基于虚拟仪器和CY7C68013的数据采集器设计

针对工程和教学实验系统对高性价比数据采集器的需要,采用LabVIEW图形化开发软件、高精度高速度的数据采器件MAX197、8051单片机和USB接口集成一体的芯片CY7C68013,实现8路12位数据采集、1路8位D/A输出1,6路数字I/O,而且具有温度检测显示功能,A/D最高采样频率可达100 kHz。该数据采集器具有较高的性价比,可推广应用。     

Automated test control and data acquisition for servo-controlled materials testing

The paper presents a viable and efficient method of automating test control and data acquisition functions for servo-controlled fracture testing based on a systems analysis approach and structured design. Using the hardware, which includes (1) a personal computer, (2) a servo-controlled electrohydraulic testing machine equipped with a special type of digital function generator, and (3) a multipurpose A/D, D/A board, an automated test control and data acquisition system for servo-controlled materials testing has been developed. The system allows: automated control of the test; rapid and reliable acquisition of several channels of data (8 differential or 16 single-ended channel capability) from static fracture or fast-rate fatigue tests; and realtime (or nearly so) graphics of the test characteristics in order to allow the operator to monitor the test. The communication and post-processing options allow user-supplied software to be incorporated in the automated system for advanced functions. These include noise filtering, signal averaging, mathematical analyses and processing, report quality graphics, and file transfer features. The system features have been validated through a series of load-controlled direct tension tests on an aluminum specimen.     

一种闭环式神经电刺激系统的设计

为了在脑电信号波形的特定相位处施加电刺激,利用NI公司的通用数据采集卡和LabVIEW虚拟仪器环境,开发了一种闭环式电刺激系统。采集卡的A/D通道采样大鼠大脑海马区的场电位信号,LabVIEW程序分析幅值和周期特性,预测即将到来的场电位θ节律的波峰或者波谷,并在指定相位处经由采集卡的数字口或者D/A通道输出所需的刺激信号,以实现闭环式刺激。实验结果表明,θ节律波峰和波谷的预测正确率分别达到92%和86%。该电刺激系统的通用性和灵活性使其能够用于多种神经节律波相位以及其他信号特征的预测,为神经电生理研究和大脑疾病的电刺激治疗提供了一种新型闭环控制刺激方法。     

时间交替ADC系统的一种动态误差补偿方法

目前有许多方法被用于补偿或减少时间交替ADC系统各个通道失配带来的误差,但这类方法仅考虑了静态效果,没有提供一种测量时间交替ADC系统误差的有效方法,对SFDR提高非常有限,并且难以满足实时性的要求.本文采用由状态空间索引的误差表对时间交替ADC系统的输出进行校准.该方法将某一通道作为参考通道,对其它通道的误差进行测量并生成由时间交替ADC系统输出状态索引的误差表,利用该误差表对各个通道的输出进行动态校准.最后将该方法用于400 MSPS/12 bit高速数字化仪的校准,在输入幅度为1 V的1 MHz正弦信号时,高速数字化仪的杂散失真可降低20 dB.     

数据采集系统设计

本系统设计主要实现的功能是：通过ADC0809模/数转换器对8通道的模拟信号进行循环测量。将测得的数据进行保存、处理和显示。数据处理功能上实现了对采集数据进行两倍放大、1/2的缩小和保持数据不变等操作,并且将处理后的数据输入到DAC0832进行数/模转换。主要解决的问题是如何进行数据采集以及怎样进行多路数据采集。     

A Raster thermal-neutron scintillation multidetector of modular type

A 100-channel scintillation multichannel detector of thermal neutrons has been designed and manufactured for modernizing the D7a neutron diffractometer on the IVV-2M reactor. The detector is built in accordance with the modular approach and allows arrangement of sensitive surfaces of channels on a cylindrical surface of arbitrary radius. The sensitive volume of a channel is a multilayer composition of stripes of an ND scintillation screen and wavelength-shifting fibers. The dimensions of the entrance aperture of the channel’s sensitive volume are 3 × 120 mm. The average detection efficiency in channels for neutrons of wavelength λ = 1.53 Å is 70%. The gamma sensitivity of the detector channels is no higher than 1 × 10^?7. The maximum counting rate of an individual channel is ≥ 1 × 10⁵ neutrons/s. Each module of the detector is an independent device and contains ten channels for neutron detection, signal-processing electronics, a high-voltage supply system, and computer-interfacing electronics. A CAN interface is used to acquire data from the modules, set the registration parameters, and control the modules.     

Low crosstalk switch unit for dense piezoelectric sensor networks

Structural health monitoring (SHM), on the basis of piezoelectric (PZT) sensors and lamb wave method, is efficient in estimating the state of monitored structures. Furthermore, to monitor large-scale structures, dense piezoelectric sensor networks are required, which usually contain many piezoelectric sensor pairs called actuator-sensor channels. In that case, considering the few data acquisition channels especially in the data acquisition board with a high sampling rate and limited quantity of signal amplifiers used in an integrated computer system, a switch unit is adopted to switch to different channels. Because of the high frequency and power of the lamb wave excitation signal, there exists a crosstalk signal in the switch unit. A large crosstalk signal is mixed into the response signal so that the on/off-line signal processing task is difficult to achieve. This paper first analyzes the crosstalk signal phenomenon, describes its production mechanism, and proposes a method to reduce it. Then a 24-switch channel low crosstalk switch unit based on a digital I/O board PCI7248 produced by Adlink technology is developed. An experiment is implemented to validate it. Its low crosstalk characteristics make it promote the real application of the SHM based active lamb wave method. Finally, a general software program based on LabVIEW software platform is developed to control this switch unit.     

树状分支传热结构层次生长优化设计技术

To design heat transfer structures for high heat flux electronic components with small space, reasonable heat transfer channel layout was the most effective approach. Aiming at the complex geometry boundaries and difficult-to-manufacture for heat transfer structures designed by topology optimization, a hierarchy growth method for optimal design of branching heat transfer structure inspired by hierarchical characteristics of natural vein branching system was suggested. Different growth control criteria were adopted for principal channels and lateral channels, which grew in succession to form heat transfer structures. Specifically, space colonization algorithm with temperature information was applied to the growth of principal channels, and the law of minimal thermal resistance was applied to control the growth of lateral channels. Several typical 2D or 3D design problems were studied by the suggested method, and the design results were compared with those of SIMP method. The results show that the heat transfer structure by hierarchy growth method has simple and clear geometry boundary, no tiny channel and gray element, therefore it is easy to be manufactured, and has good thermal performance.     

Assessment of stage–discharge predictors for compound open-channels

The accurate prediction of flood levels and velocities is a prerequisite to any appropriate management of river valleys, where the mitigation of environmental, economic or human losses caused by flood events is of paramount importance. During these events, rivers frequently acquire a compound channel configuration.Due to the 3D nature of compound channel flows, the stage–discharge curves are not as easily predicted as in single channels. Despite the availability of 2D and 3D flow models that may solve this question, 1D methods are often preferred due to the reduced data required and to the much shorter processing time. In the last five decades, important research efforts have been devoted to the improvement of 1D predictors of stage–discharge curves in compound channels. In this study, the accuracy of seven of those methods is assessed by comparing their predictions with a large experimental dataset, comprising symmetrical and asymmetrical compound channels with vertical and inclined main channel sidewalls, and smooth and rough floodplains. To the authors’ best knowledge, this is the most comprehensive assessment of stage–discharge predictors for straight compound channels since it involves the highest number of predictors applied to the widest data set.It was concluded that the methods that account for the momentum transfer between the main channel and the floodplains display considerably better results than the traditional methods. For relative depth (ratio between floodplain and main channel flow depths) higher than 0.25, predicted discharges for the methods that account for the turbulent momentum exchange are within 5% of observed values. Depending on whether the flow depth or the flow discharge is the pertinent variable, two different methods seem to be the most appropriate to produce precise and safe predictions.     

基于VB编程的电位滴定数据采集及处理系统

采用基于USB接口的高精度24位A/D数据采集卡,连接滴定装置和pH计,设计了一个数据采集与处理系统,包括用采集卡将化学滴定过程中的体积信号和测量信号转换为数字输入计算机、通过VB编程实时显示、处理以及存贮。利用该系统将滴定曲线的一阶导数实时变换为突跃指数,对有机弱酸的总量进行电位滴定分析,得到了准确、稳定和可靠的结果。     

基于FPGA技术的新型膜片钳数字接口逻辑设计

为了满足膜片钳实验的需求，本课题设计了一种多通道的数据采集系统。它利用FPGA控制技术实现同步工作模式，即要求输入输出数据点与点在时间上对准；采样率在1kHz到350kHz范围内可调；8路ADC和4路DAC通道之间相互独立，并可以同时工作；本文将着重介绍FPGA控制逻辑部分的设计。     

增大A／D带宽的非线性方法及其实现

提出用非线性方法来实现数据采集系统中所要求的具有大带宽的Ａ／Ｄ转换电路。该方法避免了采用价格昂贵的位数高的Ａ／Ｄ,实现的Ａ／Ｄ转换具有良好的动态特性,在实际应用中确实可行,具有较好的通用性。     

Design of U-shape milled groove conformal cooling channels for plastic injection mold

Besides the solid free-form fabrication technology, milling operation is an alternative applicable method to make complex cooling channels conform to the surface of the mold cavity. This paper presents the U-shape milled groove conformal cooling channels and proposes the design optimization process in order to obtain an optimal cooling channels’ configuration and target mold temperature. The relation between the cycle averaged thermal behavior of the mold cavity and the two-dimensional configuration of cooling channels was first investigated thoroughly by an analytical method. Design of experiment and 2D simulation were done to obtain the mold wall temperature and to check the feasibility of the analytical method. The optimization process of the free-form conformal cooling channels is based on the combination of both analytical method and 3D CAE simulation. The analytical step relies on explicit mathematic formulas, so it can approach the neighboring optimal solution quickly. Subsequently, the three-dimensional heat transfer simulation is applied to fine-tune the optimization results. A case study for a plastic car fender was investigated to verify the feasibility of the proposed method. The results show that conformal cooling channel gives a uniform cooling, reducing the cooling time and increasing the molded part’s quality with less effort of plastic designers and high computational efficiency.     

Shape optimization of flow channels based on lattice Boltzmann method

A new optimality criterion algorithm is presented for producing modified shape designs for fluid flow inside channels. To compute the fluid motion in a channel, the lattice Boltzmann method (LBM) was used based on D2Q9 and D3Q15 lattice spaces associated with the Bhatnagar-Gross-Krook (BGK) collision term. An experiential optimality method to design channels with the lowest pressure drop along the passage is introduced. The positions of solid cells and fluid cells are exchanged based on the strain rate tensor at the solid-fluid interface. To obtain the optimized shape, the cells are changed until the optimality condition is obtained with the restriction of constant fluid volume. Examples are presented to validate the algorithm, including an elbow tube as well as symmetrical and nonsymmetrical Tjunction channels. The validation exercises demonstrate that the algorithm is suitable for optimal channel design.     

基于反熔丝FPGA的多路数据采集单元

针对多路高速数据采集单元硬件部分,设计了基于反熔丝FPGA的多路数据采集方案.分析了浪涌电流的危害以及抑制浪涌电流的方法,阐述了反熔丝FPGA的优越特点,并对系统的各组成模块进行了详细的说明.设计采用反熔丝FPGA器件A32100DX作为系统的主控器件,实现了A/D转换、模拟开关选通控制以及数字信号的并串转换等功能.     

基于 Zynq 的 16 通道高精度数据采集系统

为了提高数据采集的精度和速率,设计了高精度、多通道的数据采集与显示系统。为了精准实现多通道数据采集与显示功能,使用赛灵思公司的 Zynq-7000 系列芯片以及 AD7606 完成多通道数据采集与显示。在设备软件设计方面, A / D 转换完成后存入 DDR3 存储器,然后采用 AXI4 总线与可编程逻辑( PL )部分通信,最后通过 ARM 驱动完成数据的实时显示。经实验证明,该系统可以良好地实现 16 通道的数据采集功能。     

微机控制的A/D自动写入扩展RAM系统

本文研究了双通道A／D自动采集存储系统，利用数据收发器及数据选通控制器分别控制RAM的数据线及地址控制线。使RAM既可由PC机控制，又可在A／D转换时自动存入数据，而不需CPU的干预。     

快速电容测量仪的研制

本文采用四个相位分量同时测量、缩短采样时间的方法，使被 电容和标准电阻上的电压分别经过不同通道进行组合测试，以减小通道间不一致的误差，改进了只分式A／D变换器转换速度慢的问题，提高了仪器的测量速度。     

基于ARM&FPGA的CCD图像识别装置

给出了一种CCD图像识别装置的设计方法,该装置以ARM与FPGA为主控芯片,设计了基于Nios Ⅱ的A/D控制模块并行控制多路CCD图像信号的数据采集和基于Nios Ⅱ的多种内核,重点介绍了基于Nios Ⅱ的LCD驱动以实现液晶显示、设计A/D采样控制模块以实现多路数据采集以及设计SL811HS驱动以实现ARM与PC的USB通信等.实验结果表明系统具有应用价值高、速度高、可靠性高、故障少等优点.     

A/D、D/A接口转换精度测试系统

文中设计了一种对A/D接口的测试与D/A接口的测试一样简单转换精度测试系统.利用此系统,用户可以灵活地选择A/D或D/A接口任意个数通道进行测试,可以根据需要修改测试数据,可以全通道测试,可以根据实际需要指定基准值.系统具有较好的可扩展性和灵活性.