Acta Metrologica Sinica

Office Online

Manuscript Tracking

Editor-in-chief

Journal Online

Current Issue

Advanced Search

Archive

Read Articles

Download Articles

Traffic

Quick Search

2018 Vol. 39, No. 3 Published: 2018-05-22

	289	Experiment Investigation on Calibration of Hot Wire Anemometer Based on Low Air Speed Reference Facility
		CUI Li-shui,LI Peng,QIU Li-rong,LI Jian-shuang
		DOI: 10.3969/j.issn.1000-1158.2018.03.01
		The low air speed reference facility is established at NIM of China, based on the device, the experiment on calibration of hot wire anemometer is investigated.The facility is described in detail and the calibration method for hot wire sensor is introduced. Based on the reciprocity principle, the sensor probe is mounted on the carriage that slides with consistent speed and the sliding stroke is measured by laser interferometer accurately during calibration process. The velocity measurement is therefore traceable to the measurement of length and time primary standards, additionally, the parameters of static equation is obtained according to theoretical module of hot wire sensor, the experimental results are consistent with theoretical equation. The experimental results and uncertainty analysis show that the expanded uncertainty of the breeze standard device is U=0.82%（k=2）, and the expanded uncertainty of calibration result of hot wire anemometer is U=2.42%（k=2）.
		2018 Vol. 39 (3): 289-293 [Abstract] ( 465 ) HTML (1 KB) PDF (973 KB) ( 866 )

	294	Research on Tungsten Probe Fabrication Device Based on the Electrochemical Etching Method
		XU Jing-tao,GAO Si-tian,HUANG Lu,LI Qi,LI Dong-sheng,WANG Ya-li
		DOI: 10.3969/j.issn.1000-1158.2018.03.02
		A tungsten probe fabrication device is proposed based on electrochemical etching method and the parameter of fabricating tungsten probe is researched.The experimental part can be used to adjust the relative position and motion parameters of the probe and the electrolyzer.The control part can be used to control and record the state of electrochemical etching.Compared with traditional fabrication device, the present device ensured to fabricate large length-to-width ratio tip by controlling the motion of tungsten probe, meanwhile, the radius of tips can be precisely controlled within 5 ~ 20 nm by controlling the etching time.
		2018 Vol. 39 (3): 294-298 [Abstract] ( 556 ) HTML (1 KB) PDF (2347 KB) ( 469 )

	299	Effect of Surface and Sub-surface Characteristics on the Contrast of Multilayer Film Grating Imaging
		ZHANG Long-fei,WANG Xing-rui,DENG Xiao,CHENG Xin-bin
		DOI: 10.3969/j.issn.1000-1158.2018.03.03
		Based on the Si/SiO2 material, a multilayer film grating with nominal pitch of 50 nm is prepared. The problem of sub -surface damage during the grinding and polishing process and wet etching uniformity is analyzed emphatically. The cross-sectional roughness and the results of the etching grating are measured and analyzed by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The results show that the decrease of the cross-sectional roughness and the uniformity of the etching in the preparation of the multilayer film grating helps to obtain a uniform high-contrast contrast multi-layer raster image for TEM measurement.
		2018 Vol. 39 (3): 299-303 [Abstract] ( 456 ) HTML (1 KB) PDF (342 KB) ( 251 )

	304	A Method of Slope Estimation Based on Clustering of Three-dimensional Point Cloud
		LI Hai-bo,CAO Yun-feng,DING Meng,ZHUANG Li-kui
		DOI: 10.3969/j.issn.1000-1158.2018.03.04
		In order to improve the precision of slope estimation in Mars landing, a method of slope estimation based on clustering of three-dimensional point cloud and random searching the optimal fitting plane was presented. The three-dimensional point cloud data obtained by light detection and ranging (LIDAR) were addressed with sparse representation. Then the data were clustered and segmented according to the sparse coefficients. So the subspaces were determined and the data points in subspace were used to fit plane. The optimal plane can be obtained by random search and the angle between the normal vectors can be got by calculation. The angle obtained equals the slope angle in value. So far, the slope angle estimation was completed. The experiments show that this method can estimate the slope angle very accurately. Compared with the common estimation method, this algorithm has low relative error.
		2018 Vol. 39 (3): 304-309 [Abstract] ( 495 ) HTML (1 KB) PDF (2143 KB) ( 640 )

	310	A Novel Data Processing Method of Measuring Wobble Errors of Vertical Axis System with Levels
		WANG Zi-hao,REN Shun-qing
		DOI: 10.3969/j.issn.1000-1158.2018.03.05
		In order to accurately appraise the wobble errors of the vertical axis system measured by two orthogonal levels, the readouts of the levels were analyzed and the error compositions are expounded.And the coupling relationships among the harmonic components of the readouts, and of the wobble errors, the plumb error of the vertical axis line, are analyzed.According to the two existing methods, transforming the processed readouts into the expressions in the fixed coordinate system, thus the two processing methods are put forward.The orthogonal and the correlative first harmonic errors are separated from the total first harmonic, namely the correlative first harmonic which is the composition of wobble errors is retained.In the end, by modifying the plumb errors, and measuring wobble errors eight times correspondingly, and the correctness of the proposed method is verified by the comparison with the identified parameters.
		2018 Vol. 39 (3): 310-315 [Abstract] ( 443 ) HTML (1 KB) PDF (408 KB) ( 262 )

	316	The Length Dimension Measurement for Large Hot Forgings Based on the Recognition of Green Laser
		WANG Ying,ZHANG Yu-cun
		DOI: 10.3969/j.issn.1000-1158.2018.03.06
		A length dimension measurement system for large hot forgings is designed. The images of each moment in the process of green laser scanning forgings are analyzed in this system. The dimension of the forging is measured according to the edge informations of forgings. First of all, the CCD camera and the green laser are driven by the motor, the real-time images of forgings and the positional information of laser line is acquired. Then whether the laser line locates on the edge of forgings is judged by image recognition. Secondly, the length dimension of forgings is obtained from recording the position information of both sides of the forging edges. The experimental results show that the maximum measurement error is less than 2 mm. So the method proposed can meet the needs of forging dimension measurement.
		2018 Vol. 39 (3): 316-320 [Abstract] ( 431 ) HTML (1 KB) PDF (377 KB) ( 767 )

	321	Subpixel Edge Detection with High Precision for Vehicle Engine Intake Manifolds
		XU Ping,XUE Ling-yun,CHANG Ying-jie
		DOI: 10.3969/j.issn.1000-1158.2018.03.07
		An accurate subpixel edge detection method based on edge pixel projection for vehicle engine intake manifolds is proposed. The light-sensitive cells on the edges are divided into two different parts. The final gray value of the edge pixel is calculated by weighted average of its both side gray statistics values. The accurate subpixel edge can be obtained by the rectangle neighbourhood model. Compared with the method based on surface fitting, experimental results show that, for the 50.00mm×40.00mm product, the standard deviation of major axis and minor axis decreases by 1.71% and 17.78%, respectively, and for the 50.05mm×40.05mm product, the standard deviation of major axis and minor axis decreases by 38.66% and 2.03%, respectively.
		2018 Vol. 39 (3): 321-325 [Abstract] ( 452 ) HTML (1 KB) PDF (317 KB) ( 269 )

	326	Error Compensation of Drive System of Vernier Measuring Instrument
		CHEN Wang-da,XU Zhi-ling,LI Zhi-fei
		DOI: 10.3969/j.issn.1000-1158.2018.03.08
		In the verification process of vernier measuring tools, when the dynamic table of the drive system in the verification device is at a low speed, the errors of the friction and backlash nonlinearity are exist between the dynamic work station and the ball screw, so the vernier measuring tools cannot be accurately moved to the test point required by the verification procedure. In order to solve the problem of the errors, the LuGre friction model and adaptive periodic recursive wavelet neural network are used to compensate the friction and backlash nonlinearity.Based on the Liroff stability analysis, the boundedness and convergence of the closed-loop system are guaranteed.The simulation results show that the performance of position tracking is improved, and the control compensation scheme is demonstrated in the driving system of the verification device, the accuracy of positive is improved by 47.6% in positive movement and 49.7% in negative movement.
		2018 Vol. 39 (3): 326-331 [Abstract] ( 415 ) HTML (1 KB) PDF (349 KB) ( 338 )

	332	Improved K-SVD image denoising algorithm
		CHENG Yi-feng,LIU Zeng-li
		DOI: 10.3969/j.issn.1000-1158.2018.03.09
		Aiming at the problem of shortage of signal utilization by traditional K-SVD. Using sparse Bayesian learning to preprocess the image signal. Combining the orthogonal matching pursuit algorithm with the improved steepest descent algorithm. Taking into account the noise atoms are present in the dictionary after the update of the dictionary, so combined with the Bartlett test method to cut off the noise atoms. Experimental results show that the method is better than the wavelet threshold denoising algorithm and the sparse representation based on DCT dictionary. Also, the method can remove the noise better, preserve image edge information, obtain higher peak signal to noise ratio, and the resulting image has a better visual effect.
		2018 Vol. 39 (3): 332-336 [Abstract] ( 454 ) HTML (1 KB) PDF (334 KB) ( 378 )

	337	Analysis of Optical Add-drop Multiplexer Based on Beam Splitter and Bidirectional Mode
		ZHU Dan-dan,PIAN Fei-fei,ZHENG Hong,ZHANG Kun,CHEN Jie-yun
		DOI: 10.3969/j.issn.1000-1158.2018.03.10
		Optical add-drop multiplexer(OADM) based on fiber Bragg grating is discussed . Two kinds of novel four wave wavelength OADM structures are analyzed. One kind of OADM is based on bidirectional type. The other kind of OADM is based on beam splitter and bidirectional type. Bidirectional OADM can transmit optical signal from two directions, this can make the system structure in the relatively small use of circulator, it can reduce system loss. The output spectrum was more close to the original spectrum. OADM based on beam splitter and bidirectional type increases transmission channel number. The OptiSystem software is used to simulate two kinds of structures, the simulation experimental results show that both kinds of OADM can implement four wavelength channels′ uploading and downloading simultaneously.
		2018 Vol. 39 (3): 337-341 [Abstract] ( 479 ) HTML (1 KB) PDF (1291 KB) ( 499 )

	342	Research on Target Tracking Algorithm of the Quadrotor Aircraft Based on Monocular Vision
		ZHANG Li-guo,LI Xiao-song,XIAO Lei,JIN Mei,DONG Hao
		DOI: 10.3969/j.issn.1000-1158.2018.03.11
		Taking AR.drone four-rotor aircraft as a research platform, a method based on AR.drone front-end monocular camera and Calman filter is proposed to track moving target in video. The RGB image obtained through color space conversion paired illumination changes HSV image is on the image by OpenCV,the OpenCV of image denoising for target tracking in the video images is used, and then detect and find the largest contour of targets in images and use the Kalman filter to modify the target location. Then the flight direction of the quadrotor is calculated to realize the tracking of the moving target in the video area of the quadrotor. The experimental results show that this method is effective for moving target tracking accuracy, stability and rapidity.
		2018 Vol. 39 (3): 342-347 [Abstract] ( 517 ) HTML (1 KB) PDF (358 KB) ( 691 )

	348	Vehicle Recognition Based on Multi-feature Extraction and SVM Parameter Optimization
		CHENG Shu-hong,GAO Xu,ZHOU Bin
		DOI: 10.3969/j.issn.1000-1158.2018.03.12
		A kind of vehicle recognition method which was based on multi-feature extraction and support vector machines(SVM) parameter optimization is proposeal. Many kinds of problems that used the single-feature can be influenced by those factors such as light, weather and shadow, etc. Those problems could be solved by our method. In addition, our method can identify the moving vehicle model. At first, the samples of vehicle are collected and begin the process of image preprocessing, a variety of features will be extracted, including geometric features, texture features and histogram of gradient features. The second, combining and testing the various features, then the results with the results of single-feature testing are compared. At last, preparing for the recognition of the vehicle by SVM which was optimized by Particle Swarm Optimization(PSO). The experimental results show that the method which is put forward can achieve a good recognition results. The recognition rate can reach more than 90%.
		2018 Vol. 39 (3): 348-352 [Abstract] ( 450 ) HTML (1 KB) PDF (619 KB) ( 773 )

	353	Detection of Transparent Lamp Parts Based on Image Matching
		ZHU Wan-yi,MU Ping-an,DAI Shu-guang
		DOI: 10.3969/j.issn.1000-1158.2018.03.13
		To satisfy the detection of transparent lamp parts in the car lights assembly,a hierarchical matching algorithm based on the image pyramid was proposed combining with the normalized cross correlation method. Histogram equalization and sharpening filtering are used to improve the gray contrast and to enhance the edge of the image. Then the image matching is realized by the normalized cross correlation similarity function, and through pyramid algorithm to improve the speed of image matching. The appropriate matching window size, pyramid layer number and similarity threshold is determined to achieve the installation of transparent parts of the lamp detection through the experiment. It has been proved that the detection rate of the transparent part can reach 95% and the average detection time is 50ms, which has high accuracy and speed.
		2018 Vol. 39 (3): 353-358 [Abstract] ( 423 ) HTML (1 KB) PDF (392 KB) ( 303 )

	359	Research on the Effective Emissivity of Conical Blackbody Cavity Based on Monte-Carlo Method
		SHEN Jiu-li,XING Ting-ting,WU Fei
		DOI: 10.3969/j.issn.1000-1158.2018.03.14
		Effective emissivity of the conical blackbody cavity is calculated by Monte-Carlo method, the method is compared with the finite element method.The influence of some factor, such as the geometrical parameters, the emissivity of the material and the distance from the cavity, on the effective emissivity of the blackbody cavity is analyzed. It indicates that the results obtained by the two methods are essentially same, that is, the ratio of cavity length to cavity radius is 6, the opening radius to cavity radius is 0.5, the cone angle is greater than or equal to 90°, the material emissivity is greater than equal to 0.5, the distance from the detector to the cavity is 15 times as large as the cavity radius. At the same time, when all the conditions above are satisfied, the effective emissivity of the conical blackbody cavity is large.
		2018 Vol. 39 (3): 359-362 [Abstract] ( 476 ) HTML (1 KB) PDF (339 KB) ( 268 )

	363	Research and Application on Radial Deviation Measuring for Vertical Tank VoIume Measurement Base on Wall-climbing Robot
		TONG Lin,ZHANG JING-yue,WANG JIN-tao,WEI Kai,SHI Wen-cai,BAO XUE-song,GUO LI-gong
		DOI: 10.3969/j.issn.1000-1158.2018.03.15
		To design an auto-measurement system of radial deviation calibration which is based on wall-climbing robot. The robot selected double crawler vertical movement and permanent magnetic adsorption, and the mechanical system, electrical system and control system is designed. One 1000m³ vertical tank as a test object, the comparison experiment was carried out with verification regulation( JJG 168—2005 and JJG 988—2004), and the result is 1 mm with reference value. Filed experiments indicate that the equipment is workable and greatly improves the efficiency and safety for the calibration.
		2018 Vol. 39 (3): 363-367 [Abstract] ( 432 ) HTML (1 KB) PDF (402 KB) ( 240 )

	368	Study on Key Technologies of Vibration Calibration Using Homodyne Interferometer
		HU Hong-bo,YANG Li-feng,YU Mei
		DOI: 10.3969/j.issn.1000-1158.2018.03.16
		For the problem of huge data encountered when homodyne interferometer is used in low frequency vibration calibration, first the properties of the spectrum of the interference is described, and then a dynamic successive phase unwrap algorithm is used, this method requires information about acceleration in the process. Based on this method, the sampling rate can be heavily reduced with losing information and a small capacity of data. During the process of the amplitude and phase angle estimation, a recursive method of least squares is recommended, with this method not only the computation of matrix inverse can be avoided, but also value of the parameters can be calculated online. To sum up, the methods proposed can broaden the low frequency range for vibration calibration using homodyne interferometer.
		2018 Vol. 39 (3): 368-372 [Abstract] ( 460 ) HTML (1 KB) PDF (777 KB) ( 484 )

	373	Research on the Enhanced Detection Method of Bearing Fault Weak Fault Signal Based on Nonlinear Coupled Bistable Stochastic Resonance
		SHI Pei-ming,SUN Peng,YUAN Dan-zhen
		DOI: 10.3969/j.issn.1000-1158.2018.03.17
		In order to solve the problem that the weak fault signal of rolling bearing is difficult to be detected, a new method based on a new nonlinear coupled bistable stochastic resonance model is proposed. Under the background of noise, stochastic resonance can enhance the output of weak signal and improve the detection of weak signal. The nonlinear coupled bistable system proposed in this paper is composed of two single bistable system with nonlinear coupling. The influence of different parameters on the phenomenon of stochastic resonance are researched through the analysis of the damping coefficient and the coupling coefficient, with the noise intensity change SNIR (signal to noise improvement ratio) response curve. The results show that the coupled bistable system is more robust than the single bistable system. In the end, the bearing fault of weak signal was enhanced by using this detection model, the proposed nonlinear coupled bistable stochastic resonance can detect weak fault signal noise in complex background.
		2018 Vol. 39 (3): 373-376 [Abstract] ( 359 ) HTML (1 KB) PDF (940 KB) ( 414 )

	377	Avogadro Constant Determination and Kilogram Redefinition
		LUO Zhi-yong,WANG Jin-tao,LIU Xiang,LI Zhan-hong
		DOI: 10.3969/j.issn.1000-1158.2018.03.18
		When the kilogram is redefined in terms of the fixed numerical value of the Planck constant h, the X-ray crystal density (XRCD) method, among others, is used for realizing the redefined kilogram. The XRCD method has been used for the determination of the Avogadro constant N_A by counting the number of atoms in a ²⁸Si-enriched crystal, contributing to a substantial reduction of uncertainty in the values of N_A and h to 2×10^-8. This method can be therefore used reversely for the mass determination of a 1 kg sphere prepared from the crystal. The key technologies of lattice constant, isotope, concentration of silicon, diameter of silicon sphere and surface oxide layer are described. The definition of atomic counting method and the method of its value reproduction are introduced. The method will be an important reference for the quality value reproduction of China after the reform of the international system of units.
		2018 Vol. 39 (3): 377-380 [Abstract] ( 544 ) HTML (1 KB) PDF (462 KB) ( 636 )

	381	Two-dimensional Sound-field Scanning Based on Optical Method
		WANG Hao-yu,FENG Xiu-juan,ZHU Hai-jiang,HE Long-biao,YANG Ping,NIU Feng,WANG Min
		DOI: 10.3969/j.issn.1000-1158.2018.03.19
		The sound field scanning scheme based on acousto-optic effect is investigated and demonstrated. By rotating and translating the loudspeaker, the laser vibrometer can measure the integral projection of the sound pressure along different positions and directions. Using the obtained projection information, the sound pressure distribution of the measured sound field can be reconstructed by inverse Radon transform algorithm. The optical method can improve the experimental efficiency and reduce the experimental time under the certain reconstructing resolution. The 2 kHz sound field emitted by the loudspeaker is reconstructed, and the result shows the two-dimensional spatial distribution of the sound pressure , the spatial and angular resolution are up to 5 mm , 10°.
		2018 Vol. 39 (3): 381-385 [Abstract] ( 413 ) HTML (1 KB) PDF (1153 KB) ( 327 )

	386	Liu-cos Chaotic System and Its Application in Acoustic Weak Signal Detection
		LIU Jian-ming,XI Jing-wei
		DOI: 10.3969/j.issn.1000-1158.2018.03.20
		According to the characteristics of three dimensional chaotic weak signal detection system, a new algorithm for determining the convergence was suggested with a combination of fourier transformation and Lyapunov algorithm. The wide area detection for acoustic weak signal by the three-dimensional Liu-cos chaotic system was proved. When the amplitude of the input acoustic signal is greater than the certain critical threshold, the output of the variable x becomes a cycle perturbation signal balanced on the input acoustic signal, the output of the variables y and z is converged to zero. The critical threshold of the Liu-cos chaotic weak signal detection system has uniqueness. It solves the two problems of the period convergence and narrow detection domain by using the traditional Duffing chaotic acoustic weak signal detection system. The actual experiment of Duffing chaotic acoustic signal detection system and three dimensional Liu-cos chaotic acoustic signal detection system were done. The performances of the chaotic systems in the actual acoustic detection experiment were analyzed.
		2018 Vol. 39 (3): 386-391 [Abstract] ( 373 ) HTML (1 KB) PDF (2218 KB) ( 259 )

	392	Short-term Power Load Forecast Based on Big Data Reduction and PCA-improved RBF Network
		ZHANG Shu-qing,REN Shuang,CHEN Rong-fei,QIAN Lei,JIANG Wan-lu,LI Pan
		DOI: 10.3969/j.issn.1000-1158.2018.03.21
		For big data feature of power load being more and more prominent, least absolute shrinkage and selection operator (Lasso) algorithm is introduced to solve the power load problem of big data by extracting features of high-dimensional data from power load and related weather factors. To avoid the adverse effect that the prediction accuracy of RBF neural network is affected severely, caused by that the autocorrelation of input space is too serious and the dimension of network is too high, the improved RBF neural network power load forecasting model is proposed based on principal component analysis. It eliminates the correlation among weather factors, excludes redundancy and extracts feature variables of multiple weather factors.The obtained weather characteristics are taken as the modeling objects of the RBF network together with the dates of historical load, which not only characterize fully the impact of weather factors on the power load, but also simplify the prediction model and accelerate the forecasting rate. Through the experiments of forecasting and analyzing to the actual power system load in a certain region of southern United States, it proved the validity and reliability of the method fully.
		2018 Vol. 39 (3): 392-396 [Abstract] ( 394 ) HTML (1 KB) PDF (1187 KB) ( 398 )

	397	A Method for Estimating Frequency Stability of Atomic Clock
		WANG Yu-zhuo,ZHANG Ai-min,ZHANG Yue,YANG Zhi-qiang
		DOI: 10.3969/j.issn.1000-1158.2018.03.22
		To evaluate reasonably the absolute frequency stability of atomic clocks in the same experimental condition, this paper analyzed the algorithm model and solving process theoretically and studied the method for estimating absolute frequency stability when correlated noises exsisted. It is evaluated by the simulated data of three atomic clocks. Under the assumption of independent noises, the deviation between the test result and theoretical value became larger with the increase of the noise correlation. Considering the noise correlation, the relative error of the test result is always less than 1.7%. The effectiveness of the method was further proved with 360-day real data of four cesium clocks in NIM (National Institute of Metrology) time keeping lab.
		2018 Vol. 39 (3): 397-400 [Abstract] ( 431 ) HTML (1 KB) PDF (691 KB) ( 335 )

	401	Design of Signal Generator Applied on Sideband Modulation Pound-Drever-Hall Laser Frequency Stabilization
		LI Chao,CHEN Hua-cai,LIN Yi-ge,WANG Qiang,LI Ye,FANG Zhan-jun
		DOI: 10.3969/j.issn.1000-1158.2018.03.23
		A 6-channel signal generator with all the output channels share the same external frequency reference is designed based on direct digital synthesizer(DDS) chip AD9959 and phase-locked loop(PLL) chip ADF4351, combined with Arduino (an open-source electronic platform based on microprocessor ATmega328) as the controller. The output range of the signal generator is 0 Hz～4.4 GHz. Its frequency, phase and amplitude are adjustable via the USB port and the control panel. By means of mixing and combining, the modulation and the demodulation RF signal are generated. The signal generator is highly integrated and low-cost, and can be an alternative to commercial signal generators in sideband modulation PDH laser frequency stabilization experiment under laboratory conditions.
		2018 Vol. 39 (3): 401-404 [Abstract] ( 533 ) HTML (1 KB) PDF (988 KB) ( 643 )

	405	Research on Calibration Method of Cable Analyzer in Far-end Attenuation-to-Crosstalk Ratio Parameter
		CHEN Long-quan,XU Wei,HUANG Zhen,ZHANG Ying-yan
		DOI: 10.3969/j.issn.1000-1158.2018.03.24
		Far-end attenuation-to-crosstalk ratio (ACR-F) is the primary parameter of digital balanced cable, also the essential test item in cable analyzer. Have proposed a calibration method on ACR-F of cable analyzer, which utilize network analyzer (NA) and impedance converter to measure insertion loss (IL) and far-end crosstalk (FEXT) in reference cable separately, and acquire the derived results. And the calibration method of ACR-F is direct comparison between the NA and cable analyzer on the reference cable. The method is confirmed through comparison with Psiber Wirexpert series cable analyzer, and extended uncertainty is also listed.
		2018 Vol. 39 (3): 405-409 [Abstract] ( 482 ) HTML (1 KB) PDF (893 KB) ( 250 )

	410	Half Value Layer Measurement of Mammography X-Ray Standard
		GUO Si-ming,LIU Ying,WU Jin-jie
		DOI: 10.3969/j.issn.1000-1158.2018.03.25
		The molybdenum target X-rays machine is used as the radiation source. A free air cylindrical chamber is designed for detecting photon.Four standard radiation qualities are established as per international standards file , the half-value layers, the second half value layer and homogeneous coefficients of each quality are measured by using curve fitting method, and standardize the quality of radiation energy can be calculated. Compared with that of BIPM, the HVL （half-value layer） deviation is around 1%.
		2018 Vol. 39 (3): 410-413 [Abstract] ( 474 ) HTML (1 KB) PDF (819 KB) ( 343 )

	414	IGSA-LSSVM Soft Sensing Model for Predicting NOx Emission of Coal-fired Boiler
		DING Zhi-ping,LIU Chao,NIU Pei-feng
		DOI: 10.3969/j.issn.1000-1158.2018.03.26
		Based on least squares support vector machine optimized by improved gravitational search algorithm (IGSA-LSSVM), an intelligent soft sensing method to accurately measure the NO_x emission of the coal-fired boiler is presented. Firstly, the GSA have the drawbacks of easy to fall into local minimum and poor global search ability, so an improved version of GSA is proposed to improve global optimal performance, using the grid algorithm that is employed to initialize the population and using the adaptive decreasing inertia weight based on fitness value of optimization problems that is introduced into position update. Secondly, IGSA is developed to find the optimal parameters of LSSVM to improve the regression accuracy and generalization ability for predicting NO_x emission. Finally, a soft computing method based on IGSA-LSSVM is established to forecast NOx emission of a 330 MW coal-fired boiler.The simulation results show that the IGSA-LSSVM model demonstrates better regression precision and generalization capability, it can accurately measure NO_x emission.
		2018 Vol. 39 (3): 414-419 [Abstract] ( 418 ) HTML (1 KB) PDF (610 KB) ( 267 )

	420	Prediction of Cement fCaO Based on Particle Swarm Optimization and Continuous Deep Belief Network
		LIU Bin,ZHAO Peng-cheng,GAO Wei,SUN Chao,LIU Hao-ran
		DOI: 10.3969/j.issn.1000-1158.2018.03.27
		It is difficult to accurately detect the content of free calcium oxide in cement clinker in real time, thus a predictive model is proposed based on continuous deep belief network. Firstly, according to the cement clinker production process, the main variables in the firing system on the effect of the free calcium in the cement clinker are obtained. With the use of grey relational analysis theory, the grey relational degree is obtained, ignoring minor factors, and a set of auxiliary variables is established. Secondly, the cement clinker fCaO content model is built by using the particle swarm optimization algorithm to optimize the parameters of continuous deep belief network. Finally, compared with prediction effect of least squares support vector machine and back-propagation, the simulation results show that the model is of high precision and strong generalization ability.
		2018 Vol. 39 (3): 420-424 [Abstract] ( 421 ) HTML (1 KB) PDF (1124 KB) ( 304 )

	425	Research on Accurate Measurement of Potassium Content in Fertilizer Reference Materials
		WANG Zhao,SHI Nai-jie,Mukram Abliz
		DOI: 10.3969/j.issn.1000-1158.2018.03.28
		A method combined with potassium tetraphenylborate gravimetric analysis and ion chromatography is adopted to measure the content of potassium in potassium sulphate which is one of the fertilizer reference materials. The content of sodium in the precipitate and the content of potassium in the residues and filtrates are measured by ion chromatography. The effects of the gravimetric method are analyzed including buoyancy correction, insolubles, residues, filtrates and sodium content contained in the precipitation. Updated by the analysis, the influencing factors are reduced to the minimum. The reference material of potassium sulfate is reproduced and measured with this method. The potassium content is 44.69%, the expanded uncertainty is 0.17%(k=2)and the uniformity and stability are both met the requirement. And its traceability is guaranteed.
		2018 Vol. 39 (3): 425-430 [Abstract] ( 442 ) HTML (1 KB) PDF (674 KB) ( 290 )

	431	Study on Temperature Control for Ring-Down Cavity
		CAO Ke,LIANG Chao-qun,GUO Rui-min,ZHANG Gui-chun,XING Su-xia,ZHAO Yu-xiang
		DOI: 10.3969/j.issn.1000-1158.2018.03.29
		A temperature control system for ring-down cavity is developed.The temperature control box with silicone heating plate on the inner wall is designed firstly, which the ring-down cavity is placed in. The internal temperature distribution is simulated. The finite element analysis and parametric scanning are carried out to get the optimized distribution and power of the heating plate to ensure the temperature uniformity along the light-transmitting part of the cavity. According to the simulation results, the actual box and heating plate are fabricated. Then, the hardware circuit system including temperature sampling module, control module and drive circuit module are designed with PID control algorithm as the core, and the corresponding control algorithm is developed to precisely control the cavity temperature change. After the precision temperature control system is completed, the standard deviation of the temperature variation along the light-transmitting part of the ring-down cavity is less than 0.01 ℃ in 8 hours.
		2018 Vol. 39 (3): 431-435 [Abstract] ( 529 ) HTML (1 KB) PDF (1051 KB) ( 307 )

	436	Comparability of Digital PCR and Next Generation Sequencing on Detection of KRAS Mutations Frequency
		DONG Lian-Hua,WANG Jing,FU Bo-qiang,DUAN Yu-hang,SUI Zhi-wei
		DOI: 10.3969/j.issn.1000-1158.2018.03.30
		Two specific detection methods for KRAS G12R and G12S mutations, based on digital PCR and next generation sequencing (NGS), respectively, were established. Taking the advantage of cell lines containing the target KRAS mutation to prepare a different proportion of G12R and G12S mutations, the analysis sensitivity and comparability of the two proposed methods was investigated. It turned out that no significant difference (p>0.05) was observed between NGS and digital PCR when measuring the sample containing mutation ratio over than 0.83%.However, the result analyzed by digital PCR was significantly different (p<0.05) from NGS, when measuring the sample containing mutation ratio less than 0.83%. There was no significant difference between the digital PCR result and the theoretical preparation value.This indicated that the two methods were comparable when analyzing high abundance of KRAS mutation, and digital PCR with higher accuracy is proper applied in the detection of low abundance KRAS mutation.The sensitive of NGS for detection of KRAS mutation is about 1%, whereas digital PCR showed a better sensitivity of 0.02% when analyzing G12S mutation.
		2018 Vol. 39 (3): 436-441 [Abstract] ( 594 ) HTML (1 KB) PDF (746 KB) ( 677 )

	442	Key Technology Research on Model Eye Device for Non-contact Tonometer
		ZHANG Jin-ming,ZHANG Zhong-li,WANG Can
		DOI: 10.3969/j.issn.1000-1158.2018.03.31
		To solve the value traceability of non-contact tonometer, through deeply analyzing of the Imber-Fick and Glodmann tonometer principle that involved in the intraocular pressure testing, a model eye device for non-contact tonometer is independently designed and developed, where the composite structure of the cornea and sclera, and the system correction method are adopted, the same corneal deformation and the inner pre-set pressure are controlled both during the testing and tracing, the external standard value of intraocular pressure are traced back to the quality and length, using a L-shaped torque balance. The experimental results show that the device has good repeatability and stability, where the resolution is up to 1 Pa, and pressure is continuously adjustable. The expanded uncertainty reaches at 0.08 kPa (k=2).
		2018 Vol. 39 (3): 442-448 [Abstract] ( 626 ) HTML (1 KB) PDF (1321 KB) ( 565 )

News

Download

Links

Copyright © Editorial Board of Acta Metrologica Sinica
Supported by:Beijing Magtech