Description of the Coupling of two Loop Antennas using Electrical Equivalent Circuit Diagrams

EMC measurements must be carried out in standardized and defined measuring environments. The frequency range between 9 kHz and 30 MHz is a major challenge for measurement technology. The established test sites are designed with an perfect elelctrically conducting ground. For the considered lower frequency range, the metrological validation is carried out with magnetic field antennas in this frequency range. The aim is therefore to take into account the ferromagnetic properties of the ground plane in such a measurement environment and to describe them analytically or numerically with an electrical equivalent circuit diagram. In this article we simplify the model to two loopantennas in Freespace without groundplane to check if the approache with the ECD will work. Therefore we use various numerical field calculation programs in the frequency range up to 30 MHz. The results from simulations are to be checked for correctness with describing them analytically or numerically. For this purpose, a model consisting of two loop antennas was created and simulated in a numerical simulation program. In order to validate the results from the simulation, two different approaches to creating an electrical equivalent circuit (ECD) are examined. The first approach is based on the real equivalent circuit diagram of a coil and the second approach forms a parallel resonant circuit of the first resonance of an antennas input impedance. The focus here is on the mutual inductance, which represents the coupling between the two antennas.

Electron beam modeling and analyses of the electric field distribution and space charge effect

In electron beam technology, the critical focus of research and development efforts is on improving the measurement of electron beam parameters. The parameters are closely related to the generation, emission, operation environment, and role of the electron beam and the corresponding medium. In this study, a field calculation method is proposed, and the electric field intensity distribution on the electron beam’s cross-section is analyzed. The characteristics of beam diffusion caused by the space charge effect are investigated in a simulation, obtained data are compared with the experiment. The simulation demonstrated that the cross-sectional electric field distribution is primarily affected by the electron beam current, current density distribution, and electron beam propagation speed.

Parallel Algorithms for Solving Inverse Gravimetry Problems: Application for Earth’s Crust Density Models Creation

The paper describes a method of gravity data inversion, which is based on parallel algorithms. The choice of the density model of the initial approximation and the set on which the solution is sought guarantees the stability of the algorithms. We offer a new upward and downward continuation algorithm for separating the effects of shallow and deep sources. Using separated field of layers, the density distribution is restored in a form of 3D grid. We use the iterative parallel algorithms for the downward continuation and restoration of the density values (by solving the inverse linear gravity problem). The algorithms are based on the ideas of local minimization; they do not require a nonlinear minimization; they are easier to implement and have better stability. We also suggest an optimization of the gravity field calculation, which speeds up the inversion. A practical example of interpretation is presented for the gravity data of the Urals region, Russia.

Magnetic Field Saturation of Non-Insulation High-Temperature Superconducting Coils during Overcurrent

Non-insulation high-temperature superconducting coils provide a much lower risk of burnout in fault/abnormal conditions, such as hot-spot quench and overcurrent. This study employs an equivalent circuit grid model, coupled with magnetic field calculation and the E–J power law of superconductors, to deeply and systematically investigate the overcurrent charging process in a double-pancake non-insulation coil. An evident saturation of the magnetic field in the axial direction of the coil was observed and verified by experiments. Experimentally, the entire process, including the behavior of the magnetic field, was consistent with the numerical results. Based on the verified model, two main points were addressed: (1) Transient current distribution inside the coil during overcurrent charging was studied. Potential quenching risks were found to be at the innermost and outermost turn near the electrodes, as well as the pancake-to-pancake connection part. (2) Magnetic field saturation, which is a unique phenomenon in non-insulation superconducting coils during overcurrent charging, was studied in detail and first quantitatively defined by a new concept “converged load factor”. Its relationship with turn-to-turn resistivity was revealed.

Method for the biomechanical analysis of aqueous veins and perilimbal sclera by three-dimensional photoacoustic imaging and strain field calculation

A method motivated by the eye’s aqueous veins is described for the imaging and strain calculation within soft biological tissues. A challenge to the investigation of the biomechanics of the aqueous vein—perilimbal sclera tissue complex is resolution of tissue deformations as a function of intraocular pressure and the subsequent calculation of strain (a normalized measure of deformation). The method involves perfusion of the eye with a contrast agent during conduction of non-invasive, optical resolution photoacoustic microscopy. This imaging technique permits three-dimensional displacement measurements of tracked points on the inner walls of the veins which are used in a finite element model to determine the corresponding strains. The methods are validated against two standard strain measurement methods. Representative porcine globe perfusion experiments are presented that demonstrate the power of the method to determine complex strain fields in the veins dependent on intraocular pressure as well as vein anatomy. In these cases, veins are observed to move radially outward during increases in intraocular pressure and to possess significant spatial strain variation, possibly influenced by their branching patterns. To the authors’ knowledge, these are the only such quantitative, data driven, calculations of the aqueous vein strains available in the open literature.

Estimation of stator and rotor forms distortions influence on operating parameters of a hydrogenerator

The field calculation was carried out using finite element method of the Ansys Maxwell software package and verification in the Matlab Simulink software. It should be noted that there are several regulatory documents that describe criteria for permissible distortion of the rotor shape, where the air gap between the stator and the rotor at diametrically opposite points should not differ from each other by more than ± 20% from the average value equal to their halfsum. In this work, a calculation was carried out covering this interval of diameter change; an analysis was carried out considering change in range of ± 35% of the air gap’s width’s value. Results of the research showed that a change in a value of the air gap up to 10% would make a significant contribution to magnitude of magnetic field induction, which increases the value of main losses in a core of magnetic circuit of the generator. Also, there is a significant decrease in voltage (from 25 to 50%) of a nominal voltage in nominal power mode, which requires increase in current in field magnetizing coil, leading to ohmic losses’ increase in rotor’s windings.

Optimization of Corona Ring Design Used in UHV Composite Insulator by PSO Algorithm

The three-dimensional model for the V and I type composite insulators used in AC 1000kV single-circuit tangent power transmission tower has been established, and conducted E-field calculation in FEM software, the results show that maximum electric field strength of corona ring used in V type insulator is about 13.9% and insulator surface 29.2% higher than that of I type, thus corona ring structure should be further optimized. So PSO algorithm has been implemented, meanwhile, submodeling technique was also used to solve such large calculation amount problem due to complexity of used model which can effectively reduce calculation amount without lose of accuracy. Then the method combining FEM and PSO algorithm has been applied to corona ring structure multi-parameter optimization used in V and I type insulators, finally, maximum E-field located in surface of ring and insulator shed can meet the electric control value, and no corona discharges can be observed when corona rings were used in actual project. The method proposed in the paper can solve structure optimization problem for large field domain and multi-media complex model, meanwhile, have reference value for researching field of insulation structure optimization with PSO algorithm.