Intracavity Measurement Sensitivity Enhancement without Runaway Noise

A method to increase the sensitivity of an intracavity differential phase measurement that is not made irrelevant by a larger increase of noise is explored. By introducing a phase velocity feedback by way of a resonant dispersive element in an active sensor in which two ultrashort pulses circulate, it is shown that the measurement sensitivity is elevated without significantly increasing the Petermann excess noise factor. This enhancement technique has considerable implications for any optical phase based measurement; from gyroscopes and accelerometers to magnetometers and optical index measurements. Here we describe the enhancement method in the context of past dispersion enhancement studies including the recent work surrounding non-Hermitian quantum mechanics, justify the method with a theoretical framework (including numerical simulations), and propose practical applications.

Energy efficient throttling control of a multi-pressure system using a genetic algorithm and model predictive control

The energy efficiency of hydraulic cylinder drives can be increased by replacing the actuator with a multi-chamber cylinder, utilising multiple supply lines with unique pressures or a combination of the concepts. Previous studies have demonstrated significant energy savings using a cascaded control system, which requires velocity feedback to stabilise the system. To avoid the need of position or velocity sensors in harsh conditions of mobile machines, this article presents a throttling control scheme, which achieves good energy efficiency on multi-pressure systems without velocity feedback. A simulation study was performed to determine the efficiency of the system, robustness against load variations and the effect of valve response time on performance.

Periodic Response Analysis of A Jeffcott-Rotor System By The Integral Equation Method

In this paper, two modified nonlinear saturation-based controllers and negative velocity feedback controllers are integrated to suppress the horizontal and vertical vibrations of a horizontally supported Jeffcott-rotor system at primary resonance excitation and the presence of 1:1 and 1:2 internal resonances. The second order approximations and the amplitude equations are obtained by applying the integral equation method to analyze the nonlinear behavior of this model. The stability of the steady-state solutions is ascertained based on the Floquet theory. The necessity of adding a negative velocity feedback to the main system is stated. The effects of different control parameters on the frequency-response curves and the force-response curves are investigated. Time histories of the whole system are included to show the response with and without control. It is shown that the saturation-based controller can reduce the system response to almost zero and the negative velocity feedback can suppress the transient vibrations and prevent the main system having the large amplitude vibration. The analyses show that analytical solutions are in excellent agreement with the numerical simulations. Finally, a comparison with previously published works is included.