纳秒级紫外/软X射线条纹相机

纳秒级紫外/软X射线条纹相机是一种利用高速扫描电路实现将纳秒级光信号转化为图像信 号的高速图像设备,它主要包括了条纹管、高速高压扫描单元、高压单元以及控制记录单元等部分。系统设计中采用近贴聚焦电子光学系统和雪崩管电路使得目前所能达到的指标为:能谱响应范围紫外～1keV,空间分辨力静态15Lp/mm,动态5Lp/mm,时间分辨力为500ps。     

高压纳秒脉冲信号的参数辨识

为了减小测量链和硬件结构给被测信号带来的测量不确定度, 通过系统分析的方法建立了高压纳秒脉冲电压测量系统模型. 根据模型分别用一阶差分方程法和卷积法实现了对测量系统特征参数的辨识, 并给出了测量系统模型的最佳阶数的确定方法以及在此模型下对输出信号的拟合结果. 根据对测量系统的辨识结果可以建立测量系统的输入输出特性, 从而还原真实的被测信号. 同样的方法还可以运用到对电流测量系统的分析及其他满足线性定常系统要求的测量中去.     

纳秒脉冲激光对水下靶材的掩模微细刻蚀加工

在激光的传输光路中加入掩模板,采用纳秒脉冲激光对水下靶材进行了掩模微细刻蚀加工,与飞秒激光微细加工相比可显著提高加工效率,加工精度由掩模保证.在所构建的试验系统中,分别在空气中、纯水中和盐溶液中进行了加工试验,在水流的作用下,激光辐照的多余热量被带走,加工边缘热影响区明显减小.同时,水下激光辐照还会在加工区域造成光学击穿,产生等离子体冲击波,在水层的约束限制作用下,加工表现出了明显的冲击波力学效应.通过这种热-力学的复合效应,使金属材料表面产生材料去除和变形的加工效果.最终在质量分数为15%的NaNO3的溶液中,利用热-力学效应和化学反应的复合作用,实现了线宽120μm左右、热影响区小、成形精度较好的微细刻蚀加工.     

高压纳秒放电脉冲参量的计算

根据等效放电回路、火花电阻公式以及巴邢定律，推导出了高压纳秒脉冲参量（脉冲幅值、半高宽）与储能电容、放电管管内气压以及管内电极间距之间关系的解析式。公式与实验能较好地吻合。     

旅客列车振动舒适性简单测量方法的研究

根据国际铁路联盟《铁路车辆内旅客振动舒适性评价准则》（UIC513），设计并开发出评价列车振动舒适性的简单方法测量系统，本文主要介绍测量仪、测量系统的基本构成和各部分功能以及舒适度指数评价的方法和原则。     

纳秒脉冲驱动下铝基微沟道等离子体放电特性研究

本文设计制作了基于铝基衬底的微沟道阵列器件,并研究了纳秒脉冲微沟道等离子体放电特性。通过调控纳秒脉冲输出波形,获得了脉冲参数对微沟道等离子体放电特性的影响规律。结果表明,相比于传统的正弦波驱动,纳秒脉冲微沟道等离子体放电更集中,耦合效应更明显,且等离子体特性更易于调控。当改变脉冲参数时,6%左右的波形过冲电压会造成微沟道等离子体放电强度~30%的改变。另外,脉冲上升沿时间越短,放电强度越高,当上升沿时间由152 ns缩短至32 ns时,放电强度可提升~30%。     

Fast Melting of Amorphous Silicon Carbide Induced by Nanosecond Laser Pulse

We report the first experimental detailed study of laser induced surface melting on the nanoscale time scale of amorphous silicon carbide layers produced by ion implantation. Time-resolved reflectivity has been used to observe the fast liquid–solid–liquid transition features, and transmission electron microscopy (TEM) was used in order to study the structure resulting after the fast solidification following the laser induced melting. By means of the evaluation of the laser fluences required to induce melting of amorphous layers of different thickness on top of a crystalline substrate, we evaluated the thermal diffusion coefficient and the melting point of the amorphous material which occurred much lower than for crystalline material. Moreover, we give evidence of amorphous-to-crystal transitions occurring in the solid phase on the nanosecond time scale, for laser irradiation at fluences below the melting threshold. A quite different crystalline structure is observed for crystallization from the liquid phase than from the solid phase.     

超枝化偶氮液晶高分子的光取向研究

研究了超枝化偶氮液晶高分子在脉冲激光辐射下的各向异性取向特性.实验结果表明:在脉冲激光辐射下,偶氮基团沿着垂直于激光的偏振方向取向,并且由于纳秒激光辐射具有强烈的热效应,偶氮基团的取向程度对激光强度变化呈现出独特的抛物线行为.经过在一定温度条件下的加热处理,偶氮基团的取向程度大大增强.     

A Simple Method to Solve Some Simple Allocation Problems

The paper discusses a classical resource allocation problem. Using elementary arguments on Lagrangian duality it is shown that this problem can be reduced to a single one-dimensional maximization of a differentiable concave function. Moreover, a simple graphical method is developed and applied to a family of well-known problems from the literature.     

确定任意形状物体最小包围盒的一种方法

最小包围盒广泛应用于碰撞检测、模具分型设计、产品包装设计以及图像处理、模式识别等领域。根据不同的应用场合对包围盒的不同要求,提出了一种简单、实用的确定任意物体最小包围盒的方法,利用现有的CAD软件本身具有确定轴向包围盒的功能,通过对AutoCAD软件的二次开发,利用程序自动确定出任意形状物体的最小体积包围盒或最小面积包围盒,以适应于不同的应用场合。     

Research on Distance Judgement Method from Point to Line to Generate a Line

Regarding the problem that the traditional straight-line generating has a low accuracy, we study straight-line generating with the distance of point to line. We explore generating a line to approximate the ideal line and the issue is to pick out the pixel point of approximating the ideal line. The paper plays a significant scientific role in elucidating linear optimization norm and it lays a foundation for showing a straight line. The algorithm is valuable for computer graphics.     

A Versatile and Simple Approach to Generate Light Emission in Semiconductors Mediated by Electric Double Layers

The light‐emitting device is the primary device for current light sources. In principle, conventional light‐emitting devices need heterostructures and/or intentional carrier doping to form a p–n junction. This junction formation is, however, very difficult to achieve for most emerging semiconductors, and the fabrication of light‐emitting devices is invariably a significant challenge. This study proposes a versatile and simple approach to realize light‐emitting devices. This proposed device requires only a semiconducting film with two electrodes that are covered with an electrolyte. This unique structure achieves light emission at a voltage slightly larger than the bandgap energy of materials. This study applies this concept to emerging direct bandgap semiconductors, such as transition metal dichalcogenide monolayers and zinc oxide single crystals. These devices generate obvious light emission and provide sufficient evidence of the formation of a dynamic p–i–n junction or tunneling junction, presenting a versatile technique to develop optoelectronic devices.     

纳秒脉冲激光照射对多壁碳纳米管薄膜形貌的影响

采用化学气相沉积法(chemical vapor deposition,CVD)自制的碳纳米管阵列为原料,经过研磨、灼烧纯化得到分散的多壁碳纳米管(multi-walled carbon nanotubes,MWCNTs).采用纳秒脉冲激光(波长355 nm),分别在不同条件下对丝网印刷法制备的MWCNTs薄膜进行照射.扫描电子显微镜(scanning electron microscope,SEM)表征结果表明,进行相互垂直的双向扫描照射的效果明显好于单向扫描照射的效果,即由前者得到的MWCNTs的网状结构的立体感更明显,单位面积的MWCNTs端点更多;随着脉冲激光能量密度的逐渐增加,突出于表面的MWCNTs端点逐渐增多,以MWCNTs为主的网状分布的轮廓逐渐清晰;脉冲激光重复频率的增加,也有利于改善MWCNTs薄膜表面的形貌.经过脉冲激光能量51.0μJ(1.03 W)、频率20 kHz的脉冲激光照射后,得到以MWCNTs为主的、立体感显著、比较稀疏的网状分布结构,且单位面积的MWCNTs端点数目显著增多.     

A New Spatiotemporal CMOS Imager With Analog Accumulation Capability for Nanosecond Low-Power Pulse Detections

High-speed cameras use the interesting performances of CMOS imagers that offer advantages in on-chip functionalities, system power reduction, cost, and miniaturization. The FAst MOS Imager (FAMOSI) project consists in reproducing the streak camera functionality with a CMOS imager. In this paper, a new imager called FAMOSI 2, which implements an electronic shutter and analog accumulation capabilities inside the pixel, is presented. With this kind of pixel and the new architecture for controlling the integration, FAMOSI 2 can work in repetitive mode for low light power and in single shot mode for higher light power. This repetitive mode utilizes an analog accumulation to improve the sensitivity of the system with a standard n-well/$ p_ sub$photodiode. The characterization has been realized in single shot mode to optimize the accumulation mode. The prototype has been fabricated in the Austriamicrosystems 0.35-$muhboxm$CMOS process. The chip is composed of 64 columns$times$64 rows of pixels. The pixels have a size of 20$muhboxm$$times$20$muhboxm$and a fill factor of 47%.     

Simulation of the Heating of a Tungsten Conductor by a Nanosecond High-Power Current Pulse

The initial stage of explosion of a thin tungsten wire by a high-power current pulse of nanosecond duration is simulated. Radial distributions of parameters of matter are obtained for two models. According to one of the models, it is assumed that an instantaneous separation into phases occurs if the parameters of metal have reached values corresponding to the binodal; in the other model, the existence of a metastable state is allowed. Phase trajectories in the P–Tand –Tplanes are given.     

A Novel Method of Arraying Permanent Magnets Circumferentially to Generate a Rotation Magnetic Field

An outer magnetic field is extensively applied to drive the movement of a clinic micro-robot. However, how to produce a suitable magnetic field is a complicated problem. Commonly, the drive magnetic field is generated by a combination of power coils. This paper presents a novel method that circumferentially arrays identical permanent magnets to generate a rotational magnetic field in the center area of the array circle. First, we distribute permanent magnets uniformly in a circle, and adjust each of them at a corresponding initial angle. All of the magnets rotate in the same direction synchronously, generating a constant strength and reverse rotation magnetic field in the center area of the circle. The rotation speed of the generated magnetic field equals that of the permanent magnets. We used two models to analyze the magnetic field, and did some numerical analyses. We set up a test-bed and carried out some experiments to prove the feasibility of the novel method. The method seems to have wide applicability in designing magnets to drive micro-robots for diagnosis and treatment.      

Generating Periodic Pulse Sequences of Nanosecond Spark Discharges in an Air Gap between Transparent Hydrogel Electrodes

Technical Physics Letters - Hydrogel electrodes transparent in the visible range have been used for the first time to generate periodic sequences of nanosecond pulsed spark discharges with current...     

环氧基片溅射钛副族氧化物薄膜的脉冲真空闪络特性

在绝缘材料表面制备半导电性及高导热系数的涂层可以明显提高材料的沿面闪络性能.采用高真空反应磁控溅射方法,在环氧基片表面溅射TiO2、ZrO2,HfO2薄膜,使用快脉冲真空闪络实验装置(50ns/600ns,前沿和半高宽时间),在真空度5×10-3Pa时,研究了上述三种氧化物薄膜的真空闪络特性.实验发现,TiO2和ZrO2薄膜以无定形态存在,表面颗粒未晶化,而HfO2薄膜已经晶化. TiO2薄膜的闪络电压最高,HfO2薄膜较低.TiO2和HfO2随着溅射时间的增加,镀膜的真空闪络电压有所提高,而ZrO2随着溅射时间的增加,镀膜的真空闪络电压有所下降.结合ANSOFT静电场仿真数据,分析了薄膜的基本特性对闪络后表面电位分布及闪络电压的影响机制.     

填脉冲法在非同频信号相位检测中的应用

采用"填脉冲式"相位测量方案设计的测相卡,可以测量信号在某一时刻的相位,并可以实现计数功能;对于频率不大于10kHz的信号,相位测量误差小于0.1°;对1kHz的信号测量实验表明测相卡的单次测量精度为0.045°;文章分析了主要的误差因素,并指出了设计中的注意事项.     

脉管制冷机特征线数值分析方法

提出运用特征线方法数值计算脉管制冷机的内部流动，提出相应离散方法，数值计算方法和特征线边初值问题的处理方法。算例结合实验进行验证，并论述了脉管制冷机部流动特征线数值分析方法的数理意义。