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自动校零功能是要求光散射法扬尘在线监测仪在长期使用过程中数据漂移后进行自我修正,以减少缺乏自净功能带来的测量误差。该文搭建扬尘监测仪校准装置,探究市场上常见3类自动校零结构(无切换阀、前置切换阀、后置切换阀)高浓度淹没实验前后对零点测量效率、仪器采样流量、测量误差的影响。研究发现3种结构仅能实现“零点测量”,未实现零点校准,而零点测量效率为无切换阀>后置切换阀>前置切换阀。此外,前置切换阀积灰容易造成传感器二次污染,后置切换阀易造成传感器污染,均会影响传感器测量误差。因此,光散射扬尘在线监测仪需与传感器校零算法或定期清洗等方式相结合来最终实现目的,现有标准、规范需进一步细化对自动校零功能的检测方法和性能指标的设定,从而提高扬尘在线监测仪测量准确性和稳定性。 相似文献
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为了得到不同频率下正交各向异性复合材料层合板的传声损失,基于传递矩阵的方法,推导出层合板的传声损失计算公式。通过建立复合材料层合板的传声计算模型,研究了层合板铺设角度、板厚度和板密度等结构参数对层合板的传声损失影响。计算结果表明:复合材料的密度与传声损失之间没有明显的线性关系,而是随着频率的增加而上升;层合板的总厚度越大,传声损失也越大,而且各层之间厚度不同,也会引起传声损失的较大改变;层合板铺层角度越大,传声损失也越大。采用传递矩阵法能充分考虑复合材料层合板的铺设方式和铺层角度等因素的影响,利用层合板层间的速度和应力连续边界条件,准确的反应复合材料层合板隔声性能。 相似文献
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曹清明 《中国新技术新产品》2023,(18):103-105
压力式验潮仪在应用过程中具有成本低、操作便捷、布设简单以及使用性能稳定的优势特征,目前已经用于水深测量中。针对压力式验潮仪的测量原理与测量过程,基于工程实际情况掌握压力式验潮仪观测值的误差来源,分别从气压与海水密度变化、潮流对潮汐测量误差等方面入手,采用零点漂移的方法修正误差。经过研究发现,修正大气压变化,减少其对压力式验潮仪应用的影响,减少设备投放深度或者使用海水密度计,所计算的潮位数据能够有效减少海水密度变化引发的影响,所得的零点漂移校正值更精准。 相似文献
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基于格型陷波滤波器的科里奥利质量流量计信号处理方法 总被引:1,自引:0,他引:1
采用比IIR型计算更为简单的自适应格型陷波滤波器对科里奥利质量流量计的流量传感器的输出信号进行滤波并求得其频率;并应用自适应谱线增强器从含有噪声的信号中提取出流量管振动的基频信号;然后采用滑动Goenzel算法计算两路信号之间的实时相位差,再根据频率和相位差计算出时间差最终求得质量流量。 相似文献
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采用具有跟踪频率变化能力的自适应归一化格型陷波器,对频率、幅值和相位均按照随机游动模型变化的科氏流量传感器信号进行滤波,以求得其频率;再采用自适应谱线增强器从含有噪声的数据中提取所需要的信号;然后采用具有重叠窗的滑动Goertzel算法计算两路信号之间的实时相位差,并通过频率和相位差计算时间差,求得质量流量。仿真结果表明该方法是有效的。 相似文献
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对JJG505-87直流比较仪式电位差计检定规程的某些条文说明如下: 1.由于一般使用者和检定人员不容易搞清楚各种误差因素与总测量误差的关系,因此,本规程把比较仪式出位差计的各项误差指标如恒流源的噪声和漂移、测量电阻的自热漂移、测量盘的线性误差、电位差计的零点漂移、磁调制器的跟踪误差等不同计量单位的指标都统 相似文献
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高精度数字检相电路设计 总被引:9,自引:0,他引:9
文章提出一种高精度数字检相电路 ,适合应用于相位法激光测距等要求精密测相的场合 .该电路采用脉冲填充法和单片机相结合 ,采取具体措施解决了零点漂移、幅值变化、频率变化等原因引起的测相误差 ,获得了高的相位测量精度和稳定性 ,文中给出了测试方法和测试结果 相似文献
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With the popularity of indoor wireless network, device-free indoor
localization has attracted more and more attention. Unlike device-based localization
where the target is required to carry an active transmitter, their frequent signal scanning
consumes a large amount of energy, which is inconvenient for devices with limited
energy. In this work, we propose the MFPL, device-free localization (DFL) system
based on WiFi distance measurement. First, we combine multi-subcarrier characteristic
of Channel State Information (CSI) with classical Fresnel reflection model to get the
linear relationship between the change of the length of reflection path and the
subcarrier phase difference. Then we calculate the Fresnel phase difference between
subcarrier pairs with different spacing from CSI amplitude time series. Finally, we get
the change of the length of the reflection path caused by target moving to achieve
distance measurement and localization. Using a combination of subcarriers with
different spacing to achieve distance measurement effectively broadens the maximum
unambiguous distance of the system. To solve the complex non-linear problem of the
intersection of two elliptic equations, we introduce Newton's method to transform the
non-linear problem into a linear one. The effectiveness of our approach is verified
using commodity WiFi infrastructures. The experimental results show our method
achieves a median error of 0.87 m in actual indoor environment. 相似文献
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介绍了微型镓基共晶固定点的灌注工艺和准绝热相变特性测量系统;结合空腔黑体和非近位安装的温度传感器,研究了Ga-Sn和Ga-Zn共晶固定点的相变温坪重复性和Ga固定点的相变温坪长期稳定性;通过特定的热环境下镓及2个镓基共晶固定点三者熔化过程中温度传感器测量到的相变温坪值,对嵌入空腔黑体底部的温度传感器进行校准,其校准结果与实验室常规校准方法得到的结果差异均小于2mK。实验结果表明:在热环境保持不变的条件下,随着相变时间的增加,相变温坪值就越靠近理论上相变物质的熔化温度,即固定点与温度传感器测孔之间的异位温差越小;对于Ga-Sn和Ga-Zn共晶固定点,温度传感器测量到的相变温坪值与加热功率呈线性关系,零功率下的单点校准温度分别为20.352℃和25.187℃。 相似文献
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Cheng Chen Yingying Wan Guangkai Fu Yapin Wang Chengmeng Li 《Journal of Modern Optics》2018,65(16):1902-1909
The three-dimensional reconstruction in phase-measuring profilometry (PMP) usually involves the phase error caused by the gamma effect of the projector. In this study, the relationship between the unwrapped phase and the phase error of every pixel is analysed, and an effective full-field phase error compensation method based on this relationship is proposed for the reduction of every pixel error. In our optimized PMP system, the full-field phase error can be detected by directly fitting the unwrapped phase of the reference plane. In addition, the relationship between the unwrapped phase and the phase error can be established by creating a phase-error lookup table for the phase error compensation of every pixel. The experimental results demonstrate the effectiveness of the proposed method in practical PMP, and the measurement errors can be reduced by a factor of least 10. 相似文献
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Liaosa Xu Sai Wang Marion R. Reynolds Jr 《Quality and Reliability Engineering International》2013,29(4):545-553
This article considers the problem of monitoring a normally distributed process variable when a special cause may produce a time‐varying linear drift in the mean. The design and application of a generalized likelihood ratio (GLR) control chart for drift detection are evaluated. The GLR drift chart does not require specification of any tuning parameters by the practitioner and has the advantage that, at the time of the signal, estimates of both the change point and the drift size are immediately available. An equation to accurately approximate the control limit is provided. The performance of the GLR drift chart is compared with that of other control charts such as a standard cumulative sum chart and a cumulative score chart designed for drift detection. We also compare the GLR chart designed for drift detection with the GLR chart designed for sustained shift detection because both of them require only a control limit to be specified. In terms of the expected time for detection and in terms of the bias and mean squared error of the change‐point estimators, the GLR drift chart has better performance for a wide range of drift rates relative to the GLR shift chart when the out‐of‐control process is truly a linear drift. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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首先对单侧电子引伸计测量结果不稳定及误差较大的原因进行了分析,然后对双侧电子引伸计的测量原理进行了介绍,建立了斜线伸长量与拉伸试样轴向伸长量之间的关系,证明了双侧电子引伸计的测量结果不受偏心拉伸的影响,其系统误差很小甚至可以为零。 相似文献
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基于车道线斜率的车道偏离检测 总被引:1,自引:0,他引:1
针对结构化道路上运动车辆的车道偏离检测问题,采用单目视觉作为感知手段,分别从针孔模型下摄像机成像的空间几何关系和图像中车道线消失点的位置特点两个方面出发,推导出车辆直行情况下车道偏离率与两侧车道线斜率比之间的简单函数关系,该函数与摄像机内外参数无关。同时完成了在摄像机不同方向角下的车道偏离率测量试验,结果表明由于行车方向瞬时变化引起的摄像机方向角微小改变对车道偏离检测的影响可以忽略。道路现场试验结果表明,上述视觉测量方法得到的车道偏离率与手工实测结果相比,其相对误差小于5%。基于车道线斜率的单目视觉检测方法避开了繁琐的摄像机参数标定过程,达到了较高的车道偏离检测精度。 相似文献