Control of oscillations in two-rotor cyberphysical vibration units with time-varying observer

In this paper the control of oscillations in the two-rotor vibration unit is studied. It is assumed that the velocity of the oscillation of the platform cannot be accurately measured. The time-varying observer is proposed to restore it. In order to guarantee stability of the frequency and amplitude of oscillations of the vibrating parts of a two-rotor vibration unit special control algorithms based on speed-gradient methodology. Simulation results confirm stability of the synchronous rotation modes of the unbalanced rotors of the vibration unit.

Control of the mechanical system oscillation with a drive under conditions of parametric uncertainty

A method for adaptive control of oscillations by cascade systems based on the energy approach and the method of highspeed big-gradient with an adjustable model is proposed. The control objectives are all trajectories limitation of a closed system and the excitation in the mechanical subsystem of oscillations with a given energy level, as well as the identification of unknown parameters for the mechanical subsystem. An example and results of computer simulation are given. Keywords high-speed big-gradient method; cascade system; adaptive management; Lyapunov function; speed gradient algorithm

Circadian control of oscillations in mitochondrial rate-limiting enzymes and nutrient utilization by PERIOD proteins

Mitochondria are major suppliers of cellular energy through nutrients oxidation. Little is known about the mechanisms that enable mitochondria to cope with changes in nutrient supply and energy demand that naturally occur throughout the day. To address this question, we applied MS-based quantitative proteomics on isolated mitochondria from mice killed throughout the day and identified extensive oscillations in the mitochondrial proteome. Remarkably, the majority of cycling mitochondrial proteins peaked during the early light phase. We found that rate-limiting mitochondrial enzymes that process lipids and carbohydrates accumulate in a diurnal manner and are dependent on the clock proteins PER1/2. In this conjuncture, we uncovered daily oscillations in mitochondrial respiration that peak during different times of the day in response to different nutrients. Notably, the diurnal regulation of mitochondrial respiration was blunted in mice lacking PER1/2 or on a high-fat diet. We propose that PERIOD proteins optimize mitochondrial metabolism to daily changes in energy supply/demand and thereby, serve as a rheostat for mitochondrial nutrient utilization.

Control of Oscillations in Second-Order Differential Equation

The article deals with the control of oscillations in a specific type of second-order differential equations. The purpose of the research is to prove the possibility of oscillation frequency control based on a change in the value of a singular perturbation parameter placed into a mathematical model of a nonlinear dynamical system at the highest derivative. The oscillation frequency change caused by a different value of the parameter is verified by numerically modelling the system.

Fast, High-Fidelity Simulation of Dynamic Thermo-Fluid States in Refrigeration Systems

A dynamic model of a heat exchanger containing a phase-changing refrigerant is presented. Due to fundamental characteristics of phase-changing fluids, the model is computationally inefficient. Remedies to this inefficiency, such as hastened computation of fluid properties, realistic heat transfer coefficient blending, and active control of oscillations in the thermodynamic state of the system are presented. These remedies are shown to minimally impact the output of the model while allowing it to execute much more quickly than real-time.