基于单片机的超声波测距系统设计

以STC89C52单片机作为核心控制电路,采用模块化的设计方案,以超声波传感器为检测功能部件,利用在空气中传播的超声波反射原理,结合单片机控制技术和超声波在空气中传播的时间差原理来测量距离。系统主要包括单片机控制模块、超声波测距模块以及距离显示模块。首先由超声波测距模块给单片机控制模块发送超声波并计时,然后由单片机控制模块统计数据并计算距离,最后由数码管显示模块显示出来测试的距离,完成测距。本设计测距精度可以达到3mm,并且能够提供2cm-400cm的非接触式距离感测功能。     

基于FPGA超声测距系统的改进

本文介绍了一种基于FPGA超声波测距系统的改进方法。文中的控制模块为黑金开发板,并且对其搭建了外围的硬件电路。目前测距模块主要是以单片机为主,这样的模块存在一些不足,如晶振频率不高、程序不宜修改和测量精度不高,并且相关的FPGA程序只有理论的研究,在实际中不能够实现相对应的功能。针对这些问题,本文主要是对现有的软件进行改进,使用了FPGA,使程序模块化,简单化。     

基于TDC-GP2的高精度超声波流量计的设计

基于高精度和可靠性的设计思想,针对传统型超声波流量计精度不高、电路复杂和需要对管道进行改装的问题,提出了一种基于FPGA和TDC-GP2高精度时间测量芯片的流量计系统设计。以FPGA为核心逻辑控制模块,结合时差法超声波流量计的原理,采用TDC-GP2实现时差的精确测量,通过串口上传数据给上位机进行数据处理和结果显示。测试结果表明,系统测量精确度和可靠性满足要求。     

基于超声波的移动测距系统设计

该系统是以空气中超声波的传播速度为确定条件,利用发射超声波与反射回波的时间差来测量障碍物的距离。本设计主要分为硬件模块和软件模块。以智能小车为平台来实现移动测距,采用PWM控制直流电机,采用AT89S52单片机进行控制及数据处理,该测距系统主要由超声波发射电路、超声波接收电路、单片机控制电路、寻迹电路、温度补偿电路、直流电机驱动电路及显示电路构成。利用所设计出的超声波测距系统,对不同的距离进行了测试,并进行了误差分析。最后对测距系统进行了验证。实验表明,该系统对室内有限范围内的障碍物距离测量具有较高的精度和可靠性。     

基于温度补偿的超声波测距仪的设计

环境温度应力对目前常用的超声波测距系统的测量精度有着重要的影响.为了提高超声波测距精度、减小测距误差、提高测距稳定性,分析了温度应力对超声波测距精度的影响,研究了超声波测距软硬件结合的温度补偿方法.以凌阳16位单片机为控制核心,研究开发了操作方便且具有语音报值功能的超声波测距仪,并通过软硬件结合的补偿方法实现了测距温度补偿.在不同的环境温度应力下的超声波测距实验结果表明:基于温度补偿的超声波测距仪与一般的超声波测距仪相比,测距平均标准差更低、测距精度更高.     

超声波测距系统的设计

介绍了一种以AT89S52单片机为核心控制器件的超声波测距系统的设计方法。系统通过测得超声波自发射到接收的往返时间,根据超声波在空气中的传播速度,计算得到测量距离。同时,为了提高超声波测距精度,采用温度传感器进行环境温度检测,对超声波的传播速度进行校正。由于超声波具有不受光、电磁波以及粉尘等外界因素的干扰,测量精度高等优点,因此,系统可以用于工业测距,距离开关,汽车安全,智能机器人等领域。     

一种高精度超声波多路同步测距系统设计

在分析传统超声波测距的基础上,研究了一种基于单片机和FPGA的高精度超声波测距系统。该系统采用了多路超声波先测速再测时测距的方法,自动调整计算过程中因环境变化而影响的声速参数变化,提高了系统的适应性,同时采用多路精确同步测量保证了测量的高精度。实验证明,该系统具备较高的灵活性,且采用125 kHz的频率也进一步提高了系统的测量精度。     

基于单片机的超声波测距系统的设计

基于超声波实现无接触式测距原理,介绍了一种基于单片机控制的超声波测距系统的设计方法。由单片机软件产生40 kHz超声波,并测量回波时间,可精确到us级。为提高测距精度,采取了温度补偿、角度补偿措施。实验表明系统具有较高的测量精度和实用价值。     

基于DSP超声波测距系统的设计与研究

超声波具有易于定向发射、反射性好、传播速度远小于光速而便于测距等特点,针对超声波这些特点,本文设计了一种抗干扰性的超声波测距系统。该超声波测距系统以数字信号处理器(DSP)为核心,结合硬件电路和软件设计方案,该电路可在2m有效范围内测定距离并显示。实验结果表明;该超声波测距系统具有实时性好、运行可靠、抗干扰能力强等优点,可以应用于智能避障、汽车交通等系统中,具有一定的实用价值。     

超声波测距仪的设计与制作

本文介绍了以AT89S51单片机为控制核心,采用SRF08型超声波测距模块构成超声波测距仪,通过单片机控制超声波轮流发射,在此过程中单片机计算发射超声波和接收到回波的时间差,继而测量出相间隔的距离。此系统硬件设计简单,性价比高,测量精度高,系统还可以通过显示模块显示当前距离,操作比较简单,具有很强的社会应用性。     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

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.