单片机控制系统中步进电机接口电路的设计

介绍了用大规模集成电路PMM871 3设计的控制和驱动 3相、4相步进电机的通用步进电机接口电路 .     

显微镜坐标自动定位系统

本设计采用ATMEL公司的单片机AT89S51对步进电机进行控制．通过I／O口输出的具有时序的方波作为步进电机的控制信号。信号经过4个差分器驱动步进电机;同时,用8个键来对电机的状态进行控制。     

单片机控制的步进电机恒流斩波细分驱动系统

在对步进电机细分驱动原理进行分析研究的基础上，提出一种新的步进电机细分驱动电路——单片机控制的步进电机恒流斩波细分驱动电路，并对其功能及特点进行了系统的阐述。     

步进电机H桥型驱动电路设计及其应用

设计了一种H桥型步进电机驱动电路，对其工作原理和功能进行了阐述。其主要特点是，使加到电机绕组上的电流信号前后沿较陡，降低了开关损耗，改善了电机的高频特性，同时具有多种保护功能．以AT89S51单片机为主控芯片，设计了基于此驱动电路的一种步进电机控制器，从硬件结构和软件编程两个方面给出了设计过程．实验证明，基于该驱动电路的控制器简单、可靠并具有优良的驱动性能．     

单片机控制步进电机细分驱动的实现研究

单片机控制步进电机已经广泛作用于各种自控场合,为了适应不同的电机和驱动电路。本文主要针对单片机控制步进电机细分驱动的实现做了初步探析。     

单片机控制步进电机细分驱动的实现研究

单片机控制步进电机已经广泛作用于各种自控场合,为了适应不同的电机和驱动电路.本文主要针对单片机控制步进电机细分驱动的实现做了初步探析.     

步进电机细分驱动技术综述

阐述了步进电机的细分驱动原理。介绍了单片机控制的放大型、斩波式、脉宽调制式等步进电机细分驱动电路的结构和控制原理,指出了各种驱动电路的应用场合和对小进电机细分驱动的相电流控制策略。     

基于L6217A的步进电机细分驱动系统的设计

步进电机作为控制执行机构,广泛应用在各种自动化控制系统和精密机械等领域,对步进电机细分方法的研究是目前步进电机研究领域的热点。本文设计了一种新型的步进电机细分驱动电路。该驱动电路主要应用双极性两相混合式步进电机驱动集成芯片L6217A,来实现电流细分功能。该电路通过单片机AT89C51进行控制。实验结果证明,所设计的控电路具有细分精度高、运行平稳且噪声小、功耗低、可靠性好、性价比高等优点.     

叠图机控制和驱动系统的研制

分析了叠图机原理，设计了叠图机控制和驱动系统．通过AT89C52单片机去控制步进电机转动，从而带动送纸胶辊和压纸胶辊按照规定尺寸进行叠图；设计了步进电机工作方式和相应的智能控制电路，其驱动电路使用IRF640等器件组成的大功率H桥式电路．系统实现了折叠多层图纸工作的自动化，不仅减轻了人工劳动，还提高了效率与叠图精度．     

基于CPLD的数控机床控制系统

采用经过优化的软件算法和智能化控制,以AT89S51单片机为控制器,产生方波脉冲和电机转向控制信号,脉冲经过CPLD调节,再经驱动电路放大驱动步进电机。     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

Editorial note for the special topic on ＂Nanopore Analysis＂

The concept of nanopore analysis, using the pore-forming protein a-hemolysin to detect individual nucleic acids at a single-molecule level, was first proposed in 1996. Over the past two decades, tremendous progress has been made in the nanopore field, and nanopore analysis has become a label-free and high-throughput method for probing bio- molecules and other analytes with single-molecule sensi- tivity, especially holds the promising for ＂third generation＂ DNA sequencing. However, challenges still remain in the experimental strategies and the design of whole nanopore-based instruments. Here, we proudly present a special topic dedicated to the topic of ＂Nanopore Analysis＂, with 8 reviews/articles providing up to date coverage of the experimental strategies, theoretical calcu- lations and simulations, and instrument design. Reviews and articles on the experimental strategies cover control of DNA partitioning into a nanopore, detection of target DNA, and the advantages of nanopore-based DNA sequencing. The theoretical calculations and simulations discuss the translocation behavior of DNA, and an inte- grated measurement system and data analysis software are presented for instrument design.     

Effects of climate change on biodiversity

1 Rise of studies on climate change＇s effects on biodiversity
Until the 1980s, climate change and biodiversity were studied as two independent disciplines for more than a century. In 1992, the Ecological Society of America＇s annual report named climate change, biodiversity, and the sustainable ecological system as the three major global environmental issues of the twenty-first century [1].     

Discussing the Expansive Learning in Modern Organizations

<正>1 Introduction Endeavours on learning methods have long occupied the mind spaces of scholars and there have been theories abound on how people learn and in what way organisations can use some of the knowledge gained in the art of learning to maximise human productivity.While the theories by themselves are not solutions to problems,they are steps of inquiry that provide us with interesting perspectives that we can use to extend our knowledge of the dimensions of learning.This paper is an exploratory work on the theories postulated by three notable scholars including Zimmerman     

Progress in Linear Scaling Non-Orthogonal Localized Molecular Orbitals Method

The non-orthogonal localized molecular orbital(NOLMO)is the most localized representation of electronic degrees of freedom.As such,NOLMOs are thus potentially the most efficient for linear scaling calculations of electronic structures for large systems.However,direct ab initio calculations with NOLMO have not been fully implemented and widely used,partly because of the slow convergence issue in the optimization of NOLMO.We devel-     

An Accurate and Universal HEOM Approach to Strongly Correlated Quantum Impurity Systems

A hierarchical equations of motion(HEOM)approach is developed for general open quantum systems coupled to fermionic environment.The HEOM method is in principle formally exact,as it resolves nonperturbatively the combined effects of many-body interaction,system-bath dissipation,and non-Markovian memory.In practice,the HEOM approach is highly accurate and efficient for the characterization of strongly correlated quantum impurity sys-     

关于有理混合吸引子的Ciric型非唯一不动点定理

本文我们应用有理混合吸引子条件去证明具非唯一不动点的映射Ciric型的若干不动点定理.结果推广并改进已知的一些结果.     

次线性算子交换子在变指数Herz-Morrey空间上的有界性

本文主要利用给出的次线性算子分别与BMO函数及Lipschitz函数生成的交换子在变指数L~(p(·))(R~n)空间上的有界性,证明了其在变指数Herz-Morrey空间MK_(q,p(·))~α~((·)),λ(R~n)上的有界性.     

利用GPS双频观测值实现PPP电离层延迟高阶项改正

给出了利用双频观测值计算L3组合电离层延迟高阶项改正的方法,并与全球电离层延迟文件的改正效果进行对比.利用赤道附近的15个国际全球卫星导航定位系统服务组织(IGS)站的数据进行比较,结果表明:2种方法计算的电离层二阶项延迟互差最大不超过1 cm,三阶项延迟互差最大不超过5 mm;电离层高阶项改正后的观测值精密单点定位(PPP)解算结果N、E、U方向互差平均值分别为0.4、0.5、1.0mm,因此2种改正方法效果在同一水平.