Coupling of External Electric Circuits with Computational Domains

Coupling of electrical circuits with 2D and 3D computational domains is very important for practical applications. To this aim, the notions of “electrical current” and “voltage” must be defined precisely and linked with local quantities (i.e., fields and potentials) in the computational domain. Apart from the static case, the definition of voltage is more complex than it may appear at a first glance, and it is usually tainted by unspoken and/or not justified assumptions. The purpose of this work is twofold: on one hand, to shed light on the definition and on the physical meaning of voltage in the case of time varying quasi-static fields and, on the other hand, to show how to establish coupling equations between lumped parameters circuit model and 2D/3D computational domains. It is demonstrated that a precise physical significance can be given to the voltage in terms of power balance only (the notion of potential is unnecessary). A couple of original operators which allow to express voltages and currents are introduced. Based on a critical analysis of the research literature, it is shown that existing coupling formulas can all be rewritten as particular cases of these two operators. The developed analysis is independent from any computational method and can be used to devise new coupling formulas.

Reducing reflectivity of stimulated Raman scattering by discretely changing phase of incident light in inertial fusion plasmas

A new method to reduce the stimulated Raman scattering (SRS) in inertial confinement fusion conditions is proposed by changing the incident light phase discretely. The proposal is first examined by three-wave coupling equations and then verified by Vlasov simulations. A remarkable decreasing in SRS reflectivity is observed when the period of phase changing is less than 2π/γ, where γ is the growth rate of SRS. By contrast, some simulations with continuously changing phase of incident light are carried out to compare their influence on SRS. In addition, the proposal may suppress the stimulated Brillouin scattering.

Phragmén-Lindelöf Alternative Results for a Class of Thermoelastic Plate

The spatial properties of solutions for a class of thermoelastic plate with biharmonic operator were studied. The energy method was used. We constructed an energy expression. A differential inequality which the energy expression was controlled by a second-order differential inequality is deduced. The Phragme´n-Lindelo¨f alternative results of the solutions were obtained by solving the inequality. These results show that the Saint-Venant principle is also valid for the hyperbolic–hyperbolic coupling equations. Our results can been seen as a version of symmetry in inequality for studying the Phragme´n-Lindelo¨f alternative results.

Investigation on the Self-synchronization of Dual Steady States for a Vibrating System with Four Unbalanced Rotors

In the field of vibration utilization engineering, to achieve the maximum degree or the highest efficiency use of the excitation force is still a hotspot among researchers. Based on this, this paper has carried out a series of synchronous theoretical analysis on the four identical unbalanced rotors (IURs) symmetrically and circularly mounted on a rigid frame (RF) model, which is used to drive a cone crusher. The dimensionless coupling equations of the four IURs are established using the improved small parameter method. The analysis of the coupling dynamics characteristics of the system shows that the four motors of the system adjust the speed through the synchronous torque to achieve synchronization, and a parameter determination method for realizing offset self-synchronization to eccentric force was put forward under the steady state of ultra-resonance. Furthermore, the relationship between the equivalent stiffness of the crushed material and crushing force and compression coefficient is discussed, and the design method of the full-load crusher working under the steady state of sub-resonance is proposed. Finally, through a series of computer simulations, the correctness of the self-synchronization of dual steady states is verified.

Rapid X-ray fluorescence analysis of intercalation compounds for molybdenum and cobalt content

Synthesizing and studying the properties of nanomaterials based on layered molybdenum disulfide, often face a need for rapid elemental analysis and prompt return of the material to the customer. Sometimes, nanoparticles of molybdenum disulfide are to be modified with metal compounds to improve the catalytic or magnetic properties of the material. We propose a method for rapid X-ray fluorescence determination of molybdenum and cobalt in the range of 10 – 50% in such compounds using a bulk method without dilution. Analytical signals were measured at the wavelengths of MoKα and CoKα lines using a VRA-30 spectrometer (Carl Zeiss, Germany; X-ray tube with Rh anode). The metal content was calculated using the derived coupling equations. The determination error ranges within ±2.7% (abs.) and 1.4% (abs.) for Mo and Co, respectively. Correctness of the method was confirmed for a batch of synthesized compounds by comparison of the results obtained with the data of XRF analysis using the dilution method traditionally used in the laboratory. The proposed rapid method provides simplification of the procedure and more than 4-fold shortening of analysis in time, the sample being preserved and can be used for further research.

Analysis of the electromagnetic wave illumination on the transmission lines with nonlinear terminations

In this paper, an unconditionally stable time-domain method is proposed to investigate the external electromagnetic (EM) field illumination on the nonlinearly loaded transmission lines. In the proposed algorithm, the field to line coupling equations and linear/nonlinear boundary conditions are incorporated and expressed in a matrix form. The derived differential matrix equations are then discretized and solved using the proposed finite difference time domain (FDTD) method approach. The discretized nonlinear matrix equations are also solved by applying a globally convergent iterative method to ensure the stability of the method. Moreover, the experimental investigations are conducted using a transverse EM (TEM) cell for a single microstrip line and a power detector circuit as a nonlinearly loaded transmission line to confirm the accuracy and stability of the proposed method. With the merit of satisfactory accuracy and unconditional stability for the entire range of time steps, the presented approach would be applicable for analyzing the microwave linear/nonlinear circuits subjected to the external incident EM wave.

THE PROPERTIES OF THE MECHANISMS WITH SIX DEGREES OF FREEDOM

Parallel mechanisms analysis and design are the main trends of advance robotic engineering. This article is devoted to the novel parallel mechanisms with six degrees of freedom. The presented mechanisms can be applied in additive technologies, robotic–assisted surgery. The proposed mechanisms contain six drives and six kinematic chains. They have the properties of a partial kinematic decoupling, which allows realized separately translational and rotational movements. The presented mechanisms is a simple kinematic scheme. The drives can provide a ratio 1:1 of with the movement of the output link. The paper considers the solution of kinematics problems, velocity analysis, singularities. The velocity problem is solved by differentiating the coupling equations. Singularities were detected by studying the properties of Jacobi matrices. The singularities depend only on the orientation of the output link. These mechanisms have a large working area free of singularities. The working area is determined by solving the coupling equations. The solved problems allow to solve the control such mechanisms in the future.

Possibilities to determine biometric parameters using airborne laser scanning data

The paper brings forward ways to solve the problem of estimating the trunk diameter using data of airborne laser scanning (LIDAR) relevant for forest inventory. At the first stage of studying, it was defined the regularities of tree height and diameter relations for various species, as well as the coefficients of coupling equations of the significance of “height-diameter” relations based on field data. At the second stage, it was calculated the relations of crown parameters (diameter and volume) and the trunk height and diameter at 1.3 m level accounting parameters dependent of species. Based on the estimated and LIDAR data, the resulting calculations of tree diameters were made with 83.2% accuracy. The proposed calculation of the trunk diameter is an important step for further development of an automated algorithm to obtain basic taxation indicators, such as the tree trunk number, height and diameter. The data got by this way can be used for high density forests while cuttings assessment using LIDAR.

COMPARISONS AMONG THREE COUPLING FORMS OF CYLINDRICAL NODAL EXPANSION METHODS

Nodal expansion method (NEM) is a typical nodal method in solving neutron diffusion equation in coarse mesh spatial discretization. NEM has been extended to cylindrical geometry in previous studies. Cylindrical NEM can be realized by different forms, where the variables in the nodal coupling equations are classified as net current, flux or partial current at the nodal surface, respectively. The three types of coupling forms of NEM have been implemented in PANGU code for the high temperature gas-cooled reactor (HTGR) physics analysis. This paper derives the three types of coupling forms of NEM, and analyzes their performance in solving the HTGR model containing void region.

Dark parameterization approach to the Benjamin–Ono equation

The novel coupling Benjamin–Ono system is obtained with the dark parameterization approach.By solving these coupling equations, three typical explicit solutions including the traveling wave solution are constructed through the special property of the anyon-[Formula: see text] algebra. Several novel types of localized excitations are depicted with some solutions.