Triangle Waveform Parameters in Chooping Driven Circuit

脉冲宽度调制（PWM）信号产生电路是步进电机斩波驱动电路的重要组成部分，其中的三角波产生电路是关系到斩波驱动电路能否正常斩波的关键.为确保电路正常工作，三角波的波形参数必须满足一定条件.1PWM信号的产生图1（A）为斩波驱动电路的原理图，虚线框内是P...The PWM signal generation process is presented.A detailed analyzes is given about the waveform and other circuit parameters.Finally, a mathematical formulas for computing parameters of waveform of the triangle wave is derived

VMOSFET Low Voltage Drive Power Supply For Stepping Motor

论述了开关管采用n沟道VMOSfET构成中功率步进电机低压驱动电源的设计；给出了斩波开关控制电路、运行或锁定稳态电流自调节电路、边沿加速电路及电机驱动用功率半导体器件的选择。The design of low voltage drive power supply For medium power stepping motor is described.It uses as n channel VMOSFET switching devices.The chopper on/ofF control circuit,autostable circuit of operation/lock stationary current and edge accelerated circuit are presented.Choice of the semiconductor devices For motor drive is also discussed

Experimental study on reperfusion of intraocular lens

作者简介: 祁明信, 男, 1945 年7 月 出生, 教授、主任医师、博士研究生 导师, 主要从事白内障的基础与临 床研究。联系电话: 0591-83570887; E-mail:qihuang@netease. com 通讯作者: 黄秀榕,E-mail:[email protected][中文文摘]目的开展晶状体再灌注的离体和动物实验研究,并对再灌注人工晶状体技术进行评价。方法采用新鲜离体幼兔眼、离体猪眼、新西兰白兔眼,应用自行研制的人工晶状体材料,进行以下实验:(1)体外固化实验;(2)晶状体前囊膜微型撕囊及其稳固性实验;(3)经微型前囊膜开口超声乳化吸出晶状体内容物实验;(4)活的新西兰白兔眼内人工晶状体再灌注实验。结果(1)按硅酮聚合物与固化剂50:1的比例可获得柔软、弹性好、固化时间短(完全固化时间为60min)的注入材料;(2)晶状体前囊膜1.8～2.0mm的连续环形撕囊口具有较好的稳定性,可经该微型开口吸出晶状体内容物并灌注材料;(3)超声能量18%、流量25mL·min-1、负压120mmHg(1kPa=7.5mmHg)为晶状体内容物经微型前囊膜开口吸出的最佳条件;(4)注入灌注材料后可形成由晶状体囊膜包裹的、置换原晶状体皮质和核的、新的再灌注人工晶状体。结论采用再灌注人工晶状体的方法可进行新型人工晶状体再灌注,可为治疗白内障和老视提供参考。[英文文摘]Objective To carry out the experimental study on reperfusion of intraocular lens(IOLs) in vitro or in animal,and to assess the technique of IOLs reperfusion.Methods The following experiments were performed by using self-developed materials in fresh rabbit eyes and pig eyes in vitro,as well as in eyes of alive New-Zea-land rabbits:(1)Solidification study of self-developed material in vitro;(2)Continuous circular capsulorhexis(CCC) in anterior capsule of lens and its stability;(3)Draw of lens contents via phaco through mini-CCC;(4)IOLs ref illing in the eyes of alive New-Zea land rabbits. Results(1) Thematerialwhich was soft, springy and short-term solidification(full solidification time was 60 minutes) were obtained in certain proportion of geland solidified agent(50:1) in vitro; ( 2)The CCC in anterior capsule of lens with 1.8-2.0 mm diameter had very good stability. The lens contents were drawn and the materialwere refilled through themini-CCC; (3) The best conditions of drawing out lens contents through m ini-CCC were phaco energy 18% , flow 25 mL·min- 1, and negative pressure 120 mmH g (1kPa=7.5 mmHg);(4) The new refilled IOLs, which were wrapped by capsule of lens and were replaced original cortex and nucleus of lens, were obtained after thematerial refillied. Conc lusion. New IOLs are refilled through this method, which can prov ide reference for the treatment of cataract and presbyopia.福建省科技三项费用;教育厅重点资助项目基金资助(编号:K98041

步进电机驱动电路及其闭环控制系统的研究

步进电机驱动电路是一种特殊的功率开关电路，本文首先 定义四个指标参数用以表征驱动电路的技术性能。 恒流斩波电路是目前性能较优良的步进电机驱动电路。本 文对其原理、设计做了较详细的讨论，并在此基础上介绍由作 者设计研制的低压驱动恒流斩波电路。该电路由于引进了“边 沿加速电路”，使电路的驱动能力大幅度提高。 转子位置检测电路是步进电机闭环控制系统的核心电路。 本文对其工作原理和实现电路的设计作了详细的讨论。学位：工学硕士院系专业：计算机与信息工程学院电子工程系_应用电子学学号：xy00020

Detection of Lead Angle InFormation in Stepping Motor

步进电机的微型计算机闭环控制系统中，超前角是自动最佳驱动的一个重要信息.本文介绍步进电机超前角信息的一种检测方法，描述转子到位判别门阳电平产生装置和中断信号产生器的设计，并提供实际测量的V＿θ~θ关系曲线和检测电路的信号波形。The lead angle is an important inFormation of microcomputer closed loopcontrolled selF-optimizing drive For stepping motor.The detecting method of the lead angle inFor-mation is presented.A detailed description is given about the design of the distinguishable gatelevel generator and the interrupt signal generator For rotor rotate to a deFinite position.The ex-periment curve of vaviation of V_θwith θ and the signal waveForm of the detecting circuits is of-Fered

离心沉降工艺对白光LED器件色区的影响

在LED点胶工艺中,由于荧光粉受自身重力影响而引发沉降问题一直阻碍白光LED器件良率的提升,本文研究了荧光粉沉降对LED器件光电参数的影响,实验结果表明LED器件的光电参数会随着荧光粉沉降发生变化,但是沉淀时间达到8 h以后,LED器件光电参数趋于稳定。基于此,本文研究采用离心沉降工艺来加速荧光粉的沉降速度,让荧光粉在短时间内加速沉降至LED芯片表面,有效解决荧光粉自身沉降引起的色漂移,改进白光LED器件色区分布,实现LED器件颜色集中度进一步提升的目标

2005～2015年CERN光合有效辐射数据集

光合有效辐射在生态学、农学以及气候学等多个学科中都有重要的应用价值。它是揭示物质与能量交换过程的基本生理变量,是光合潜力、潜在产量的评估研究和作物生长模拟研究、土壤碳的固定模拟研究中不可缺少的关键数据之一。该数据集涵盖了中国8个典型陆地生态类型、中国生态系统研究网络(CERN)下属的40个辐射观测站观测的光合有效辐射日均值,时间跨度为2005～2015年。通过对传感器的集中标定与规范的数据质量控制方案,保障了观测数据的可靠性与可比性。采用光谱仪、辐射标准灯传递辐射基准方案,对光合有效辐射传感器进行集中标定与比对,标定精度小于5%,符合世界气象组织(WMO)标准;采用极值法对观测的光合有效辐射数据进行质量控制