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《测试技术学报》2016,(5)
落锤装置可用于传感器系统的准静态校准、塑性测压器具的准动态标定、材料冲击性能测试以及发射药、炸药等爆炸材料的撞击感度测试等.在实验过程中,重锤由于摩擦阻力等影响可能无法正常下落,因而导致实验结果异常.本文简要介绍了落锤装置,基于PLC控制系统,针对重锤下落速度测量的特殊性,采用定距测时法,控制高速计数器发出时间间隔为0.01ms的高速脉冲,将重锤上的凸台经过测速环时产生的上升沿信号作为中断触发信号,通过记录两个凸台经过测速环时发出的高速脉冲个数可得到时间间隔,从而实现落速的测量,证明了该方法可解决因PLC扫描周期引起的测速结果不准确或无法测速等问题. 相似文献
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基于脉冲强磁场的高温超导薄膜YBa2 Cu3 O6.45霍尔效应研究 总被引:2,自引:0,他引:2
对高温超导材料常态特性的研究与理解,将会对超导电性机理本身的研究提供关键参考信息.在常态特性研究中,以常态电荷传输特性尤其是霍尔效应的测量最为引人注目.然而,T<Tc时试样常态特征被材料本身的超导电性掩盖了,为获得材料在Tc温度以下的常态特性,我们在高达50T的脉冲强磁场中进行霍尔效应测量,可有效抑制超导电性.本文主要介绍了50T左右脉冲强磁场的实验技术,特别是脉冲磁体、实验探钟及测量线路的设计.随后,对高温超导薄膜YBa2Cu3O6.45在强磁场中的霍尔效应测量进行了详细阐述. 相似文献
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本文阐述了基于89C51单片机的汽车行驶速度检测仪的软硬件设计,分析了其测速原理及误差来源,并探索了实现方案. 相似文献
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从实际监控项目出发,阐述基于PIC18F452单片机的监控终端系统组成、设计方法及步骤,重点分析和讨论中断程序设计中如何利用定时器中断实现PWM控制;如何利用外触发中断实现电机转速的采集。 相似文献
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A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling. 相似文献
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An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a
rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate
agreement is demonstrated between the derived relations and experimental data. 相似文献
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水三相点是开尔文热力学温度的唯一基准点,也是ITS-90国际温标重要的定义固定点。因此,水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来,中国计量科学研究院研制出一系列高质量的水三相点容器,加强了水三相点的研究,为不确定度的分析提供了更为可靠的实验依据。同时,不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此,根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明,其扩展不确定度为0.16mK(k=2.69,P=0.99)。 相似文献
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Liebert A Wabnitz H Grosenick D Möller M Macdonald R Rinneberg H 《Applied optics》2003,42(28):5785-5792
A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue. 相似文献
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