China Institute of Metrology | Date: 2017-06-21
The present invention relates to a novel objective method for assessing high contrast resolution of images based on Rayleigh criterion and a testing operating method. The novel objective method for assessing high contrast resolution of images based on Rayleigh criterion involves combining the Rayleigh criterion with regional pixel intensity profiles for simultaneous application to high contrast resolution images of CT equipment, which allows objective assessment by using the Rayleigh criterion after the drawing of the regional pixel intensity profiles; the introduction of a normalized margin and the use of a Lanczos window function for interpolation processing on original images enable a considerably practical, time-effective and operable objective assessment method that is convenient for testers to use and also easy for CT equipment operators to use. Such a method, just like a modulation transfer function (MTF) method, is capable of tracking subtle and slow changes of the high contrast resolution of CT equipment in the life cycle thereof objectively and accurately, thus allowing improvement of the use efficiency of the CT equipment in the life cycle thereof; therefore, the method is suitable for extensive popularization and application.
Quan C.,China Institute of Metrology
Food Chemistry | Year: 2014
This work described the assignment of purity values to six carbohydrate certified reference materials, including glucose, fructose, galactose, lactose, xylose and sucrose, according to the ISO Guides 34 and 35. The CRMs' purity values were assigned based on the weighted average of quantitative nuclear magnetic resonance method and mass balance approach with high resolution liquid chromatography - evaporative light scattering detection. All the six CRMs with following value amount fractions: glucose (GBW10062) at a certified purity P ± U (k = 2) of (0.99 ± 0.005)%; fructose (GBW10063) at (0.99 ± 0.005)%; galactose (GBW10064) at (0.99 ± 0.007)%; lactose (GBW10065) at (0.99 ± 0.008)%; xylose (GBW10066) at (0.99 ± 0.007)% and sucrose (GBW10067) at (0.99 ± 0.008)%, respectively were certified. The homogeneity of the CRMs was determined by an in-house validated liquid chromatographic method. Potential degradation during storage was also investigated and a shelf-life based on this value was established. © 2013 Elsevier Ltd. All rights reserved.
Yuan Z.,China Institute of Metrology
Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument | Year: 2012
Aiming at the problems of actual temperature measurements and the defects of classical radiance thermometry theory, the concept of generalized effective radiance temperature (GERT) is proposed, which adopts gray-body as the reference radiator. Furthermore, the relationship between the "subjective" characteristic (integral GERT) measured by band-pass radiation thermometer and the "objective" characteristic of surface effective radiation (GERT) is exposited with the equivalent wavelength theory. The general characteristics of the GERT and its conversion relationship with the generalized, effective and classical radiance temperatures are summarized. GERT theory is a development of the classic apparent temperature theory with blackbody as the reference radiator, which can express and explain the practical measurement results of radiation thermometers in theory, including the measurement results of the radiation thermometers with the correction function of instrument emissivity.
Yang B.,China Institute of Metrology
Guocheng Gongcheng Xuebao/The Chinese Journal of Process Engineering | Year: 2014
In order to deal with the problem that empirical model of by-product gas consumption in iron and steel enterprises cannot accurately predict the by-product gas consumption, the analysis of by-product consumption user and its characteristics is carried out. Support vector machine is used to classify the by-product gas consumption. It combines Powell calculation, simulated annealing arithmetic calculation, and support vector regression machine (SVRM), a model of PSA (Powell simulated annealing)-SVRM to predict the by-product gas consumption has been established. By-product gas consumption data in some iron and steel enterprises are used in the model. The results show that the prediction accuracy for sintering, steelmaking and continuous casting processes is 94.8%, 94.9% and 100%, respectively, with the relative mean error of 2.5%, 2.8% and 2.1%, respectively, which indicates that this PSA-SVRM model is suitable to prediction of the by-product gas consumption. Wilcoxon sign rank test proves the effectiveness of PSA-SVRM model.
China Institute of Metrology and Zhejiang University | Date: 2012-08-16
The infrasound generating device based on a displacement-feedback type vibration exciter comprises a displacement-feedback type vibration exciter system, an infrasound generating chamber (3) and a laser vibrometer (1); the displacement feedback mechanism is adopted in the vibration exciter (2). The piston (31) is driven by the vibration exciter to move in a sinusoidal manner in the cavity (35) of the airtight infrasound generating chamber (3) and the standard infrasonic pressure signal with low harmonic distortion can be achieved. The displacement of the moving part (22) of the vibration exciter (2) can be measured by the laser vibrometer (1) through the measurement beam (15) injecting into the vibration exciter (2) through the optical channel running through the vibration exciter and the standard infrasonic pressure can also be obtained. The value of the standard sound pressure produced by the infrasound generating chamber is calculated. Such value is used as the calibration reference for the infrasound sensors (4) to be calibrated in order to achieve the primary calibration of the infrasound sensors. The standard infrasonic sensor can be installed inside the infrasound generating chamber (3) and the output of the standard infrasonic sensor can be used as the reference for the infrasonic sensor (4) to be calibrated in order to achieve the secondary calibration of the infrasound sensors. This invention has the advantages of technical maturity, high feasibility, easy to realize, high calibration accuracy and so on.
China Institute of Metrology | Date: 2014-08-15
The present invention discloses a rectangular ion trap device and method for ion storage. The device comprises a front end cover including left electrode, middle layer insulator, and right electrode, wherein the left electrode and the right electrode are respectively positioned at both sides of the middle layer insulator; a rear end cover, wherein the rear end cover has the same axis as the front end cover, and the central position of the rear end cover electrode is penetrated; the front and rear electrodes and the upper and lower electrodes are symmetric along the axis of the front end cover, and these electrodes form a space region for ion storage about the axis between the front end cover and the rear end cover electrode. The present invention can increase the number of ions in storage within a unit time prominently.
China Institute of Metrology and Zhejiang University | Date: 2012-05-03
The electromagnetic vibration exciter system with an adjustable electro-viscoelastic suspension device comprises an electromagnetic vibration exciter, a power amplifier and an adjustable electro-viscoelastic suspension device, which acts as the suspension device of the electromagnetic vibration exciter. The adjustable electro-viscoelastic suspension device contains a displacement sensor detecting the displacement of the moving component, a first adjustable amplifier and a second adjustable amplifier, a differentiator, an adjustable phase shifter, an adder and a proportioner. The linearity of the stiffness and damping of the exciter system is excellent, which can be adjusted as need through the adjustment of gain of the adjustable amplifier, the proportioner, the adjustable phase shifter. This invention has adjustable and linear parameters and it is also easy to be realized.
China Institute of Metrology and Zhejiang University | Date: 2012-05-03
The vibration exciter system with a feedback control unit based on an optical linear encoder comprises a vibration exciter, a signal generator and a power amplifier. The exciter system further comprises an optical linear encoder converting the displacement of the moving component of the exciter into A/B pulse with a phase difference of 90, a filtering, shaping and level translator unit converting the A/B pulse into standard pulse with standard shape and level, a subdivider and orientation recognizer unit refining the standard pulse and recognizing the moving orientation, an analog converter unit converting the refined standard pulse into analogue signal that reflects the displacement of the moving component. The standard signal outputted by the signal generator and the converted analogue signal are inputted into a subtracter as the minuend and subtrahend respectively. The output of the subtracter is inputted into the power amplifier and then into the vibration exciter as a driving signal. The present invention has a high precision.
China Institute of Metrology | Date: 2014-01-28
The present invention discloses a method for measuring absolute value of non-linear error and an apparatus thereof. The method comprises: placing N reflecting plates jointed together at the sample port of the optical measuring instrument at the same time, wherein each of reflecting plate has a same covering area at the sample port; placing an aperture along light paths of the optical measuring instrument; adjusting the number of reflecting plates as used according to a position in the measuring range of the optical measuring instrument where the non-linear error is required to be measured; following every adjustment, acquiring the output results when the adjusted reflecting plates are placed at the sample port; performing a computation processing for non-linear error to the output results; and acquiring the non-linear error of the output results of the optical measuring instrument.
China Institute of Metrology | Date: 2014-01-15
A method for quasi-synchronous tuning of wavelength or frequency of grating external-cavity semiconductor laser and a corresponding semiconductor laser are provided. A grating or mirror is rotated around a quasi-synchronous tuning point (Pq) as rotation center, so as to achieve the frequency selections by grating and resonance cavity in quasi-synchronous tuning, wherein the angle of the line between the quasi-synchronous tuning point (Pq) and a conventional synchronous tuning point (P0) with respect to the direction of light incident on the grating is determined according to the angle difference between the incidence angle and diffraction angle of light on the grating. According to present invention, approximately synchronous tuning of laser is achieved with a simple and flexible design.