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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.

Klaus Hoffmann
MEASUREMENTS AND SIMULATION OF GUIDING EFFECTS WITH FLAT BELT CONVEYORS

Flat conveyor belts supported and driven by cylindrical drums run in a state of instability because of lack of guiding forces. Faults such as asymmetry in the position or shape of pulleys and idlers, uneven load distribution or acting transverse forces such as those induced by friction will make the belt run out of true. On the other hand, some of these effects are used for guiding flat running belts.
This paper deals with the guiding effects of two significant features; the skewed cylindrical pulley and the conical pulley. In the first part the implemented measurements are described and in the second part a mechanical model is established for both features. Finally, in the third part measurements are compared with simulation results to verify the developed mechanical model.

Stjepan Jecic Rudolf J. Beer, Janos Kodvanj, Martin Fleischmann
SHRINKING OF POLYMERS IN TECHNICAL PROBLEMS CONSISTING OF TWO DIFFERENT PARTS DETERMINED BY 3D PHOTOELASTICITY USING GAMMA IRRADIATION

To solve spatial technical problems by three dimensional photoelasticity it is necessary to fix the optical effect in the model. In order to avoid the well known disadvantages of the classical freezing method ionising irradiation is used for that purpose. With this method it is not necessary to enlarge the scaling-factor for the displacement which is in some cases very important especially when shrinking is used to develop the fringe pattern. In addition fixation with ionising irradiation can be carried out without elevated temperatures. The most important advantage compared with the freezing method is given by the fact that Poisson’s ratio of the polymers is in this way practically the same as in the simple two dimensional photoelasticity. This is very important because using the classical freezing method temperature treatment above the glass temperature is needed and in this temperature range Poisson’s ration of the polymer is practically the same as in plasticized zones so that by using the classical freezing method it is not possible to distinguish between the elastic and the plasticized zones of the model. The mentioned features were already shown in case of two dimensional contact problem. New materials introduced by Beer at all opened additional possibilities in modelling more complex problems. However dealing with models consisting of two (or even more) different parts we have to keep in mind that shrinking in such models causes residual stresses and for that reason an accompanying rheological process is going on.

L. Casarotto, R. Tutsch, R. Ritter, H. Dierke, F. Klose, H. Neuhäuser
TRACKING THE PROPAGATION OF DEFORMATION BANDS BY MEANS OF AN OPTICAL SCANNING EXTENSOMETER

The Portevin-Le Châtelier effect has been investigated by means of an optical extensometer during tensile deformation of Al-3wt%Mg specimens. The propagation of bands with a concentrated deformation has been detected and its velocity measured. A real-time scanning of the phenomenon makes it possible to track the band propagation with an optical sensor.

Vygantas Augutis, Darius Gailius, Arturas Milinskas
MEASUREMENT OF THE SHRINKING FORCE OF CATHODE RAY TUBE’S SHRINK FIT RIM BAND

The paper describes some Cathode Ray Tubes (CRT) Implosion Protection Systems (IPS) and their possible control methods.
The implosion of CRT (tube) is prevented by using the Shrink Fit Rim Band (SFRB) reinforcing the edge of the tube so that it cannot bulge outwards. The main parameter of SFRB is the shrinking force. Measurement of such a shrinking force is a very important SFRB quality control method herewith of safe CRT. In this paper we consider several methods of shrinking force measurement:
- Magnetization method;
- Barkhausen’s noise method;
- CRT imitator-measurer.
Magnetization method can be successfully used for the measurement of shrinking force. However, there have been found some regularities of this method, which partly limit its application in a number of cases. This method cannot be used when the shrinking force changes its direction. It is applicable only when controlled material is magnetized.
Barkhausen’s noise method is rather effective in the control of shrinking force. However as the Barkhausen’s noise depends not only upon stresses in material but also upon chemical and structural composition of material, there is a problem of calibration.
CRT imitator-measurer provides sufficient accuracy of measurement; therefore it can effectively measure the shrinking force. The device is successfully used in carrying out experiments in Ekranas Co.

Krzysztof Gniotek
CONTROLLABILITY OF OBJECTS MEASURED FOR THE NEED OF EXPERIMENT DESIGN

Methods of experiment design require performing measurements in selected input space points of a model of the object measured. To make it possible, an object must have a property called controllability. In the paper, controllability criteria have been formulated based on the fundamental principles of metrology. In addition, restrictions of controllability of certain objects of measurement have been described. Finally, consequences of disregarding the criterion for controllability occurring at a stage of the verification of the model have been described.

Boris Katz, Liron Anavy, Irina Telent
EVALUATION OF FUNCTIONAL PARAMETERS MEASUREMENT’S ACCURACY FOR A "LEMON"/"BARREL" SHAPED BODY

These article sums our calculations and experiments of "lemon"/"barrel" shaped bodies; we’ve analyzed 4 methods for the measurements of the important parameters and calculated the uncertainty of each method.

Klaus Meissner
MEASURING PROBLEMS ON PROFILE COMPARISONS OF DIGITALIZED FREEFORM AREAS

The measurement of elements of Roll-Works is difficult, because the roughness and the profile-curves are important for the quality of production. Specifications of quality-parameters are not given, but the effects of fault Roll-Works we can see. Through the measurement and the analysis with graphs, which showed the differences in the profile-curves, we recognized the characteristic differences of the faulty Elements of Roll -Works. The transparencies allow the visual control of the elements, which is an easy method to find out the quality parameters for our problem.

Sonko Osawa, Toshiyuki Takatsuji, Tomizo Kurosawa
STEP-GAUGE CALIBRATION USING AN INTERFEROMETRIC COORDINATE MEASURING MACHINE AND THE UNCERTAINTY

There are many kinds of geometrical gauges used for calibration of machine tools and coordinate measuring machines (CMMs). A step-gauge is a kind of calibration gauge. It consists of many short gauge blocks and a base bar. Gauge blocks were directly calibrated by an interferometer using method of exact fraction. The method, however, does not apply to the calibration of step-gauges because of their complicated structure. The calibration works are very important missions in national metrology institutes (NMIs). We developed the step-gauge calibration system that consisted of a CMM and an interferometer. We describe the system scheme of a step-gauge calibration system using a conventional CMM combined with an interferometer and the evaluation of the measurement uncertainty. The uncertainty in measurement using this system is about 0.5 µm (k = 2) for 1-meter measurement.

Page 845 of 888 Results 8441 - 8450 of 8878