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2017 Vol. 38, No. 1 Published: 2017-01-22

	1	Sound Speed Measurement for Carbon Dioxide Near the Critical Region
		ZHENG Rong-wei,FENG Xiao-juan,WU Si,ZHAO Xin-yue,ZHANG Jin-tao,HUAN Ke-wei
		DOI: 10.3969/j.issn.1000-1158.2017.01.01
		Using a cylindrical acoustic resonator, the speed of sound in CO2 at the temperature from 303.10～303.18 K and pressure from 3.855～7.534 MPa is measured. The relative uncertainty of the speed of sound in CO2 is 0.035% at pressure lower than 7.1 MPa and 0.15% at pressure higher than 7.3 MPa. The relative deviation between present data and the calculation from the equation of state is 0.005%～-0.4%. The measurement results can be used to improve the equation of the state of CO2. The experimental system and method can be used in the measurement of CO2 and other working fluids in a wider temperature range in the next future.
		2017 Vol. 38 (1): 1-6 [Abstract] ( 737 ) HTML (1 KB) PDF (1564 KB) ( 1118 )

	7	International Research Overview of Inversion Approach of Carbon Emission Measurement in Urban Area
		HU He-ming,WANG Chi,ZHANG Jin-tao
		DOI: 10.3969/j.issn.1000-1158.2017.01.02
		Urbanization has concentrated over 50% of the global population and more than 70% of the carbon emissions. Uncertainties in carbon emissions are very large or unknown at the spatial scale of individual cities, and 50% to 100% errors are not uncommon. The temporal and spatial distribution of greenhouse gas concentration is introduced, and the basic idea of carbon emission inversion model is described. Current NIST funded studies in several cities using top-down approach to estimate carbon emissions. Based on measurement of greenhouse gas concentration and accurate dispersion models that can operate at the city scale, carbon emissions in urban area can be estimated by inversion method. NIST researches are summarized and future works in this field by NIM of China are in plan.
		2017 Vol. 38 (1): 7-12 [Abstract] ( 897 ) HTML (1 KB) PDF (5084 KB) ( 1444 )

	13	Investigation on Line Shape for N₂-broadened CO Near 1.6 μm
		ZHAO Xin-yue,LIN Hong,YANG Lei,QIAN Jin,LI Hui,ZHANG Jin-tao
		DOI: 10.3969/j.issn.1000-1158.2017.01.03
		Frequency-stabilized cavity ring-down spectroscopy is developed for tracing gas concentration with very high sensitivity and accuracy in recent years. However, line shape is the key factor affecting the concentration measurement based on the spectrum method. Using the frequency-stabilized cavity ring-down spectroscopy to study the N2-broadened CO lineshape for R12(3←0) line, six line profiles are used to investigate the relationship between the lineshape parameters. The results show that VP is not proper profile for describing the lineshape, pCqSDNGP is the best profile to obtain the parameters for CO absorption spectrum.
		2017 Vol. 38 (1): 13-18 [Abstract] ( 780 ) HTML (1 KB) PDF (1310 KB) ( 741 )

	19	Research on Phase Change Characteristic of Miniature Gallium Fixed-point Using Quasi-adiabatic Measurement Method
		XU Chun-yuan,XIA Cai-juan,HAO Xiao-peng,SUN Jian-ping,WEN Ping,SONG Jian,YUAN Zun-dong
		DOI: 10.3969/j.issn.1000-1158.2017.01.04
		The formation process of miniature Ga fixed-point which can be used for in situ calibration, the structure and working principle of the quasi-adiabatic testing system are described.The phase change characteristic of miniature Ga fixed-point is measured using this quasi-adiabatic testing system. The results show that the melting point of Ga fixed-point has strong linear relationship with the heating power. The linear fitting factor R2 is 0.995 7. The lower the heating poweris, the closer to the standard temperature of Ga fixed-point it becomes. Further more, the repeatability of the melting points of Ga is better than 2 mK under the same quasi-adiabatic testing system.
		2017 Vol. 38 (1): 19-22 [Abstract] ( 672 ) HTML (1 KB) PDF (1238 KB) ( 548 )

	23	The Temperature Segregation Area of Asphalt Pavement Detection Method Based on Infrared Thermal Images
		ZHANG Yu-cun,HOU Xin-yu
		DOI: 10.3969/j.issn.1000-1158.2017.01.05
		A temperature segregation area of asphalt pavement detection method based on infrared thermal images is proposed. The asphalt pavement temperature in the infrared thermal image and the improved gray image edge segmentation model are combined to create a temperature segregation area of asphalt pavement detection model. The model parameters are solved by using duality method. BP neural network optimization and the least squares fitting are combined to establish the relationship between the asphalt pavement temperature of the infrared thermal image and gray in the model, and detect the temperature segregation areas of the asphalt pavement. Finally, the feasibility of the proposed method is verified by simulation experiments and the method lays the theoretical foundation for engineering construction of roads, scientific research and other areas of infrared thermal image processing.
		2017 Vol. 38 (1): 23-27 [Abstract] ( 594 ) HTML (1 KB) PDF (2348 KB) ( 515 )

	28	Research on Measurement Method of Thermal Diffusivity of Materials Based on Thermography
		LI Yang,HOU De-xing,YE Shu-liang
		DOI: 10.3969/j.issn.1000-1158.2017.01.06
		The thermal diffusivity measurement method of the thin specimens based on thermography technology is researched and improved, and the theoretical model is developed from two-dimensional model to three-dimensional model, so that the materials with bigger thickness can be measured by this method.The characteristic condition, which must be satisfied when this measurement method can be used, is that the relationship between the spatial derivatives of temperature in Z-direction and temperature difference between the surface temperature of material and environmental temperature is a linear relation. The effects of conducting distance and excitation time on the characteristic condition are analyzed, and the relevant problems of signal to noise ratio by the simulation experiment are also studied. Setting the conducting distance and excitation time according to the simulation analysis when measure the thermal diffusivity of 304 stainless steel, the results show that the deviation of the measurement for the stainless steel with thickness of 1 mm and 2 mm is less than 3.0%, and the deviation of the measurement for the stainless steel with thickness of 5 mm is 4.1%, so the range of application of the measuring method is expand.
		2017 Vol. 38 (1): 28-33 [Abstract] ( 559 ) HTML (1 KB) PDF (1019 KB) ( 748 )

	34	Study on Uncertainty Evaluation of Annual Performance Factor Based on Air-enthalpy Method
		HANG Chen-zhe,XU Ding-hua,MA Guo-yuan,ZHANG Hai-yun,TENG Jun-heng
		DOI: 10.3969/j.issn.1000-1158.2017.01.07
		Based on air-enthalpy method model expressed in direct measurement parameters, the uncertainty of annual performance factor (APF) was evaluated using Monte Carlo method combined with GUM. As air-enthalpy method is nonlinear and GUM is only perfectly suitable for the linear model, the rated cooling capacity uncertainty and the rated heating capacity uncertainty obtained using GUM were verified primarily by MCM, and the differences between results obtained by GUM and MCM were lower than 2‰. On this basis, uncertainty results of five different measurement conditions were given, and these parameters were used as the inputs of simulation. The adaptive Monte Carlo method simulation flow chart of APF was given, and APF uncertainty of an air conditioner was evaluated, the result was 0.09 kW·h/(kW·h)(k=2).
		2017 Vol. 38 (1): 34-39 [Abstract] ( 680 ) HTML (1 KB) PDF (829 KB) ( 600 )

	40	The Calibration Method of Working Rediation Thermometer with Fixed Emissivity
		YU Shi-fan,CUI Chao,WANG Xiao,XIONG Yu-ting,SHEN Cai-zhong
		DOI: 10.3969/j.issn.1000-1158.2017.01.08
		The principle for the calibration of working radiation thermometer with fixed emissivity is discussed and analyzed. It is necessary to apply the surface radiation source in the calibration, the emissivity of which could be consistent with that of thermometer to ensure the accuracy of temperature quantity value transfer. The temperature errors from the deviation of both emissivities are also discussed, and the error calculation formula is given, in the case of 0.95(emissivity)and 700 K(temperature) the maximum temperature error is up to 15 K.The radiation thermometers could directly measure the pratical temperatures for the targets, if the emissivity of target is the same as that of thermometer.
		2017 Vol. 38 (1): 40-42 [Abstract] ( 639 ) HTML (1 KB) PDF (393 KB) ( 807 )

	43	Preparation of Probe Tips Applied to Tuning Fork Atomic Force Microscopy
		WANG Ya-li,XIONG Yan-yan,GAO Si-tian,ZHOU Yan-jiang,SHI Yu-shu
		DOI: 10.3969/j.issn.1000-1158.2017.01.09
		The system of tungsten probe tips preparation using electrochemical etching method is introduced. It can automatically and quickly control the corrosion on or off through the real-time detection of the electrochemical etching weak current signal and power-off time is 0.3 ms. The system has prepared the desired profile of the exponential probe. Analyzing the relationship between the electrolysis voltage, electrolyte concentration and the corrosion current, the optimum parameters for corrosion will be determined. The quartz tuning fork and homemade tungsten probe bonding constituted an atomic force microscope probe, this will make a force curve test in amplitude modulation mode. The results showed that the homemade tungsten probe can meet the requirements of AFM scanning head. Tuning fork signal is stable to identify changes in the movement of 10 nm. For the development of high performance tuning fork AFM provides the experimental technology base.
		2017 Vol. 38 (1): 43-46 [Abstract] ( 649 ) HTML (1 KB) PDF (1284 KB) ( 1197 )

	47	Research on an Indirect Calibration Method of Micro/nano Coordinate Measuring Machine
		SHI Yu-shu, GAO Si-tian, SONG Xiao-ping, GUO Xin, CHEN Si-wen, PI Lei,LI Wei, LI Qi, LI Shi, WANG Xing-wang
		DOI: 10.3969/j.issn.1000-1158.2017.01.10
		Since the high precision performance index of micro/nano coordinate measuring machine cannot be calibrated accurately, an indirect calibration solution is proposed. The measurement indication error of the micro/nano coordinate measuring machine is measured by gauge blocks and ball plate with hemispheres; The probing error is measured by calibration sphere. And a calibration experiment is done on the micro/nano coordinate measuring machining at National Institute of Metrology. The experimental results show that the error of indication of a CMM for size measurement is less than 0.2 μm, and the probing error is only 0.125 μm. The experiment results indicate that the error of indication of a CMM for size measurement and probing error are both less than their maximum permissible error, verifying the reasonability and feasibility of the calibration plan.
		2017 Vol. 38 (1): 47-50 [Abstract] ( 772 ) HTML (1 KB) PDF (1233 KB) ( 710 )

	51	Measurement uncertainty analysis of CMM in product inspection and conformance testing
		CHEN Xiao-huai,JIANG Rui,WANG Han-bin,XU Lei,CHENG Yin-bao,CHENG Zhen-ying
		DOI: 10.3969/j.issn.1000-1158.2017.01.11
		Uncertainty of the CMM in product inspection was evaluated based on the indexes of quantum property by using the method of measurement system analysis. Using the measurement uncertainty as the quality index of product inspection, considering the accuracy of product design, the mathematical model of the misjudgment probability in product inspection was established, based on the tolerance of product design and the measurement result combining with its uncertainty. A product inspection experiment was conducted with CMM . The reasonable evaluation of the measurement system's indexes of quantum property were given, the conformity assessment was carried out based on the uncertainty of product inspection, misjudgment probability was calculated. Finally, the feasibility and operability of the method were verified.
		2017 Vol. 38 (1): 51-55 [Abstract] ( 643 ) HTML (1 KB) PDF (3322 KB) ( 1019 )

	56	Calculation of Correlated Color Temperature by Single-dimension of Hue
		ZHANG Hang,PAN Hao,XU Jun,YU Xi,WU Meng-ying,LIU Chao,ZHOU Hai-bo
		DOI: 10.3969/j.issn.1000-1158.2017.01.12
		The definition of correlated color temperature and the contradiction of correlated color temperature in three different uniform chromaticity diagrams(CIE1960UCS, CIE1976UCS and CIE1976LAB) are investigated, and a new method based on single-dimension of hue is proposed. The corresponding relation between color temperature and hue was established in the Munsell color system, and the new iso-temperature lines in three uniform chromaticity diagrams are delineated by ignoring the influence of saturation on color temperature. By comparing the new method for correlated color temperature with the traditional method, the physics meaning of the new method is clearer, and low difference is existed in the results from different chromaticity diagrams.
		2017 Vol. 38 (1): 56-59 [Abstract] ( 705 ) HTML (1 KB) PDF (803 KB) ( 1208 )

	60	Face Recognition under Complex Illumination Based on Multi-scale Weberface and Gradientface
		CHENG Shu-hong,LIU Jie
		DOI: 10.3969/j.issn.1000-1158.2017.01.13
		Aiming at the problem of the effect of Complex Illumination on face recognition rates, an integrated method based multi-scale Weber-face and gradient-face is proposed. The method starts with defining the multi-scale Weber-face, which can effectively describe the face texture structure and reduce the influence of different lighting to some extent. Then multiscale face and GF are fused to extract the face illumination invariant. Finally, multi-class support vector machine is employed for face authentication. The experiments are executed both on CMU-PIE and Yale B face databases. The experimental results have indicated that the proposed method can effectively eliminate the influence of face recognition under complex illumination and the recognition rates are superior to Weber-face, multiscale Weber-face and gradient-face, even single sample images with serious light as training sample images can also work well.
		2017 Vol. 38 (1): 60-64 [Abstract] ( 859 ) HTML (1 KB) PDF (1686 KB) ( 576 )

	65	Research on Unconstrained Face Recognition Based on DBNs Network
		ZHAO Yi-zhong,LIU Wen-bo
		DOI: 10.3969/j.issn.1000-1158.2017.01.14
		To overcome the technical difficulties like high degrees of freedom and the complicated interference factors in unconstrained face recognition, an algorithm for unconstrained face recognition based on DBNs network is proposed with the adoption of deep learning theory. Based on relative entropy sparse restrictions and dropout mechanism, the optimization algorithm is designed. As for the problem of small sample in practice, an algorithm based on hybrid DBNs network model is proposed, which generates simulated samples with CNNs model to train the DBNs network. When tested by the standard face library, the experimental results show that the average recognition accuracy of DBNs and hybrid DBNs reach 97.0% and 90.3% respectively, which satisfy the practical using demand
		2017 Vol. 38 (1): 65-68 [Abstract] ( 545 ) HTML (1 KB) PDF (800 KB) ( 1010 )

	69	Compressed Sensing Reconstruction Algorithm Based on Hybrid Sampling
		ZHANG Shu-qing,HU Yong-tao,WANG Shi-hao,JI Bing-shuo,JIANG Wan-lu
		DOI: 10.3969/j.issn.1000-1158.2017.01.15
		In order to improve the image reconstruction quality and the reconstruction time with high compression ratio, a compression perception reconstruction algorithm based on hybrid sampling is proposed. The image is divided into the interested and non-interested area. It used the orthogonal matching pursuit (OMP) algorithm with better quality of recovery for the interested area, and the Stagewise Orthogonal Matching Pursuit algorithm with the recovery time shorter for the non-interested area. In the interested image, the gray level of the parts except the interested region is set to zero, so as to increase the rate of sampling and image sparse degree. Experiments show that this method could restore the interested area of an imagine better, and maintain a high compression ratio.
		2017 Vol. 38 (1): 69-72 [Abstract] ( 545 ) HTML (1 KB) PDF (953 KB) ( 717 )

	73	A Two-step Stereo Matching Based on the Local Texture Features and Image Segmentation
		CHEN Hua,ZHANG Zhi-juan,LIU Gang,HU Chun-hai,WANG Shu-tao
		DOI: 10.3969/j.issn.1000-1158.2017.01.16
		To solve the problem of meeting accuracy and speed requirements simultaneously, a two-step stereo matching method is proposed. According to the local texture features, a transform is adopted to the couple of images, and the reference image is segmented with mean shift algorithm, the first matching based on the support region with arbitrary shape and size was used to form a parallax constraint, then the second matching based on fixed window is adopted to obtain the initial disparity map. Finally, the disparity map is optimized by the different reliabilities classification. The experiment results show that the algorithm has higher matching speed and accuracy.
		2017 Vol. 38 (1): 73-77 [Abstract] ( 560 ) HTML (1 KB) PDF (1596 KB) ( 614 )

	78	Study on Physiological Slice Trabecular Recognition Based on Multi-feature-found
		YE Han-xiao,JIN Hong-ting,YUAN Xin,YING Hang
		DOI: 10.3969/j.issn.1000-1158.2017.01.17
		Target recognition is a development trend of bone histomorphometry. Study on the characteristics of image information, it is necessary to discriminate trabecular bone of bone tissue sliced by yin hung-hematoxylin. Analysis bone tissue image histogram channel characteristics of HSL color space, based on the image segmentation threshold of color channels, by Lazy Snapping method, it will obtain the image features of trabecular bone in-depth information, and it will improve scanning seed filling algorithm to extract multi feature information by fusion target area. The results show that extract trabecular bone by analysis image multi-feature let repetitive operation improve, improved scanning seed filling algorithm let complex image such as trabecular extraction speed from ten minutes to 257ms. Improved scan line algorithm can get the robust target area more quickly.
		2017 Vol. 38 (1): 78-81 [Abstract] ( 777 ) HTML (1 KB) PDF (928 KB) ( 1006 )

	82	Research on the design of pneumatic tube based on the acoustic vector sensor in the continue flow
		DAI Hai-fa,TAO Jian-wu,YU fei
		DOI: 10.3969/j.issn.1000-1158.2017.01.18
		As an important part of the flush air-data sensing (FADS) system, the pneumatic tube has an important influence on the reliability and measurement accuracy of the system. In this paper, the knowledge of fluid dynamics is used to build the dynamic response model of pneumatic tube in the continue flow and the transfer function is deduced. Through the transfer function, the dynamic characteristic of the pneumatic tube has been analysised, furthermore, the design criteria for the pneumatic tube has been formulated. Finally, the simulation results have been showed to prove the dynamic response model and the design criteria of the pneumatic tube, thus providing reference to the design of the FADS system.
		2017 Vol. 38 (1): 82-86 [Abstract] ( 515 ) HTML (1 KB) PDF (389 KB) ( 535 )

	87	Development of Dust Sampler Based Flow Closed-loop Control
		WU Fu-xiang,CHEN Jian-ge,WANG Jing-yu
		DOI: 10.3969/j.issn.1000-1158.2017.01.19
		Contrary to dust sampler based on open-loop flow control whose sample volume existed errors with the load changes, a closed-loop flow control gas sampler was proposed and studied. A closed loop control system was constituted, using a micro gas mass flow sensor, adjustable micro-pump and controller. Combined with incremental PID control algorithm with dead and method of point accumulated gas sampling, this will eliminate errors caused by changes in load. Finally, the experimental results show that the gas flow of sampler closed-loop control have good linearity and high precision.
		2017 Vol. 38 (1): 87-90 [Abstract] ( 688 ) HTML (1 KB) PDF (322 KB) ( 518 )

	91	The Influence of Sinusoidal Parameters in Evaluation of Effective Bit of ADC Converters by Curve-fit Method
		LIANG Zhi-guo
		DOI: 10.3969/j.issn.1000-1158.2017.01.20
		Aiming at the evaluation of effective of bit of ADC converters, the influences of sinewave parameters are studied in detailed. Through experiment, one can get the conclusion: the best condition of minimum evaluation error of effective bit is that, 1) the peak to peak amplitude of sinusoidal should be odd number times of least significant bit (LSB), 2) the offset of sinusoidal must be integer times of LSB, 3) the initial phase of sinusoidal can’t influence the evaluation results of effective bit of ADC. when the offset of sinewave is the integer times of LSB adds 0.5LSB, it can make the worst error. This conclusion can be used in evaluation of effective bit of ADC converters.
		2017 Vol. 38 (1): 91-97 [Abstract] ( 537 ) HTML (1 KB) PDF (6469 KB) ( 502 )

	98	Manufacturing and Characterizing of Broadband on-Wafer SOLT Calibration Standards
		LIU Chen,WU Ai-hua,SUN Jing,LIANG Fa-guo
		DOI: 10.3969/j.issn.1000-1158.2017.01.21
		On the GaAs substrate the SOLT calibration kits for on-wafer S-parameter test are designed. Using simulation method, the delay and loss of the offset transmission line on every standard in the calibration kits are characterized, and using measurement method based on NIST multiline TRL calibration, the capacitance of open standard parts and the inductance of the short standard are extracted. Subsequently the impedance of load standard is known by DC resistance measurement. Finally, the tests using independent developed SOLT calibration kits and NIST multiline TRL calibration are preformed. The results show that at the frequency below 20 GHz, the maximum deviation of the transmission magnitude is 0.1 dB, and the maximum deviation of transmission phase is 3.5 degree.
		2017 Vol. 38 (1): 98-101 [Abstract] ( 687 ) HTML (1 KB) PDF (1786 KB) ( 1019 )

	102	Research on Uniformity of Field and Fluctuation of RMS Delay in Reverberation Chamber
		GUO Xiao-tao,HE Zhao,HUANG Jian-ming,ZHOU Xin,WANG Shao-hua
		DOI: 10.3969/j.issn.1000-1158.2017.01.22
		Based on the validation of field uniformity, fluctuation of root-mean-square (RMS) delay simulated in reverberation chamber is also investigated, by considering the disturbance introduced by mechanical stirring and positions of receiving antenna. The field uniformity of reverberation chamber is proved to be better than 2.5dB, and the range of RMS delay is also quantitatively evaluated. The differences between the field uniformity and the fluctuation are analyzed for indicating the different roles that they played in some applications.
		2017 Vol. 38 (1): 102-105 [Abstract] ( 611 ) HTML (1 KB) PDF (841 KB) ( 596 )

	106	A Multi-target Detecting Algorithm for Automobile Anti-collision Radars
		ZHANG Jian,TONG Rui,ZHOU Dao-kui,YANG Wen-hua,HUANG Zheng-feng,QI Hao-chen
		DOI: 10.3969/j.issn.1000-1158.2017.01.23
		In view of the shortage of multi-target detecting function in traditional FMCW range radars, a novel target detecting algorithm is developed, which is based on the combination of FSK radar. A similar trapezoid frequency modulated waveform is adopted to realize the effective detection of single and multiple targets. The radar working with this algorithm can not only detect the distance and velocity of single target, but also these parameters of multiple targets. The simulations and verifications are performed by MatLab software. The results show that the novel algorithm can catch the targets accurately, while the precision in measurement is satisfactory. This multi-target detecting algorithm will be applicative to millimeter wave anti-collision radars.
		2017 Vol. 38 (1): 106-111 [Abstract] ( 623 ) HTML (1 KB) PDF (2262 KB) ( 997 )

	112	Study on Fault Diagnosis Method for Rotating Machinery Based on Adaptive Stochastic Resonance and AMD
		SHI Pei-ming,SU Cui-jiao,ZHAO Na,HAN Dong-ying,TIAN Guang-jun
		DOI: 10.3969/j.issn.1000-1158.2017.01.24
		Aiming at the problem of fault diagnosis for rotating machinery with very low signal-to-noise ratio under strong noise background, a fault diagnosis method for rotating machinery based on AMD and stochastic resonance is proposed. If the frequency components of the signal are known, signal with different frequency components can be decomposed into single frequency signal using the AMD method, especially to decompose a signal with closely spaced frequency components. For the fault feature frequency can be predicted in rotating machinery fault diagnosis, AMD method is used to extract fault feature frequency signal in mechanical vibration signal and add low intensity noise to the signal firstly. Then, the signal with noise is put into the optimal stochastic resonance system and denoising and enhancing the signal. Finally the spectrum of the signal is obtained, if the frequency spectrum contains the fault feature frequency, it shows that the faults exist in mechanical vibration signal. Through the extraction of the rolling bearing fault signal feature proved that the method has a good effect.
		2017 Vol. 38 (1): 112-116 [Abstract] ( 478 ) HTML (1 KB) PDF (1494 KB) ( 773 )

	117	The Establishment of the On-site Calibration Device for 2πα and 2πβ Particle Emission Rate Measurement
		LI Ze-xi,HE Hai-jiang,LIANG Jun-cheng,SHAN Jian,GAN Ya-zhou,YANG Zhi-jie,LIU Hao-ran,ZHANG Ming
		DOI: 10.3969/j.issn.1000-1158.2017.01.25
		Based on a large-area, windowless, gas-flow proportional counter, an alpha/beta 2π emission rate on-site calibration device is established. Performance tests are taken and the results show that the plateau of alpha lasts from 700 V to 1 500 V, the length is up to 800V and the slope is 0.25% per 100V, the plateau of beta lasts from 1650V to 2050V, the length is up to 400V and the slope is 0.44% per 100V. This on-site calibration device is used to measure the standard surface sources which are calibrated by the the absolute alpha/beta 2π emission rate measuring system, the results are well agreed with the standard values within the range of uncertainties.On-site measurement of another group of standard surface sources are taken, values of corrected results are agreed with the values calibrated in previous cycles within the range of uncertainties, which verifies the feasibility of this calibration device to deliver the on-site standard values.
		2017 Vol. 38 (1): 117-122 [Abstract] ( 629 ) HTML (1 KB) PDF (936 KB) ( 974 )

	123	Evaluation and Real Time Updating of Measurement Uncertainty Based on Bayesian Information Fusion
		JIANG Rui,CHEN Xiao-huai,WANG Han-bin,XIAO Ying,XU Lei,CHENG Yin-bao,CHENG Zhen-ying
		DOI: 10.3969/j.issn.1000-1158.2017.01.26
		Based on the principle of Bayesian information fusion and statistical inference, the dynamic evaluation model of uncertainty was established and the uncertainty of measurement results was updated in real time. The maximum entropy principle and hill-climbing algorithm were introduced to determine the prior distribution probability density function and the likelihood function of the sample information. The distribution of posterior distribution of PDF was calculated by combining the Bayes formula. And the optimal estimation of uncertainty was achieved. The case and simulation showed that the measurement uncertainty obtained by Bias and maximum entropy method was more accord with the standard requirement.
		2017 Vol. 38 (1): 123-126 [Abstract] ( 608 ) HTML (1 KB) PDF (1761 KB) ( 1052 )

	127	The Comparison of Absolute Gravimeters CCM.G-K2 and NIM-3A Absolute Gravimeter
		WU Shu-qing,LI Chun-Jian,XU Jin-yi,SU Duo-wu,FENF Jin-yang,JI Wang-xi
		DOI: 10.3969/j.issn.1000-1158.2017.01.27
		Based on laser interference technology and free-fall theory, the National Institute of Metrology (China) has developed the latest NIM-3A type absolute gravimeter.This instrument has participated in the 9th international comparison of absolute gravimetries CCM.G-K2,according to the published result of CCM.G-K2,the NIM-3A type absolute gravimeter with the combined standard uncertainty of 5.3 μGal is agreed with the key comparison reference value and the degree of equivalence is gained.
		2017 Vol. 38 (1): 127-128 [Abstract] ( 749 ) HTML (1 KB) PDF (265 KB) ( 592 )

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