Analysis Of Measurement Errors Research Articles

A large scale of apparent sudden movements in Japan detected by high-rate GPS after the 2011 Tohoku Mw9.0 earthquake: Physical signals or unidentified artifacts?

A moment magnitude Mw9.0 earthquake hit northeastern Japan at 14:46:18 (Japan Standard Time), March 11, 2011. We have obtained 1 s precise point positioning solutions for 1198 GEONET stations. Although GPS position time series have been routinely investigated and used as waveforms for dynamic inversion of earthquakes, we focus on exploring the spatial displacement features of GEONET stations for this earthquake. A movie inspection of high-rate GPS waveforms leads us to find that 76.21% of the GEONET stations in the Japanese islands subsided suddenly within 1 s between 14:59:45 and 14:59:46, Japan local time, with an average displacement of -,2.43, 2.83 and -,4.75 mm in the east, north and vertical components, respectively, about 15 min after the 2011 Tohoku earthquake. We have performed different types of independent tests, namely measurement error analysis, processing the GEONET data with a different software system, a statistical hypothesis testing under a simple assumption of sign distributions, the test computation of the displacement field outside of the Japanese islands and an independent test with the Japanese strong motion borehole network KiK-net, to see whether these sudden movements actually occurred. The first four independent tests are passed almost without any doubt, and the direction of the average sudden displacements is roughly consistent tectonically with the direction of subduction of the Pacific plate. Because there are only 78 KiK-net borehole stations available for an independent seismic test, the KiK-net results are marginally consistent with those of GEONET. In the daily seismological and geophysical practice, one may then conclude that the sudden movement within the second is real after passing these five independent tests. However, a further epoch-by-epoch check pinpoints a few more seconds with even a higher probability of sudden displacement from the 20-min three-component high-rate GPS waveforms after the main shock, or more precisely, the seconds between 14:59:04 and 14:59:05, 15:01:04 and 15:01:05, and 15:03:39 and 15:03:40 with 80.80, 84.14 and 85.89% of the GEONET stations simultaneously moving upward, southward and westward, respectively. Although these probabilities are very high, it may hardly be imagined that a large scale of sudden movements could occur repeatedly between 14:59:04 and 15:03:40. The high-rate GPS results imply that some detected sudden movements after the earthquake could be unidentified artifacts of GPS data processing, though we cannot rule out the possibility that the detected sudden movements in Japan after the 2011 Tohoku Mw9.0 earthquake are real physical signals.

Measurement of Equivalent BRDF on the Surface of Solar Panel with Periodic Structure

The surface of a complex material with a periodic structure is equivalent to the surface of a uniform material, and the measurement and data processing methods for the equivalent optical BRDF of a solar panel based on a large-scale spot are proposed. Based on a solar simulator, high-intensity light illuminometer, low-intensity light illuminometer and precise rotary platform, the BRDF automatic measurement platform is built. Spot size optimization and a measurement radius optimization method are proposed. The measurement results show that the BRDF of the solar panel has specular reflection characteristics, but that it still differs from the solar cell in the half width of the BRDF curve. Measurement error analysis is performed for the measurement process; its value is 6.74%. The measurement results can be used to improve the understanding of the optical reflection characteristics of the solar panel. Meanwhile, the method can also be used to measure and characterize the coatings of heat insulation material and scattering coating. The measurement data also has practical reference value for evaluations of improvements of the light absorption of the surface functional material. Finally, it can be used to simulate the target image scene.

Measurement error analysis of a cross correlation algorithm with a threshold centroiding method

The measurement error of a cross correlation algorithm with a threshold centroiding method, which is not only related to the background noise variance, the image spatial variance, the size of the reference image, and the image sensor parameters, but also concerned with the half width at half maximum and the threshold value of the cross correlation function, is derived theoretically in detail. Our general calculation formula of the measurement error of the cross correlation algorithm with the optimal normalized threshold value of 0.6035 is fit for the arbitrary sampling condition and extended target. Furthermore, the experimental results of the measurement error of the cross correlation algorithm using different sunspots taken by the correlating Shack-Hartmann wave-front sensor are compared with the theoretical measurement error. The experiment results agree well with the theoretical results.

Turbine blade temperature error as measured with an optical pyrometer under different wavelengths and blade TBC thickness.

The optical pyrometer is a widely used instrument for measuring the temperature of gas turbine blade targets. However, one of the limitations of this instrument is the measurement error caused by reflected radiation from the high-temperature surrounding environment. This paper presents an analysis of such measurement error with consideration of a wavelength detection range of 2.5 to 22μm with blade thermal barrier coatings (TBCs) ranging from 18 to 279μm. Surface temperature distributions were simulated using the software ANSYS CFX. Radiation heat transfer was calculated based on discretized triangular surface elements. The variation characteristics of relative temperature error under different wavelengths and TBC thicknesses were obtained. The results obtained are well suited to provide theoretical guidance for choosing the wavelength of a pyrometer when measuring blade temperature with different TBC thickness, and can also be used to provide a method for estimating and correcting the temperature error.

Study on the Application of Ultrasonic Wave in Foundation Settlement Monitoring

Abstract In view of the high cost and poor accuracy in monitoring the internal layered settlement of foundation soil mass, this study has introduced an ultrasonic ranging technique into the layered settlement monitoring of civil engineering foundations. It has also developed a special ultrasonic monitor capable of generating different frequencies (e.g., 200kHz, 400kHz). It has also selected two oscilloscopes that can match the frequencies, the pipe fitting materials, reflecting materials, and propagation mediums that are related to the burying of the ultrasonic monitoring system into a soil mass. After that, it has calibrated the propagation velocity of ultrasonic waves under different water temperatures, tested the ranging technique, and obtained an effective range of at least 45 m. Then, it has carried out actual measurement comparison and error analysis, which show that the accuracy of the ultrasonic monitoring system is in the order of millimeters. Finally, an indoor ultrasonic-monitored settlement simulation test has been carried out. The ultrasonic-monitored burying system has been buried into the soil mass, and the ultrasonic monitoring system has been used to measure the layered settlement of the soil mass after rolling compaction and compression. The comparison with the actual measurements shows that the measurements by the ultrasonic monitoring system are highly accurate. The ultrasonic monitoring system can therefore be used to monitor the settlement of foundation soil mass.

室内空间测量定位系统共模误差分析与消除

室内空间测量定位系统共模误差分析与消除

基于偏振成像的方位测量误差建模与分析

基于偏振成像的方位测量误差建模与分析

基于XGBoost的无人机测温误差分析

基于XGBoost的无人机测温误差分析

矿井特殊环境下角度测量误差分析

矿井特殊环境下角度测量误差分析

中红外大气背景辐射测量系统及误差分析

中红外大气背景辐射测量系统及误差分析

Measurement error analysis of cross correlation algorithm with threshold centroiding method

Measurement error analysis of cross correlation algorithm with threshold centroiding method

Analysis and correction of probe location errors in spherical near-field antenna measurement

Spherical Near-Field Antenna Measurement is a very important method in characterizing an antenna under test (AUT). The antenna far-field radiating pattern can be derived from a spherical wave expansion of the near-field data. Near-field data used for obtaining the spherical mode coefficients depends on the sampling probes. The probe correction, such as probe calibration, probe compensation, is crucial in near-field to far-field transformation procedure. This paper gives analysis of the influence caused by the deviation of the probe location including radial and tangential direction, and proposes Taylor series as a method to modify the radial location errors. The simulation results show that the modified radiating far-field data with the probe location errors in the radial direction fits better with the ideal situation.

UNCERTAINTY ANALYSIS OF A WEB-BASED DATA ACQUISITION SYSTEM FOR POULTRY MANAGEMENT WITH SENSOR NETWORKS

This paper presents a web-based data acquisition system developed by LabVIEW software program using for environment monitoring of poultry management. Measurement error and uncertainty analysis should be conducted accurately to maximize the reliability of this system. An algorithm for uncertainty analysis was proposed to estimate the sensor networks with calibration and validation processes fulfilling the standards of Guide to the Expression of Uncertainty in Measurement (GUM). For different environmental sensors, values of uncertainties were calculated with the methods of type A and type B evaluation through a case study. Environmental parameters including air temperature, relative humidity and CO2 concentration of a compartment housing for a small-group (n=90) of laying hens with a perch aviary system were measured in a 24-h period with an interval of 5 min. Results showed that the expanded uncertainty of the data acquisition system lies above 1.02℃, 5.54% and 67.8 ppm over the sensors data from air temperature, relative humidity and CO2 concentration with perch system for laying hens. Moreover, the relative uncertainty of this system was estimated by 15.9%. Therefore, the web-based data acquisition system has a considerable potential to ensure correct decision making when served for poultry production based on more reliable uncertaity analysis and data evaluation.

Simultaneous Measurement Method and Error Analysis of the Six Degrees-of-Freedom Motion Errors of a Rotary Axis

Error measurement of a rotary axis is the key to error compensation and to improving motion accuracy. However, only a few instruments can measure all the motion errors of a rotary axis. In this paper, a device based on laser collimation and laser interferometry was introduced for simultaneous measurement of all six degrees-of-freedom motion errors of a rotary axis. Synchronous rotation of the target and reference rotary axes was achieved by developing a proportional–integral–derivative algorithm. An error model for the measuring device was established using a homogeneous transformation matrix. The influences of installation errors, manufacturing errors, and error crosstalk were studied in detail, and compensation methods for them were proposed. After compensation, the repeatability of axial and radial motion errors was significantly improved. The repeatability values of angular positioning error and of tilt motion error around the y axis and x axis were 28.0″, 2.8″, and 3.9″. The repeatability values of translational motion errors were less than 2.8 μm. The comparison experiments show that the comparison errors of angular positioning error and tilt motion error around the y axis were 2.3″ and 2.9″, respectively. These results demonstrate the effectiveness of our method and the error compensation model.

Error tolerance and effects analysis of satellite vibration characteristics and measurement error on TDICCD image restoration

Satellite vibrations during exposure time could lead to image motion degradation, and image restoration methods are commonly used to compensate for such degradation. However, effects of space-variant image degradation characteristics due to the vibrations for time delayed integration (TDI) camera and real-time measurement errors of the vibration motion are rarely taken into account during the restoration process, which will bring final restored image processing error. In this paper, the analytical model of vibration motion is first deduced mathematically and then the space-variant modulation transfer function (MTF) degradation and corresponding influence factors are analyzed. Meanwhile, the effect of measurement errors is theoretically explained on that basis of high-performance restoration model. Then the effects of the space-variant MTF and measurement errors for different frequencies, amplitudes and sampling rate on image restoration performance are further presented. Finally, influences of above factors affecting restoration quality are verified and the relationships between them are established experimentally. Subsequently, the error tolerance of satellite vibration itself and measurement specifications are quantitatively generated from the practical application point of view, which can provide a valuable reference for future satellite platform design and the specifications determining of TDICCD camera.

Vision measurement error analysis for nonlinear light refraction at high temperature.

For vision measurement at high temperature, pixel error from light refraction by high temperature is a problem that cannot be neglected. The refractive index distribution is nonlinear around the high-temperature component, leading to the light deflection. In this paper, the influence of measurement parameters on the deflection of imaging light and the accuracy after binocular reconstruction are systematically analyzed. The heat transfer theory is used to simulate the air temperature distribution near the measured component, and the corresponding refractive index distribution of air is obtained according to the refractive index formula. Then, the imaging measurement model of the nonlinear refractive index air medium for the high-temperature component is established to obtain the light deflection error. The binocular vision system reconstruction theory is applied to evaluate the measurement error between the theoretical reconstruction point and the object point. The influences of error sources, such as the temperature, optical wavelength, and camera parameters, are investigated systematically. It is found that temperature and base distance are the largest error sources on the final measurement error when the measured distance is fixed.

Body Shame dan Gangguan Makan Kajian Meta-Analisis

The number of person with eating disorders is increasing almost all over the world. The exact cause of an eating disorder is difficult to determine. The feeling of shame caused by negative judgments on one’s body has a positive correlation to the emergence of pathological eating behavior. Furthermore, the position of body shame as a variable in research on eating disorders is still inconsistent in some studies, consequently, it is placed as a mediating variable to self-objectification. This study attempted to see whether there is a direct correlation between body shame and eating disorders using meta-analysis procedure. The analysis of sampling error and measurement error made on 34 studies from 21 articles. The result of the analysis showed that body shame and eating disorder are strongly correlated (r=0.547) with α = 0.05.

A method for direct thickness measurement of wavy liquid film in gas-liquid two-phase annular flow using conductance probes

Gas-liquid two-phase annular flow widely exists in industrial fields such as chemical engineering, petroleum, nuclear reactors and so on. The liquid film plays major influences on the performance of heat and mass transfer in gas-liquid two-phase annular flow. In this paper, a conductance probe with adjustable insertion depth is designed to measure the wavy liquid film thickness, which is a direct method unaffected by the change of conductance. Then, a calculation method of time-average liquid film thickness using duty ratio weight is proposed. The effects of the insertion depth increment and statistical time on measurement error are analyzed, and the mathematical expressions of relative error are derived. The verification experiments are carried out in the gas-liquid experimental facility at Tianjin University. Through the measurement error analysis, a system error compensation calculation method is presented, which improves the measurement accuracy obviously. The average relative error is better than 1.00% at different insertion depth increments in the statistical time T = 5 s. The proposed method does not need the real flow calibration because the relationship between liquid film thickness and conductance isn’t involved in the process of measurement.

Simulation Analysis of Airfoil Deformation of Agricultural UAV under Airflow Disturbance Based on ANSYS

In order to meet the needs of analysis and correction of measurement errors in airborne distributed POS systems, the simulation analysis method of airfoil deformation of agricultural unmanned aerial vehicle (UAV) based on ANSYS, which is carried out under airflow disturbance, is discussed in this paper. The Pro/E virtual model data is imported into the ANSYS STRUCTURAL module, and the airfoil structure and material property parameters are set; the atmospheric turbulence model based on the k-epsilon model is established by using the ANSYS Fluent fluid dynamics module, the fluid boundary conditions are set in combination with the airfoil virtual structure, then the surface pressure value of the airfoil is obtained by finite element analysis; finally, combining the virtual structure and material information of the airfoil, the deformation parameters of different points of the airfoil relative to the fixed end can be simulated and solved. The method and result are studied in this paper to provide a reference for the analysis of the influence of airflow disturbance on the airfoil morphology and the evaluation of the POS measurement error.

Novel De-Embedding Methodology and Broadband Microprobe Measurement for Through-Silicon Via Pair in Silicon Interposer

In this paper, a novel de-embedding methodology is proposed for through silicon via (TSV) characterization by using a set of simple yet efficient test patterns. For all the test patterns, full wave models are developed and the electrical performance of the test patterns is analyzed thoroughly. Furthermore, broadband measurements are performed for the test patterns to verify the accuracy of the developed full wave models up to 40 GHz. Correlation between measurement and simulation results is discussed after optimizing the full wave models based on scanning electron microscope measurement. Analysis of measurement error is available as well. The proposed de-embedding method is applied to both the simulation and measurement results to extract the electrical characteristics of the TSV pair. Good agreement between the de-embedded results with analytical solution and the full-wave simulation for a standalone TSV pair indicates that the proposed de-embedding method works effectively up to 40 GHz. Finally, sensitivity analysis with regard to manufacturing tolerance of the test patterns to the final de-embedded results is performed.