Cylindrical Conductor Research Articles

Fast and Numerically Stable Analytical Computations for the Power Induced in Cylindrical Multilayered Conductors Under External Magnetic Fields

Despite the spectacular development of numerical methods, the use of analytical formulas to solve electromagnetism problems in multilayered complex structures still remains attractive due to their much shorter computation time. One of the most essential computations is a calculation on the proximity effects observed in a wire that is immersed in an external harmonic electromagnetic field. The mathematical model of this problem is known and contains Bessel functions, which are numerically unstable for very low and high arguments. In this article, a novel numerically stable algorithm for the computation of proximity effects and power induced in a multilayered cylindrical structure is presented.

ANALYSING THE EFFECT OF DISCONTINUITY OF ELECTRICAL CONDUCTIVITY OF SOIL ON GROUND RESISTANCE

In addition to the direct application of the method of images the article also shows the application of complex images in the cases with two or more discontinuity boundaries of the specific electrical conductivity. The article analyzes the effect of neglected images in determining ground resistance, in a single-layer soil model, and goes on to analyse the error due to modelling single-layer soil which by its characteristics is most accurately described as double-layer. In modelling the soil the technique of simple and complex images was applied. To keep the presentation simple and make the models comparable, a normal horizontally inserted cylindrical conductor was taken as ground conductor. The results obtained are shown analytically and graphically and discussed.

On the use of the skin effect for eddy-current control of cylindrical metal products

In this paper, the fundamentals of the theory of the skin effect as applied to long cylindrical ferromagnetic conductors when exposed to a high-frequency electromagnetic field are considered. The results of this study can be used to process experimental data obtained, as a result, of studying the fatigue properties of ferromagnets.

Research on Value-Seeking Calculation Method of Icing Environmental Parameters Based on Four Rotating Cylinders Array

This paper calculates and analyzes the collision and freezing characteristics of water droplets on the cylindrical conductors with different diameters and deduces the variation law of icing weight change rate on different diameters rotating cylindrical conductors with wind speed, ambient temperature, liquid water content, and median volume diameter. Then, a prediction and value-seeking method of icing environment parameters based on rotating circular conductors is determined. The laboratory test results show that the measured values of ambient temperature T, wind speed U, liquid water content w and median volume diameter MVD are in good conformity with the reference values measured by other instruments, and the average errors of each parameter are 3.41%, 5.44%, 6.08% and 7.20%, respectively. The field natural experiment was carried out at Hunan Xuefengshan Energy Equipment Safety National Observation and Research Station. The obtained icing environmental parameters were substituted into the icing simulation calculation model of the LDQ-100 glass insulator. Compared with the field experiment results, the simulated ice shape and the field ice shape were in good agreement. The error between the numerical calculation results of the icing weight and the field icing weight of the experimental insulator was less than 6%.

Microwave Scattering Characteristics of a Cylindrical Conductor Coated by Dispersive Metamaterials with an Intervening Air Gap

Microwave Scattering Characteristics of a Cylindrical Conductor Coated by Dispersive Metamaterials with an Intervening Air Gap

Analytical Solutions to Eddy-Current-Induced Field in Cylindrical Conductor Considering Velocity Effect

Electromagnetic nondestructive testing methods to inspect metal rods and pipes are widely used in industrial production. When the scanning speed of the electromagnetic coil is close to the magnitude of eddy current diffusion speed in conductive specimens, the coil motion will significantly affect the distribution of the eddy current field and detection signal. In this article, based on the basic equations and boundary conditions of electromagnetic field problems for moving conductors, the eddy-current analytical model of coaxial relative motion between the coil and the cylindrical conductor rod is solved by using Fourier transform method, and the impedance change expression of the pick-up coil is obtained. The theoretical results are in excellent agreement with the experimental results, which verify the analytical expression of impedance change. Furthermore, the effects of a conductor moving velocity and excitation frequency on impedance-change modulus values for differential and absolute pick-up coils are analyzed, respectively. The theoretical methods proposed in this article quantitatively analyze the velocity effect on the eddy current field, which can be applied to fast real-time eddy current testing for conductive specimens.

A Direction-Finding Antenna Inserted into the Surface of Cylindrical Conductor Body

In this letter, a direction-finding (DF) antenna inserted into the surface of a cylindrical conductor body, with the conductor material in front of the antenna, is presented. To minimize a gain reduction in the axis direction of the cylindrical conductor, an aperture of an openended waveguide antenna is modified, and the conductor body is deformed. The antenna is operated at the X-band, and its direction finding performance using an amplitude comparison method is analyzed. To verify the validation of the performance of the antenna, the analyzed results are compared to the measurement results.

A Method for Calculating Grounding Resistance of Reinforced Concrete Foundation Grounding Systems

Tower foundations have been used as grounding electrodes to reduce the area of the grounding devices. However, it is difficult to calculate the grounding resistance due to the complex structure of the reinforced concrete foundation. A method for calculating grounding resistance of reinforced concrete foundations is proposed in this paper. The method equates the complex foundation structure into a cylindrical conductor and then calculates the grounding resistance with the help of the method of moments, which simplifies establishment of the simulation model and reduces the extensive computation. In addition, the applicability of the equal cross-sectional area method and the equal cross-sectional perimeter method is analyzed. It shows that both methods are applicable only when the concrete resistivity is close to the soil resistivity. The equal cross-sectional area method is applicable when the concrete resistivity is within twice the soil resistivity, while the equal cross-sectional perimeter method is applicable when the concrete resistivity is approximately same or less than the resistivity of the soil.

Analysis of heat pulse measurements in double-layered soils with the heating probe positioned at the layer interface

In the case where a heat-pulse (HP) sensor installed in a layered soil with the heating and sensing probes positioned at different layers, the HP measurement violates the underlying assumption of soil homogeneity for the cylindrical perfect conductors (CPC) theory that is used to interpret the HP data. In this study, laboratory and numerical studies were performed to evaluate the heat transfer patterns and models to analyze HP measurement data when heating probe was positioned at the interface of a double-layered soil with different upper- and lower-layer properties. A parameterized hetero-CPC model was proposed to describe temperature-by-time curves at the sensing probes in the upper and lower soil layers. The hetero-CPC estimates matched well with the simulated values, and its accuracy relied on the thermal property differences between the soil layers. The heat distributions caused by heat pulse inputs in the layered soils showed semi-circular isotherms with different radii centered on the heating source, therefore showing discrepancies in heat fluxes for the upper and lower soil layers. The proposed hetero-CPC model was able to accurately describe the combined effects of finite probe properties and heterogeneous soil thermal property values on the HP data in a double-layered soil system with the heating probe positioned at the layer interface.

Terahertz Bessel and "perfect" vortex beams generated with a binary axicon and axicon with continuous relief

Comparative studies of characteristics of Bessel and "perfect" vortex beams with a topological charge 9, created using a binary silicon axicon and a "holographic" diamond axicon with continu-ous profile at a wavelength of 141 μm, are carried out. Beams with linear and radial polarization are investigated. An example of the use of a perfect radially polarized beam for the excitation of vortex plasmon-polaritons on a cylindrical conductor is given.

Transient Analysis Method of an Axially Magnetized Novel Passive Eddy Current Damper for Suppressing Lateral Vibrations

A passive eddy current damper (PECD) can be adopted to provide a damping effect and drag force in rotating structure applications. The damping effect is formed as the result of induced eddy current, while the drag force is produced as the result of the repulsive force between the same axially poled magnets. However, modeling and approximating the damping effect, repulsive force, stiffness, the magnetic flux density (MFD) distribution, and eddy current prompted in PECD is a challenging task because of the complicated structure and operational conditions. This paper presents a new method for modeling and estimating the dynamic parameters of novel PECDs such as the damping effect, repulsive force, and stiffness for suppressing vibration in rotating structure applications. This self-powered, cost-effective PECD utilizes four arc-shaped and single ring-shaped permanent magnets with a cylindrical conductor placed between the arc magnets and the ring magnet to generate a damping effect and spring. Eddy currents are generated in the cylindrical conductor as the effect of the relative motion of the ring magnet concerning the arc magnets. An accurate and transient analysis method of the proposed system is carried out by using a three-dimensional finite-element method (3D-FEM). According to the procedures applied in the FE model solution, this new numerical method is appropriate and validated for analyzing PECDs and gaining good results by configuring the conductor and permanent magnets symmetrically. Finally, this novel 3D transient analysis method presents a perfect ability and accuracy for both modeling and calculating the PECD parameters.

Calculation of Basic Average Drift Characteristics of Free Electrons in a Metallic Conductor with Electric Current

The results of an approximate calculation of theaveraged values of speeds of vmz of a longi-tudinal drift of lone electrons, and of circular frequencies of ωmz change of longitudinal elec-tronic waves de Broglie and of lengths of λmz of longitudinal electronic waves de Broglie in the metal of round cylindrical conductor with an electric axial-flow current of conductivity of i0(t) of different kinds (permanent, variable, and impulsive) and amplitude-time parameters (ATP). The results of verification of the obtained calculation correlations for speeds of vmz drift of lone electrons and lengths of λmz of electronic de Broglie waves in the examined con-ductor demonstrate their validity and working capacity. The obtained data confirm the quan-tum-wave nature of the electric current of conductivity of the indicated kinds of i0(t) and of ATP in a metallic conductor.

Cylindrical Linear Induction Motor for Vertical Transfer: Fundamental Consideration on Vertical Vibration during Transportation

In a conventional elevator, the vibration and twisting of the cable become a serious problem when the cable is very long. Therefore, an elevator using a method that omits the counterweight and is moved by an actuator on a single cable with both ends fixed was considered. However, contact between the actuator and the cable decreases the efficiency and damages the cable owing to the inclusion of foreign matter. Therefore, this paper proposes a vertical transportation system which moves above a long and uniform conductor cable without contact by using a cylindrical linear induction motor (LIM) as the actuator. A cylindrical LIM above the reaction plate, which is a cylindrical shell-shaped conductor, has an advantage that the magnetic force acts on the reaction plate uniformly. This is expected to suppress the vibration in the gap direction. However, a conventional LIM drives the mover in the horizontal direction, and system design guidelines for a device that can directly exert thrust in the vertical direction have yet to be established. Therefore, we constructed a model for analyzing the cylindrical LIM and performed electromagnetic field analyses by the finite element method. The thickness of the reaction plate was varied in the analyses and the effect on the generated thrust was investigated. From the analysis results, the optimum thickness of the cable was determined by obtaining the range of the magnetic flux density acting on the cable.

Wideband Gain Enhancement of an AMC Cavity-Backed Dual-Polarized Antenna

A novel low-profile wideband antenna is proposed with high-gain, high-isolated, and dual-polarized properties. It consists of two mutually-orthogonal bowtie-shaped dipole radiators, four rectangular parasitic elements, and a cylindrical artificial magnetic conductor (AMC) cavity. By introducing parasitic elements, additional resonance is generated, and the bandwidth is widened. The gain is mainly improved by the cylindrical metallic wall and wideband AMC of the cavity. The AMC operates in ±90 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sup> reflection phase band-gap bandwidth of 2.35-4.25 GHz, and its equivalent circuit model is developed to understand the working mechanism. The orthogonal placement of two dipole radiators ensures polarization diversity and high isolation. The impacts of various environmental conditions on antenna performance are investigated. To verify the concept of design and demonstrate its excellent performance features, a prototype is fabricated and measured. The proposed wideband antenna has a height of 0.18 wavelength at the center frequency. The measured -10-dB impedance bandwidth is from 2.16 to 3.96 GHz, where the realized gain is 8.34-10.96 dBi and the radiation efficiency is more than 81.8%. High isolation of > 28.65 dB and low envelop correlation coefficient (ECC) of < 2.74 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> are also achieved between antenna elements. It can be used in the base station for intelligent Internet of Vehicle (IoV) applications, covering the bands of WLAN, WiMAX, Bluetooth, LTE, and 5G sub-6 GHz.

Determination of the conductor resistance during their explosion in vacuum under conditions of skinning the current

The work is devoted to the investigation of the features of the conductor explosion in a vacuum under the conditions of skinning the current, and specifically, the effect of the magnetic field nonlinear diffusion wave spreading over the exploded conductor on its electrical properties. Experiments on the explosion of conductors were carried out on the IMRI-5 pulse power generator. The exploded conductor was soldered to the cathode and mechanically clamped between the plates on the anode. In the experiments, we used two types of conductors, cylindrical and flat (foils). Cylindrical conductors were of two types: copper (0.5 mm in diameter) and aluminum (0.44 mm in diameter). Foils were also of two types: copper with a thickness of 300 microns and aluminum with a thickness of 200 microns. The foil width varied from 1 to 3 mm. The length always remained 30 mm. To calculate the circuit inductance and calculate the corrections for the real conductor inductance, we used a load that was either a copper foil 600 μm thick and 1 cm wide, or a copper conductor with a diameter of 2 mm (short circuit mode).

Investigation of the near-surface matter density radial distribution in the skin explosion of cylindrical conductors

Investigations of the near-surface plasma formation process during skin explosion of cylindrical duralumin and copper conductors in rapidly increasing magnetic fields with their induction up to 500 T were carried out. The formation of plasma on the conductor surface was recorded by its glow in the visible range using a four-frame optical camera with an exposure time of each frame of 3 ns. The internal structure of the surface plasma, the assessment of the density of matter in it and its radial distribution were investigated using radiography pictures obtained by X-ray transmission with hv > 0.8 keV, which is formed at the “hot point” of the X-pinch. The dependences of the load substance density on its radius were determined and constructed from the obtained X-ray diffraction patterns at different points in time from the beginning of the current. So at 216 ns at a radius of 1.8 mm of a duralumin conductor with an initial radius of 1.485 mm, the density of the substance is estimated to be 0.0068 g/cm3.

The initial stage of the plasma formation at skin explosion of cylindrical conductors

The formation of plasma on the surface of the electrically exploded conductor is a key issue in terms of the energy introduced into the metal substance. The purpose of this work was to study the dynamics of dense plasma formation on the metal surface at magnetic induction values of 200-600 T and its rising rates of (2-6) T/ns. The experiments were carried out on a terawatt MIG generator with current amplitude up to 2.5 MA and rise time of 100 ns. In experiments, skin electrical explosion of cylindrical conductors made of different materials and with different diameters was studied. The formation of plasma on the surface of the conductor was recorded using a four-frame optical camera with an exposure time of 3 ns for each frame. It was shown that when the current increases, “spots” appear on the surface of a cylindrical conductor. These spots are the centers of plasma formation. Later in the time, longitudional plasma channels were registered. In course of subsequent merging of the channels relatively uniform plasma formation occurs. The paper discusses the features of the dynamics of plasma formation as a function of the peak and the rising rate of the magnetic field induction.

Integral form of the cylindrical perfect conductors solution for the dual‐probe heat‐pulse method

AbstractThe dual‐probe heat‐pulse (DPHP) method is useful for measuring soil thermal properties. Measurements are made with a sensor that has two parallel rods: one for introducing a pulse of heat and one for measuring change in temperature. Thermal properties are obtained by fitting a solution to the temperature data. The cylindrical perfect conductors solution of Knight et al. (https://doi.org/10.2136/vzj2011.0112) allows for accurate determination of those properties because it accounts for the finite radius and finite heat capacity of the rods. In this note, we show how their solution can be written in integral form. Specifically, we rearrange their Laplace‐domain solution and perform contour integration in the complex plane to express their solution as the integral of a real function over the positive real axis. This form of their solution is easier to evaluate and thus improves its accessibility for routine use in determining thermal properties with the DPHP method.

On Reactive Force in Thin Unclosed Conductor and Displacement Current

The linear momentum density carried by electromagnetic fields creates the hidden force acting on the displacement current between ends of an unclosed conductor with alternative electric current. This force compensates the self-force exerted by the unclosed conductor with zero thin. The magnetic field produced by displacement current does not contribute to the force acting on the conductor. The unclosed conductor can move under action of the self-force.&#x0D; At small heights of cylindrical open conductor, the reactive force equivalent to the self-force becomes very large

A problem of thermo-magnetoelasticity for a system of parallel electrical conductors by Cartesian harmonic polynomials and rational functions

A method proposed earlier, relying on the use of harmonic Cartesian polynomial and rational functions, is extended here to find a semi-analytical solution to the uncoupled, two-dimensional problem of thermo-magnetoelasticity for a system of long parallel, non-intersecting, transversely isotropic elastic cylindrical electrical conductors. Results are presented for two conductors of equal circular normal cross-sections carrying currents of equal densities flowing along the same direction, subjected to Robin-type thermal boundary conditions. Quantities of practical interest are represented graphically and discussed. Consideration of a system of electrical conductors is of practical importance in power plants and in various technological instruments, where it is required to assess the interaction between conductors. The obtained formulas for the magnetic vector potential may be of importance for the determination of the coefficients of self- and mutual inductance of long electric conductors, otherwise difficult to calculate by standard methods. Comparing the results with those of a single conductor allows us to assess the interaction between conductors.