基于PLC和Ethernet的铣刨机无线测控系统设计

针对某铣刨机,研制了无线测控系统,其主要由PLC、通信模块、继电器、触摸屏、路由设备、远程终端等组成;在系统设计中,基于GE ifix环境开发了基于Ethernet的测控软件,解决了不同操作系统平台和硬件环境下的兼容问题;提出了主机掉线PLC状态自保持、无线控制与本地控制冗余和控制指令优先级划分的技术思路,实现了系统可靠运行;该系统具备本地控制与无线遥控两种控制方式,并已在该铣刨收机上得到应用,实现了平台所有操作的无线遥控,无指令丢失和误动作。     

随机共振实验

介绍了随机共振现象的基本原理、模拟电路,给出了一组实验结果,并绘制了实验曲红,分析了随机共振产生的原因。     

可压缩κ-ω方程紊流模型及其应用

前言U前可用于工程应用的各种紊流模型中,在对逆压梯度下有无分离流动、低雷诺数区域流动以及对可压缩流动,特别是高速紊流流动等问题的精确数值模拟上,除多重尺度模型外,预测精度较理想的是k一。两方程模型。在k一。模型的开发和应用上,Wilcox及Menter等［‘－’］?..     

In-situ TEM observation of the evolution of helium bubbles in Mo during He+ irradiation and post-irradiation annealing

The evolution of helium bubbles in purity Mo was investigated by in-situ transmission electron microscopy (TEM) during 30 keV He⁺ irradiation (at 673 K and 1173 K) and post-irradiation annealing (after 30 keV He⁺ irradiation with the fluence of 5.74×10¹⁶ He⁺/cm² at 673 K). Both He⁺ irradiation and subsequently annealing induced the initiation, aggregation, and growth of helium bubbles. Temperature had a significant effect on the initiation and evolution of helium bubbles. The higher the irradiation temperature was, the larger the bubble size at the same irradiation fluence would be. At 1173 K irradiation, helium bubbles nucleated and grew preferentially at grain boundaries and showed super large size, which would induce the formation of microcracks. At the same time, the geometry of helium bubbles changed from sphericity to polyhedron. The polyhedral bubbles preferred to grow in the shape bounded by {100} planes. After statistical analysis of the characteristic parameters of helium bubbles, the functions between the average size, number density of helium bubbles, swelling rate and irradiation damage were obtained. Meanwhile, an empirical formula for calculating the size of helium bubbles during the annealing was also provided.     

Electronic and optical properties of 3N-doped graphdiyne/MoS2 heterostructures tuned by biaxial strain and external electric field

The construction of van der Waals (vdW) heterostructures by stacking different two-dimensional layered materials have been recognised as an effective strategy to obtain the desired properties. The 3N-doped graphdiyne (N-GY) has been successfully synthesized in the laboratory. It could be assembled into a supercapacitor and can be used for tensile energy storage. However, the flat band and wide forbidden bands could hinder its application of N-GY layer in optoelectronic and nanoelectronic devices. In order to extend the application of N-GY layer in electronic devices, MoS₂ was selected to construct an N-GY/MoS₂ heterostructure due to its good electronic and optical properties. The N-GY/MoS₂ heterostructure has an optical absorption range from the visible to ultraviolet with a absorption coefficient of 10⁵ cm^-1. The N-GY/MoS₂ heterostructure exhibits a type-Ⅱ band alignment allows the electron-hole to be located on N-GY and MoS₂ respectively, which can further reduce the electron-hole complexation to increase exciton lifetime. The power conversion efficiency of N-GY/MoS₂ heterostructure is up to 17.77%, indicating it is a promising candidate material for solar cells. In addition, the external electric field and biaxial strain could effectively tune the electronic structure. Our results provide a theoretical support for the design and application of N-GY/MoS₂ vdW heterostructures in semiconductor sensors and photovoltaic devices.     

Vacuum-gap-based lumped element Josephson parametric amplifier

We propose a lumped element Josephson parametric amplifier with vacuum-gap-based capacitor.The capacitor is made of quasi-floating aluminum pad and on-chip ground.We take a fabrication process compatible with air-bridge technology,which makes our design adaptable for future on-chip integrated quantum computing system.Further engineering the input impedance,we obtain a gain above 20 dB over 162-MHz bandwidth,along with a quasi quantum-limit noise performance.This work should facilitate the development of quantum information processing and integrated superconducting circuit design.     

超临界CO2-丙烷混合物管内传热特性数值研究

采用SST k-w湍流模型对超临界CO₂/丙烷混合工质水平管内的传热特性进行数值模拟研究。管径d=4 mm,加热段L₂=800 mm;混合工质浓度配比为100/0、95/5、90/10、85/15、80/20、75/25;质量流速为150～250 kg·m^?2·s^?1;热流密度为30～40 kW·m^?2,入口温度293 K,入口压力7.5～30 MPa。随着丙烷浓度的增加,CO₂/丙烷二元混合工质的临界压力降低,临界温度升高,丙烷浓度从5%增加到25%,换热系数峰值降低6.19%～31.45%,但增加丙烷浓度可提高拟临界温度后的换热效果。P=7.5～8.5 MPa,换热系数有明显峰值;P=20～30 MPa,换热系数变化规律无明显峰值,并随压力的升高而减小。混合工质的换热系数随质量流速的增大而增大。同一流体温度所对应的换热系数,随着热流密度的增加而减小。     

发动机喷流对火箭气动特性影响

开展了考虑底部发动机喷流影响的火箭气动特性CFD仿真设计,比较了有/无喷流时火箭附近流场结构、表面压力分布、整体气动力/力矩特性在亚/超声速段的差异,结果显示,发动机喷流对火箭亚声速段的轴向力、法向力和俯仰力矩特性均有较为显著的影响,且有减小尾部空气舵气动控制力矩的影响,而超声速段的影响仅限于轴向力。该仿真结果与飞行试验气动辨识结果较为一致。基于仿真分析结果,可建立一种折中考虑喷流影响的气动特性设计方法,供火箭精细化气动特性设计参考使用。      

涡旋光激光器研究进展(特邀)

涡旋光激光器能够输出具有特定空间结构的高能量、高质量的涡旋光束.涡旋光束在光通讯、光操控、超分辨成像等领域都有潜在的应用前景.本文介绍了涡旋光束的产生原理及其应用,综述了近期涡旋光激光器的发展历程,同时也对涡旋光激光器的发展趋势进行了展望.