基于AT89S52单片机的超声波倒车雷达系统的设计

利用超声波测距原理,出于低成本、高精度的目的,提出了一种基于AT89S52的超声波倒车雷达系统的设计方案。硬件部分采用AT89S52单片机作为控制器,主要有超声波发射电路、超声波接收电路、温度检测电路、LCD显示电路和报警电路。本文在分析超声波测距原理的基础上,给出了实现超声波倒车雷达系统的软件设计流程图和硬件设计电路图。该系统测量精度为1cm,完全能够满足汽车倒车系统的设计要求。     

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。     

基于伪随机序列自相关性的新型超声波测距系统

针对传统超声波传感器存在受环境因素影响大、抗干扰能力差等缺陷,提出了一种新型超声波测距系统的设计方法.该超声波测距系统基于伪随机序列自相关性原理,采用模块化设计,可准确地测量出超声波的传播速度和渡越时间,进而计算出障碍物的距离.采用低功耗,高性能的TMS320VC5509A DSP作为信息处理器,采用基于快速傅里叶变换(FFT)的相关判别算法,有效地提高了实时性.改进了超声波接收电路,采用高速绝对值电路代替传统的检波电路,可高效地从接收到的超声波信号中解调出伪随机序列.根据所设计的超声波测距系统的工作原理,提出了适用于该系统的误差校正方法.在干扰存在的情况下,进行了性能测试实验,实验结果表明,该超声波测距系统的测距误差在1.8%以内,具有良好的抗干扰性.     

AT89C52超声波测距倒车防撞报警系统

利用AT89C52单片机作为主控制器,结合超声波测距原理,实现倒车防撞报警功能。进行系统硬件和软件的设计,检波接收电路和温度补偿电路分别采用了CX20106A和DS18820两款集成芯片,减小了电路间的相互干扰,提高了精度。该系统的最大测距误差不超过1cm,测距范围为10～300cm。另外,系统还具有结构简单,体积小,使用方便等特点。     

具有语音播报功能的超声波液位测量系统设计

超声波测距相比于其它测距方法,具有非接触、高精度、价格低、使用方便等优越性。针对实际应用的需要,设计了一种以单片机为主控芯片的具有语音实时播报和无线收发功能的超声波液位计系统。首先介绍了超声波测距原理,然后设计了系统硬件、系统方案及各个电路模块,包括发射电路、接收电路、语音播报电路、无线收发电路等,其次设计了系统软件程序。最后进行了系统测试。测试结果表明在加入温度补偿后测量精度可以达到0.8%,语音播报和无线收发稳定。     

一种新型超声波测距仪的设计与研究

与其他测距方法相比,超声测距具有更大的优势和更广泛的应用前景.本文详细阐述了一种基于AT89S51单片机的新型超声波测距方式.超声波几乎不被光线、烟雾、电磁场等所干扰;此外,超声波换能器的内部构造比较简易、空间利用率高并且易小型化与集成化.该系统着重设计单片机的硬件接线模块、超声波发射模块以及接收模块.空气中的超声波传播速度对温度有一定的依赖性,因此,为进一步提升系统的测量精度,在此基础上设计了基于DS18B20的温度补偿电路,同时设计了WT588D智能语音提示电路和用来提示或者报警的蜂鸣器以此达到实际使用时方便快捷的目的,最后由显示电路显示.文章最后通过实验仿真以及通过硬件进行测距实验验证了该系统具有良好的测量精度和抗干扰性的优点.     

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。     

具有温度补偿功能的超声波测距系统设计

介绍了超声波测距的原理,利用超声波传感器作为核心器件,采用温度补偿的方法实现了对5 cm~4 m距离的准确测量。系统由STC89C52单片机、DS18B20温度传感器、超声波传感器HC-SR04以及数码管显示电路组成。测量结果表明,该系统误差不超过3 cm,系统硬件结构简单、成本低、性能可靠,有一定的实用价值。     

基于MAXQ7667的超声波测距系统应用研究

针对一般大量程的超声波测距系统其精度不高的问题,设计了一种高精度的超声波测距系统。该系统采用Maxim公司的MAXQ7667作为控制器,通过设计的发射电路、接收电路、温度补偿电路、MAXQ7667自身所拥有的高信噪比及其数字信号处理能力,克服了一般超声测距系统低精度的缺点。实验表明,该超声测距系统的量程在8米内的绝对误差不大于1cm,相对误差小于0.5%。     

基于ARM处理器的两路超声波测距仪设计

结合嵌入式处理器LM3S1607与超声波传感器设计一种智能超声波测距装置,采用ARM内核芯片LM3S1607的32位嵌入式微处理器与两片P89LPC938单片机和超声波传感器发送与接收模块,通过I2C串行总线上下位机的通信架构,实现两路超声波测距.通过高精度温度传感器LM75A实现了对超声波测距系统的温度测量,对超声波的声速进行了补偿,提高了测量精度,同时具有LCD液晶显示测试距离,语音播放距离功能.设计和开发了相应的接口电路及应用程序,介绍了两路超声波测距仪的设计方法.     

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.     

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.     

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.