Dan D. Micu

Layer recurrent neural network solution for an electromagnetic interference problem

The paper presents an original contribution related to the implementation of a neural network artificial intelligence (AI) technique through Matlab environment, on the study of induced AC voltage in the underground metallic pipeline, due to nearby high voltage grids. The advantage yields in a simplified computation model compared to FEM, and implicitly a lower computational time. In comparison with other neural network solutions identified in the literature, where the induced AC potential is directly evaluated, the authors of this paper propose a new neural network solution to evaluate MVP on the studied domain, using a larger training database for a large panel of different geometries.

Evaluation of induced AC voltages in underground metallic pipeline

Purpose – The purpose of this paper is to make a study of electromagnetic interference between electrical power lines and nearby underground metallic pipelines.Design/methodology/approach – The equivalent electrical circuit of the studied electromagnetic interference problem between electrical power lines and nearby metallic pipelines is created and solved using a loop currents technique based on a hybrid method. The used circuit solving technique was implemented in a software application developed by the authors.Findings – The authors have identified the influence of phase sequence on induced voltage level in an underground pipeline for a double circuit electrical power line. Also the effect of different normal operation and phase to earth fault currents have been revealed.Practical implications – The study has been made through a research project with the Romanian gas transportation company, in order to find the proper protection techniques for underground metallic pipelines.Originality/value – The pape...

Inductive and conductive interference problems for practical cases solved with special interpolation algorithms

In the paper are presented and discussed practical cases of subdivision of the right of way AC Power Lines / electric traction line / gas pipeline in sections (a circuit model) and also are briefly presented analytical solutions of the induced voltages and current densities in victim structures. Is created a special interpolation algorithm based on global interpolation functions for precise evaluation of the induced voltages values in different points on the underground pipeline, taking into account the measured data. Also, are applied numerical interpolation methods and/or nonlinear curve fitting procedures for determining a continuous function between the magnetic permeability and electrical induced currents, because in practice, there are only a set of available reactance measurements.

Public lighting systems an energy saving technique and product

Energy service techniques for public lighting systems are briefly discussed. Proposals for energy savings and a product conception are then made. Voltage regulation principle proves to be an efficient way of bringing quality and economies in the administration of public lighting. Behavior and experimental results of the proposed voltage chopper are next evaluated.

Energy Efficient Coils for Magnetic Stimulation of Peripheral Nerves

The preoccupation for improving the quality of life, for persons with different handicaps, led to extended research in the area of functional stimulation. Due to its advantages compared to electrical stimulation, magnetic stimulation of the human nervous system is now a common technique in modern medicine. A difficulty of this technique is the need for accurate focal stimulation. Another one is the low efficiency of power transfer from the coil to the tissue. To address these difficulties, coils with special geometries must be designed.

Numerical methods for induced voltage evaluation in electromagnetic interference problems

A numerical procedure employing the finite-difference method (FDM) is used in order to calculate the induced voltages across points on a underground pipeline, running parallel to a faulted line, and remote earth. A comparison is made between the results obtained with FDM and FEM. We develop a mathematical differential model and based on contour integral method was obtained the numerical form of the Helmholtz equation. We determine directly the numerical form of equation for non-homogeneous media, to clearly put in evidence the electromagnetic phenomena. A physical model for experimental calculus of induced voltage in an underground pipeline will be created based on the differential numerical model.

Magnetic Coils Design for Focal Stimulation of the Nervous System

The technique of magnetic stimulation of nerve fibres represents a new direction of research in modern medicine. This study starts from a major limitation of the coils used for magnetic stimulation: their inability to specifically stimulate the target tissue, without activating the surrounding areas. The first goal of this study was to determine the optimal configuration of coils for some specific applications and evaluate the distribution of the electric field induced. Once the coil configuration established, we address other issues that need to be solved: achieving smaller coils, reducing power consumption (the low efficiency of power transfer from the coil to the tissue is a major drawback) and reducing coil heating.

Simulation of interferences between power lines and gas pipelines in unbalanced phase currents state

Purpose – The purpose of this paper is to compute the values of induced voltages and currents in an underground gas pipeline, which shares the same right of way with a high voltage power line (HVPL) in unbalanced phase currents regime, in order to detect the possibility of the AC corrosion occurring in the pipeline.Design/methodology/approach – The analysis of the induced voltages in metallic structures (gas pipeline) was done using a professional analysis and modeling software which uses the electromagnetic field method.Findings – It was shown that during fault conditions, large currents and voltages are induced on the pipelines, which may pose a threat to operating personnel and equipment. Induced voltages also occur in cases of unbalanced phase currents of the HVPL, which may pose a threat voltage that could lead to damages of the underground gas pipeline due to corrosion phenomena.Practical implications – Because the electromagnetic field approach involves complicated analytical expression and introdu...

Lightning-Inverse Reconstruction by Remote Sensing and Numerical-Field Synthesis

An inverse remote-sensing procedure is presented for reconstructing the spatial waveform of the lightning return stroke current throughout a numerical-field synthesis procedure, based on working regularization methods. The approach uses as input data the acquisition of time-domain recordings of the electric and/or magnetic field generated by the lightning current, at various locations on the ground and converts these signals into harmonics by Fourier decomposition. This combination between the proposed solving procedures and harmonic filtering yields numerical results that are in good agreement with the testing functions.

Identification of an equivalent model for the permanent magnets of a magnetron sputtering device

Purpose – The aim of the work was to obtain an auxiliary instrument able to give the magnetic configuration of a magnetron sputtering device for operation with targets, magnetic and non magnetic, with different heights, starting from a device with no detailed information of the source.Design/methodology/approach – An inverse problem has been dealt with. A 2D numerical analysis has been performed, which utilizes as a starting point a model identified with a simple analytical procedure based on measurements.Findings – A satisfactory equivalent model has been identified, and validated in several different conditions.Originality/value – The proposed approach can be applied when no detailed information of the source is available, in the case of a cathode without a ferromagnetic yoke.