FLAT CIRCULAR SOLENOID BETWEEN MASSIVE BIFILAR COILS. ANALYSIS OF ELECTROMAGNETIC PROCESSES

An analysis and numerical estimates of induction effects in the metal of a flat circular solenoid located between the branches of an external bifilar coil in a flat inductor system excited by unidirectional currents in the bifilar windings are presented. Such a device, the design of which was first proposed earlier by the authors of this work, is of practical interest for circuits of equipment for magnetic-pulse processing of metals. The use of the considered inductor system makes it possible to minimize the influence of induction effects on electromagnetic processes in the metal of the internal inductor. Numerical estimates are obtained for the induced currents excited in the metal of the inner circular inductor placed between the outer windings of the bifilar coil. It is shown that in the low-frequency mode of acting fields, the time dependence of the excited current is a derivative of the time dependence of the exciting current and the transverse distribution of the current in the metal of the internal inductor is a linear dependence passing through the central axis of the inductor. In the high-frequency regime of acting fields, the time dependence and the radial distribution of the excited current coincide with the corresponding analogs for the exciting current, and the transverse distribution of the induced current is characteristic of a sharp surface effect, when the induced current is displaced to the boundary surfaces of the metal. It is proved that the minimum influence of the fields of the external bifilar on the electromagnetic processes in the internal inductor should be observed in the low-frequency mode, when the spatial superposition of multidirectional induced currents adds up to the zero value of the excited electromotive force of induction. The results of the analysis based on the specific calculations performed are aimed at finding the conditions for the successful technical implementation of the proposed inductor system. The creation of workable models of the proposed inductor systems and experiments to determine the real conditions for their maximum efficiency are seen as very promising in the direction of subsequent research.

Controllable electromagnetic negative stiffness spring for vibration isolator: Design, analyses and experimental verification

In this study, a novel negative stiffness spring is developed. The developed spring possesses the characteristics of the controllable stiffness and can be employed in vibration isolation system with a low resonance frequency. The controllable electromagnetic negative stiffness spring (CENSS) is obtained by the coaxial permanent magnets (PMs) and the circular current-carrying coils. The stiffness control is accomplished by changing the current in the coils. Furthermore, the mathematical model of CENSS is established, based on the filament method. According to the model, the relationship between the exciting current and the axial stiffness is obtained. Moreover, the influence of the structural parameters of CENSS on the magnetic force and the stiffness is analyzed. The results demonstrate that the thickness of PMs and the coils have the ability to adjust the range of the negative stiffness. Finally, performance experimental study of CENSS in the stiffness domain is carried out under different exciting currents and thicknesses. The experimental results have shown a good agreement with the model. It demonstrates that the performance of negative stiffness in CENSS can be controlled efficiently by the exciting current and optimized by the thickness.

The Annual Review of Applied Linguistics at 40: Looking Back and Moving Ahead

It is a privilege to be Editor-in-Chief of the Annual Review of Applied Linguistics in 2020 as it celebrates its 40th year. This is my fifth issue as Editor. I will begin this short introduction by paying tribute, with the help of Bill Grabe (Northern Arizona University), to the founding editor of the journal, Robert Kaplan (1929–2020). Without Robert Kaplan, none of us would be reading these pages. We will then turn to some comments from each of the previous editors on a few of the highlights of their time editing the journal, along with words for the future. After this, I will describe some recent updates, go through a few of the historical successes of the journal, and then turn to the contents of the exciting current issue, “Looking back and moving ahead.”

The Role of Geterogeneity in Synchronization of Spiking Neural Networks

The diversity and heterogeneity of neurons and synapses is an important factor in the functioning of the brain. In our work, we investigated the role of heterogeneity of neural populations in the occurrence of synchronous modes in a network connected by exciting links in the presence of an external exciting input. Using Monte-Carlo modeling and the semi-analytical modeling the distribution of the refractory density of neuron integrators and Hodgkin – Huxley neurons, we showed that there is a range of parameters for the stimulating current and the strength of connections in the population where the effects of neuronal heterogeneity on the threshold or on the stimulating current are opposite. For large values ​​of synaptic weights and subthreshold values ​​of the exciting current, heterogeneity contributes to the emergence of a synchronous mode in the neural network, while at the same time reducing the coupling strength and increasing the exciting current. The heterogeneity reduces the tendency of the neural network to synchronize. The results obtained make it possible to reconcile the known data on the effects of heterogeneity in the regulation of the synchronous regimes arising in the neural ensembles of the brain.

Turn-to-Turn Short Circuit Diagnostic Improvement Method Based on ANN for Synchronous Generator Excitation Winding

The paper describes the determination method of quasi-reactive power for synchronous generator turn-to-turn short circuit diagnostics. A proposed method allows to determine the relation between the exciting current and quasi-reactive power at the generator leading to a high probability. This relation is the basis of the determination method of turn-to-turn short circuit availability and its severity.