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2020 Vol. 41, No. 2
Published: 2020-02-28
 
129 The Quantized Redefinition of the SI and its Signification
MA Ai-wen,QU Xing-hua
DOI: 10.3969/j.issn.1000-1158.2020.02.01
The revision of the International System of Units (SI) was approved by the 26th General Conference on Weights and Measures(CGPM 2018). The definitions of the kilogram, the ampere, the kelvin and the mole are based on the new physical concepts, the definitions of the meter, the second and the candela are reformulated. Using the rules of nature to create the rules of measurement, since then, the definitions of all the SI basic units have been derived from a set of seven defining constants and have been quantized. The new SI is more stable and universal, it provides opportunities and challenges in the fields of metrology for National Metrology Institutes around the world.
2020 Vol. 41 (2): 129-133 [Abstract] ( 364 ) HTML (1 KB)  PDF (561 KB)  ( 599 )
134 Uncertainty Analysis and Evaluation of Form Measurement Task for CMM
CHENG Yin-bao,CHEN Xiao-huai,WANG Zhong-yu,WANG Han-bin,LI Hong-li,LI Ya-ru
DOI: 10.3969/j.issn.1000-1158.2020.02.02
The coordinate measuring machine (CMM) uncertainty for evaluating the form errors-oriented measurement tasks has been systematically studied, thus the rapid and reliable evaluation of the CMM measurement uncertainty can be realized.Two uncertainty combined methods based on Guide to the Expression of Uncertainty in Measurement (GUM) and Monte Carlo method are provided.The feasibility of the evaluation method has been verified by measurement example of flatness.The experimental result shows that precision significance of uncertainty determined by GUM is unreliable, the expanded uncertainty increased by 11.1% compared with actual situation.To systematically solve the problem of the CMM uncertainty for evaluating the measurement tasks targeting form errors is typical and representative, which can be effectively applied to solve the uncertainty evaluation problems of other precision instruments.
2020 Vol. 41 (2): 134-138 [Abstract] ( 351 ) HTML (1 KB)  PDF (720 KB)  ( 533 )
139 Research on On-line Automatic Measurement Method of Enameled Wire Diameter
CHEN Jia-yan,JING Li-meng,ZHOU Juan,HONG Tao
DOI: 10.3969/j.issn.1000-1158.2020.02.03
An online automatic detection method of enameled wire diameter is proposed, a kind of enameled wire shock-absorbing mechanism based on pulley block is designed, which can solve the problem that the vibration amplitude is too large and the wire diameter is not easy to be detected in the process of enameled wire production. Firstly, median filtering, fixed threshold segmentation and Sobel edge detection were carried out on the collected enameled wire original image, and then sub-pixel edges were obtained by cubic spline interpolation, and upper and lower edge lines were fitted by least square method, and finally the enameled wire diameter was calculated by the method of segmentation edge line. Field test results show that the resolution of the system developed by this method is 0.00018mm, meeting the requirements of the enterprise detection accuracy ±0.001mm, The detection results are 0.1619±0.0001mm, the confidence probability P=0.95, and the degree of freedom ν=24, the repeatability test is in good consistency with the test results obtained by quality inspection institutions.
2020 Vol. 41 (2): 139-146 [Abstract] ( 310 ) HTML (1 KB)  PDF (1342 KB)  ( 335 )
147 International Comparison and Result Analysis of Spectral Radiance
DAI Cai-hong,WANG Yan-fei,WU Zhi-feng,LI Ling
DOI: 10.3969/j.issn.1000-1158.2020.02.04
Based on BB3500M high temperature blackbody, the fourth-generation primary standard apparatus of spectral radiance was developed at National Institute of Metrology (NIM) in the spectral wavelength from 220nm to 2550nm.A group of stable tungsten strip lamps were used as the transfer standards.The temperature measurement of the high temperature blackbodies were traced to the Pt-C and Re-C fixed point blackbodies and checked against the WC-C fixed-point blackbody, and the consistency of the temperature realized by NIM and All Russian Research Institute for Optical and Physical Measurements (VNIIOFI) at 3021 K was better than 70mK.Spectral radiance was realized by two different entrance systems at NIM respectively, and the imaging ratio of the two system were 0.58 and 1.00, the solid angle were 0.006sr and 0.008sr.The relative deviation of spectral radiance was less than ±0.40% by using the two system at all wavelengths.With the new developed primary standard apparatus, NIM took part in the international comparison of spectral radiance APMP-PR.S6.The comparison result shows that the average relative deviation are 0.59%, 0.44% and 0.34% respectively in ultraviolet, visible and near infrared wavelength.The average relative deviation in the whole wavelength is 0.46%.The measurement standard uncertainty of spectral radiance of NIM are 0.95%, 0.50%, 0.41% and 0.80% at 250nm, 400nm, 800nm and 2500nm respectively.The comparison result verified the performance of NIMs new national standard apparatus of spectral radiance.
2020 Vol. 41 (2): 147-152 [Abstract] ( 296 ) HTML (1 KB)  PDF (881 KB)  ( 301 )
153 Improvement of the Richardson-Lucy Algorithm in Blurred Image Restoration
ZHANG Jian-guo,TA Yang-yang,JIANG Rui-jiao,YAO Tai-an,WANG Yan-zhu
DOI: 10.3969/j.issn.1000-1158.2020.02.05
In order to solve the problems of easy producing blurred image in the embedded system and low speed of Richardson-Lucy restoration algorithm when acquiring images, a micro-image processing model based on Richardson-Lucy and two-dimensional wavelet transform were proposed, the Richardson-Lucy algorithm was improved to improve the blurred image restoration rate, and to increase the image processing rate of the embedded system to meet the requirements of high real-time performance, so as to achieve more ideal results. The experimental data analysis proved that the proposed composite algorithm can improve the restoration rate and the defintion of image restoration.
2020 Vol. 41 (2): 153-158 [Abstract] ( 307 ) HTML (1 KB)  PDF (1431 KB)  ( 361 )
159 Research the Progresses on Measurement of Thermal Conductivity of Graphene and Graphenes Composites
ZHOU Yi,LIN Hong,FENG Xiao-juan,QIU Ping,SHE Shi-gang,ZHANG Jin-tao
DOI: 10.3969/j.issn.1000-1158.2020.02.06
Graphene, which has thermal conductivity surpasses most materials and broad application prospects, is a hot and difficult topic in current material research. Over the past decade, due to the rapid development of graphene industry, the accurate measurement of graphenes thermal conductivity is becoming more and more urgent. Definitions, preparation methods of graphene and graphenes composites and application in heat dissipation are reviewed. Traditional measurement methods of thermal conductivity, the laser flash-Raman spectroscopy method and electrothermal microbridge method for graphene are introduced. The measured values reported in some existing literatures are also compared. Prepared and measured samples which compounded of reduced graphene oxide and polypropylene by injection moulding, then find serious anisotropy form the measurement results of thermal diffusivity. Also, other problems in the measurement are pointed out and the causes of these problems are analyzed. Finally, summarize and prospect the measurement research on thermal conductivity of graphene and graphene‘s composites.
2020 Vol. 41 (2): 159-169 [Abstract] ( 425 ) HTML (1 KB)  PDF (1098 KB)  ( 1230 )
170 Experimental Study on the Start-up Characteristic and Isothermal Performance of the N-methyl Pyrrolidone Heat Pipe
TONG Wen-yu,ZHANG Guang-ming,YU Li-li,YAN Xiao-ke,ZHANG Kai
DOI: 10.3969/j.issn.1000-1158.2020.02.07
A medium-temperature heat pipe fixed-point furnace that reproduces the freezing point of tin needs to select a medium-temperature heat pipe with a suitable working medium. Two gravity heat tubes(1#, 2#)with N-methyl pyrrolidone (NMP)as working fluid were developed, and the experimental study on the start-up characteristic and isothermal performance of NMP heat pipe under the same constant temperature heating conditions were carried out. The results showed that the start-up time and the stability of No.2 heat pipe is superior to the No.1 and the NMP heat pipe can be operated in the temperature range from 170℃ to 320℃. In addition, the start-up characteristic and isothermal performance can be affected by the fabrication process of the heat pipe. Under the same operating conditions, the more reasonable the heat pipe fabrication process, the higher the upper temperature of the heat pipe condensation section.
2020 Vol. 41 (2): 170-174 [Abstract] ( 238 ) HTML (1 KB)  PDF (1276 KB)  ( 274 )
175 The Research on the Constraint Formulas of EMFs as a Standard Pt-10% Rh/Pt Thermocouple
ZHENG Wei,TANG Lei
DOI: 10.3969/j.issn.1000-1158.2020.02.08
The characteristics of Pt-10% Rh/Pt thermocouple on temperature versus EMFs were described with the calibration results on three fixed point temperatures. In ITPS-68 temperature scale, Pt-10% Rh/Pt thermocouple was selected as interpolation equipment, and its three fixed point EMFs should be restrained to meet the certain formulas. The new constraint formulas on three different fixed point temperatures were derivable from traditional requirement in IPTS-68 to regulate the standard Pt-10% Rh/Pt thermocouple characteristics, and were verified to be efficient by the original data of the great amount of thermocouples from the calibration service laboratory of National Institute of Metrology. The rejection ratio of standard thermocouple at Zn fixed point was slightly raised from 0% to about 3% when the new constraint formulas were applied.
2020 Vol. 41 (2): 175-178 [Abstract] ( 300 ) HTML (1 KB)  PDF (370 KB)  ( 353 )
179 Numerical Simulation and Experiment of Gas Mass in pVTt Standard Container under Isothermal Boundary Condition
LIU Ruo-xuan,ZHU Ming-zheng,SHEN Yu-ming
DOI: 10.3969/j.issn.1000-1158.2020.02.09
Focusing on a 36m3 horizontal pVTt standard container, the intake process and homogeneous process of the gas in the container were numerically simulated in constant wall temperature and constant velocity as the inlet boundary condition. A new algorithm for calculating the average temperature in the standard pVTt container was proposed, whose name was mass temperature average. The simulation results showed that in the natural convection process after gas intake, the average mass temperature of the gas in the container slowly decreased with time in parabolic shape and tended to wall temperature, while the average pressure drops sharply and quickly reached uniformity. Through numerical simulation and experimental verification, it was found that the gas mass in the container was linear with lnT.
2020 Vol. 41 (2): 179-184 [Abstract] ( 331 ) HTML (1 KB)  PDF (930 KB)  ( 292 )
185 Research on a New Constrained Servo System Control Strategy
FU Rong-rong,LI Dong-yu,TIAN Yong-sheng,WANG Han
DOI: 10.3969/j.issn.1000-1158.2020.02.10
A new constrained complex follow-up system-cup and ball pendulum system was proposed. The new system was modeled by the method of lagrange dynamics. controllability and observability of the system were studied firstly. Two control methods of state feedback controller with pole assignment and LQR optimal control based on genetic algorithm were used to achieve the experiment comparison in this paper. Through the comparative analysis, state feedback controller with pole assignment has better robustness and transient characteristics. And LQR optimal control based on genetic algorithm has better steady-state characteristics and shorter tuning time. Meanwhile, compared with state feedback controller with pole assignment LQR optimal control based on genetic algorithm is more targeted in terms of parameter selection, therefore it is convenient for practical application.
2020 Vol. 41 (2): 185-189 [Abstract] ( 297 ) HTML (1 KB)  PDF (422 KB)  ( 227 )
190 Research on Sub-pixel Extraction Algorithm of Geometric Center of Gravity Method
XU Cong-yu,GAO Yu-ting,XU Jun,YANG Ya-ru,HU Zong-jiu
DOI: 10.3969/j.issn.1000-1158.2020.02.11
To achieve the ultra-low rotating speed online measurement, a geometric center of gravity subpixel extraction algorithm based on microscopic image was proposed.Firstly, the measurement of ultra-low rotation speed was transformed into translational measurement according to the microscopic image method,the surface fitting method and gradient method which are commonly used at presentnot only take longer to extract sub-pixel but also have weak anti interference ability, thesub-pixel extraction algorithm of the geometric center of gravity method solved these problems.The core of the geometric center of gravity method was to calculate the index value of the difference between the reference pixel gray value and the integer pixel gray value within the range of 3×3 pixel on the basis of the integer pixel extraction, then extracted the sub-pixel value from the acquired 3-point index value by using the geometric center of gravity method.Through the verification of micro-displacement captured images by grating reference platform, the average time of geometric center of gravity method was less than 0.2s, which was shorter than the surface fitting method and the gradient method.The standard deviation of the extract subpixel value was less than one thousandth of a pixel, which conformed to the basic requirements of ultra-low rotating speed online measurement.
2020 Vol. 41 (2): 190-197 [Abstract] ( 300 ) HTML (1 KB)  PDF (1508 KB)  ( 254 )
198 Relative Gravity Measurement Campaign during the 10th International Comparison of Absolute Gravimeters
LIU Shan-liang,WU Shu-qing,FENG Jin-yang,WANG Qi-yu,JI Wang-xi,SU Duo-wu,LI Chun-jian
DOI: 10.3969/j.issn.1000-1158.2020.02.12
As pilot lab, National Institute of Metrology (NIM) organized national metrology institutes or designated institutes from 14 countries in the world to participate in the 10th international comparison of absolute gravimeters (CCM.G-K2.2017). Due to the reference height of different types of absolute gravimeters is different, the relative gravity measurements of the comparison mainly focus on transferring the absolute gravity value from the different reference heights to the same reference height. According to the preliminary results of the comparison, the combined standard uncertainty of relative gravity measurement was better than 4μGal, which ensured the validity and accuracy of the final result of the comparison.
2020 Vol. 41 (2): 198-201 [Abstract] ( 297 ) HTML (1 KB)  PDF (412 KB)  ( 419 )
202 Degradation Feature Extraction Method of Hydraulic Pump Based on Integrated Complete Ensemble Empirical Mode Decomposition and Fuzzy Entropy
JIANG Wan-lu,KONG De-tian,LI Zhen-bao,TONG Xiang-wei,YUE Wen-de
DOI: 10.3969/j.issn.1000-1158.2020.02.13
Aiming at the fact that the vibration signals of hydraulic pumps have the characteristics of nonlinear, non-stationary and low signal to noise ratio, a feature extraction method based on complete ensemble empirical mode decomposition and fuzzy entropy integrated is proposed. Firstly, the vibration signals of the hydraulic pump are decomposed into several intrinsic mode functions by means of complete ensemble empirical mode decomposition. Secondly, the correlation coefficients between each intrinsic mode function and the original signal are calculated, and the components with higher correlation coefficients are selected to obtain their fuzzy entropies, then the degradation characteristics are obtained. Finally, taking the measured data in different degradation states of hydraulic pump as an example, the variable predictive model based class discriminate method is used to verify the effectiveness of the proposed feature extracted method. The experimental results show that the method has higher precision in extracting the hydraulic pump degradation characteristics, and the accuracy rate of degenerate state identification is increased to 100%.
2020 Vol. 41 (2): 202-209 [Abstract] ( 278 ) HTML (1 KB)  PDF (697 KB)  ( 225 )
210 A New Method for Calculating the Sound Pressure Level of Anechoic Chambers
CHEN Huan,TANG Qiu,LIN Hai-jun,TAN Xiao-ming,LUO Peng,TENG Zhao-sheng
DOI: 10.3969/j.issn.1000-1158.2020.02.14
The inverse square law for calculating the sound pressure level was proposed in JJF 1147-2006 “Calibration Specification for Acoustic Performance of Anechoic Rooms and Hemi-anechoic Rooms”, causing a large deviation of sound pressure level near the sound source. For this problem, a new method of adding the air absorption attenuation factor and selecting the actual sound pressure level at the measurement position of 1 m to calculate the sound pressure level of the anechoic chamber is proposed. Through comparative experiments, the above situation can be well improved and the calibration accuracy can get increased.
2020 Vol. 41 (2): 210-213 [Abstract] ( 267 ) HTML (1 KB)  PDF (378 KB)  ( 282 )
214 Research on Micro-crack Localization Imaging Based on Vibro-acoustic Modulation
LING Tian-hao,ZHENG Hui-feng,HE Hong-ru,HU Liu-chen,CAO Yong-gang
DOI: 10.3969/j.issn.1000-1158.2020.02.15
In order to accurately identify micro-cracks in metal components, a localization imaging method combining vibration acoustic modulation technology and delay superposition algorithm is proposed. By introducing the basic principle, the finite element software is used to simulate the vibration and acoustic modulation of the aluminum plate model with rectangular micro-cracks, and the non-linear damage signal is extracted as the pixel feature. The location imaging is carried out by using the delay superposition algorithm, and the influencing factors of the imaging are analyzed. In the experiment, a vibration acoustic modulation detection system was set up to locate the circular micro-cracks in the aluminum plate, which verified the feasibility of the above method. The results show that the imaging results are basically consistent with the original crack position on the aluminum plate, indicating that the positioning imaging method can effectively locate the micro-cracks.
2020 Vol. 41 (2): 214-220 [Abstract] ( 306 ) HTML (1 KB)  PDF (1680 KB)  ( 659 )
221 Research on the Traceability Technology of VOR Signal
HE Zhao,ZHANG Yi-chi,GUO Xiao-tao,HUANG Jian-ming,NIE Mei-ning,TAO Yi
DOI: 10.3969/j.issn.1000-1158.2020.02.16
Based on a phase generator and frequency modulation (FM) / amplitude modulation (AM) instruments, a standard very high frequency omnidirectional range (VOR) signal generator is established to realize the traceability of VOR phase quantity to the national phase standard, which cannot be achieved using traditional method of direct digital synthesizing. According to the uncertainty analysis, the extended uncertainty of VOR phase is less than ±0.020° (k=2), while that of VOR modulation depth is ±0.2% (k=2). This standard VOR signal generator can be used to calibrate commercial avionic instruments for VOR signal generation and demodulation.
2020 Vol. 41 (2): 221-224 [Abstract] ( 264 ) HTML (1 KB)  PDF (1089 KB)  ( 244 )
225 Research on Ensemble Algorithm for Chinese Emotion Classification Based on Differential Evolution
YANG Meng-yue,WEI Wei,LU Hui-juan,LU Hai-feng
DOI: 10.3969/j.issn.1000-1158.2020.02.17
Sentiment classification is a text classification task that extracts emotional tendencies from text. Ensemble learning combines several classifiers to achieve a better classification effect than component learners on the task of emotional classification. However, due to the different performance of component learners on data sets, the weights of component learners in the ensemble method were not well-distributed. Aiming at the weight optimization problem of component learners in ensemble learning, a classification method based on differential evolution to optimize the weights of component learners was proposed and applied to Chinese text sentiment classification. Using the classification accuracy as the fitness value, the weight combination of five component learners was optimized by differential evolution algorithm, and experiments were performed on the review corpus of the three fields. The experimental results showed that compared with the general ensemble method, the proposed classification method has better classification performance in sentiment classification.
2020 Vol. 41 (2): 225-230 [Abstract] ( 284 ) HTML (1 KB)  PDF (1104 KB)  ( 302 )
231 An Optimized Planar Array Capacitance Imaging Algorithm Based on FCM
WEN Yin-tang,CAO Peng-peng,TIAN Hong-gang,ZHANG Yu-yan,LUO Xiao-yuan
DOI: 10.3969/j.issn.1000-1158.2020.02.18
In order to improve the accuracy of planar array capacitance imaging, an imaging algorithm based on fuzzy C-means algorithm(FCM) data optimization is proposed. According to the characteristics of capacitance data of planar array electrodes, in order to reduce the influence of capacitance measurement error on dielectric constant, application of FCM algorithm to the continuous convergence of measured capacitance to achieve data optimization. On this basis, a defect detection experiment was carried out on a kind of insulating material adhesive layer, and the image correlation coefficient of the reconstructed image was improved, and the image reconstruction error was reduced. The experimental results show that the proposed optimization algorithm can obtain more stable and effective capacitance data, and the reconstruction accuracy of glue layer defect image has been greatly improved.
2020 Vol. 41 (2): 231-237 [Abstract] ( 318 ) HTML (1 KB)  PDF (1971 KB)  ( 280 )
238 Design of Atomic Time Scale Publication System for Multiple Laboratories
ZHU Jiang-miao,WANG Xing,GAO Yuan,WANG Shi-biao,ZHANG Jing,ZHAO Wei-bo
DOI: 10.3969/j.issn.1000-1158.2020.02.19
Design of atomic time scale publication system for multiple laboratories is based on the modular design of atomic clock data provided by eight domestic punctual laboratories.The system includes the three modules, the processing of atomic clock data, the calculation of atomic time scale and the publication of atomic time scale data, using MATLAB for data processing and time scale calculation, and using GUI for data visualization design.The system has clear process of the algorithm, simple function modules and friendly human-machine interface.The actual data operation results show that the time difference between the integrated atomic time scale and UTC of the system is better than ±10ns, and the data release content meet the needs of the scientific research in related fields in China.
2020 Vol. 41 (2): 238-242 [Abstract] ( 279 ) HTML (1 KB)  PDF (877 KB)  ( 258 )
243 The Standardization of Metrological Technology for Pulsar Time Steering Atomic Clocks in the Open-loop
DONG Jiang
DOI: 10.3969/j.issn.1000-1158.2020.02.20
Recently, the project of Pulsar Time Steering Atomic Clocks has begun in Europe. They and some domestic teams both are based on the traditional folding mode of Pulsar Data Unit of TOA (Time of Arrival) and Pulsars Ephemeris Prediction to study the open-loop clock control algorithm. Based on the characteristics and technical requirements of metrology, ar technical implementation plan is put forward. Our scheme can solve the autoregression and absorption effects of traditional pulsar observations, and all the measured parameters can be traced back to the linking, which provides the feasibility for the closed-loop control of the atomic clock by pulsars.
2020 Vol. 41 (2): 243-249 [Abstract] ( 309 ) HTML (1 KB)  PDF (1213 KB)  ( 343 )
250 Research on the Method of Traceability the Value of Standard Radon Monitor
YAN Yi-fan,LIANG Jun-cheng,YANG Zhi-jie,WANG Ren-bo
DOI: 10.3969/j.issn.1000-1158.2020.02.21
The method of preparing high-accuracy standard radon source by using the absolute activity measuring device was studied, and the source of the value transfer with the uncertainty of activity expansion of 0.8% (k=2) was obtained. According to the basic principle of the calculation of the standard radon volume activity,calibrated the effective volume of the small dedicated radon chamber for value transfer, the expanded uncertainty of its effective volume is 0.46% (k=2). Calibration of the reference instrument (AlphaGUARD type standard measuring instrument for radon) used in general standard equipment (standard radon chamber), obtained the average volume activity response is 1.01, and the expanded uncertainty of the volume activity response is 3.2% (k=2).
2020 Vol. 41 (2): 250-256 [Abstract] ( 262 ) HTML (1 KB)  PDF (2244 KB)  ( 368 )
257 Study on the Equivalence of Water Equivalent Materials to Water under High-energy X-ray
WANG Zhi-peng,XING Shu-ming,WANG Kun,JIN Sun-jun,FAN Fu-you,LIU Fu-bin
DOI: 10.3969/j.issn.1000-1158.2020.02.22
The problems in the calibration of accelerator using water equivalent materials were described. Three commonly used water equivalent materials were compared to water phantom in measurements of absorbed dose to water. Two Farmer-type cylindrical chamber, PTW 30013 and IBA FC65-G, were used in measurements. The calibration factors of absolute dose between water phantom and water equivalent materials at two depth, 5cm and 10cm, were listed. Through the results of daily stability nearly seven months, the necessity of daily calibration of the accelerator was explained. The dose drift of accelerator and the possible causes were given. By measuring the output factor of twelve radiation fields, the water equivalent material is consistent with water in the relative measurement. Finally, the suggestions and precautions for the water equivalent material in the calibration of high energy X-ray were given.
2020 Vol. 41 (2): 257-262 [Abstract] ( 299 ) HTML (1 KB)  PDF (1475 KB)  ( 267 )
263 Classification Recognition of Three Dimensional Fluorescence Spectrum Traditional Chinese Medicine Based on LLE-RF
FAN Feng-jie,XUAN Feng-lai,BAI Yang,JI Hui-fang
DOI: 10.3969/j.issn.1000-1158.2020.02.23
To research the non-linearity of the three dimensional fluorescence spectrum signal of traditional Chinese medicine, locally linear embedding (LLE) algorithm was used to extract the feature of three dimensional fluorescence spectrum signals for tonifying herbs. On the basis of the three dimensional fluorescence spectrum and contour line spectrum of 24 traditional Chinese medicines of different concentrations measured by fluorescence spectrometer,and ensemble empirical mode decomposition (EEMD) algorithm for noise reduction, the LLE algorithm was used to extract the characteristics of the three dimensional fluorescence spectrum data after noisereduction.Then, the extracted features were classified and identified by using random forest (RF) algorithm.In order to verify the effectiveness of LLE algorithm, the principal component analysis (PCA) algorithm was compared. Experimental results showed that the classification accuracy of the LLE-RF combination algorithm was 95%, which was higher than PCA-RF algorithm which proved the effectiveness of the algorithm.
2020 Vol. 41 (2): 263-268 [Abstract] ( 305 ) HTML (1 KB)  PDF (1816 KB)  ( 639 )
269 Determination and Evaluation of the Uncertainty of the Formaldehyde Emission in Wood-based Panel
XIE Mei-mei
DOI: 10.3969/j.issn.1000-1158.2020.02.24
The wood-based panel formaldehyde emission was tested by the desiccators method in GB/T 17657-2013 "Test method for physicochemical properties of wood-based panel ", the process of the detection was studied. All kinds of uncertainties were analyzed, which affected determination of formaldehyde emission and evaluated the components of uncertainty according to the JJF 1059.1-2012 "Evaluation and Expression of Uncertainty in Measurement" . The results showed that the formaldehyde emission was (1.06±0.05) mg·L-1, when expanded uncertainty coverage factor k=2, fiducially probability P=95％. The analysis showed that the uncertainty of the reference value and the repeated determination of the sample contributed the most, followed by the uncertainty which was introduced by the variation of the standard curve fitting.
2020 Vol. 41 (2): 269-272 [Abstract] ( 257 ) HTML (1 KB)  PDF (360 KB)  ( 245 )
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