Electrical Characterization Method for Resonance Performance of Photo-Elastic Modulators

As a kind of resonant device, the modulation efficiency of the photo-elastic modulator (PEM) is determined by its inherent resonance characteristics, including the resonance frequency and quality factor (Q-factor). The existing methods used to characterize the resonance performance of the PEM are mainly based on the optical method to measure the vibration parameters, but these methods are more complex, have a high cost, and are not able to accurately measure the quality factor. Therefore, this paper proposes an electrical characterization method based on impedance measurement. In this method, an equivalent circuit model for the PEM is established. By measuring the impedance vs. frequency curve of the PEM and using the equivalent circuit model for fitting analysis, we can obtain the parameters of the equivalent circuit model. With these parameters, we can eventually calculate the natural resonance frequency and quality factor. The above method was applied to some commercial PEM products for experimental verification. The experimental results show that this method can accurately measure the natural resonance frequency and quality factor of the PEM, and the error is less than 0.03%.

Optimum transfer characteristics of the Tesla transformer on the first and second half-waves of output voltage

The elements of the theory of the Tesla transformer are stated, the exact solution of the equations of the dynamics of currents and voltages in the transformer circuits through the generalized parameters of the circuits (Q-factors of the primary and secondary circuits, the coupling coefficient of the circuits and mismatching factor of the natural resonance frequencies of the circuits) is given, under the assumption of their constancy. The optimal transfer characteristics of the processes of charging the capacitive storage of the secondary circuit of the transformer on the first and second half-waves are given, demonstrating the capabilities of the Tesla transformer.

Pauling’s Conceptions of Hybridization and Resonance in Modern Quantum Chemistry

We employ the tools of natural bond orbital (NBO) and natural resonance theory (NRT) analysis to demonstrate the robustness, consistency, and accuracy with which Linus Pauling’s qualitative conceptions of directional hybridization and resonance delocalization are manifested in all known variants of modern computational quantum chemistry methodology.

Numerical and experimental investigation of the dynamics of ultrasound contrast agents excited at higher multiples of their natural resonance frequency

In this work the Hoff model for microbubble oscillations was used together with bifurcation diagrams to investigate microbubble behavior for a range of the system control parameters (driving frequency and pressure, microbubble size and shell parameters). We have shown that if the microbubble sizes are optimized so that their resonance frequency is a fraction of the sonication frequency (1/3, 1/4...), above a certain pressure threshold, the microbubbles can emit higher order subharmonics at (1/3, 2/3...) of the sonication frequency. Experimental results (using Artenga and in-house made lipid microbubbles with a 25 MHz, 30 cycle pulse using 0.1-2.5 MPa pressures) showed subpopulations of the microbubbles that were able to show this behaviour by scattering ultrasound according to the theoretical predictions (e.g. having two frequency maxima for subharmonics at f/3 and 2f/3). The ring-down analysis of the natural free oscillations of these microbubbles confirmed the theoretical resonance predictions.

Numerical and experimental investigation of the dynamics of ultrasound contrast agents excited at higher multiples of their natural resonance frequency

In this work the Hoff model for microbubble oscillations was used together with bifurcation diagrams to investigate microbubble behavior for a range of the system control parameters (driving frequency and pressure, microbubble size and shell parameters). We have shown that if the microbubble sizes are optimized so that their resonance frequency is a fraction of the sonication frequency (1/3, 1/4...), above a certain pressure threshold, the microbubbles can emit higher order subharmonics at (1/3, 2/3...) of the sonication frequency. Experimental results (using Artenga and in-house made lipid microbubbles with a 25 MHz, 30 cycle pulse using 0.1-2.5 MPa pressures) showed subpopulations of the microbubbles that were able to show this behaviour by scattering ultrasound according to the theoretical predictions (e.g. having two frequency maxima for subharmonics at f/3 and 2f/3). The ring-down analysis of the natural free oscillations of these microbubbles confirmed the theoretical resonance predictions.

Analysis and Research on the Comprehensive Performance of Vehicle Magnetorheological Regenerative Suspension

Magnetorheological (MR) regenerative suspension system can not only achieve excellent comprehensive suspension performance but also effectively recover and utilize vibration potential energy, which has been a research hotspot in the field of vehicle engineering. In this paper, for the 1/4 vehicle’s MR regenerative suspension system parallel with a tubular permanent magnet linear motor (TPMLM), the dynamic model of the MR semi-active suspension system and the TPMLM finite element model are established separately to form a joint simulation platform. The simulation analysis of the comprehensive suspension performance and regeneration performance under different road excitations is performed. The results show that installing TPMLM does not change the natural resonance frequency of the suspension system, which ensures good driving comfort and handling stability. At the same time, it has considerable regeneration power. This research can provide a reference for the stability analysis and popularization of the vehicle’s MR regenerative suspension system.