Phase tracking algorithms detect both real and imaginary components of outer hair cell nonlinear membrane capacitance that exhibits dielectric loss.

Outer hair cell (OHC) nonlinear membrane capacitance (NLC) represents voltage-dependent sensor charge movements within prestin (SLC26a5) that drive OHC electromotility. Dielectric loss, a shift in charge movement phase from purely capacitive to resistive, is likely indicative of prestin interaction with the viscous lipid bilayer and has been suggested to correspond to prestin power output. The frequency response of NLC in OHC membrane patches has been measured with phase tracking and complex capacitance methodologies. While the latter approach can directly determine the presence of dielectric loss by assessing charge movement both in and out of phase with driving voltage, the former has been suggested to fail in this regard. Here we show that standard phase tracking in the presence of dielectric loss does indeed register this loss. Such estimates of NLC correspond to the absolute magnitude of complex NLC, indicating that total charge movement regardless of phase is assessed, thereby validating past and present measures of NLC frequency response that limits its effectiveness at high frequencies. This observation has important implications for understanding the role of prestin in cochlear amplification.

Phase Tracking Sequences for 5G NR in 52.6-71 GHz Band: Design and Analysis

This paper presents a novel approach to the phase tracking reference signal (PTRS) design for phase noise impact compensation in the 5G NR communication systems intended to work in a new 52.6 GHz to 71 GHz frequency band. For detailed problem illustration, the phase noise compensation algorithms are discussed and explained, from the basic common phase error (CPE) compensation to the MMSE-base inter-carrier interference (ICI) filtering. Performance of the different phase noise compensation algorithms is investigated for the baseline PTRS accepted in the current 5G NR specification and compared with the newly proposed approach to the PTRS design. This approach is based on nulling the subcarriers adjacent to the reference signals to minimize influence of the ICI on the estimation process. It was shown that new nulling PTRS design outperforms currently used distributed PTRS structure. In addition, numerical results represent a trade-off between the filter size and the amount of the allocated training resources to achieve better performance. It was shown that proposed PTRS structures and processing algorithms give ICI compensation level very close to optimal scheme and thus, different approaches (such as time domain compensation) may be required for further progress.

Dynamics of the Vibration System Driven by Three Homodromy Eccentric Rotors Using Control Synchronization

To solve the limitation of vibration synchronization, this paper investigates the dynamics of a vibration system driven by three homodromy eccentric rotors (ERs) using control synchronization. According to the synchronous condition and the stability condition, the changes of the phase differences of the three-ERs system and the two-third ERs system are obtained. Based on the electromechanical mathematic model of the vibration system and the master-slave control strategy, the synchronous target that three ERs achieve the same phase motion is converted into velocity and phase tracking of ERs. Considering the coupling characteristic of the self-adjusting of the system in the state of vibration synchronization, the velocity and phase controllers are designed by employing discrete-time sliding mode control. An experimental system for control synchronization is designed, including hardware composition and software programming. For the feedback signal used to match control targets, a method of calculating velocity and the phase difference is proposed from engineering. Recording the rotational velocities, phase differences, and system response, three group experiments with different control schemes are achieved. According to the experimental data, the coupling characteristic of the vibration system adopting control synchronization is analyzed, which can provide the basis for designing vibration machines using control synchronization.