Search

During the normal laying and operation of a three-core umbilical cable, AC current can easily lead to AC electrochemical corrosion on the outer surface of the steel tube. To explore the electrochemical corrosion mechanism and the factors affecting the three-core umbilical cable, this paper optimizes the internal induced potential calculation method for three-core umbilical cables. It analyzes the changes in the characteristics of the induced potential and explores the variations in the density of induced current under different conditions. The research results show that by optimizing the calculation method for the induction potential of the umbilical cable's steel pipe, for the electromagnetic significance of the smallest repeating unit, the induction potential on the steel pipe's surface exhibited a cyclic change. The peak part of the induction potential is most likely to experience electrochemical corrosion. Additionally, reducing the radius of the outer insulation aperture of the steel pipe and improving the conductivity of seawater will increase the density of the induced current in the insulation aperture, thereby increasing the risk of electrochemical corrosion. As the cable pitch and AC frequency increase, the current density in the steel pipe pores will also rise. [ABSTRACT FROM AUTHOR]

The Helmholtz coil constant (k h) is a crucial standard in magnetic moment measurement devices for permanent magnet materials. To overcome the problem of lowaccuracy of the direct-current (DC) calibration method, this study used a constant sinusoidal current in the Helmholtz coil and measured the induced voltage of the detection coil with known coil turns and coil area. Subsequently, the k h was calculated. The noise signal deduction rate in the induction voltage of the detection coil was greater than 99%, its influence on the induction voltage is less than 0.005%, and the repeatability of the calibration results is 0.003% (1δ). The results reveal that the alternating current (AC) method and orthogonal calculation (OC) can accurately measure the valid values of the voltage signal under the influence of the spatial stray field during the calibration of k h.

During the normal laying and operation of a three-core umbilical cable, AC current can easily lead to AC electrochemical corrosion on the outer surface of the steel tube. To explore the electrochemical corrosion mechanism and the factors affecting the three-core umbilical cable, this paper optimizes the internal induced potential calculation method for three-core umbilical cables. It analyzes the changes in the characteristics of the induced potential and explores the variations in the density of induced current under different conditions. The research results show that by optimizing the calculation method for the induction potential of the umbilical cable’s steel pipe, for the electromagnetic significance of the smallest repeating unit, the induction potential on the steel pipe’s surface exhibited a cyclic change. The peak part of the induction potential is most likely to experience electrochemical corrosion. Additionally, reducing the radius of the outer insulation aperture of the steel pipe and improving the conductivity of seawater will increase the density of the induced current in the insulation aperture, thereby increasing the risk of electrochemical corrosion. As the cable pitch and AC frequency increase, the current density in the steel pipe pores will also rise.

Abstract: Human body is charged during walking. Continuous monitoring of the body potential has been made using an induction electrode set on ceiling of a room. The body voltage estimated from the induced voltage was a few hundred volts and dependent on material of shoes, as expected. The induced voltage varied periodically while walking and the waveform was different depending on examinees or manner of walking, even the same footwear was used. In this study, spectrum analysis was made on the acquired voltage, and frequency component was compared. The voltage spectrum of 4 different persons, and 3 different walking patterns of one person were obtained, and their correlation was compared. The results indicate that the spectrum was different depending on the examinees. Among the tested 4 examinees, personal identification was possible using the correlation of the induced voltage while walking. This novel contactless body potential monitoring method can be applied to many new fields such as medical practice and food factory. [Copyright &y& Elsevier]

When metallic telecommunication lines carrying digital signals are laid adjacent to ac supply lines in an office or a house, then the noise generated by the ac supply lines is induced on the telecommunication lines and the quality of transmission may be degraded. To calculate the induced voltage generated directly between the cores of a telecommunication line requires accurate values of the coupling admittance or coupling impedance between the two lines corresponding to the cable construction and the problem becomes very complicated. This paper proposes a simple method of estimating the voltage induced between the cores of a telecommunication line when the telecommunication line is laid adjacent to an ac supply line. The amount of coupling from the primary circuit with an open-circuited terminal and with a short-circuited terminal to the secondary circuit is measured. Using this value, the characteristics of the induced voltage corresponding to an arbitrary value of terminal impedance of the primary or secondary circuit simply are estimated. The validity of the estimation method was confirmed by experiments. [ABSTRACT FROM AUTHOR]