Search

To reduce the lubrication failure of water-lubricated bearings under short-term harsh conditions, preliminary experiments have shown that temporarily supplying a small amount of lubricating oil into a bearing as a secondary lubricant can improve the load capacity of the water film therein. However, the physical flow and diffusion state of this secondary lubricant (oil) in water are unclear. Therefore, a mixed lubrication model and a volume-of-fluid model are incorporated to study the diffusion behavior of a small amount of lubricating oil in a water-lubricated bearing. The results show that there is a backflow effect in the local area inside the bearing, where the fluid velocity is in the opposite direction to the linear velocity of the shaft. This backflow effect intensifies with increasing eccentricity ratio, which enlarges the oil-free zone in the middle part of the bearing. In the convergence area at the water inlet end of the bearing, the water supply pressure and backflow effect prevent the lubricating oil from escaping. Increasing the shaft speed has a positive effect on the diffusion of the oil and the load capacity of the fluid. To enhance the assisted lubrication effect of the oil, the oil injection port should be set in the loading zone to avoid the backflow zone. This research provides some fundamental data for reducing the friction and wear of water-lubricated bearings under harsh conditions. [ABSTRACT FROM AUTHOR]

Optoelectronic synapses are considered to be important cornerstones in the construction of neuromorphic computing systems because of their low power consumption, high operating speeds, and high scalability. In this work, we demonstrate an optoelectronic synaptic device based on a ZnO/HfOx heterojunction in which optical potentiation/electrical depression behaviors and nonvolatile high current state can be implemented. The heterojunction device exhibits conductance evolution with high linearity. The excellent optoelectronic memristive behavior of the device can be attributed to the interface barrier between ZnO and HfOx, which hinders the recombination of photo-excited electron–hole pairs to increase the carrier lifetime, and realizes the nonvolatile high current state. More importantly, the artificial vision system based on optoelectronic synaptic devices can achieved a high recognition accuracy of 96.1%. Our work provides a feasible pathway toward the development of optoelectronic synaptic devices for use in high-performance neuromorphic vision systems. [ABSTRACT FROM AUTHOR]

A thermal-assisted electroforming (TAE) method is proposed to address the current overshoot issue and improve the resistive switching (RS) performance of electrochemical metallization (ECM) memory with a Cu/amorphous carbon (a-C)/Pt structure. In the initial electroforming process, thermal treatment can promote the electrochemical formation of metallic conductive filament (CF). The required electroforming voltage is reduced, and the undesirable overshoot current is suppressed. As a result, the RS performance of the cell is improved, including reduced RS parameter fluctuations, enlarged off/on ratio, and enhanced cycling endurance. The cell can be operated with a low compliance current (ICC) of 50 μA, which is among the lowest value of reported a-C-based ECM memories. Benefit from the low ICC, multilevel memory with five nonvolatile resistance states in a single cell is obtained. The main role of the TAE method is interpreted as to avoid the extreme high-temperature caused by the overshoot current. Conductive-atomic force microscopy mapping implies that the suppression of overshoot current can avoid over-injection of Cu cations into the a-C layer, facilitating CF with a simple structure and low randomness. The present work offers a feasible approach for addressing the current overshoot issue and improving the performance of ECM memory. [ABSTRACT FROM AUTHOR]

To study corona discharge in air, it is important to measure the electric field in the discharge space, which is directly related to the corona discharge process. In this paper, we present a method for measuring the electric field with electro-optical modulation. This method uses space laser modulation based on Bi4Ge3O12 (BGO) crystals, and we suggest using the dual optical path difference method to improve the measurement performance. The measurement error is analyzed from theory, including the measurement error of a highly inhomogeneous electric field and the error due to theoretical approximation. In system calibration, the system noise and the dual optical path difference method were analyzed. The dynamic linear range is determined, and measurement effectiveness in the severely nonuniform electric field is verified by comparison with a finite element numerical simulation. We measured the electric field in Trichel pulses under negative dc voltage and found electric field pulses. These measurement results show that the characteristics of Trichel pulses are directly related to the electric field. Therefore, this method can provide strong support for the study of corona discharges. [ABSTRACT FROM AUTHOR]