Non‐vacuum field desorption ion source implemented under super‐atmospheric pressure

Standard field desorption (FD) ionization is implemented under high vacuum condition. In this paper, non‐vacuum FD is performed under a super‐atmospheric pressure environment using untreated tungsten wires as FD emitter, and the ion source was coupled to a commercial linear ion trap mass spectrometer. The operating pressure of the ion source was 6 bars which was high enough to provide sufficient dielectric strength to the working gas so that the high voltage that was required for FD could be applied to the emitter without occurrence of electrical discharge. Non‐volatile sample deposited on the bare tungsten wire FD emitter was heated by flowing direct current through the emitter. Similar to vacuum FD, the formation of conical protrusion of the liquefied sample layer under the strong electric field was also observed. Using the present ion source, high pressure field‐desorption of polar neutral compounds, organic salts and ionic liquids is demonstrated. Copyright © 2012 John Wiley & Sons, Ltd.     

双包层EYDFA增益钳制效果的理论研究

基于速率方程的离散算法,实现了环形腔控制方案下,双包层EYDFA增益钳制的分析,研究了单、多信道情况下增益、噪声指数钳制的效果。结果表明：对于单信道EYDFA,随着衰减器衰减系数的增大,EYDFA的增益钳制范围增大,但信号增益钳制的幅度减小,且信号噪声指数增大;对于多信道EYDFA,只要激光谐振不被破坏,各信道增益都能得到有效钳制。     

基亏μC／OS-Ⅱ的高精度超声波测距系统设计

介绍一种以ARM处理器LPC2138为核心,采用超声波回波信号的A／D采样检测原理,实时测距,液晶屏显示的便携式系统。该系统利用ARM处理器处理速度快的优点,自行处理A／D采样速度。系统的测距范围在0．1-4．5m内,测量精度为1cm,实时性好,准确方便,有较高的推广价值。     

Optimal asymmetrical back plane biasing for energy efficient digital circuits in 28 nm UTBB FD-SOI

In this work we propose an optimal back plane biasing (OBB) scheme to be used in a UTBB FD SOI technology that minimizes the energy per operation consumption of sub threshold digital CMOS circuits. By using this OBB scheme, simulations show that more than 30% energy savings can be obtained with low threshold voltage (LVT) devices in comparison with classic symmetric back plane biasing (SBB) schemes. Additionally, this OBB scheme allows to adjust the performance of the circuit with very small energy penalties. A very simple and intuitive model, for sub threshold digital CMOS circuits, was developed to justify the benefits obtained by OBB. The results predicted by the model are confirmed with extensive simulation results. We show that the OBB approach can be applied easily to a given circuit just based on the information provided by a logic simulation of the circuit (or even an analysis of its structure) and simple electrical simulations of the pMOS and nMOS transistors. Finally, we show that the variability in the energy consumption is improved by using OBB and suggests that new sizing methodologies must be studied to fully benefit from the wide back plane voltage range available in UTBB FD SOI technology for the design of robust energy efficient digital circuits.     

有尾焰动力飞行体电磁脉冲效应数值分析

 利用时域有限差分方法分析了动力段飞行体的等离子体高温尾焰对飞行体电磁脉冲效应的影响。计算结果表明：尾焰的存在极大地改变了飞行体蒙皮上感应电流密度的波形及分布;带尾焰飞行体感应皮电流密度不同于无尾焰时的情况;飞行体蒙皮感应电流密度的波形为衰减振铃信号波形,振铃周期等于电流波在整个飞行体和尾焰长度上流动两次的时间。     

(FD)~2TD计算金属表面场增强

本文首次利用依赖于频率的时域有限差分法(FD)2TD来计算隐失波激励下金属粒子表面的场增强。首先,利用(FD)2TD计算了三维球形银粒子的表面场增强,与国外文献[11]中用不同方法对此问题的计算结果进行了对比,结果较为相符,说明我们自己编写的(FD)2TD程序是可信的。然后,利用此程序计算了在全内反射条件下,处于介质板上纳米尺度边长的正三角形银粒子表面的场增强,给出了该正三角形银粒子三角端点存在场增强的所谓"热点"并给出了该处的场增强值随样品距离的变化曲线。     

CAN FD控制器中可变速率的实现

传统的CAN总线受环路延迟的影响,传输速率无法突破1Mbps.本文根据CAN FD协议标准与国际标准ISO11898,采用硬件描述语言verilog设计,实现了CAN FD控制器的可变速率功能.控制器采用状态机实现对数据帧的接收,采用改变组成bit位中最小时间单元tq的周期长度实现速率切换,并在数据帧的data域应用二...     

毫米波测云雷达回波信号衰减补偿仿真研究

针对毫米波测云雷达受云雨衰减的问题,从雷达I、Q信号角度出发,模拟毫米波测云雷达回波I、Q信号并假设一定的探测环境,进行雷达回波信号衰减补偿仿真试验.试验结果表明,雷达电磁波信号穿过雨区和云区时,在远距离处衰减量很大,通过衰减补偿,信号强度明显增强,目标信号突出.     

混合二肽的场解吸质谱

为了探索生物化学、生物医学中混合寡肽的分析问题,对未衍生的混合二肽场解吸质谱进行了研究(图1和图2)。在图1图2中出现了所有二肽的准分子离子[M+H]~+,除此外还出现了[2M+H]~+、[M_(AB)+H]~+、[M_(AC)+H]~+等集聚离子,这些集聚离子能用于进一步确定各个肽的分子量。