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Eugen Trapet, Vit Zeleny, Pavel Skalnik, Vaclav Bauma
DETERMINING ERRORS OF A ROTARY TABLE USING A SELFCENTERING HEAD (as one of EU MTCHECK project outputs)

To determine partial geometric errors of coordinate measuring machines (CMM), laser interferometers are used, but more and more also calibration-fit objects – artifacts. Most of all, objects with balls – ball-plate, ball-bar are used. The EU MTCHECK project intends, as one of its goals, to use these artifacts not only for calibration of coordinate measuring machines, but also for calibration of computer numeric control (CNC) machine tools. Partners in the project were the following companies, institutes and universities: UNIMETRIK, Spain (coordinator), CMI, Czech Republic, IBS, Netherlands, UNIZAR, Spain, MECANER, Spain and FIDIA, Italy. As more and more CMM and CNC machines are equipped by the so-called fourth axis, another partial output was determining errors of this rotary axis.

Hiroshi Watanabe
THEORY OF COARSE-GRAINED INFORMATION

Measurement should be objective in principle. However, the accuracy of measurement often depends on various factors, including instruments of measurement, adopted intentionally or made available accidentally, and from a practical point of view, it is important to choose a suitable degree of the accuracy of measurement for the intention of measurement. The present paper discusses some information-theoretical aspects of the relationship between the degree of the accuracy of nominal description of objects and the interdependence among groups of those objects within a formal framework of clustering, where a new entropic measure of interdependence is applied to estimate the change of the interdependence when the nominal description becomes more `coarse’ so that several objects appear to be identical, and are grouped into the same class. The degree of interdependence is often measured by (sum of entropies of partial systems) - (entropy of the whole). Close examination shows, however, that instead of simple formal entropy we should take rather (the number of the members of a group) × (entropy of the group). The result also implies that in integration of information channels the average entropy plays an important role. A brief discussion is also made on elicitation of so-called information granules.

Eugen-Georg Woschni
MEASUREMENT OF FREQUENCY AND TIME - ERRORS DUE TO SYNCHRONIZATION EFFECTS AND ERROR CORRECTION

After an introduction to the mathematical theory of rheolinear systems the application of the results leads to the fact that due to the synchronization there arises a frequency deviation even outside of the synchronization range. The errors caused by this effect were investigated and consequences for highprecision frequency or time measurement and methods of error-correcting are obtained.

Shaomin Zhou, Jouko Halttunen
CONSITENCY PROFILE MEASUREMENT IN PULP BASED ON ELECTRICAL IMPEDANCE TOMOGRAPHY

This paper describes a low cost system to measure the consistency profile of pulp based on electrical impedance tomography (EIT). A 16-electrode sensor is applied to acquire the cross-sectional data. Data acquisition is controlled by a single-chip computer, which receives commands from host computer, initializes hardware, acquires data and sends them to host computer via a serial port. All the measurement parameters such as the amplitude and frequency of the injected current can be set by software in host computer. The consistency profile image is reconstructed by modified Newton-Raphson algorithm. Comparing to conventional method, it is non-invasive and low cost.

Hubert Zangl, Stefan Cermak, Bernhard Brandstätter, Gerald Gruber, Georg Brasseur
A BEM-APPROACH FOR SIMULATION AND OPTIMIZATION OF CAPACITIVE SENSOR TOPOLOGIES

In order to optimize front-end topologies of capacitive sensors precise knowledge of the coupling capacitances is important. These capacitances are not easily accessible by means of measurement without significantly altering them, and therefore a numeric method for determining them is advantageous. In this paper we use a Boundary element formulation for this task. Certain aspects of numerical accuracy of the formulation used are addressed. Results from simulations and optimizations are presented and compared with experimental results for validation of the approach.

Blaz Santic
NEW EVALUATING METHOD FOR TESTING OF SIMPLE GEOMETRY AND WORK PIECES

The paper describes a new approach based on Chebyshev method, which is stabilized by an arbitrary small weighing of least-squares principle in order to permit the reliable and repeatable examination of the best fit geometric elements in a simple and very complex geometry. Field of application of new method is geometry quality control in automotive and machinery building industry, in plastic forming etc. The method can be also used for further investigations of margin and stability conditions of Chebyshev method.

Blaz Santic
COMPUATION METHOD FOR TESTING OF WORK PIECES USING COMPLETE GAUGING

The paper describes a new precision evaluation method for testing of the work pieces under enveloping conditions using complete gauging, as defined by ISO 1101 and ISO 2692. The method permits a reliable examination of the best fit elements in a very complex geometry under consideration of all defined links between the geometric elements and all defined tolerance zones, with the least fault zones.

Zobeida Cisneros, Ivan Apolo, Teresa Vera, Leo Van Biesen, Tesfa Ghebreegziabeber, Ma. del Pilar Cornejo, Francisco Torres
INVENTORY INTO A DIGITAL LIBRARY OF THE COMPLETED STUDIES TO ASSES THE CHARACTERIZATION OF THE GULF OF GUAYAQUIL BASED ON THE PERFORMING INFORMATION UTILIZING ELECTRONIC CHARTING AND DISPLAY SYSTEMS A

The university institution plays an important role as generator and bank of information through research (starting with thesis works), human and technological resources, while keeping up-to-date with the demands of the community on the formation of professionals. It is the commitment of the authors and the whole of the research team to elaborate, with all the means available at the academic institutions they belong to, this Geographic Information System to accomplish the goal of providing the stakeholders in the Gulf of Guayaquil (GG), Ecuador, objective means for decision-making. The methodology applied to build up digital thematic information useful for management of the ecosystem of the Gulf of Guayaquil consists of:
1. Set-up an Electronic Charting and Display System - ECDIS with the database inventory and the digital cartography available;
2. Select out of the databank that information that is competent and constitute with it a geographic database suitable for the identification of regions in the gulf;
3. Work out spatial relationships with the output of that selection to characterize the gulf in terms of spatial and temporal driving factors;
4. Produce presentation maps synthesizing the results of the analysis. Several of the maps realised are discussed, which show the analysis performed on the variables that describe natural and man-driven activities in the GG. For instance, at the base of an Internet-accessible alert system lies information on production and management of shrimp farms in the region, summarised in an index that is used to map the variation between the monthly performance and the historical one. A second example shows rather a lesser abstraction of the information, and shows layers describing the natural set-up regarding the hydro-dynamics of the inner estuary, which would be a second building block toward the integrated vision on how to manage the ecosystem in view of the economic interests, and also the sustainability ones.

Mathias J. Niemann
NEW SIGNAL PROCESSING METHOD OF TRANSIT TIME MEASUREMENT

The cross-correlation function is commonly used to measure the transit time between two similar signals. The maximum value of the cross-correlation function corresponds to the transit time. The other way to measure this is to add the two signals. This method is comparable with the well known interference measurement technique. In the spectrum of the added signals after filtering a cosine function can be determined. The frequency of this function is directly proportional to the transit time.

Vedran Mudronja, Biserka Runje, Srdan Medic
EXAMPLES OF APPLYING MONTE CARLO SIMULATIONS IN THE FIELD OF MEASUREMENT UNCERTAINTIES OF THE STANDARD OF LENGTH

Recently, the Monte Carlo simulations (MCS) have been increasingly applied in the field of estimating the measurement uncertainties. The MCS method is based on random number generation from the probability density functions for each input value and forming of experimental probability density function of the output value. The paper presents calculation examples of the measurement uncertainty in calibration of the standard of length by using the MCS method. The MCS method is implemented for validation of the realised measurement uncertainties by GUM method in calibrating the standard of length.

Page 912 of 938 Results 9111 - 9120 of 9371