Precious‐Metal‐Free Electrocatalysts for Activation of Hydrogen Evolution with Nonmetallic Electron Donor: Chemical Composition Controllable Phosphorous Doped Vanadium Carbide MXene

The insufficient strategies to improve electronic transport, the poor intrinsic chemical activities, and limited active site densities are all factors inhibiting MXenes from their electrocatalytic applications in terms of hydrogen production. Herein, these limitations are overcome by tunable interfacial chemical doping with a nonmetallic electron donor, i.e., phosphorization through simple heat‐treatment with triphenyl phosphine (TPP) as a phosphorous source in 2D vanadium carbide MXene. Through this process, substitution, and/or doping of phosphorous occurs at the basal plane with controllable chemical compositions (3.83–4.84 at%). Density functional theory (DFT) calculations demonstrate that the P? C bonding shows the lowest surface formation energy (ΔG_Surf) of 0.027 eV Å^?2 and Gibbs free energy (ΔG_H) of –0.02 eV, whereas others such as P‐oxide and P? V (phosphide) show highly positive ΔG_H. The P3–V₂CT_x treated at 500 °C shows the highest concentration of P? C bonds, and exhibits the lowest onset overpotential of –28 mV, Tafel slope of 74 mV dec^?1, and the smallest overpotential of ‐163 mV at 10 mA cm^?2 in 0.5 m H₂SO₄. The first strategy for electrocatalytically accelerating hydrogen evolution activity of V₂CT_x MXene by simple interfacial doping will open the possibility of manipulating the catalytic performance of various MXenes.     

Analysis of adjacent channel interference using distribution function for V2X communication systems in the 5.9‐GHz band for ITS

Many use cases have been presented on providing convenience and safety for vehicles employing wireless access in vehicular environments and long‐term evolution communication technologies. As the 70‐MHz bandwidth in the 5.9‐GHz band is allocated as an intelligent transportation system (ITS) service, there exists the issue that vehicular communication systems should not interfere with each other during their usage. Numerous studies have been conducted on adjacent interfering channels, but there is insufficient research on vehicular communication systems in the ITS band. In this paper, we analyze the interference channel performance between communication systems using distribution functions. Two types of scenarios comprising adjacent channel interference are defined. In each scenario, a combination of an aggressor and victim network is categorized into four test cases. The minimum requirements and conditions to meet a 10% packet error rate are analyzed in terms of outage probability, packet error rate, and throughput for different transmission rates. This paper presents an adjacent channel interference ratio and communication coverage to obtain a satisfactory performance.     

Effects of CH2F2 and H2 flow rates on process window for infinite etch selectivity of silicon nitride to ArF PR in dual-frequency CH2F2/H2/Ar capacitively coupled plasmas

The process window for the infinite etch selectivity of silicon nitride (Si₃N₄) layers to ArF photoresist (PR) and ArF PR deformation were investigated in a CH₂F₂/H₂/Ar dual-frequency superimposed capacitive coupled plasma (DFS-CCP) by varying the process parameters, such as the low frequency power (P_LF), CH₂F₂ flow rate, and H₂ flow rate. It was found that infinitely high etch selectivities of the Si₃N₄ layers to the the ArF PR on both the blanket and patterned wafers could be obtained for certain gas flow conditions. The H₂ and CH₂F₂ flow rates were found to play a critical role in determining the process window for infinite Si₃N₄/ArF PR etch selectivity, due to the change in the degree of polymerization. The preferential chemical reaction of hydrogen with the carbon in the hydrofluorocarbon (CH_xF_y) layer and the nitrogen on the Si₃N₄ surface, leading to the formation of HCN etch by-products, results in a thinner steady-state hydrofluorocarbon layer and, in turn, in continuous Si₃N₄ etching, due to enhanced SiF₄ formation, while the hydrofluorocarbon layer is deposited on the ArF photoresist surface.     

Fast Bit Gather, Bit Scatter and Bit Permutation Instructions for Commodity Microprocessors

Advanced bit manipulation operations are not efficiently supported by commodity word-oriented microprocessors. Programming tricks are typically devised to shorten the long sequence of instructions needed to emulate these complicated bit operations. As these bit manipulation operations are relevant to applications that are becoming increasingly important, we propose direct support for them in microprocessors. In particular, we propose fast bit gather (or parallel extract), bit scatter (or parallel deposit) and bit permutation instructions (including group, butterfly and inverse butterfly). We show that all these instructions can be implemented efficiently using both the fast butterfly and inverse butterfly network datapaths. Specifically, we show that parallel deposit can be mapped onto a butterfly circuit and parallel extract can be mapped onto an inverse butterfly circuit. We define static, dynamic and loop invariant versions of the instructions, with static versions utilizing a much simpler functional unit. We show how a hardware decoder can be implemented for the dynamic and loop-invariant versions to generate, dynamically, the control signals for the butterfly and inverse butterfly datapaths. The simplest functional unit we propose is smaller and faster than an ALU. We also show that these instructions yield significant speedups over a basic RISC architecture for a variety of different application kernels taken from applications domains including bioinformatics, steganography, coding, compression and random number generation.     

Low‐Power 512‐Bit EEPROM Designed for UHF RFID Tag Chip

In this paper, the design of a low‐power 512‐bit synchronous EEPROM for a passive UHF RFID tag chip is presented. We apply low‐power schemes, such as dual power supply voltage (VDD=1.5 V and VDDP=2.5 V), clocked inverter sensing, voltage‐up converter, I/O interface, and Dickson charge pump using Schottky diode. An EEPROM is fabricated with the 0.25 μm EEPROM process. Power dissipation is 32.78 μW in the read cycle and 78.05 μW in the write cycle. The layout size is 449.3 μm × 480.67 μm.     

Simulation Models for Investigation of Multiuser Scheduling in MIMO Broadcast Channels

Spatial correlation is a result of insufficient antenna spacing among multiple antenna elements, while temporal correlation is caused by Doppler spread. This paper compares the effect of spatial and temporal correlation in order to investigate the performance of multiuser scheduling algorithms in multiple‐input multiple‐output (MIMO) broadcast channels. This comparison includes the effect on the ergodic capacity, on fairness among users, and on the sum‐rate capacity of a multiuser scheduling algorithm utilizing statistical channel state information in spatio‐temporally correlated MIMO broadcast channels. Numerical results demonstrate that temporal correlation is more meaningful than spatial correlation in view of the multiuser scheduling algorithm in MIMO broadcast channels. Indeed, the multiuser scheduling algorithm can reduce the effect of the Doppler spread if it exploits the information of temporal correlation appropriately. However, the effect of spatial correlation can be minimized if the antenna spacing is sufficient in rich scattering MIMO channels regardless of the multiuser scheduling algorithm used.     

Signal Synchronization Using a Flicker Reduction and Denoising Algorithm for Video‐Signal Optical Interconnect

A video signal through a high‐density optical link has been demonstrated to show the reliability of optical link for high‐data‐rate transmission. To reduce optical point‐to‐point links, an electrical link has been utilized for control and clock signaling. The latency and flicker with background noise occurred during the transferring of data across the optical link due to electrical‐to‐optical with optical‐to‐electrical conversions. The proposed synchronization technology combined with a flicker and denoising algorithm has given good results and can be applied in high‐definition serial data interface (HD‐SDI), ultra‐HD‐SDI, and HD multimedia interface transmission system applications.     

Silicon based on-chip antenna using an LC resonator for near-field RF systems

This paper presents the silicon based on-chip antenna using a LC resonator. The proposed antenna consists of a stacked capacitor and a spiral inductor on silicon substrate. The spiral inductor structure without underpass was proposed for improvement the performance of the silicon based-antenna. The resonant frequency of the fabricated antenna was measured as 465 MHz. Its return loss was 23.4 dB at resonant frequency. The antenna has a gain of ?35.75 dBi due to small size and silicon substrate. However, the fabricated antenna has good performance in the near-field.     

Compensation of oxygen defects in La-silicate gate dielectrics for improving effective mobility in high-k/metal gate MOSFET using oxygen annealing process

Oxygen incorporation for compensation of oxygen defects is investigated with La-silicate dielectrics in directly contacted with the Si substrate. The amount of oxygen is controlled by the temperature of annealing in oxygen atmosphere (oxygen annealing) and the thickness of the gate electrode. The positive shift in flatband voltage (V_FB) by oxygen incorporation is an experimental evidence for defects compensation in La-silicate dielectrics. Optimum oxygen annealing provides the V_FB shift toward positive direction without increasing equivalent oxide thickness (EOT). Although the oxygen annealing degrades the interfacial property at La-silicate/Si interface, subsequent forming gas annealing (FGA) can recover the interfacial property. It is experimentally revealed that the positive V_FB shift of La-silicate dielectrics is stable even after subsequent FGA. The supplied oxygen in La-silicate is expected to maintain even after reducing process. Movement of Fermi level toward the Si valence band edge caused by oxygen incorporation is successfully observed by XPS. Moreover, no chemical reaction between La-silicate and Si substrate by oxygen annealing are confirmed from TEM observation and analyses of X-ray photoelectron spectra. It is experimentally demonstrated that effective hole mobility can be improved without increase in EOT by combination of oxygen annealing and FGA.     

An experimental study on time delay control of actuation system of tilt rotor unmanned aerial vehicle

This paper presents an actuation control system for the Smart Unmanned Aerial Vehicle (SUAV), a tilt rotor aircraft that is being developed by the Korea Aerospace Research Institute. The actuation system, which consists of flaperon, rotor, and nacelle tilt, should be controlled to track the position command sent from the flight controller. However, substantial variations in the aerodynamic load on the actuation system make it difficult to achieve the desired level of control performance. In this study, the actuation system was controlled using the Time Delay Control (TDC) law. The experimental results show that the following control performance specifications are completely satisfied under load variation from 0 to 455 kgf: bandwidth of 4 Hz, overshoot of 2.5%, and steady state error of 1% for flaperon and rotor actuation system. Especially, the accuracy was within the noise level of the steady state position error over broad ranges of the load. In addition, the command filter was applied to the TDC command to mitigate the effects of the phase delay that occurs when a sinusoidal command is applied. Furthermore, an actual flight test was performed, which clearly showed the effectiveness of the proposed control scheme. This promising control performance shows that TDC is an effective alternative for controlling the actuation system of the SUAV with substantial load variation.