**8. References**


shown that an improvement of 1% to 3% is attainable with ECG signal linearisation employing second- and third-order Volterra synthesisers, respectively. Conventional methods (based on the power spectrum) of fetal heartbeat detection have a success rate in the range of 70%. The second hybrid system has a significantly higher classification rate. The classification rate of fetal heartbeats for non-coincident maternal and fetal QRScomplexes is 99.21%. The classification rate of fetal heartbeats for coincident maternal and fetal QRS-complexes is 0%. This means that the hybrid bispectral contours technique fails to resolve the fetal beat when both the mother and fetal QRS-complexes are synchronised. The bispectral contour template matching technique improved the classification rate by approximately 4% over and above that of the third-order cumulant template matching technique. The difference in performance is not due to better resolvability of the latter over the former in the case of coincident maternal and fetal QRS-complexes, as both techniques fail in this respect. But, it is due to the fact that the BIC template matching technique can resolve a few of the fetal QRS-complexes occurring within the T-wave region of the mother. Non-invasive classification of a particular type of ECG abnormality, late potentials, was investigated. This has been achieved by the prudent use of their third-order cumulant 1-d slices. A four-layer neural network classifier based on modified back-propagation algorithm and incorporating adaptive feature enhancement weights applied to its input layer during its learning phase has been successfully tested. Classification rate obtained from 3000 cardiac cycles of normal, confirmed, and suspected abnormal subjects is 90%. In a separate study conducted on the same data a sophisticated recurrent back-propagation network achieved less that 80% success rate. However, the instability issues of the latter network

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Caudill, M. & Butler, C. (1992) *Understanding Neural Networks: Computer Explorations*, MIT press. Crowe, J. A. et al., (1995) Sequential recording of the abdominal fetal electrocardiogram and

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No. 8, pp. 681-693, August.

**8. References** 


**12** 

*1Romania 2Greece* 

**Artificial Intelligence Techniques Applied to** 

Dan D. Micu1, Georgios C. Christoforidis2 and Levente Czumbil1

**Power Lines and Metal Pipelines** 

*2Technological Educational Institution of West Macedonia, Kozani,* 

*1Technical University of Cluj-Napoca,* 

**Electromagnetic Interference Problems Between** 

European ecological regulations meant to protect nature and wild life along with construction cost reduction policies generated a set of government regulations that limit the access to new transmission and distribution corridors. As a result, gas, water or oil supply pipelines are forced to share the same distribution corridors with Electrical Power Lines

The electromagnetic fields generated by high voltage electrical power lines produce AC interference in the nearby metallic structures. Therefore, in many cases these underground or above ground utilities supply Metal Pipelines (MP) are exposed to effects of induced AC currents and voltages (CIGRÉ 1995, Dawalibi & Southey 1989). Especially in case of power line faults, the resulting AC voltage in unprotected pipelines may reach thousands of volts.

(EPL), AC Railway Systems or Telecommunication Lines (figure 1).

Fig. 1. Common distribution corridor. Right of way.

**1. Introduction** 

Schetzen, M. (1980) *The Volterra Wiener theory of the non- linear systems*. New York: Wiley.

