Research on the Plasma Anemometer Based on AC Glow Discharge

A new plasma anemometer based on AC glow discharge is designed in this article. Firstly, theoretical analysis of plasma anemometer working principle is introduced to prove the feasibility of the experimental measurement method. Then the experiments are carried out to study the effects of different parameters on the static discharge characteristics of the plasma anemometer system, by which the system optimization methods are obtained. Finally, several groups of appropriate parameters are selected to build the plasma anemometer system based on resistance capacitance coupling negative feedback AC glow discharge, and different airflow speeds are applied to obtain the achievable velocity measurement range. The results show that there is a linear relationship between airflow velocity and discharge current in an allowable error range, which can be applied for airflow velocity measurement. Negative feedback coupling module, which is composed of the coupling resistance and the coupling capacitance, has good effects on improving the system stability. The measurement range of the airflow velocity is significantly increased when the electrode gap is 3 mm, coupling resistance is 470 Ω, and coupling capacitance is 220 pF.

Spontaneous Synchronization in Two Mutually Coupled Memristor-Based Chua’s Circuits: Numerical Investigations

Chaotic dynamics of numerous memristor-based circuits is widely reported in literature. Recently, some works have appeared which study the problem of synchronization control of these systems in a master-slave configuration. In the present paper, the spontaneous dynamic behavior of two chaotic memristor-based Chua’s circuits, mutually interacting through a coupling resistance, was studied via computer simulations in order to study possible self-organized synchronization phenomena. The used memristor is a flux controlled memristor with a cubic nonlinearity, and it can be regarded as a time-varying memductance. The memristor, in effect, retains memory of its past dynamic and any difference in the initial conditions of the two circuits results in different values of the corresponding memductances. In this sense, due to the memory effect of the memristor, even if coupled circuits have the same parameters they do not constitute two completely identical chaotic oscillators. As is known, for nonidentical chaotic systems, in addition to complete synchronizations (CS) other weaker forms of synchronization which provide correlations between the signals of the two systems can also occur. Depending on initial conditions and coupling strength, both chaotic and nonchaotic synchronization are observed for the system considered in this work.

Novel Emitter-Segmented Power HBT with 2-D Non-Uniform Segment Spacing for High Thermal Stability

With the aid of the thermal model, thermal resistance matrix of emitter-segmented power HBT is proposed to represent thermal effects. The effect of 2-dimensional (2-D) inter-segment spacing on thermal stability of device is studied. It is shown that the increase of inter-segment spacing could effectively decrease thermal coupling resistance, lower temperature of center segments, and hence improves the thermal stability. Furthermore, a novel emitter-segmented power HBT with 2-D non-uniform segment spacing is proposed, in which the non-uniformity of segment temperature is improved by 75.26% and the maximum power level difference of emitter segment is improved by 55.84%, when compared with uniform segment spacing HBT. Therefore the technique of 2-D non-uniform segment spacing is a better method for enhancing the thermal stability of power HBTs.

BIFURCATIONS AND HYPERCHAOS FROM A DC DRIVEN NONIDENTICAL JOSEPHSON JUNCTION SYSTEM

The dynamics of a resistively coupled system of nonidentical Josephson junctions (JJ) with dc feedings is explored theoretically. The effects of system parameters on the dynamic features are defined and equilibrium features of the system of equations are explored in such a nonidentical JJ system for the first time. By using center manifold reduction, the inverse of coupling resistance R cp is considered as the main bifurcation parameter. The bifurcation at the vicinity of the equilibrium point is found to be transcritical, stable and unstable regimes are also indicated analytically. It is observed that the amplitudes of the output voltages on the coupling resistance R cp are changeable and mostly uncorrelated for two parts of superconducting junction system. Such a system exhibits very rich dynamics from periodic to chaotic behavior for certain parameter sets. While the regular characteristics are observed for moderate and lower feeding currents, chaotic and highly-complex patterns are obtained for relatively higher values of them. Besides, a wider hyperchaotic region is found for wide ranges of parameters after the determination of phase diagrams compared to the earlier studies. The nonidentical nature of JJs governs the complicated dynamics on the phase space. The present circuitry can be utilized for various purposes such as stable, chaotic or hyperchaotic behavior depending on the parameters Ii and R cp .