500 fps图像采集及实时显示关键技术研究

为了获得高速运动目标的位置与姿态信息,分析目标瞬态事件发生的机理和运动规律,提出了以现场可编程门阵列(FPGA)为核心的高帧频图像采集及实时显示的设计方案。研究了高速互补金属氧化物半导体(CMOS)数字图像传感器LUPA1300-2,并以此为基础研究了500fps图像采集及实时显示系统的关键技术,以FPGA为核心设计了基于高速低压差分信号(LVDS)接口的图像采集模块、色彩复原模块及图像缓存模块。通过图像采集实验,验证了系统设计稳定可靠,满足现场实时性的要求。     

基于稀疏布阵的实时三维成像声纳系统

水下实时三维成像声纳系统可以有效地提高对水下目标探测及识别的能力,本文提出基于稀疏面阵的实时三维成像声纳系统,该系统包括3个部分:窄带信号发射系统、稀疏布阵接收系统及信号处理系统。信号处理系统在远场情况下采用二维FFT波束形成获得目标三维成像,近场情况下采用自聚焦二维FFT波束形成获得三维成像结果。相比于直接相移波束形成,稀疏布阵情况下采用二维FFT波束形成算法具有更小的计算量和内存需求量的优势。基于该成像算法,设计并实现一套实时三维成像声纳系统,通过多次湖上及海上实验对该系统进行测试,实验结果表明:该系统可以获得水下近场及远场目标的三维图像并满足实时成像的要求。     

Investigations of some aspects of the spray process in a single wire arc plasma spray system using high speed camera

A high speed camera has been used to record and analyze the evolution as well as particle behavior in a single wire arc plasma spray torch. Commercially available systems (spray watch, DPV 2000, etc.) focus onto a small area in the spray jet. They are not designed for tracking a single particle from the torch to the substrate. Using high speed camera, individual particles were tracked and their velocities were measured at various distances from the spray torch. Particle velocity information at different distances from the nozzle of the torch is very important to decide correct substrate position for the good quality of coating. The analysis of the images has revealed the details of the process of arc attachment to wire, melting of the wire, and detachment of the molten mass from the tip. Images of the wire and the arc have been recorded for different wire feed rates, gas flow rates, and torch powers, to determine compatible wire feed rates. High speed imaging of particle trajectories has been used for particle velocity determination using time of flight method. It was observed that the ripple in the power supply of the torch leads to large variation of instantaneous power fed to the torch. This affects the velocity of the spray particles generated at different times within one cycle of the ripple. It is shown that the velocity of a spray particle depends on the instantaneous torch power at the time of its generation. This correlation was established by experimental evidence in this paper. Once the particles leave the plasma jet, their forward speeds were found to be more or less invariant beyond 40 mm up to 500 mm from the nozzle exit.     

不同破乳方法下作用时间对乳状液破乳效果影响的试验研究

利用自行设计的高频脉冲离心破乳试验系统,配置稳定的W/O乳化液进行不同作用时间下油水乳状液的破乳分离试验研究。分别研究了不同电压下纯电场的作用时间及耦合作用和联合作用不同转速下作用时间对破乳效果的影响规律,研究表明纯电场中高电压下的作用时间的影响明显优于低电压。低转速下,耦合作用和联合作用效果与作用时间均成正比。高转速下,耦合作用效果与作用时间成反比,联合作用下随着时间变化无明显规律。     

汽轮机组非平稳运行过程振动数据的时间序列分析

时间序列的分析方法已经在许多工程领域得到广泛而成功的应用。文中通过对实际电厂运行汽轮机组非平稳过程中轴系振动数据的相关分析 ,对汽轮机组振动数据非平稳时间序列的MA(q)模型的识别和建模进行初步的探讨。为验证MA(q)模型对于汽轮机组非平稳过程中的振动数据分析的有效性 ,分别采用MA(2 )、AR(2 0 )和 3阶多项式回归分析的方法 ,利用现场实测数据进行对比预测实验。实验结果表明利用MA(2 )模型的预测效果明显优于采用AR(p)模型预测方法和传统的多项式回归预测方法的预测结果 ,从而验证采用MA(q)模型对于汽轮机组非平稳运行过程中振动信号分析研究的有效性。     

焊接缺陷磁光成像动态检测与识别

为了实现焊接缺陷的自动检测,研究一种交变磁场激励下焊缝表面及亚表面缺陷的磁光成像动态无损检测方法。分析了基于法拉第磁致旋光效应的焊接缺陷磁光成像机理,并结合交变磁场原理推导出励磁变化与动态磁光成像的关系。探索低碳钢板的亚表面焊缝磁光成像特征试验,验证了所提方法可用于检测焊缝亚表面的未熔合缺陷。最后对高强钢焊缝特征的动态磁光图像进行分析,采用主成分分析法和支持向量机(PCA-SVM)模式识别方法建立了焊接缺陷分类模型。试验结果表明,所提方法可以识别高强钢焊件中的焊缝特征(未熔透、裂纹、凹坑和无缺陷),缺陷分类模型的整体识别率达到92.6%,能够实现焊缝表面及亚表面缺陷的自动检测。     

用于闪电瞬态电场测量的高速采集系统设计

利用A/D转换芯片AD9057和基于Pockels效应的闪电电场传感器设计了一个闪电瞬态电场测量的高速采集系统,给出了高速采集系统的硬件电路和软件程序设计流程图。该系统主要包括:闪电电场传感、高速A/D转换、数据存储、数据处理。通过对闪电电场高速采集系统的硬件和软件设计,解决了数据采集过程中存在的高速A/D转换的速度与低速智能管理的速度不匹配问题,实现了带宽为0~10MHz的闪电瞬态电场信号采集。     

基于PCI总线控制器的高速大容量实时数据采集

介绍了PCI总线控制器专用芯片S5933的组成、Mailboxes、FIFO和Pass-Thru的基本概念,以及性能和使用方法,并针对高分辨率成像光谱仪数据采集的指标要求,提出了以PCI总线控制器S5933为核心的双路高速、大容量、实时数据采集与实时存储的实现方法,在该方法中通过利用PCI总线控制器的FIFO工作模式以及“双路并行复用”技术,实现了双路数据的实时采集与存储,实验表明数据实时采集与存储速率可达8MB/s,完全满足指标要求,而且具有电路简洁,数据采集速率高和容易扩展等特点.     

DSP运动控制器与PCI总线的接口设计

由于DSP具有高速实时处理能力和丰富的外设功能,目前,以DSP为核心处理器的运动控制器已经成为开放式运动控制器的发展主流,并得到广泛的应用。本文介绍了以DSP为核心处理器的开放式运动控制系统结构,并重点设计使用接口芯片PCI9030完成DSPTMS320LF2407和PCI总线的接口电路,实现了以DSP为核心处理器的运动控制器与上位机进行实时高速数据传输。     

Detection of micro gap weld using magneto-optical imaging during laser welding

Accurate seam tracking plays a critical role in acquisition of good weld. During laser butt joint welding, the laser beam focus must be controlled to follow the weld trajectory. The key problem to be solved is the automatic identification of weld position. An approach to detect the micro gap weld (gap width is less than 0.05 mm) based on magneto-optical imaging (MOI) is proposed. The laser butt joint welding of carbon steel was carried out. A magnetic excitation device was used to magnetize the weldment, and it was found that magnetic field distribution at the weld was different from other regions. The magnetized weldment was detected by using a magneto-optical sensor, and magneto-optical images of the weld were captured. By analyzing and processing weld MO images with low contrast and strong magnetic field noises, the weld center position could be detected accurately. Weld MO images at different laser welding speeds were investigated to analyze the varieties of image characteristics. Experimental results indicated that the magneto-optical imaging technique could be applied to detect the micro gap weld accurately, which provides a novel approach for automatic identification and tracking of micro gap weld during laser welding.     

基于模糊PID的DSP经编电子送经控制系统设计

设计了一种新型经编电子送经控制系统。系统以DSP为主控制器。针对控制对象的不确定性,采用了自整定模糊PID控制算法,可实现PID参数的在线自整定。实践证明该控制系统具有实时性好、响应快、稳定性高等优点,使经纱张力保持稳定,以满足经编机高速化和高质量的要求。     

COMBINE HARVESTER INSTRUMENTATION SYSTEM FOR USE IN PRECISION AGRICULTURE

A crop yield and field performance mapping system for New Holland TC-56 rice combine harvester (RCH) for precision agriculture applications has been developed using LabVIEW. A Dewe-2010 PC data acquisition system has been used as a core unit to collect and store the real time field data from different sensors and a differential global positioning system to determine the exact latitude, longitude, and altitude of RCH. Modular software allows programming flexibility in developed hardware. The spatial information has been measured and recorded in real time field testing. Sensors have been calibrated in a laboratory under specific conditions, and excellent measurement linearity has been obtained for most of parameters. The crop and yield performance maps have been obtained in real time from the field tests conducted in Malaysia. These maps will be used in precision agriculture to improve areas of low yield and to improve productivity of rice.     

Construction and characterization of the fringe field monochromator for a field emission gun

Although some microscopes have shown stabilities sufficient to attain below 0.1 eV spectral resolution in high-resolution electron energy loss spectroscopy, the intrinsic energy width of the high brightness source (0.3-0.6 eV) has been limiting the resolution. To lower the energy width of the source to 50 meV without unnecessary loss of brightness, a monochromator has been designed consisting of a short (4 mm) fringe field Wien filter and a 150 nm energy selection slit (nanoslit) both to be incorporated in the gun area of the microscope. A prototype has been built and tested in an ultra-high-vacuum setup (10(-9) mbar). The monochromator, operating on a Schottky field emission gun, showed stable and reproducible operation. The nanoslits did not contaminate and the structure remained stable. By measuring the current through the slit structure a direct image of the beam in the monochromator could be attained and the monochromator could be aligned without the use of a microscope. Good dispersed imaging conditions were found indicating an ultimate resolution of 55 meV. A Mark II fringe field monochromator (FFM) was designed and constructed compatible with the cold tungsten field emitter of the VG scanning transmission microscope. The monochromator was incorporated in the gun area of the microscope at IBM T.J. Watson research center, New York. The monochromator was aligned on 100 kV and the energy distribution measured using the monochromator displayed a below 50 meV filtering capability. The retarding Wien filter spectrometer was used to show a 61 meV EELS system resolution. The FFM is shown to be a monochromator which can be aligned without the use of the electron microscope. This makes it directly applicable for scanning transmission microscopy and low-voltage scanning electron microscopy, where it can lower the resolution loss which is caused by chromatic blur of the spot.     

Repetitive sub-gigawatt rf source based on gyromagnetic nonlinear transmission line

We demonstrate a high power repetitive rf source using gyromagnetic nonlinear transmission line to produce rf oscillations. Saturated NiZn ferrites act as active nonlinear medium first sharpening the pumping high voltage nanosecond pulse and then radiating at central frequency of about 1 GHz: shock rise time excites gyromagnetic precession in ferrites forming damping rf oscillations. The optimal length of nonlinear transmission line was found to be of about 1 m. SINUS-200 high voltage driver with Tesla transformer incorporated into pulse forming line has been designed and fabricated to produce bursts of 1000 pulses with 200 Hz repetition rate. A band-pass filter and mode-converter have been designed to extract rf pulse from low-frequency component and to form TE(11) mode of circular waveguide with linear polarization. A wide-band horn antenna has been fabricated to form Gaussian distribution of radiation pattern. The peak value of electric field strength of a radiated pulse at the distance of 3.5 m away from antenna is measured to be 160 kV/m. The corresponding rf peak power of 260 MW was achieved.     

生化分析仪用快速多波长分光光度系统设计

设计了一种用于半自动生化分析仪的快速多波长分光光度系统.系统采用了平面衍射光栅、专用阵列探测器、对数放大器以及高稳定恒流源,有效地提高了仪器的整体性能,同时降低了生化分析仪的成本.     

一种新型多功能快速分光式膜厚仪

介绍了一种高性能的多通道光学薄膜膜厚监控系统的设计与制作,系统使用了ＣＣＤ作为线阵探测器。详细论述了光源、接收器以及光纤导光系统的设计过程。实验表明该设备可以用于高精度高速测量,也适合于监控制作多层膜滤光片。     

电火花加工机床的一种神经网络快速进给控制装置

电火花加工过程是一个复杂的微观、瞬变过程,实施有效的实时控制是一个比较困难的问题。本文提出了一种用数字式神经网络高速调节器并增加并行的滞后补偿线路和脉间设定值信号切除线路,快速控制电极进给的控制装置,从而有效地实现了电火花加工过程的实时控制。     

A compact CCD‐monitored atomic force microscope with optical vision and improved performances

A novel CCD‐monitored atomic force microscope (AFM) with optical vision and improved performances has been developed. Compact optical paths are specifically devised for both tip‐sample microscopic monitoring and cantilever's deflection detecting with minimized volume and optimal light‐amplifying ratio. The ingeniously designed AFM probe with such optical paths enables quick and safe tip‐sample approaching, convenient and effective tip‐sample positioning, and high quality image scanning. An image stitching method is also developed to build a wider‐range AFM image under monitoring. Experiments show that this AFM system can offer real‐time optical vision for tip‐sample monitoring with wide visual field and/or high lateral optical resolution by simply switching the objective; meanwhile, it has the elegant performances of nanometer resolution, high stability, and high scan speed. Furthermore, it is capable of conducting wider‐range image measurement while keeping nanometer resolution. Microsc. Res. Tech. 76:931–935, 2013. © 2013 Wiley Periodicals, Inc.     

等离子体焊接除尘装置设计与数值模拟

基于等离子体放电吸附原理，提出吸尘-滤尘-荷电-除尘新工艺来净化焊接烟尘，并设计了能实时跟踪焊接烟尘源的除尘装置。确定了两电极板的长度与间距等参数，对等离子体静电吸附装置进行了荷电计算与三维电场分析，研究了烟尘颗粒在电场中的运动轨迹及其变化规律；利用COMSOL软件进行仿真分析，讨论了烟尘粒径、入口气体流速和板间电压对烟尘颗粒吸附效果的影响。分析结果表明：板间电压在0.6~2.4 kV范围内，在电场中运动时间t≥0.1 s时，该除尘装置对0.1~1 μm粒径的烟尘颗粒能够实现快速有效地吸附，且获得了显著的净化效果。