基于单片机的自动电阻测试仪的设计

本文设计的自动电阻测试仪主要由恒流源测量电路,测量信号放大电路,继电器组切换电路,步进电机驱动电路组成,以C805117020单片机最小系统为数据处理和控制核心,具有100Ω、1kΩ、10kΩ、10MΩ四个量程。各档位可进行自动切换。具有电阻筛选的功能,可以测量连续变化的电阻值并实时显示绘制曲线。该设计结构简单,运行可靠,精度高,具有较高的性价比和实用价值。     

可编程模拟器件在小信号测量系统中的应用

介绍一种小信号测量系统的设计。该系统利用了在系统可编程模拟器件ispPAC10完成模拟前端的多路信号选择、放大、调理(对信号滤波、积分、求和)及缓冲电路的设计。为了减少系统本身的零漂,系统使用了简单的精密电阻网络进行零漂的调整。89C51常用8位单片机和ICL7135 4位半双积分ADC实现了量程的自动切换,增益可控,并可用LED显示测量值。该电路的调试简单,测试精度高。     

基于单片机的数字频率计及信号发生器

在该系统中,实现光控方波与三角波信号的频率控制和显示输出;系统由光控器件、非正弦信号发生电路、波形整形电路、信号周期检测电路和周期显示电路等四个部分组成。光控器件由光敏电阻组成,随着光强的不同其电阻值也不同,由阻值的变化来决定三角波和方波的频率。波形整形电路由LM311构成的滞回比较器来实现整形,考虑到输入信号会有干扰,故采用滞回比较来实现,具有响应快,精度高的特点。信号周期检测电路模块由单片机构成的频率计来检测。本系统中频率的测量采用直接测频法来实现,而周期是频率的倒数,故可在软件中实现将频率转换成周期。为适应实际工作的需要,本次设计给出了一种较小规模和单片机(AT89C2051)相结合的频率计的设计方案,不但切实可行,而且体积小、设计简单、成本低、可测频带宽,大大降低了设计成本和实现复杂度。在本系统中还实现用按键来实现周期显示与频率显示的切换,频率测量范围是1Hz～50KHz,周期显示为20us～999ms。硬件电路是用MULTISIM绘图软件绘制而成,软件部分的单片机控制程序,是以KeilC做为开发工具用C语言编写而成,而频率计的实现则是选用MULTISIM仿真软件来进行模拟和测试。     

基于ADμC812单片机的可燃性气体监测报警仪的设计

主要介绍可燃性气体监测报警仪的设计,他由可燃性气体传感器、信号放大电路、模/数转换、单片机、显示部分、键盘控制、报警输出、应用系统软件等组成。从传感器出来的微电流信号,经过放大电路进行放大后送入单片机内,单片机采用美国ADI公司生产的ADμC812型单片机,这款单片机带有8通道12位的A/D,可直接进行数据采集。此外,他的存储资源丰富、可进行在线编程,各方面均符合设计的要求。显示部分采用74LS164芯片和LED数码管进行显示;报警输出采用固体继电器与蜂鸣器控制报警;软件设计采用单片机C语言编程。     

自动量程切换电压测量系统设计

电压测量是电子系统中不可或缺的一项技术,随着待测电压动态范围的急剧扩大,需要能实现量程自动切换的测量方法。提出一种自动量程切换电压测量系统的设计方法,该系统基于程控增益放大器器件,使用单片机控制其增益实现量程的自动切换。针对信道误差、温度漂移等问题,采用通道自校准技术,降低了信道对于测量的误差。通过对实际软硬件的测试表明,该系统能准确根据大小信号调整量程,并对系统及环境误差有一定的抗干扰能力。     

基于FPGA具有自动量程转换功能的信号采集电路设计

随着被测信号动态范围的扩大,测量仪器必须具备自动量程功能,由此本文提出了一种具有自动量程功能的信号采集电路的设计方法。基于逐次比较的思路,该电路利用模拟电路对信号进行识别,通过FPGA控制继电器切换至合适量程,从而实现自动量程功能。在实际测试中,该电路能对信号进行快速、准确量程识别,有效保证了测量精度。因此该采集电路适用于电压表、示波表等测试仪器信号采集部分的设计,并且具有成本低、结构简单、稳定可靠的特点。     

Design of automatic range switching circuit of acquisition based on FPGA signal

随着被测信号动态范围的扩大,测量仪器必须具备自动量程功能,由此本文提出了一种具有自动量程功能的信号采集电路的设计方法。基于逐次比较的思路,该电路利用模拟电路对信号进行识别,通过FPGA控制继电器切换至合适量程,从而实现自动量程功能。在实际测试中,该电路能对信号进行快速、准确量程识别,有效保证了测量精度。因此该采集电路适用于电压表、示波表等测试仪器信号采集部分的设计,并且具有成本低、结构简单、稳定可靠的特点。     

基于AD4130的高精度温度采集系统设计

介绍了一种基于AD4130芯片的高精度温度采集系统,系统以单片机（MCU）为核心,设计4路AD4130电路作为信号采集放大及AD转换电路,可实现8路高精度温度传感器测量,具有自动校准,恒定电流源输出、自动量程切换,适用于负温度系数（NTC）传感器精密测量,也适应PT100、PT1000、PTC传感器测量,设计RS485异步通讯接口电路作为信号输出电路,可实现与上位机通讯。这种新型温度采集系统采用10μA的电流源输出,降低了传感器自热,实现了温度高精度检测。     

新型交流数字电压表设计

设计一种基于AT89C51单片机的量程自动转换的数字电压表,以AT89C51,AD574为核心器件,采用运算放大器和集成多路模拟开关电路设计了电压表量程自动切换技术,构成完备的测量系统.可以对0～500 V电压范围的电压进行量程自动转换的精确测量.该设计具有体积小,驱动电流小,动作快,结构简单,操作方便的优点,可用于实验教学中.     

程控增益放大器和自动调整增益放大器的设计

在很多信号采集系统中都需要进行量程切换，最常用的方法就是调整放大器的增益，而且在很多场合需要软件来控制放大器增益，或者放大器能自动调整增益，本文结合一些新近推出的集成芯片，给出了实现这两种放大器的一些实用电路。     

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.     

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.     

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.