Sub‐Millimeter‐Scale Monolayer p‐Type H‐Phase VS2

2D H‐phase vanadium disulfide (VS₂) is expected to exhibit tunable semiconductor properties as compared with its metallic T‐phase structure, and thus is of promise for future electronic applications. However, to date such 2D H‐phase VS₂ nanostructures have not been realized in experiment likely due to the polymorphs of vanadium sulfides and thermodynamic instability of H‐phase VS₂. Preparation of H‐phase VS₂ monolayer with lateral size up to 250 µm, as a new member in the 2D transition metal dichalcogenides (TMDs) family, is reported. A unique growth environment is built by introducing the molten salt‐mediated precursor system as well as the epitaxial mica growth platform, which successfully overcomes the aforementioned growth challenges and enables the evolution of 2D H‐phase structure of VS₂. The honeycomb‐like structure of H‐phase VS₂ with broken inversion symmetry is confirmed by spherical aberration‐corrected scanning transmission electron microscopy and second harmonic generation characterization. The phase structure is found to be ultra‐stable up to 500 K. The field‐effect device study further demonstrates the p‐type semiconducting nature of the 2D H‐phase VS₂. The study introduces a new phase‐stable 2D TMDs materials with potential features for future electronic devices.     

Achieving Rich and Active Alkaline Hydrogen Evolution Heterostructures via Interface Engineering on 2D 1T‐MoS2 Quantum Sheets

Large‐scale production of hydrogen from water‐alkali electrolyzers is impeded by the sluggish kinetics of hydrogen evolution reaction (HER) electrocatalysts. The hybridization of an acid‐active HER catalyst with a cocatalyst at the nanoscale helps boost HER kinetics in alkaline media. Here, it is demonstrated that 1T–MoS₂ nanosheet edges (instead of basal planes) decorated by metal hydroxides form highly active ${\text{edge}}_{{\text{1T‐MoS}}_{\text{2}}}$/ ${\text{edge}}_{\text{Ni}{(\text{OH})}_{\text{2}}}$ heterostructures, which significantly enhance HER performance in alkaline media. Featured with rich ${\text{edge}}_{{\text{1T‐MoS}}_{\text{2}}}$/ ${\text{edge}}_{\text{Ni}{(\text{OH})}_{\text{2}}}$ sites, the fabricated 1T–MoS₂ QS/Ni(OH)₂ hybrid (quantum sized 1T–MoS₂ sheets decorated with Ni(OH)₂ via interface engineering) only requires overpotentials of 57 and 112 mV to drive HER current densities of 10 and 100 mA cm^?2, respectively, and has a low Tafel slope of 30 mV dec^?1 in 1 m KOH. So far, this is the best performance for MoS₂‐based electrocatalysts and the 1T–MoS₂ QS/Ni(OH)₂ hybrid is among the best‐performing non‐Pt alkaline HER electrocatalysts known. The HER process is durable for 100 h at current densities up to 500 mA cm^?2. This work not only provides an active, cost‐effective, and robust alkaline HER electrocatalyst, but also demonstrates a design strategy for preparing high‐performance catalysts based on edge‐rich 2D quantum sheets for other catalytic reactions.     

Trilayer Nanomesh Films with Tunable Wettability as Highly Transparent,Flexible, and Recyclable Electrodes

Metallic mesh materials are promising candidates to replace traditional transparent conductive oxides such as indium tin oxide (ITO) that is restricted by the limited indium resource and its brittle nature. The challenge of metal based transparent conductive networks is to achieve high transmittance, low sheet resistance, and small perforation size simultaneously, all of which significantly relate to device performances in optoelectronics. In this work, trilayer dielectric/metal/dielectric (D/M/D) nanomesh electrodes are reported with precisely controlled perforation size, wire width, and uniform hole distribution employing the nanosphere lithography technique. TiO₂/Au/TiO₂ nanomesh films with small hole diameter (≤700 nm) and low thickness (≤50 nm) are shown to yield high transmittance (>90%), low sheet resistance (≤70 Ω sq^?1), as well as outstanding flexural endurance and feasibility for large area patterning. Further, by tuning the surface wettability, these films are applied as easily recyclable flexible electrodes for electrochromic devices. The simple and cost‐effective fabrication of diverse D/M/D nanomesh transparent conductive films with tunable optoelectronic properties paves a way for the design and realization of specialized transparent electrodes in optoelectronics.     

一种可调节电流的电流型PWM直流转换器

介绍一种用于驱动发光二极管(LED)的可调节电流的电流型PWM直流转换器.该直流转换器由于接有一个外接电阻,可以通过调节外接电阻的大小来调节输出电流.输出电流调节范围在5～40mA之间.主要分析了电路的输出电流调节功能,和这种输出电流可变的电流型PWM直流转换器的电流和电压反馈环的反馈实现原理.并简要介绍了这种带电流调节功能的PWM直流转换器的工作原理,最后给出了电路在输出不同电流时使用HSPICE软件对反馈参考电压,PWM锁存器输出波形的仿真结果.     

信息技术对抑郁症心理调适的模式开发创新研究——基于VR沉浸技术的应用

随着科技的不断发展,虚拟现实技术(以下简称VR技术)也在不断的创新,VR技术在当今社会被广泛推崇,多个重要领域都发现了它的重要性,它在未来的发展趋势势必也会只增不减,现已逐渐将此技术应用到医学方面,该文通过高频发生的抑郁心理问题现状,结合SWOT分析方法,通过研究VR技术与抑郁症心理调适交叉结合的创新模式,推动VR技术在异常心理调适与数字化模式上的探索.     

一种新型宽频带信号发生器的设计与实现

本文设计并实现了一种新型的宽频带信号发生器.系统以单片机AT89S52和芯片MAX038为控制核心,由D/A转换器TLC5615、中文字库液晶显示块、放大电路和大功率调整等电路组成.通过4×4键盘输入给定值,由芯片MAX038产生波形与频率,再由CAT5113设定幅值,最后用中文液晶显示输出的幅值和频率.该信号发生器的突出特点是:输出频率范围宽(1 Hz～1.2 MHz),可实现输出频段的选择和实时调控,提高了输出波形的频率精度.     

超大口径平面反射镜的光学检测（特邀）

在简要总结了各种检测大口径反射镜难点的基础上,为了实现30 m望远镜（TMT）超大口径第三反射镜的高精度检测,提出了一种融合五棱镜扫描技术和子孔径拼接测试技术的新方法。大口径反射镜分阶段依次进行了五棱镜扫描测试和子孔径拼接检测,对该技术的基本原理和基础理论进行了分析和研究,制定了检测30 m望远镜第三反射镜（口径为3.5 m×2.5 m）的方案,对其测试流程、五棱镜设计、五棱镜扫描像差拟合、拼接最优化算法等进行了详细分析,并对30 m望远镜第三反射镜的原理镜进行了实验验证,其最终拼接检测面形的均方根值（RMS）和斜率均方根值（slopeRMS）分别为28.676 nm和0.97 μrad。     

基于子空间分解的快速盲均衡解调算法

基于高阶统计的盲均衡算法需要大量的观测数据,当观测数据有限或信道变化较快时,由于模型失配将使均衡性能严重下降,因此短数据、快收敛是近年来盲均衡技术研究的主要方向之一。本文讨论了基于子空间分解的信道识别和盲均衡技术,利用卡尔曼滤波方程,给出了一种快速收敛的盲均衡解调算法,算法只需要较少的数据样本,仿真结果表明该方法是有效的。     

SISAR中运动目标全息信号的表示及仿真研究

在运用阴影逆合成孔径雷达(SISAR)对运动目标进行成像和识别研究中,需要得到相关目标的全息信号。该文在分析目标侧影轮廓与其全息信号关系的基础上,导出了一种更具普遍意义的全息信号的表达形式,式中的各组成具有明确的物理含义。为验证其在实际应用中的有效性,以外场试验获得两种目标的全息信号为比较对象,参照外场试验条件进行了仿真。比较结果说明了该仿真方法实际有效。