Research on Precise Control of a Cylinder Delay Oscillation System Based on Response Surface and Genetic Algorithm

A cylinder time-delay oscillation system can be constructed by using air bag and throttle valve. The air bag and throttle valve are used to realize the time-delay transmission of pressure in the feedback circuit, and the feedback pressure is used to promote the reversing of two position five-way valve, so as to realize the reciprocating action of the cylinder. The experimental design is carried out based on the simulation analysis, and the response surface is constructed based on the experimental data to clarify the relationship between the cylinder dwell time and the main component parameters. Based on response surface, genetic algorithm is used to search for the best control parameters to realize the accurate control of cylinder dwell time.

Model Decoupled Synchronization Control Design with Fractional Order Filter for H-Type Air Floating Motion Platform

H-type motion platform with linear motors is widely used in two-degrees-of-freedom motion systems, and one-direction dual motors need to be precisely controlled with strict synchronization for high precision performance. In this paper, a synchronous control method based on model decoupling is proposed. The dynamic model of an H-type air floating motion platform is established and one direction control using two motors with position dependency coupling is decoupled and converted into independent position and rotation controls, separately. For the low damping second-order oscillation system of the rotation control loop, a new fractional order biquad filtering method is proposed to generate an antiresonance peak to improve the phase and control gain of the open loop system, which can ensure system stability and quick attenuation for external disturbances. In the multiple-degree-of-freedom decoupled control loops, a systematic feedback controller design methodology is proposed to satisfy the given frequency domain design specifications; a feed-forward control strategy is also applied to compensate the disturbance torque caused by the platform motion. The simulation and experimental results demonstrate that the proposed synchronization control method is effective, and achieves better disturbance rejection performance than the existing optimal cancellation filtering method and biquad filtering method.

Detection of uncoupled circadian rhythms in individual cells of Lemna minor using a dual-color bioluminescence monitoring system

The plant circadian oscillation system is based on the circadian clock of individual cells. Circadian behavior of cells has been observed by monitoring the circadian reporter activity such as bioluminescence of AtCCA1::LUC+. To deeply analyze different circadian behaviors in individual cells, we developed the dual-color bioluminescence monitoring system that automatically measured the luminescence of two luciferase reporters simultaneously at a single-cell level. We selected a yellow-green-emitting firefly luciferase (LUC+) and a red-emitting luciferase (PtRLUC) that is a mutant form of Brazilian click beetle ELUC. We used AtCCA1::LUC+ and CaMV35S::PtRLUC. CaMV35S::LUC+ was previously reported as a circadian reporter with a low amplitude rhythm. These bioluminescent reporters were introduced into the cells of a duckweed, Lemna minor, by particle bombardment. Time series of the bioluminescence of individual cells in a frond were obtained using a dual-color bioluminescence monitoring system with a green-pass- and red-pass filter. Luminescence intensities from the LUC+ and PtRLUC of each cell were calculated from the filtered luminescence intensities. We succeeded in reconstructing the bioluminescence behaviors of AtCCA1::LUC+ and CaMV35S::PtRLUC in the same cells. Under prolonged constant light conditions, AtCCA1::LUC+ showed a robust circadian rhythm in individual cells in an asynchronous state in the frond, as previously reported. In contrast, CaMV35S::PtRLUC stochastically showed circadian rhythms in a synchronous state. These results strongly suggested the uncoupling of cellular behavior between these circadian reporters. This dual-color bioluminescence monitoring system is a powerful tool to analyze various stochastic phenomena accompanying large cell-to-cell variation in gene expression.

Nonlinear Dynamic Study of Oscillation System Featuring Quasi-Zero and Asymmetric Stiffness

This paper will broaden our previous works about the asymmetric and quasi-zero stiffness oscillator named AQZSO. In this paper, the dynamic stiffness of the AQZSO will be investigated. Then, the condition for which the minimum dynamic stiffness is quasi-zero around the equilibrium position is also determined. By using Multi-Scale method, the fundamental resonance response of the AQZSO subjected to the vibrating base is analyzed, in which the dynamic stiffness is expressed as a fifth-order approximate polynomial through expanding Taylor series. The stability of the response is then found out via nonlinear Routh-Herwitz criterion. Moreover, because of existing the sliding friction between the cylinder and piston, the nonlinear and varying-time dynamic characteristics, the complex dynamic response of the AQZSO is the need for discovery by performing direct integration of the original dynamic equation through using 5th-order Runge-Kutta algorithm. In this work, the friction force model of cylinder will be identified through virtual prototyping technique and genetic algorithm. Additionally, the Poincáre map is also employed to analyze the bifurcation phenomenon, coexistence of multiple solutions. The traction basin of the period-1, period-2 and period-3 solution is determined, indicating that the attractor basin is influenced by the asymmetric of the stiffness curve. This research will offer a useful insight to design low frequency vibration isolation systems.

Respiratory Impedance Measured using Impulse Oscillometry in a Healthy Urban Population

This study derives normative prediction equations for respiratory impedance in a healthy asymptomatic urban population using an impulse oscillation system (IOS). In addition, this study uses body mass index (BMI) in the equations to describe the effect of obesity on respiratory impedance.Data from an urban population comprising 472 healthy asymptomatic subjects that resided or worked in lower Manhattan, New York City were retrospectively analysed. This population was the control group from a previously completed case-control study of the health effects of exposure to World Trade Center dust. Since all subjects underwent spirometry and oscillometry, these previously collected data allowed a unique opportunity to derive normative prediction equations for oscillometry in an urban, lifetime non-smoking, asymptomatic population without underlying respiratory disease.Normative prediction equations for men and women were successfully developed for a broad range of respiratory oscillometry variables with narrow confidence bands. Models that used BMI as an independent predictor of oscillometry variables (in addition to age and height) demonstrated equivalent or better fit when compared with models that used weight. With increasing BMI, resistance and reactance increased compatible with lung and airway compression from mass loading.This study represents the largest cohort of healthy urban subjects assessed with an IOS device. Normative prediction equations were derived that should facilitate application of IOS in the clinical setting. In addition, the data suggest that modelling of lung function may be best performed using height and BMI as independent variables rather than the traditional approach of using height and weight.