基于霍尔传感器的直流电机转速测量系统设计

本文介绍了基于霍尔传感器,采用单片机C8051F060控制的直流电机转速测量控制系统的工作原理及软硬件设计方法.通过7279实现在LED上直观地显示电机的转速值.此外,还可以根据需要调整控制电机的转速.测试结果表明,该转速测量系统满足设计要求,并且具有硬件结构简单,性价比较高,易于调节电机转速及系统性能稳定等优点.     

基于霍尔传感器的直流电机转速测量系统设计

本文介绍了基于霍尔传感器,采用单片机C8051F060控制的直流电机转速测量控制系统的工作原理及软硬件设计方法.通过7279实现在LED上直观地显示电机的转速值.此外,还可以根据需要调整控制电机的转速.测试结果表明,该转速测量系统满足设计要求,并且具有硬件结构简单,性价比较高,易于调节电机转速及系统性能稳定等优点.     

基于霍尔传感器转速测量电路研究与设计

本文提出了基于霍尔传感器的转速测量电路,通过在直流电机的转子上安装金属齿轮,在电机的带动下模拟被测物体的转动,使得霍尔传感器两端产生感应电动势,信号调理电路将其转换成数字脉冲信号,单片机通过统计脉冲个数从而实现转速的测量。     

基于单片机的齿轮转速测量系统

齿轮转速是工业生产中的重要参数。设计了一种基于单片机的高精度齿轮转速测量系统，该系统以集成式霍尔齿轮传感器为敏感元件，单片机为控制核心实现了齿轮转速的高精度测量。     

基于霍尔传感器电机转速的单片机测量

介绍了一种基于89C52单片机平台,采用霍尔传感器实施电机转速测量的方法,硬件系统包括脉冲信号产生、脉冲信号处理和显示模块,重点分析了脉冲信号处理电路,并采用C语言编程,通过实验检测电机转速信号。结果表明该方法具有简单、精度高,稳定性好的优点。     

基于单片机的电机测速系统设计

文章设计了以单片机STC89C51为硬件的控制核心,用霍尔传感器进行测量的直流电机转速测量系统。通过对方案的分析,文章确定了系统的硬件设计和软件设计,该系统具有频率响应快、抗干扰能力强等特点。     

电机扭矩转速测试仪的设计与实现

根据在旋转动力机械设备中扭矩和转速测量的要求,利用现有的电机扭矩转速传感器,设计了一种电机扭矩转速测试仪,实现了电机扭矩、转速的高精度测量。在硬件上,以单片机(R8C/25)作为数据处理核心,采用隔离变压器设计线性直流稳压电源,减少了传统的开关电源供电造成的电磁干扰,且传感器输出信号经高速光耦隔离,提高了系统的抗干扰能力。在软件上,采用定时脉冲计数的方式,利用单片机的事件计数功能和外部中断功能同步对扭矩和转速脉冲信号进行计数,并计算出当前的扭矩值和转速值,进而可计算出轴输出功率,同时将测量值实时动态的显示在数码管上。最终,对传感器进行校验,结果验证了系统设计方案的正确性。     

基于霍尔和光电传感器特性新型转速测量装置的设计与开发

基于霍尔和光电传感器特性,设计开发了主要用于霍尔和光电传感器特性测试、转速测量的实用装置;将两种传感器特性测试及应用装置设计制作合二为一成一套仪器,实验装置和电路简便实用,成本低,外观与电路设计制作有一定新颖性,并且适用于多种霍尔和光电传感器件;测量范围广,抗干扰能力强;在实际教学实践中得到很好的应用,有利于培养和提高学生工程实践能力、设计与创新能力,促进实现举一反三融会贯通的教学目的和要求,实践效果较好,具有一定拓展空间和推广价值。     

基于霍尔效应的转速传感器在核电厂的应用

本文重点阐述的是美国ELECTRO-SENSORS公司生产的基于霍尔效应的转速传感器在核电厂汽动泵超速控制系统中的应用,其中包括霍尔传感器的测量原理、转速探头安装注意事项、使用说明等具体内容。通过本文的介绍,让更多的核电仪控工作者了解到霍尔传感器在核电厂仪控系统的应用。     

霍尔传感器在机车测速中的应用研究

测速装置在机车控制系统中占有非常重要的地位，对测速装置的要求是分辨能力强、高精度和尽可能短的检测时间。现介绍了应用霍尔传感器通过测量磁场强度，来得到稳定的脉冲方波信号，实现机车转速的测量。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.