Structured methods for improving flow measurement accuracy in pipelines

2020 ◽  
pp. 30-35
Author(s):  
Gurami N. Akhobadze
Keyword(s):  
Flow Measurement ◽  
Measurement Accuracy ◽  
Directional Coupler ◽  
Signal To Noise Ratio ◽  
Scattered Wave ◽  
Orthogonal Polarization ◽  
Flow Sensors ◽  
Information Signal ◽  
Mass Flows ◽  
Processing Device

In the age of digital transformation of production processes in industry and science the development and design of intelligent flow sensors for granular and liquid substances transferring through pipelines becomes more important. With this in view new approaches for improving the accuracy of microwave flowmeters are proposed. Taking into account the characteristics ofelectromagnetic waves propagating through a pipeline, a wave scattered by inhomogeneities of the controlled medium is analyzed. Features of the transformation of the polarized scattered wave limiting the geometric dimensions of the pipeline and optimizing the values of the useful scattered signal are revealed. Expediency of collection of the information signal with orthogonal polarization of the scattered wave and through a directional coupler is substantiated. The method of estimating the measurement accuracy with reference to the signal-to-noise ratio at the input of the processing device is given. The research results can be used in cryogenic machine engineering to measure volume and mass flows of liquid cryogenic products.

scholarly journals Radiant measurement accuracy of micrometeors detected by the Arecibo 430 MHz Dual-Beam Radar

2004 ◽  
Vol 4 (3) ◽  
pp. 621-626 ◽  
Author(s):  
D. Janches ◽  
M. C. Nolan ◽  
M. Sulzer
Keyword(s):  
Measurement Accuracy ◽  
Signal To Noise Ratio ◽  
Side Lobe ◽  
Beam Axis ◽  
Main Beam ◽  
High Signal ◽  
Precise Knowledge ◽  
Dual Beam ◽  
Arecibo Observatory ◽  
Meteoric Material

Abstract. Precise knowledge of the angle between the meteor vector velocity and the radar beam axis is one of the largest source of errors in the Arecibo Observatory (AO) micrometeor observations. In this paper we study ~250 high signal-to-noise ratio (SNR) meteor head-echoes obtained using the dual-beam 430 MHz AO Radar in Puerto Rico, in order to reveal the distribution of this angle. All of these meteors have been detected first by the radar first side lobe, then by the main beam and finally seen in the side lobe again. Using geometrical arguments to calculate the meteor velocity in the plane perpendicular to the beam axis, we find that most of the meteors are travelling within ~15° with respect to the beam axis, in excellent agreement with previous estimates. These results suggest that meteoroids entering the atmosphere at greater angles may deposit their meteoric material at higher altitudes explaining at some level the missing mass inconsistency raised by the comparisson of meteor fluxes derived from satellite and traditional meteor radar observations. They also may be the source of the observed high altitude ions and metalic layers observed by radars and lidars respectively.

scholarly journals CALIPSO lidar calibration at 1064 nm: version 4 algorithm

2019 ◽  
Vol 12 (1) ◽  
pp. 51-82 ◽  
Author(s):  
Mark Vaughan ◽  
Anne Garnier ◽  
Damien Josset ◽  
Melody Avery ◽  
Kam-Pui Lee ◽  
...  
Keyword(s):  
Molecular Model ◽  
Signal To Noise Ratio ◽  
High Spectral Resolution ◽  
Orthogonal Polarization ◽  
Radiometric Calibration ◽  
Calibration Target ◽  
Full Account ◽  
High Spectral Resolution Lidar ◽  
532 Nm ◽  
Calibration Coefficients

Abstract. Radiometric calibration of space-based elastic backscatter lidars is accomplished by comparing the measured backscatter signals to theoretically expected signals computed for some well-characterized calibration target. For any given system and wavelength, the choice of calibration target is dictated by several considerations, including signal-to-noise ratio (SNR) and target availability. This paper describes the newly implemented procedures used to calibrate the 1064 nm measurements acquired by CALIOP (i.e., the Cloud-Aerosol Lidar with Orthogonal Polarization), the two-wavelength (532 and 1064 nm) elastic backscatter lidar currently flying on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission. CALIOP's 532 nm channel is accurately calibrated by normalizing the molecular backscatter from the uppermost aerosol-free altitudes of the CALIOP measurement region to molecular model data obtained from NASA's Global Modeling and Assimilation Office. However, because CALIOP's SNR for molecular backscatter measurements is prohibitively lower at 1064 nm than at 532 nm, the direct high-altitude molecular normalization method is not a viable option at 1064 nm. Instead, CALIOP's 1064 nm channel is calibrated relative to the 532 nm channel using the backscatter from a carefully selected subset of cirrus cloud measurements. In this paper we deliver a full account of the revised 1064 nm calibration algorithms implemented for the version 4.1 (V4) release of the CALIPSO lidar data products, with particular emphases on the physical basis for the selection of “calibration quality” cirrus clouds and on the new averaging scheme required to characterize intra-orbit calibration variability. The V4 procedures introduce latitudinally varying changes in the 1064 nm calibration coefficients of 25 % or more, relative to previous data releases, and are shown to substantially improve the accuracy of the V4 1064 nm attenuated backscatter coefficients. By evaluating calibration coefficients derived using both water clouds and ocean surfaces as alternate calibration targets, and through comparisons to independent, collocated measurements made by airborne high spectral resolution lidar, we conclude that the CALIOP V4 1064 nm calibration coefficients are accurate to within 3 %.

scholarly journals The Influence of Laser Linewidth on the Brillouin Shift Frequency Accuracy of BOTDR

2018 ◽  
Vol 9 (1) ◽  
pp. 58 ◽  
Author(s):  
Qing Bai ◽  
Min Yan ◽  
Bo Xue ◽  
Yan Gao ◽  
Dong Wang ◽  
...  
Keyword(s):  
Probe Pulse ◽  
Measurement Accuracy ◽  
Signal To Noise Ratio ◽  
Gain Spectrum ◽  
Laser Source ◽  
Laser Linewidth ◽  
Optical Time Domain Reflectometer ◽  
Brillouin Gain ◽  
Optical Time ◽  
Shift Frequency

This paper analyzes the influence of laser linewidth on the measurement accuracy of a frequency-scanning Brillouin optical time domain reflectometer (FS-BOTDR), allowing for both the width of Brillouin gain spectrum and the signal-to-noise ratio (SNR) of the BOTDR system. The measurement accuracy of the Brillouin frequency shift (BFS) is theoretically investigated versus the duration of the probe pulse and the linewidth of the laser source, by numerically simulating how a FS-BOTDR works and evaluating the Brillouin gain spectrum (BGS) width and the system SNR. The simulation results show that the BFS accuracy is improved as the laser linewidth becomes narrower when the probe pulse width is fixed. We utilize five types of lasers with respective linewidths of 1.05 MHz, 101 kHz, 10.2 kHz, 3.1 kHz, and 98 Hz to compare the BFS measurement accuracy over a ~10 km optical sensing fiber. The experimental results demonstrate that the root-mean-square error (RMSE) of BFS decreases with the laser linewidth narrowing from 1.05 MHz to 3.1 kHz, which is in good agreement with the numerical simulation. However, the RMSE of BFS increases when the laser linewidth is less than 3.1 kHz, which may arise from the coherent Rayleigh noise due to a too narrow laser linewidth. The results can provide a theoretical basis and experimental guidance for choosing the appropriate laser linewidth in BOTDR.

Umbilical venous blood flow measurement: accuracy and reproducibility

2008 ◽  
Vol 32 (4) ◽  
pp. 587-591 ◽  
Author(s):  
F. Figueras ◽  
S. Fernández ◽  
E. Hernández-Andrade ◽  
E. Gratacós
Keyword(s):  
Blood Flow ◽  
Flow Measurement ◽  
Measurement Accuracy ◽  
Venous Blood ◽  
Venous Blood Flow ◽  
Blood Flow Measurement

scholarly journals Comparison of cloud statistics from spaceborne lidar systems

2008 ◽  
Vol 8 (23) ◽  
pp. 6965-6977 ◽  
Author(s):  
S. Berthier ◽  
P. Chazette ◽  
J. Pelon ◽  
B. Baum
Keyword(s):  
Signal To Noise Ratio ◽  
Simple Algorithm ◽  
Middle Latitude ◽  
Global Scale ◽  
Orthogonal Polarization ◽  
Space Technology ◽  
Laser Altimeter ◽  
Vertical Column ◽  
Inter Tropical Convergence Zone ◽  
Stratospheric Clouds

Abstract. The distribution of clouds in a vertical column is assessed on the global scale through analysis of lidar measurements obtained from three spaceborne lidar systems: LITE (Lidar In-space Technology Experiment, NASA), GLAS (Geoscience Laser Altimeter System, NASA), and CALIOP (Cloud-Aerosol LIdar with Orthogonal Polarization). Cloud top height (CTH) is obtained from the LITE profiles based on a simple algorithm that accounts for multilayer cloud structures. The resulting CTH results are compared to those obtained by the operational algorithms of the GLAS and CALIOP instruments. Based on our method, spaceborne lidar data are analyzed to establish statistics on the cloud top height. The resulting columnar results are used to investigate the inter-annual variability in the lidar cloud top heights. Statistical analyses are performed for a range of CTH (high, middle, low) and latitudes (polar, middle latitude and tropical). Probability density functions of CTH are developed. Comparisons of CTH developed from LITE, for 2 weeks of data in 1994, with ISCCP (International Satellite Cloud Climatology Project) cloud products show that the cloud fraction observed from spaceborne lidar is much higher than that from ISCCP. Another key result is that ISCCP products tend to underestimate the CTH of optically thin cirrus clouds. Significant differences are observed between LITE-derived cirrus CTH and both GLAS and CALIOP-derived cirrus CTH. Such a difference is due primarily to the lidar signal-to-noise ratio that is approximately a factor of 3 larger for the LITE system than for the other lidars. A statistical analysis for a full year of data highlights the influence of both the Inter-Tropical Convergence Zone and polar stratospheric clouds.

Effect of the Bed Sand Wave on Cross-Section Discharge Measurement and Calculation in Physical Model

2013 ◽  
Vol 405-408 ◽  
pp. 2072-2076
Author(s):  
Qiang Wan ◽  
Yong Tao Cao
Keyword(s):  
Physical Model ◽  
Cross Section ◽  
Flow Measurement ◽  
Measurement Accuracy ◽  
Correction Method ◽  
Sand Wave ◽  
Discharge Measurement ◽  
Sand Ripple ◽  
River Bed ◽  
Bed Form

t is analyzed of the effect of the bed form change on the cross section flow measurement and calculation in the flume with the sand ripple bed or smooth bed. The reason is researched that the flow measurement error is caused by the river bed ripple. The Correction method is analyzed under the condition of different discharge and riverbed morphology. So the support is provided in order to improve the physical model discharge measurement accuracy.

Metrological Performances of Fiber Bragg Grating Sensors and Comparison with Electrical Strain Gauges

2011 ◽  
Vol 495 ◽  
pp. 53-57
Author(s):  
Marco Borotto ◽  
Enrico De Cais ◽  
Marco Belloli ◽  
Andrea Bernasconi ◽  
Stefano Manzoni
Keyword(s):  
Fiber Bragg Grating ◽  
Thermal Effects ◽  
Measurement Accuracy ◽  
Signal To Noise Ratio ◽  
Bragg Grating ◽  
Light Spectrum ◽  
Static Tests ◽  
Measurement Systems ◽  
Fiber Bragg Grating Sensors ◽  
Fbg Sensors

The fiber Bragg grating sensors (FBGs) have been recently introduced: they present a photorecord grating on the fiber itself, which allows the reflection of a certain wavelength of the input light spectrum. The applied strain is estimated relying on changes of the reflected wavelength. One of the possible applications that has prompted us to study this type of sensors is the possibility to create smart dynamometric structures based on carbon fiber by embedding FBGs. Many papers are available in literature about some applications with smart structures but there is not yet an appropriate metrological characterization about these FBG sensors, their strengths and weaknesses: for these reasons it was deemed useful making several tests on FBG sensors in terms of measurement accuracy, signal to noise ratio, ability to compensate for thermal effects and their behavior for dynamic applications. All these results have been compared to electrical strain gauge ones, which represent the actual reference strain measurement systems. The various solutions to compensate for thermal effects have offered several information for further analyses and the basis for a future use of these sensors for static or semi-static tests. Being fully aware of FBGs characteristics allows to draw down guidelines about their integration in composite materials for the most different applications, understanding in a better way the sensor response.

Research on Linear Array TDI-CCD System with Noise Suppression

2013 ◽  
Vol 274 ◽  
pp. 266-269
Author(s):  
Ke Ming Li ◽  
Chao Zhang
Keyword(s):  
Measurement Errors ◽  
Measurement Accuracy ◽  
Noise Suppression ◽  
Linear Array ◽  
Signal To Noise Ratio ◽  
Software Implementation ◽  
Image Measurement ◽  
Correlated Double Sampling ◽  
The Mathematical Model ◽  
Processing Circuit

Noises in the imaging process will result in image measurement errors, so whether these noises can be effectively suppressed is the key to improve the measurement accuracy. This paper analyzes the noise components of TDI-CCD system from three perspectives, builds the mathematical model of typical noises, designs correlated double sampling noise processing circuit for TDI-CCD system, realizes the software implementation of hardware design and achieves the purpose to improve the signal-to-noise ratio and image quality

scholarly journals CALIPSO Lidar Calibration at 532 nm: Version 4 Nighttime Algorithm

2017 ◽  
Author(s):  
Jayanta Kar ◽  
Mark A. Vaughan ◽  
Kam-Pui Lee ◽  
Jason L. Tackett ◽  
Melody A. Avery ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Calibration Procedure ◽  
Stratospheric Aerosol ◽  
Airborne Lidar ◽  
High Spectral Resolution ◽  
Orthogonal Polarization ◽  
Radiometric Calibration ◽  
Data Set ◽  
Langley Research Center ◽  
532 Nm

Abstract. Data products from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on board Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) were recently updated following the implementation of new (version 4.1) calibration algorithms for all of the level 1 attenuated backscatter measurements. In this work we present the motivation for and the implementation of the version 4.1 nighttime 532 nm parallel channel calibration. The nighttime 532 nm calibration is the most fundamental calibration of CALIOP data, since all of CALIOP’s other radiometric calibration procedures – i.e., the 532 nm daytime calibration and the 1064 nm calibrations during both nighttime and daytime – depend either directly or indirectly on the 532 nm nighttime calibration. The accuracy of the 532 nm nighttime calibration is significantly improved by raising the molecular normalization altitude from 30–34 km to 36–39 km to substantially reduce stratospheric aerosol contamination. Due to the greatly reduced molecular number density and consequently reduced signal-to-noise ratio at the higher altitudes used to avoid aerosols, the signal is averaged over a larger number of samples. The new calibration procedure is shown to eliminate biases introduced in earlier versions and consequently leads to an improved representation of stratospheric aerosols. Validation results using airborne lidar measurements are also presented. Biases relative to collocated measurements acquired by the Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) are reduced from 3.6 % ± 2.2 % in the version 3 data set to 1.6 % ± 2.4 % in the version 4.1 release.

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