Buonanno, M. Dell'Isola, A. Frattolillo
DESIGN AND CHARACTERISATION OF A DOUBLE-PISTON PRESSURE BALANCE IN HIGH PRESSURE

The paper describes the design and the analysis of a new kind of pressure balance intended to operate up to 500 MPa. The design can be considered as a calculation test to evaluate the possibility to produce a pressure balance whose changes in effective area with pressure (and, consequently, the elastic distortions) are small if compared to other pressure balances operating in the same pressure range and, furthermore, it presents an extended measurement range. The method used for the theoretical characterisation is an improvement of a numerical method using a finite element method.

Klaus Hoffmann, Robert Liehl
MEASURING SYSTEM FOR CHARACTERISATION OF THE INTERACTION BETWEEN CROSSWIND AND GONDOLA INCLINATION OF ROPEWAYS

The crosswind stability of an operating ropeway is an essential factor for its system security in adverse weather conditions. This paper introduces a mobile measuring system for characterisation of the crosswind stability of ropeways, firstly describing the measuring concept and the measuring sensors, then presenting some data records of the cross inclination of the gondola and the corresponding wind speed.

Pavel Macura, Rostislav Kubala
EXPERIMENTAL ANALYSIS OF RESIDUAL STRESSES AT PRODUCTS FOR THE RAILWAY TRAFFIC

The contribution is devoted to the problems of residual stress measurement and reduction at the products for the railway traffic. The measurements were performed by means of cutting, ultrasonic and hole-drilling strain gage methods. Two variants of hole-drilling method were used – method with the full and incrementally drilled depth of hole. The different methods of measurement show often the different results, therefore the standards of the measurement methods for the products were worked out. At the railway traffic the standards of the measurement methods and of the allowed values of residual stresses were elaborated for railway rails, axles and wheels.

Galina M. Gorbova, Mikhail M. Gorbov, Gerard C.M. Meijer
ANALYSIS OF CAPACITANCE AND LINEARITY OF GAUGE CHARACTERISTIC OF COPLANAR MICRO-DISPLACEMENT SENSOR

Capacitive sensors can be applied for measuring different kind of non-electrical quantities, such as geometrical dimensions of subjects, thickness of films, displacement and vibration of grounded surfaces, position of the object and others.
Existing three-electrode micro-displacement sensors, made in the shape of flat capacitor geometry, do have high values of sensitivity, but they also have notable non-linear behaviour over their whole gauge characteristics.
A three-electrode coplanar sensor, subject of this paper, can be designed by calculation in such a way, that its gauge characteristic does have relatively large section with relative error of the non-linearity of its gauge characteristic equals 0,051% within certain ratio of sensor dimensions.
The method of direct field-strength determination, in combination with the method of conformal mapping, is used for a precise analytical calculation of the sensor capacitance. Analysis of the capacitance and special cases of sensor design has been discussed.

Jianbo Zhang, Maarten Korsten, Paul Regtien
A VISION SYSTEM FOR ONLINE WEAR DETECTION

Wear detection has traditionally restricted itself to offline study and measurement. In this paper a vision system for online monitoring and detection of wear is described. This system uses a video zoom microscope and a high-resolution monochrome camera to capture the image series of a moving surface under study. An algorithm based on multichannel filtering for the detection of wear patterns is presented. The wear patterns are extracted by filtering the acquired image using a Gabor filter bank with multiple narrow spatial frequency and orientation channels. Experiments show the feasibility and usefulness of the proposed vision system and detection method of wear patterns.

Hiroki Yamamoto, Nobuharu Aoshima
QUATERNION DATA ANALYSIS OF THREE AXIS ACCELERATION MEASURED WITH NEWLY DEVELOPED SMALL SENSOR BALL

In order to show a concrete application of the signal processing based on quaternion expression, a prototype of sealed measurement module which could be thrown into the stream of liquid or powdery materials was developed. This module’s shape is a small ball of about 40 mm across in diameter. And it consists of low power one-chip microcontroller, a couple of dual axis accelerometer, EEPROM, and batteries. So that, it can measure and record three dimensional acceleration by itself. As a preliminary experiment, the small sensor ball were suspended with a thick cord and swung by the speed controlled motor. Then, the data recorded under such condition were analyzed by using the spectra upon a form of quaternion. Through the experiments and observations, we could confirm that the small sensor ball could acquire data successfully. And, the relationships between the trend of the ball’s motion and recorded data were considered under the present test condition. If the weight and measuring range are improved in futer, this sensor ball system will grow to an evaluating system of a state of stream in a closed container such as mixing or churning device.

Damir Semenski
OPTICAL METHOD OF CAUSTICS - FULFILLED EXPERIMENTAL APPLICATION TO THE CONTACT PROBLEM

Experimental optical method of caustics is established for solving the singularity at the crack tip through the stress intensity factor evaluation. Method is advantageously improved in application to mechanically anisotropic materials such as fiber-reinforced composites. Recently, the experiments are performed for different types of isotropic body contacts and the analysis of optical effects. Task of experiments is prediction of the future of inspected material surface and the assessment of structure damage. Theoretical fundamentals will prospectively provide the application of the method of caustics to the contact of the structural parts made of composites.

Alfredo Cigada, Remo Sala, Emanuele Zappa
ON THE REDUCTION OF SUB-PIXEL ERROR IN IMAGE BASED DISPLACEMENT MEASUREMENT

Image based measurement techniques allow for quick and contact-less measurement of single or multiple target displacement, shape, orientation and so on. The subpixel analysis increases the vision based displacement resolution. In the present paper resolution and uncertainty of 1D camera based displacement measurements is analysed, paying particular attention to the target geometry effect on the results. Comparison between camera based and laser interferometer displacement measurement is performed and some target modifications are tried, in order to reduce measurement uncertainty, due to sub-pixel systematic effect; the use of including the systematic effect into uncertainty, is wrong in theory but in practise often justified by the usual need of coarse and speed measurements.
The uncertainty in target displacement estimation given by three different image analysis algorithms is also tested in the case of rectangular, rhomboidal and circular targets.

Dominik Sankowski, Jacek Senkara, Krzysztof Strzecha
IMAGE PROCESSING ALGORITHMS IN ASSESSMENT OF QUALITY OF SOLDERS

In this paper a new segmentation algorithm based on the k ñnearest neighbours statistical decision rule is presented. This algorithm was designed for use in systems of quantity image analysis, especially in industrial measurement systems. This algorithm was implemented in a system measuring surface tension and wetting angle parameters, knowledge of which is extremely important for the assessment of quality of solders, for example.

Page 892 of 936 Results 8911 - 8920 of 9356