W波段扩展互作用器件均匀磁聚焦电子光学系统

扩展互作用器件,采用三个线圈和一个磁极实现均匀磁场分布。根据理论计算采用有限元法磁学(FEMM)仿真软件对所求磁场进行了建模分析,依据FEMM计算的磁场结合静电电子枪,采用CST仿真软件对高电流密度、高压缩比的电子注在均匀聚焦磁场的作用下传输进行优化。经过计算得出,在工作电压为17 kV、阴极发射电流密度小于10 A/cm2的条件下,由皮尔斯电子枪发射的电子注在均匀磁场的聚焦作用下传输良好,通过率为100%,得到了导流系数为0.175μP的电子枪,在均匀磁场区形成了高电流密度、高压缩比的电子注,平均电流密度达到343.17 A/cm2,压缩比为32,电子注横纵速度比为7.2%。

高电流密度实心电子束均匀磁场聚焦电子枪的设计

针对W波段小型化扩展互作用器件对电子枪及其对电子束的需求,设计了采用均匀磁场聚焦的高电流密度实心电子束电子枪。首先考虑现阶段阴极发射能力和扩展互作用器件对电子束的需求下完成了静电电子枪的设计;在此基础上,将电子枪分为静电聚焦区、过渡区和均匀磁场区三个部分,通过理论计算得出了理想的均匀聚焦磁场分布。在此基础上建立了高电流密度实心电子束均匀磁场聚焦电子枪的三维粒子仿真模型,工作电压为17 kV,阴极发射电流为19.3 A/cm2的条件下得到了压缩比为33,束电流为668 mA,平均束半径为0.182 mm,平均束电流密度为642.4 A/cm2的高电流密度实心电子束。仿真结果表明,该电子束在半径为0.25 mm的电子通道内的流通率达到了100%,理论计算和三维粒子仿真的结果符合得很好。

关于虚拟现实——核心概念与工作定义

本文透彻地论述了虚拟现实的若干重要方面（内涵、模型、构成、特征和支撑技术等），并首次提出了虚拟实现的工作定义。此外。

SDZ-Ⅱ型电子针疗仪原理与使用体会

本文分析了SDZ-Ⅱ型电子针疗仪的原理,说明主要器件的作用,针对故障进行处理,判别仪器正常与否,并加以改进。

Design concerns of room and pillar retreat panels

Why do some room and pillar retreat panels encounter abnormal conditions？ What factors deserve the most consideration during the planning and execution phases of mining and what can be done to mitigate those abnormal conditions when they are encountered7 To help answer these questions, and to determine some of the relevant factors influencing the conditions of room and pillar （R ＆ P） retreat min- ing entries, four consecutive R ＆ P retreat panels were evaluated. This evaluation was intended to rein- force the influence of topographic changes, depth of cover, multiple-seam interactions, geological conditions, and mining geometry. This paper details observations were made in four consecutive R ＆ P retreat panels and the data were collected from an instrumentation site during retreat mining. The pri- mary focus was on the differences observed among the four panels and within the panels themselves. The instrumentation study was initially planned to evaluate the interactions between primary and secondary support, but produced rather interesting results relating to the loading encountered under the current mining conditions. In addition to the obse^ation and ｜ll^trumentation, numerical modeling was per- formed to evaluate the stress condi~!ons. Both the LaModel 3.0 and Rocscience Phase 2 programs were used to evaluate these four panels, The results of both models indicated a drastic reduction in the vertical stresses experienced in these panels due to the full extraction mining in overlying seams when compared to the full overburden load. Both models showed a higher level of stress associated with the outside entries of the panels. These results agree quite well with the observations and instrumentation studies performed at the mine. These efforts provided two overarching conclusions concerning R ＆ P retreat mine planning and execution. The first was that there are four areas that should not be overlooked during R ＆ P retreat mining： topographic relief, multiple^seaPa stress relief, stress concentrations near the gob edge, and geologic changes in the immediate roof. The second is that in order to successfully retreat an R ＆ P panel, a three-phased approach to the design and analysis of the panel should be conducted： the planning phase, evaluation phase, and monitoring phase.

Hardware Neural Networks Controlled MEMS Rotational Actuators and Application to Micro Robot

Hardware neural networks controlled rotational actuators and application to an insect type micro robot are reported in this paper. Millimeter size rotational actuators are fabricated by combining MEMS （Micro Electro Mechanical System） technology and shape memory alloy based artificial muscle wires. The actuator is composed of a pair of disk rotators and each rotor is suspended by four artificial muscle wires that are connected to the silicon frame. The rotational motion is generated by flowing the electrical current to each wire successively. Two actuators of different sizes are fabricated. The large actuator shows the displacement of 0.5 mm at the cycle time of 4 s. The small actuator shows 0.3 mm at 2 s. For controlling the actuator, the hardware neural networks are used. The hardware neural networks are composed of electrical circuits imitating cell bodies, excitatory synapses and inhibitory synapses. Four signal ports are extracted from four pairs of excitatory and inhibitory neurons and they are connected to the actuator. The small actuator is applied to the robot and built in the mid body of the robot. The shaft of the actuator is connected to the link mechanisms that transform the rotational motion to the locomotion. The appearance dimensions of the robot are 4.0, 2.7, 2.5 mm width, length and height. The robot performs forward and backward foot step like insects. The speed is 26.4 mm·min^-1 and the stepping width is 0.88 mm. Also, the robot changes the direction by external trigger pulses.

Scattering Theory of Current Noise in Nanoscale Devices with Electron-electron and Electron-phonon Interactions

In this paper, we derive a unified scattering theory model for current noise based on the equivalent contact model of the scattering region. Our model seamlessly covers the whole range of transport regimes from coherent transport to incoherent transport and it also includes the effects of Pauli exclusion and Coulomb interaction on shot noise.

Interlayer interactions in anisotropic atomically thin rhenium diselenide

In this work, we study the interlayer phonon vibration modes, the layer-number- dependent optical bandgap, and the anisotropic photoluminescence （PL） spectra of atomically thin rhenium diselenide （ReSe2） for the first time. The ultralow frequency interlayer Raman spectra and the polarization-resolved high frequency Raman spectra in ReSe2 allow the identification of its layer number and crystal orientation. Furthermore, PL measurements show the anisotropic optical emission intensity of the material with its bandgap increasing from 1.26 eV in the bulk to 1.32 eV in the monolayer. The study of the layer-number dependence of the Raman modes and the PL spectra reveals relatively weak van der Waal＇s interaction and two-dimensional （2D） quantum confinement in the atomically thin ReSe2. The experimental observation of the intriguing anisotropic interlayer interaction and tunable optical transition in monolayer and multilayer ReSe2 establishes the foundation for further exploration of this material in the development of anisotropic optoelectronic devices functioning in the near-infrared spectrum, which is important for many applications in optical communication and infrared sensing,

Recent advances in spin transport in organic semiconductors

The spin relaxation time is long in organic semiconductors because of the weak spin-orbit and hyperfine interactions,leading to intensive study on spin transport in organic semiconductors.The rapid progress towards utilizing spin degree of freedom in organic electronic devices is occurring.While the spin injection,transport and detection in organic semiconductors are demonstrated,the fundamental physics of these phenomena remains unclear.This paper highlights recent progress that has been made,focusing primarily on present experimental work.

Bimetallic oxide coupled with B-doped graphene as highly efficient electrocatalyst for oxygen evolution reaction

Developing electrocatalysts with high performance and low cost for the oxygen evolution reaction(OER)is of great importance for fabricating renewable energy storage and conversion devices.Here,a series of boron-doped graphene(BG)-supported bimetallic oxides of Co and Ni were obtained and served as OER electrocatalysts.Surprisingly,the annealed Co-Ni-Ox/BG with a Co/Ni ratio of 1:1 exhibits high performance toward oxygen evolution in alkaline electrolyte.The overpotential is only 310 mV at the current density of 10 mA cm-2,superior to many mono-metallic oxides reported before,and even comparable to the commercial RuO2.The regulation of charge distribution in bimetallic oxides and the strong synergistic coupling effects together contribute to the superior electrocatalytic performance of the Co-Ni-Ox/BG toward OER.This study also offers several effective ways to design high-performance OER electrocatalysts for water splitting.