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In addressing the challenge of the multiplicative fading introduced by passive reconfigurable intelligent surface (RIS) in high-speed railway scenarios, an effective solution is the deployment of an active RIS. However, the conventional fully-connected architecture of active RIS, characterized by a multitude of active elements, results in excessive hardware costs and power consumption. Consequently, a sub-connected architecture of active RIS was proposed, with the aim of simultaneously considering the system's energy efficiency and the transmission rate in train-ground communication. Initially, a system model for active RIS-assisted multi-user scenarios was established, taking into account the distinctive features of the high-speed railway environment. Subsequently, the problem of maximizing system energy efficiency was formulated by considering constraints on the maximum transmission power of the base station, the transmission power of the active RIS, and the phase-shift matrix of the active RIS. Through the utilization of Lagrange dual transformation and quadratic transformation from fractional programming theory, the non-convex problem was transformed into a convex optimization problem. Finally, an alternating optimization algorithm was proposed for the joint optimization of beamforming and the phase-shift matrix of the active RIS. Simulation results indicate that, compared to traditional passive RIS and fully-connected of active RIS architectures, the proposed solution effectively addresses the multiplicative fading issue. Additionally, the proposed solution achieves higher energy efficiency while meeting user transmission rate requirements.

The mechanisms of deposition and solidification processes of molten droplets after collision with the substrate during arc spraying were investigated by Fluent simulation. Subsequently, the Al, ZnAl alloys and Zn–Al pseudo-alloy coatings were prepared by arc spraying through parameter optimization. Furthermore, the electrochemical properties of arc-sprayed Al, ZnAl alloys and Zn–Al pseudo-alloy coatings corroded in 3.5 wt% NaCl solution for different days were studied. The electrochemical impedance spectra (EIS) investigation indicated that the pitting corrosion occurred on the surface of Al coating, and even the substrate material also appeared to be corroded. In comparison, the Zn–Al pseudo-alloy coating has both pure Zn and Al coatings in a corrosive environment with the cathodic effect of sacrificial anode protection and the shielding effect of a passivated protective film. As a result, it has an excellent corrosion resistance. Meanwhile, the corrosion mechanism of arc-sprayed Al, ZnAl alloys and Zn–Al pseudo-alloy coatings was further characterized by the combination of SEM surface morphology and XRD pattern after the corrosion. Furthermore, the wear resistance of the above-mentioned coatings was examined, and the investigations showed that the arc-sprayed Zn–Al pseudo-alloy coatings also have an excellent wear resistance.

Electrochemical discharge machining (ECDM) is a well-known process for machining of particulate reinforced metal matrix composites (MMCs). However, ECDM process suffers several drawbacks such as the lower material removal rate (MRR), high risks of tool wear rate (TWR) and relatively poor surface quality, etc. This study proposes a kind of electrochemical discharge grinding machining (ECDGM) method which employs a special shaped tool electrode. During the process, not only the can the hybrid action of electrochemical dissolution, spark erosion, and abrasive grinding improve the performance of machining MMCs, but also the special shaped of the tool electrode can be used to discharge the machined debris. And thus a higher machining efficiency and lower TWR can be obtained. The performance of developed process was conducted on machining of SiC particulate reinforced aluminum workpiece. The role of peak curre+nt, pulse duration, duty cycle, rotary speed and abrasive grit size has been investigated on MMR and TWR using the nonabrasive round electrode, abrasive round electrode, and abrasive shaped electrode respectively. The experimental results showed that using the shaped abrasive electrode for machining MMCs can achieve a higher MRR and lower TWR, as compared to the non-abrasive round electrode, abrasive round electrode. Besides, the orthogonal method was employed to analyze the relative importance of the machining parameters on MRR and TWR, it has been observed that MRR is affected by the processing parameters following the order of rotary speed > peak current > duty cycle > pulse duration, and TWR is following the order of peak current > duty cycle > pulse duration > rotary speed.

High mobility of thin film transistor (TFT) is critical to liquid crystal display (LCD) for high performance. We have developed an ultra‐high mobility (> 50 cm2 /V•s) Top Gate Self‐alignment (TGSA) bilayer oxide TFT technology, achieving on‐state current over 60μA and excellent electrical stress stability, which makes it possible to achieve high resolution, high refresh and narrow‐bezel simultaneously. Dual gate driving TGSA TFT exhibits even higher mobility to support a source line DEMUX 1:2 circuit design. A 12.7 inch 3K*2K TDDI TPC LCD with 120Hz refresh rate, DEMUX design and 1.5mm narrow‐bezel was fabricated. This first ultra‐high resolution TDDI TPC LCD product indicates the superiority of our high ultra‐mobility TGSA bilayer oxide TFT technology. [ABSTRACT FROM AUTHOR]