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- 摘要
- 关键词
- 实验方案
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过滤筛选
- 2015
- Calibration process of OSL detectors
- Iodine-131
- OSL-BeO
- Dosimetry of staff and patients
- Optically Stimulated Luminescence (OSL)
- Akdeniz University
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Calibration method of 1D laser rangefinder for large-scale 3D measurement under harsh environment
摘要： Vision measurement has encountered the bottlenecks in capturing and processing the images of laser spots under harsh working environment of strong sunshine and complex background. Breaking through the camera calibration, we propose that the corresponding relationship between pixel coordinates of laser spots, but not the camera, and measurement distances generated from laser rangefinder is directly calibrated under good working environment. The pixel coordinates of laser spots can be obtained from the calibration model and measurement distances during practical measurement. The imaging of laser spots by camera is no longer needed. Experimental results demonstrate that the measurement errors are in the millimeter level within 20 m distance outdoors.
关键词： vision measurement,laser rangefinder,harsh working environment,calibration
更新于2025-09-23 15:21:01
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EXPRESS: Analysis of Natural Gas Using a Portable Hollow-Core Photonic-Crystal-Coupled Raman Spectrometer
摘要： The low accessibility of natural gas fields and transporting pipelines requires portable online analyzers of the composition of natural gas, ensuring nearly chromatographic precision and capable of in situ analysis of a wide range of gases, including infrared-inactive ones (hydrogen, oxygen, nitrogen, chlorine). We have developed an express method of gas analysis meeting all requirements for the analysis of natural gas and its derivative mixtures using a portable 532 nm Raman spectrometer rigidly connected to a hollow-core crystal photonic fiber.
关键词： hollow-core photonic crystal fiber,HC-PCF,Raman spectrometry,gas chromatography,natural gas,calibration gas mixture
更新于2025-09-23 15:21:01
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Evaluation of calibration methods to construct a 3-D environmental map with good color projection using both camera images and laser scanning data
摘要： In mobile robot navigation, restoration of the environment around the robot in a 3-D map is necessary for self-location, route planning, and detecting surrounding obstacles. We construct the 3-D color environmental map using both camera images and laser scanner (LIDAR) point cloud data. In the map, the RGB values are provided to the LIDAR point cloud data by projecting the point cloud onto the simultaneously acquired image. The projection parameters can be determined by measuring the calibration boards using both the camera and the LIDAR. In this paper, we have constructed a method to evaluate the accuracy of projection applicable to any calibration methods. And, then, we found that the calibration points in the central position of an image are important to obtain good projection parameters and that additional points at side positions also can improve the accuracy of the projection.
关键词： 3-D mapping,SLAM,Calibration,Data fusion
更新于2025-09-23 15:21:01
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Calibration-free quantitative analysis of D/H isotopes with a fs-laser filament
摘要： The analytical characteristics of D/H isotopes with a fs-laser filament are investigated via analyzing a set of D-enriched water samples with D concentrations ranging from 0.5 to 20%. The filament emission spectra feature a narrow peak width and near-zero continuum spectral component. The characteristics of Balmer lines (a, b and g) are evaluated, and the Balmer-a line is selected for isotope analysis. Isotopic information is extracted from filament emission spectra through four different approaches: spectral deconvolution least squares algorithm (SDA), partial least squares regression-internal validation (PLSR-IV), partial least squares regression-cross validation (PLSR-CV) and partial least squares regression-calibration free (PLSR-CF). A multivariate spectral fitting procedure is established in the SDA. Fine structure components (FSCs) of Ha and Da were integrated in the SDA, and it shows improved analytical performance compared to the conventional SDA which is carried out by fitting the experimental spectra with two Lorentzian or Voigt functions. It is also found that the SDA with FSCs gives more accurate results than PLSR-IV and PLSR-CV. Furthermore, the analytical performance is significantly improved by the use of PLSR-CF, in which the PLSR calibration matrix is constructed with a synthetic spectra set. The improvement of accuracy for the given sample set further allows a calibration curve exhibiting an R2 exceeding 0.998 and a slop of 1.009. In addition, the calibration procedure with isotopically enriched standard samples is not necessary in PLSR-CF, demonstrating its flexibility over classical chemometric approaches.
关键词： fs-laser filament,PLSR,spectral deconvolution,calibration-free analysis,Balmer lines,D/H isotopes
更新于2025-09-23 15:21:01
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Laser based method for dynamic calibration of thermocouples
摘要： In dynamic temperature measurement, thermocouple sensors are widely used in harsh environments, and their dynamic characteristics directly affect the accuracy of dynamic temperature measurement. When the dynamic characteristics do not meet the requirements of dynamic test, dynamic errors will occur. In order to obtain the dynamic characteristics, it is necessary to calibrate the thermocouple dynamically. In this paper, a dynamic calibration system for the thermocouple was built. In the system, a high power laser was used to generate pulse temperature excitation. In order to realize the uniform heating, the laser beam homogenization system based on microlens array was studied and added to the dynamic calibration system. The homogenization system was designed and simulated, and the uniformity of the laser spot was measured after homogenization. A K-type butt-welded thermocouple was dynamically calibrated by using the dynamic calibration system. The dynamic mathematical model of the thermocouple was obtained by the system identification method, and the dynamic characteristics of the thermocouple were analyzed.
关键词： pulse excitation,laser,dynamic calibration,microlens array,thermocouple
更新于2025-09-23 15:21:01
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A self-calibration method for error of photoelectric encoder based on gyro in rotational inertial navigation system
摘要： As a precision goniometer, photoelectric encoder plays an important role in rotational inertial navigation system (RINS). The encoder is used to measure the rotate angle of rotating mechanism for attitude calculation and feedback of motor control. However, the experiment shows that there are position-related errors in the encoder output, so calibration is necessary in high precision applications. This paper presents a calibration method designed by the characteristics of encoder errors and the structure of a tri-axis RINS. In RINS, the gyro sensitive axis can be coincided with the motor axis by gimbals rotation, and then the gyro and the photoelectric encoder measure the same angle, so the error can be calculated as the difference between the encoder output and the integral of gyro output. The error will be analyzed through Fourier method, then the error will be ?tted by least squares method and a harmonic model will be established. The veri?cation experiments demonstrate that the angle measurement error is reduced from ± 4000 to ± 200, and the attitude output error drops 7500. The calibration method is proved to be experimentally effective.
关键词： error compensation,gyro,rotational inertial navigation system,self-calibration,photoelectric encoder
更新于2025-09-23 15:21:01
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First experience with Belle II Aerogel RICH detector
摘要： The Aerogel Ring-Imaging Cherenkov (ARICH) detector provides particle identification information in the forward endcap part of Belle II. It efficiently separates charged kaons from pions for momenta between 0.5 GeV/c and 4.0 GeV/c. Optical photons are emitted in a double layer aerogel radiator and detected by Hybrid Avalanche PhotoDetectors. ARICH was installed in Belle II at the end of 2017, the first phase of a complex detector calibration of electronic signals and preparation for physics signals calibration has been successfully concluded. Cherenkov rings, created by cosmic rays as well as by charged particles from beam collisions, have been observed. The kaon identification efficiency using D±? decays has been studied and its calibration is expected by the end of the commissioning phase when sufficient data is available.
关键词： Cherenkov detectors,Calibration,Particle identification,Optical photons,Beam collisions
更新于2025-09-23 15:21:01
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A new static method of calibration for low-cost laser triangulation systems
摘要： As a non-contact high-ef?ciency method, laser triangulation has long been studied by many scholars. Building such a system usually requires calibration where system parameters are found or amended to achieve the targeted precision. Traditional calibration methods require using either precise movement or high precision gauge object that are accompanied with extra manufacturing cost and auxiliary equipment/devices and hence increase the overall cost as well as prevent widespread applications, for instance, due to required environment conditions to be ful?lled. A new static method was, therefore, proposed to calibrate a system without need of a motion or a high precision gauge object to be deployed. The method relies on preparation of the data on a scalar compound target with a geometric estimator as quality indicator. Based on this method, three versions of a low-cost prototype were built, which achieved sub-millimeter precision. Although the precision is suf?cient for a measurement often used manufacturing large panels, higher precision is achievable with additional work which is to be undertaken in the future. The proposed method makes tradeoff between precision and cost. This was followed by testing on the measurement of a small panel part as application-case study. The proven feasibility of the method proposed suggested potential of developing low-cost, inline industrial system (large or small) for inspecting sheet parts during manufacturing, especially panel component manufacturing, including that from metal sheets and composite materials.
关键词： Calibration,Inspection,Panel manufacturing,Measurement,Modelling,Laser triangulation
更新于2025-09-23 15:21:01
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Analysis of Salt Mixture Contamination on Insulators via Laser-Induced Breakdown Spectroscopy
摘要： The composition of contamination deposited on transmission line insulators can affect their surface flashover voltage. Currently, there is no rapid on-line method to detect this contamination composition in power grids. In this paper, we applied laser-induced breakdown spectroscopy (LIBS) to analyze contamination on insulator surfaces. Usually, Na and Ca salts are found in contamination along with various sulfate, carbonate, and chloride compounds. As an element’s detection method, LIBS can only measure a certain element content, for example, Ca. The mixture of various compounds with the same cations can influence the LIBS signal. The influence of mixing ratios on the calibration curves and relative spectral intensity was studied via LIBS. Na2CO3, NaHCO3, CaSO4, and CaCO3 samples containing different proportions of Na and Ca were prepared. The linear correlation coefficients (R2) for the Na and Ca calibration curves generated using various mixing ratios were analyzed. The results showed that the mixture ratio did not dramatically affect the linear calibration curves for mixtures containing the same cations. This finding may significantly reduce the difficulty of applying LIBS analysis for complex contamination on insulators. The laser energy density had effects on the spectral characteristics of the measured elements. The partial least-square regression (PLSR) model can improve the accuracy of Na and Ca prediction.
关键词： salt,insulators,calibration curves,laser-induced breakdown spectroscopy,contamination
更新于2025-09-23 15:21:01
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Construction of global and robust near-infrared calibration models based on hybrid calibration sets using Partial Least Squares (PLS) regression
摘要： Near-infrared spectroscopy (NIR) models built on a particular instrument are often invalid on other instruments due to spectral inconsistencies between the instruments. In the present work, global and robust NIR calibration models were constructed by partial least square (PLS) regression based on hybrid calibration sets, which are composed of both primary and secondary spectra. Three datasets were used as case studies. The first consisted of 72 radix scutellaria samples measured on two NIR spectrometers with known baicalin content. The second was composed of 80 corn samples measured on two instruments with known moisture, oil, and protein concentrations. The third dataset included 279 primary samples of tobacco with known nicotine content and 78 secondary samples of tobacco with known nicotine concentrations. The effect of the number of secondary spectra in the hybrid calibration sets and the methods for selecting secondary spectra on the PLS model performance were investigated by comparing the results obtained from different calibration sets. This study shows that the global and robust calibration models accurately predicted both primary and secondary samples as long as the ratios of the number of primary spectra to the number of secondary spectra were less than 22. The models performance was not influenced by the selection method of the secondary spectra. The hybrid calibration sets included the primary spectral information and also the secondary spectra; rendering the constructed global and robust models applicable to both primary and secondary instruments.
关键词： global and robust models,hybrid calibration set,Near-infrared spectroscopy,partial least squares (PLS) regression
更新于2025-09-23 15:21:01