共查询到20条相似文献,搜索用时 62 毫秒
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本文对一台在用的6.7 MN叠加式力标准机进行技术改造,具体是对力标准机的液压控制系统进行改造。在改造中,运用了双泵联动控制技术和自适应PID控制技术,并且采用24位高精度仪表,以提高液压系统的控制精度和稳定性,解决叠加式力标准机检定传感器时由于控制问题带来的误差,同时提高设备使用率。经过检定,6.7 MN叠加式力标准机的技术改造达到了预期目标。 相似文献
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考虑到各种标准机的特点并结合实际工作情况,本项目所研制的叠加式力标准机采用一个比被检定的测力仪准确度高的传感器作为标准,将其与被校准或检定的传感器串联,并以液压方式加载。通过研究分析伺服控制、液压动力系统的转速转矩、液压源的流量等关键参数以及控制软件,实现了0.03级高准确度叠加式力标准机的研制。 相似文献
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油田基层的计量仪表种类繁多,外观各异,检定周期不同;同时由于野外作业或现场工况差,造成仪表的损坏和报废率居高不下。如何管理这些仪表,使它们在检定周期和使用周期中,在现场中发挥最大作用?本文结合基层生产特点,阐述了仪表管理方面的一些新认识。 相似文献
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叠加式力标准机作为力值计量标准器,广泛应用于各行业。叠加式力标准机采用标准传感器与被测传感器比对的方法实现力值的加载控制,通过对力值施加过程及压电陶瓷力发生装置的逆压电效应工作原理分析,结合计算机和微电子控制技术,设计力标准机专用控制软件实现其自动加载控制、数据采集、数据处理、报表输出等功能;并对力标准机进行数据测试及功能测试,测试结果满足国家检定规程要求。 相似文献
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提出了一种温度传感器测温偏差校准结果的压力工况修正方法,并以某裸露式温度传感器为例,进行了测温偏差的压力工况修正。根据雷诺准则,通过改变马赫数的方式来替代压力的改变,对测温偏差的计算修正结果进行了验证。结果表明,计算修正结果与试验数据比较接近,所提出的压力工况修正方法,可以为常压条件下该型温度传感器的测温偏差校准结果提供修正的依据,同时也为其它类型温度传感器的压力工况修正提供了参考。 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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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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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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Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995. 相似文献