TDX-200透射电镜照明系统的计算与仿真

透射电子显微镜(transmission electron microscopy,TEM)的照明系统包括电子枪和聚光镜,它要求能提供最大亮度的电子束,照射在样品上的电子束孔径角必须能在一定范围内调节,照明斑点的大小可按需要选择。在调试过程中需要预先对照明系统激励参数进行计算。基于TDX-200透射电子显微镜,对双聚光镜照明系统的功能实现进行了理论分析,结合实际尺寸进行了理论计算与实际仿真,并在实际调试过程中进行了初步验证。     

TDX-200透射电子显微镜灯丝像的调节

透射电子显微镜（transmission electron microscopy,TEM）在工作状态时要求精确的合轴,电子枪作为TEM电子光学系统主要部件之一,要求电子源必须与镜筒中整个电磁透镜系统严格合轴,否则会造成到达样品的电子束流减少,引入球差等不良影响。在操作中灯丝像的对称性是判断电子枪是否合轴的重要判据。研究了TDX-200透射电子显微镜灯丝像的调节过程,给出了透射电子显微镜灯丝像的具体调节步骤,并通过课题室透射电子显微镜TDX-200进行了实际验证。     

一种电磁纵走式双帘焦平面快门

针对某航空摄影相机宽幅面、高频次成像的特点,结合各种类型快门的工作特性,设计和研制了一种焦平面帘幕式快门。采用旋转电磁铁启动快门的上紧运动,结合扇形齿轮、凸轮和连杆等传动组件完成上紧操作,利用电磁衔铁的吸合来锁定上紧状态,然后通过依次释放前后帘的电磁衔铁,在动力弹簧的驱动作用下,使前后帘叶片组之间形成一个固定宽度的狭缝,该狭缝从像面扫过时对成像介质形成曝光,通过程序改变后帘电磁衔铁释放的延迟时间值,可达到调节曝光时间的目的。通过快门测试设备的检测结果来看,该快门的曝光时间调节范围为2～20 ms,绝对误差为0.1 ms,曝光均匀性优于10%,最高工作频率为8 fps,成像试验的结果表明快门能够满足面阵航摄相机的成像要求。     

一种电子警察抓拍机快门优先的自适应联动测控方法

针对常规抓拍机进行抓拍时关键参数相对固定致使成像图像出现图像模糊、曝光不足或曝光过度等不足,研究了一种电子警察抓拍机快门优先的自适应联动测控方法,以高质量地获取道路机动车流量急剧增加导致道路交通中闯红灯等违章信息.研究结果表明,通过对抓拍机的关键性能参数进行自适应调节,即利用地感线圈测得的车速计算抓拍机的曝光时间及利用抓拍机试拍的图像计算闪光指数和光圈大小并作相应的参数调整,可以实现电子警察抓拍机快门优先的自适应联动控制,从而满足电子警察抓拍机在各种光照环境下均能实现对高速运动的违章车辆的高质量成像,具有重要的实际参考价值.     

磁场的智能数字测量系统原理和设计

介绍用霍尔效应测量磁场的原理和方法。设计了使用霍尔传感器测量磁场的硬件电路和主程序框图 ,同时详细分析了不平衡电动势的自动补偿电路和自动量程切换技术实现的方法。本智能磁场测量系统既适合测量直流磁场 ,又可测量交变磁场 ,且体积小 ,性能高 ,适用频率范围宽。     

基于脉冲原理的电压型在线保养装置设计

通过研究铅酸蓄电池负极板硫化失效机理,设计了一套基于脉冲除硫技术,主电路采用Boost升压拓扑电路的电压型铅酸蓄电池在线自动保养装置。实验结果表明,所设计的装置可以通过硬件和软件程序的调节实现高频、高幅值的充放电脉冲,实现了对铅酸蓄电池的在线保养。     

200MW机组DEH功频控制原理的组态设计

主要介绍了采用HIACS－3000实现DEH功频控制原理的组态设计，以供火电厂热控人员参考。     

基于深度学习的TEM纳米材料图像识别与粒径统计

对于催化材料,纳米颗粒的大小和形状等结构信息对催化性能有着重要的影响,基于透射电子显微镜图像的纳米颗粒识别与统计是获取这些信息的主要手段.本文提出一种基于深度学习的深度可分离卷积U-Net网络架构,以核壳结构纳米材料为数据集,采用交叉熵损失函数、加权交叉熵损失函数、IoU损失函数和Dice损失函数作为优化目标,分别对网...     

低压电力线载波抄表系统的原理及主站软件的设计

重点介绍了由于其自身的特点而受到广泛重视的低压电力线载波抄表方式的设计原理,并叙述了一种基于Win-dows98、WindowNT4.0平台切实可行的自动抄表系统的主站软件的设计情况。     

一种新型自动重合闸控制器的设计原理与工程实现

本文介绍了一种新型基于 80C196单片机和大规模现场可编程芯片的自动重合控制器的硬软件结构和工程实现     

Japan's commercial development of the electron microscope

Americans have a picture of Japan as a country which, in the years after the Second World War, was able to produce only inexpensive and shoddy goods. This picture is not, however, entirely accurate. For example, the first electronic product exported from Japan to America after the war was not, as most suppose, the transistor radio but a highly complex research tool, the electron microscope. Today, Japan manufacturers the majority of the world's electron microscopes. How could a country cut off from the West's scientific research establishment in 1939 and in economic ruin in 1945 be competitive as early as the 1950's in producing such complex technology? This short article, based largely on an interview with two of the founders of one important Japanese microscope manufacturer (JEOL) gives a few clues. Rather than present a detailed history of the company, the author identifies seventeen factors that contributed to the company's success     

新输电线路设计规范对杆塔设计的影响性分析

2020年国家电网基建部发布了一系列电网工程设计建设的技术标准,为探讨新规范对杆塔的影响,首先对输电线路工程影响较大的如电气、荷载等设计规范进行了分析,阐述其修订要点;接着对原杆塔通用设计采用数理统计分析方法,给出新规范对杆塔的影响.结果表明,本次输电线路相关规范的修订,对低电压等级的线路杆塔影响较大,无论是在电气间隙...     

扫描电子显微镜图像荷电现象的研究

扫描电子显微镜在观察材料样品表面形貌领域应用广泛。在日常的实验过程中经常会遇到导电性能不佳的样品,这会产生不同程度的荷电现象,对图像质量以及样品的形貌表征都产生了极大的影响,时刻困扰着操作人员。为了克服这一问题,通过调整仪器参数设置、选择探测器以及辅助导电等手段,经过实验比对、理论验证,提出了7种方法,这些方法可以减轻或消除荷电效应对图像质量的影响,适用于当今主流的场发射扫描电子显微镜,应用广泛、适用性强。     

基于PCI总线的超声显微镜研究与设计

为了提高超声成像系统检测复合板材料的分辨率,设计了一种基于PCI总线的全自动工业超声显微镜,研制了主频为20MHz的专用超声换能器,波列只有一个周期;其A／D部分具有250MHz的采样速度,同时用CPLD芯片对信号进行处理,结合计算机技术,其检测结果直接在计算机上显示,并能够对检测结果进行数据处理、表达、传送、存储等,使超声显微镜成像检测系统能够检测到O．2mm当量的缺陷。     

Charging of deformed semicrystalline polymers observed with ascanning electron microscope

A scanning electron microscope technique is employed to investigate the charging response of stretched semi-crystalline polypropylene (PP) and high density polyethylene (HDPE). The results reveal that the charging response of these insulating polymers varies with the amount of deformation due to stretching. The curves of charging response as a function of extension for HDPE and PP both can be divided into four regions showing up, down, and up and down trends, respectively. These four regions are related to four different deformation stages in the semicrystalline polymers, and polaron formation appears to be appropriate for the interpretation of the charging behavior     

Imaging of tissue microstructures using a multimodal microscope design

We investigate a microscope design that offers high signal sensitivity and hyperspectral imaging capabilities and allows for implementation of various optical imaging approaches while its operational complexity is minimized. This system uses long working distance microscope objectives that enable for off-axis illumination of the tissue, thereby allowing for excitation at any optical wavelength and nearly eliminating spectral noise from the optical elements. Preliminary studies using human and animal tissues demonstrate the feasibility of this approach for real-time imaging of intact tissue microstructures using autofluorescence and light scattering imaging methods.     

Contingent transmission rights in the standard market design

We define transmission rights that are compatible with the Federal Energy Regulatory Commission's proposed standard market design (SMD) and that provide flexibility in the points of receipt or delivery of energy contracts. The contingent transmission rights introduced here provide a viable, flexible method for defining SMD-compatible rights for transmission customers having current (pre-SMD) transmission rights that cover multiple points. These contingent rights can be bought and sold in the transmission rights auctions under SMD.     

高压输电线路设计冰厚的取值

本文分析设计冰厚取值对输电线路工程造价的影响,考虑充分利用线路的过载能力来抵御稀有覆冰,参考省内外冰取值的设计和运行经验,对设计冰厚的取值提出建议。     

Impact of electromagnetic field management on the design of 500 kV transmission lines

The electric and magnetic field (EMF) issue has become an area of increasing public concern. There is a heightened sensitivity among the public to the siting and construction of new, and the upgrading of existing electric facilities. There is substantial scientific uncertainty and no widespread agreement among scientists as to how the presently available information regarding the possible health effects of electric and magnetic fields should be interpreted. Animal and epidemiological studies are inconclusive on whether exposure to EMF can cause human health effects.

Minimizing electric and magnetic field strength is one of the many factors to consider in the planning and design of a transmission system. It must be considered along with other issues such as safety, environmental concerns, reliability, insulation and electrical clearance requirements, aesthetics, cost, operations and maintenance. The field reduction techniques described in this paper are proven methods, and the new techniques are explained thoroughly and incorporated taking into consideration the percentage field reduction, maintenance, and operational reliability.

The constraints for electric and magnetic field reduction by line compaction and optimization of bundles configuration are studied taking into consideration the international accepted minimum clearances. The importance of the phase configuration and sequence is also demonstrated. Novel-field cancellation methods are presented. Systematic comparisons of the effectiveness of different line designs in reducing the EMF are included.