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Hindrances associated with examination of two-layer structures with use of the eddy current method

Dziczkowski L., Dziczkowska M.

Archives of Materials Science and Engineering

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2009

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Vol. 35, nr 1

39-46

EN

Purpose: Determination and description of essential phenomena that occur during examination of two-layer structures with use of the eddy-current method. Development of guidelines to establish procedures that make it possible to find out optimum frequencies of eddy currents, for which measurements of the outer film covering the examined structure exhibit best performance. Estimation of errors that occur when measurements of both geometrical and electrical parameters of the upper film within the two-layer structures are carried out simultaneously. Design/methodology/approach: During the design and scalling of the devices based on phenomenon of eddy currents implying changes of contact coil impedance components, significant influence of the electromagnetic field frequency on measurement results was observed. Additionally, some other phenomena can be observed which causes invalid interpretation of devices indications. Basing on a mathematical model of a contact coil located above a conductive non-ferromagnetic two-layer plate, the sensitivities to the measured parameters are determined. The developed mathematical model serves and the basis to calculate theoretical values of errors when all parameters of the outer film on the examined structure are measured simultaneously. Findings: Depending on specific applications, recommendations enabling proper choice of the electromagnetic field frequency are formulated. Practical implications: Describred phenomena and calculations are useful for the designers of the devices utilising the phenomenon of eddy currents, and also for the users of flaw detectors and conductometers. Remarks included in this paper can be useful for proper interpretation of the observed results and phenomena. Originality/value: Determination of impact coefficients that define how parameters of the two-layer structure are vulnerable to impedance components of the measuring contact coil.

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Warstwa adaptacyjna ATM (AAL)

Dziczkowska M.

Zeszyty Naukowe. Elektronika / Politechnika Śląska

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2000

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z. 12

237--250

PL

Praca zawiera opis funkcji warstwy adaptacyjnej w sieci ATM. Szczególną uwagę zwrócono na omówienie algorytmu kontroli sekwencji komórek dla warstwy AAL1, przedstawiono sposoby ochrony przed błędami i zgubieniem komórek ATM.

EN

This papar describes the basic principal of adaptation layer AAL1 in ATM networks. The aim of this document is analyse the algorithm to detect lost and mininserted cells in AAL1, to examine protection against errors and cell loss.

3

Problemy związane z odtwarzaniem zegara taktującego wyjściowy strumień danych z sieci ATM przy implementacji warstwy AAL1.

Dziczkowska M.

Zeszyty Naukowe. Informatyka / Politechnika Śląska

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1999

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z. 36

215-231

PL

Na zebraniu CCITT w Melbourne (grudzień 1991) zdecydowano zastosować metodę odtwarzania zegara taktowania danych, zwaną Synchronous Residual Time Stamp (SRTS) w sieciach ATM (Asynchronous Transfer Mode). Metoda ta wykorzystuje RST (Residual Time Stamp ) do zmierzenia i przesłania informacji o różnicy częstotliwości ogólnodostępnego zegara odniesienia, istniejącego w sieci fn i zegara strumienia danych fs. Treścią artykułu jest prezentacja metody SRTS, wskazanie jej zalet i wad, omówienie sposobu ochrony przed błędami i zgubieniem komórek ATM.

EN

In the CCITT meeting help at Melbourne (December 1991), it was decided to use the source clock frequency recovery method: Synchronous Residual Time Stamp- SRTS, for the circuit emulation services in ATM - Asynchronous Transfer Mode networks. This method uses RTS (Residual Time Stamp) both to measure and carry information concerning the frequency difference between a common reference clock , derived from the network fn, and a service clock fs. The aim of document is analyse the SRTS method to examine protection against errors and cell loss.