Piezoelectric Ultrasonic Local Resonant Ultra-Precision Grinding for Hard-Brittle Materials.

Hard-brittle materials are widely used in the optics, electronics, and aviation industries, but their high hardness and brittleness make it challenging for traditional processing methods to achieve high efficiency and superior surface quality. This study aims to investigate the application of ultrasonic local resonant grinding to sapphire to improve the efficiency and meet the requirements for the optical window in the surface roughness of the material. The resonant frequency of a piezoelectric ultrasonic vibration system and the vibration amplitude of a grinding head's working face were simulated and tested, respectively.

Bidirectional Drive with Inhibited Hysteresis for Piezoelectric Actuators.

Piezoelectric actuators with a flexible displacement amplification structure are widely used in the fields of precision driving and positioning. The displacement curve of conventional piezoelectric actuators is asymmetrical and non-linear, which leads to large non-linear errors and reduced positioning accuracy of these piezoelectric actuators. In this paper, a bidirectional active drive piezoelectric actuator is proposed, which suppresses the hysteresis phenomenon to a certain extent and reduces the non-linear error.

Bidirectional Active Piezoelectric Actuator Based on Optimized Bridge-Type Amplifier.

Piezoelectric actuators based on bridge displacement amplifying mechanisms are widely used in precision driving and positioning fields. The classical bridge mechanism relies on structural flexibility to realize the return stroke, which leads to the low positioning accuracy of the actuator. In this paper, a series bridge mechanism is proposed to realize a bidirectional active drive; the return stroke is driven by a piezoelectric stack rather than by the flexibility of the structure.

Inherent mechanism of frequency drift affected by constraint conditions for rotary piezoelectric motors.

The optimum drive frequency of rotary piezoelectric motors is in the vicinity of the resonance frequency of piezoelectric vibrators. Previous studies reveal that the resonance frequency is inconstant and is drifting with the variation of constraint conditions, of which the solutions generally focused on optimizing the drive circuits and control algorithms, while the working principle and equivalent modeling about frequency drift are still indistinct. By introducing the unknown parameters including stiffness coefficients and loss factors, the equivalent physical models and mathematical derivation are investigated.

Suppression of Tafazzin promotes thyroid cancer apoptosis via activating the JNK signaling pathway and enhancing INF2-mediated mitochondrial fission.

Tafazzin has been found to be associated with tumor progression. Mitochondrial homeostasis regulates cancer cell viability and metastasis. However, the roles of Tafazzin and mitochondrial homeostasis in thyroid cancer have not been explored.

Noninvasive estimation of assist pressure for direct mechanical ventricular actuation.

Direct mechanical ventricular actuation is effective to reestablish the ventricular function with non-blood contact. Due to the energy loss within the driveline of the direct cardiac compression device, it is necessary to acquire the accurate value of assist pressure acting on the heart surface. To avoid myocardial trauma induced by invasive sensors, the noninvasive estimation method is developed and the experimental device is designed to measure the sample data for fitting the estimation models.

[Design and implementation of pupil auto-tracking system in the perimeter].

The pupil auto-tracking system is a key component of the full-automatic perimeter. Taking the advantage of integral image in counting characteristic value rapidly, we studied the relationship between training stages and total error detection rate based on the training of Adaboost strong classifier. Besides, a testing strategy of amplification detection window was introduced, and a multi-stage cascaded eye classifier for eye detection was proposed finally.