Fields Of Different Configurations Research Articles

Collective behavior of boreholes and its optimization to maximize BTES performance

Borehole layout strongly affects the behavior of borehole heat exchangers (BHEs) and changes the performance of a borehole thermal energy storage (BTES). This study investigates the existence and importance of the optimum collective behavior of BHEs to maximize the performance of BTES. Charge benefit ratio, storage efficiency and configurational benefit factor are proposed as performance indicators for better and finer performance evaluations of BTES systems. A small-scale BTES consisting of ten boreholes arranged on a concentric double-ring layout is considered as an application. Performance variations with the inner and the outer radii of the borehole field are analyzed for the first five years of operation. The temperature fields of different configurations show the transition from collective to individual behavior of boreholes, which leads to an optimal radial configuration maximizing the performance indicators. It is seen that the indicators strongly depend on both inner and outer radii and they reach their maximums for the same distinct radial configuration. The optimum arrangement can almost double the thermal performance indicators. It is thus of great importance to optimize collective behavior to maximize the usage of stored thermal energy. The results are qualitatively general and represent the common behavioral patterns of BTES systems.

The influence of a rotating magnetic field on the thermal effect in magnetic fluid

The physical principles of magnetic hyperthermia are based on the heat generation of magnetic nanoparticles under the influence of applied magnetic fields of different configurations. The choice of a suitable methodology for generating a magnetic field can significantly affect the resulting thermal effect and thus the efficiency itself. The technical details of the apparatus generating a rotating magnetic field and a comparison of the efficiency when the alternating magnetic field is applied are analyzed. While the mechanism of the temperature rise is the same, as shown by the fitting of the dT/dt curves, the intrinsic loss power differs significantly. It was found that the rotating magnetic field produces a thermal effect that is more than twice that of the alternating magnetic field under similar experimental conditions.

Dynamics of a flexible ferromagnetic filament in a rotating magnetic field.

Flexible magnetic filaments have garnered considerable attention as prospective materials for the creation of different microdevices. We describe a theoretical model of a ferromagnetic filament and derive its equations of motion by variational techniques. The numerical algorithm used to solve the filament dynamics in magnetic fields of different configurations is described. It is found that in a rotating field the filament transitions between synchronous and asynchronous regimes with respect to the rotating field, similarly to a rigid magnetic dipole. The mean angular velocity of the filament is well described by a relation valid for a rigid magnetic dipole with quantitative differences attributable to the flexibility of the filament.

Development of Hybrid Transport Systems for Delivering Cryogenic Fusion Targets Into Focus of High-Power Laser System or ICF Reactor

We present our results on utilization of the quantum levitation effect for HTSC samples (superconducting ceramics based on YBa2Cu3O7−x and SuperOx J-PI-12-20Ag-20Cu superconducting tapes) in magnetic fields of different configurations with respect to developing special carriers for hybrid systems of noncontact transport of cryogenic targets in ICF experiments. We implement the obtained results for developing and engineering of “HTSC-MAGLEV” delivery system to minimize the risk for damage of the fuel layer at the target acceleration and during target injection into the center of the ICF reaction chamber.

Simulation of Low Thrust Spacecraft Guided Motion for a Number of Missions in the Solar System

Models of spacecraft guided motion in the gravitational fields of different configurations were developed. Parameterization of the optimal control laws for all the trajectory segments of the spacecraft moving in the N-body gravitational field was realized. The dependence patterns of control laws on mission purposes were determined. The simulation of the number of missions in the Solar system was performed: low Earth orbit – L1 and L2 of the Earth-Moon and the Sun-Earth systems, L1 – L2 and L2 – L1 of the Earth-Moon and the Sun-Earth systems, low Earth orbit – asteroid Eros, low Earth orbit – Venus, low Earth orbit – Mars. Moreover, the Venus gravity assist maneuver was considered.

Study of charged particle motion in fields of different configurations for developing the concept of plasma separation of spent nuclear fuel

The concept of plasma separation of spent nuclear fuel in a plane perpendicular to the magnetic field in an electric potential of special configuration is developed. A specific feature of the proposed approach consists in using an accelerating potential for reducing energy and angular spread of plasma ions at the entrance to the separator chamber and a potential well for the spatial separation of ions with different masses. The trajectories of ions of the substance imitating spent nuclear fuel are calculated. The calculations are performed for azimuthal and axial magnetic fields and model electric field configurations corresponding to different geometries of the separator chamber. It is shown that, using magnetic fields with a characteristic strength of 1 kG and electric potentials of up to 1 kV inside a region with a linear size less than 100 cm, it is possible to separate ions of spent nuclear fuel with energies from 0.2 to 3 eV. The calculations were performed for a collisionless mode in the single-particle approximation. Possible variants of the experimental facility for plasma separation of spent nuclear fuel are proposed.

Numerical investigation of the velocity field and separation efficiency of deoiling hydrocyclones

Three-dimensional simulation of a multiphase flow is performed using the Eulerian-Eulerian finite volume method in order to evaluate the separation efficiency and velocity field of deoiling hydrocyclones. The solution is developed using a mass conservation-based algorithm (MCBA) with collocated grid arrangement. The mixture approach of the Reynolds stress model is also employed in order to capture features of turbulent multiphase swirling flow. The velocity field and separation efficiency of two different configurations of deoiling hydrocyclones are compared with available experimental data. The comparison shows that the separation efficiency can be predicted with high accuracy using computational fluid dynamics. The velocity fields are also in good agreement with available experimental velocity measurements. Special attention is drawn to swirl intensity in deoiling hydrocyclones and it is shown that the differences in velocity and volume fraction fields of different configurations are related to swirl distribution.

Combined effect of DC magnetic fields and free surface stresses on the melt flow and crystallization front formation during 400 mm diameter Si Cz crystal growth

The paper describes an analysis of 400 mm diameter Si Czochralski growth with applied direct current magnetic fields of different configurations and strengths, using 3D unsteady numerical simulation. The numerical model is based on the Navier–Stokes equations coupled to heat transfer and electric current flow in the crystallization zone, including the calculation of the crystallization front geometry. The obtained results are discussed with regard to study optimal crystal growth parameters providing dislocation free crystal growth with a low vacancy concentration.

Words to a problem of multiplicity of carbenelike systems in the external electric fields

AbstractA possibility of multiplicity change for carbenelike systems in external electric fields of different configurations on an example of carbene CH2 and silylene SiH2 is considered by using semiempirical INDO approximation and ab initio calculations with 6‐311G**//6‐311G** and 6‐311G**//3‐21G basis sets taking into account the correlation effects on the level of second‐order Møller‐Plesset perturbation theory (MP2). It is shown that, namely, the nonuniformity of the electric field is the factor that determines the multiplicity of carbenelike structures in external electric fields and that may affect the reactivity of carbenes and carbene analogues. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004

Magnetic force microscope study of the micromagnetics of submicrometer magnetic particles

A high-resolution, high-sensitivity magnetic force microscope (MFM) with the ability to image in an in situ magnetic field is described. This MFM has been used to investigate the micromagnetics of nanolithographically produced magnetic particles. It is shown that the particles’ switching fields can be determined without being perturbed by the stray fields from the sensing tip. This allows the study of the evolution of the particles’ magnetic states as a function of applied field and the direct observation of cooperative switching among interacting particles. The switching fields of individual particles are compared with remanent magnetization data, taken with an alternating gradient magnetometer, on both isolated and interactive arrays of particles. A method is described for estimating the strength of the interaction between particles by comparing the switching fields of different configurations of particle moments created by using the MFM tip as a local field source. Finally, a novel remanent magnetization state has been observed which provides a check on the validity of micromagnetic numerical simulations.

Characteristics of radiation emitted from a gas laser tunable by a strong magnetic field

A calculation is made of the polarization of the active medium of a gas laser subjected to strong magnetic fields of different configurations when the Zeeman splitting of the gain line is considerably greater than its Doppler broadening. Two-frequency emission is considered for any value of the angular momentum of the levels of dipole transitions and an allowance is made for depolarizing atomic collisions. The results are used to investigate the characteristics of radiation emitted from one- and two-mode lasers with an anisotropic resonator tuned by the Zeeman effect.

Stabilization of Long Electric Arcs by Rotating Magnetic Fields of Different Configurations

AbstractThe results of the investigation of the direct current electric arc under the influence on it of the rotating magnetic fields of the inductors with a different number of poles pairs are given in the article.The analysis and the comparison of the arc energetic characteristics and of its movement parameters in the rotating magnetic fields of different configurations were carried out.The comparison of the experimental data and of the results of the theoretical analysis of the arc movement in the 2‐poles and 4‐poles inductors fields was carried out.A number of original methods for the application of the researched type of the magnetic effect on the electric discharge in plasma techniques and technology was suggested.

Resonant modes of magnetostatic waves in a normally magnetized disk

It is assumed that the resonance absorption of magnetostatic waves is caused by those standing waves set up in a normally magnetized disk. The resonance conditions are derived for magnetostatic waves pinned at the small edge of the disk, and the excitation of different sets of modes of magnetostatic waves by rf magnetic fields of different configurations is described. The resonance conditions are combined with the inhomogeneous internal magnetic field of a disk to analyze the absorption spectrum of the disk. Experimental observations of the modes are performed using a disk of single-crystal yttrium iron garnet, at C- and X-band frequencies, and at ordinary temperatures. Some experimental results are compared with the theory and it is shown that the analysis gives a satisfactory description of the observed absorption spectra.