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Abstract:
[Abstract]In this paper, a three-axis fiber optic gyro detection system based on superradiant LED light source is designed.Synchronous use of temperature control and constant current drive circuit to ensure the normal operation of the SLD in the full temperature range, the power part of the surge protection design, effectively avoid the transient impact caused by switching power supply or environmental changes, to achieve the protection effect of the device.The detection system monitors the output bias voltage of the photodetector in light and no light, and calculates the system loss of the assembled optical path through numerical analysis, so as to judge whether the technical specifications of the optical path of the fiber optic gyroscope meet the design requirements.Finally, the experiment verifies the function of the three-axis fiber optic gyro combined optical path detection system in the batch production process, the accuracy stability of the fiber optic gyro reaches 87%, and the qualified rate of the finished product is increased to 96%.
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The equivalent capacitance method is the main calibration method for monopole antennas given in CISPR 16-1-6. The principle is to use an equivalent capacitor to simulate an actual monopole element for the calibration of the corresponding antenna factor, and the electric capacity of this equivalent capacitor is equal to the capacity of the monopole antenna itself. Based on the working principle of the equivalent capacitance method, a miniaturized and highly versatile antenna calibrator is designed. Simulation and experimental results show that the calibrator can be well applied to the calibration work of the monopole antenna. The evaluation process and results of the measurement uncertainty of the method are given, and the results show that the extended uncertainty of the measurement results is about 1.7 dB (k=2) when the antenna factor of the monopole antenna is calibrated by this device.
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The performance of different probes varies because of the uneven production of probe manufacturers, so the development of electric field calibration device becomes particularly important. In order to satisfy the calibration requirements of low frequency and high field strength of the electric field probes, a set of low frequency electric field standard is developed by using parallel plates in this paper. The parallel plates are composed of two square aluminous plates with a side length of 1m and the board spacing of 0.5 m. The frequency range is DC~10 kHz and electric field strength range is 0~3000 V/m. Through theoretical analysis, software simulation and experiments, the influences of the side effect, material, shape, frequency of the parallel plates and other factors on the standard field are discussed, and finally, the uncertainty evaluation is performed. A new measurement model is proposed, and seven uncertainty factors such as the voltage at both ends of the plate, plate spacing, the uniformity of the field distribution, probe fixture, probe alignment, the limited size of parallel plate and probe influence are measured respectively and the extended uncertainty is U=6.84%(k=2). The results show that the electric field standard developed in this paper can meet the calibration requirements of low frequency electric field probes.
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Uncertainty evaluation is an important part for the dissemination of the value of a quantity. After the publishing of “JJF 1059.2-2012 Monte Carlo Method for Evaluation of Measurement Uncertainty”, the Monte Carlo method is more and more frequently used for uncertainty evaluation in a variety of metrology area. A Python script for uncertainty calculation is programmed using the Monte Carlo method and the adaptive Monte Carlo method. Taking an example of the calibration of a 100 MPa oil piston gauge, the script was used to evaluate the uncertainty of the effective area of the piston gauge calibrated. The influence of the uncertainty of individual input quantity and its probability distribution on the uncertainty of the output quantity was studied, and the Monte Carlo method based uncertainty was compared to the uncertainty evaluated using traditional method. It is shown that the uncertainty of the calibrated effective area is mainly contributed by the uncertainty of the effective area of the reference piston gauge. The uncertainties evaluated using Monte Carlo method and traditional method are consistent in general, and the expanded relative uncertainties are 32 ppm. The probability distribution of the calibrated effective area is dominated by the probability distribution of the main uncertainty contributor, which is the effective area of the reference piston gauge studied in this work.
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The microwave blackbody provides the microwave radiometer with high-precision brightness temperature signals for the accurate calibration of the observed target’s radiative signal. The emissivity of the microwave blackbody is a crucial parameter affecting its radiative characteristics; hence, accurately measuring the blackbody emissivity is of significant importance for enhancing the calibration precision of the radiometer and ensuring the traceability and effective transfer of measurement values. Currently, the blackbody emissivity is mainly obtained indirectly by measuring the reflectivity. This paper implements two calibration methods in the free-space monostatic reflection coefficient measurement: the offset-short calibration method and the sliding-load calibration method, utilizing time-domain gating techniques to address the influence of multipath reflection signals during small reflection measurements. A reflectivity measurement system was established, and the reflectivity of the same blackbody target was measured within the 75 GHz-110 GHz frequency band, with the results analyzed and compared. The error terms solved by the two calibration methods exhibit high consistency, and the measured emissivity reached levels of 0.999~0.9999. When the measurement target satisfies the approximation conditions, the sliding load calibration method is more efficient. Finally, using the offset-short method as an example, the Monte Carlo method was employed to evaluate the uncertainty of the solved blackbody target reflection coefficient.
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With the increasing number of cars in our country, the pollution problem caused by automobile exhaust is becoming more and more serious, in order to control environmental pollution problems, China promulgated the “People’s Republic of China Air Pollution Prevention Law” as early as 1987. In 2013, the international EURO VI standard (Euro VI A-VI D) was implemented worldwide, and China promulgated the GB 18352.6-2016 “Limits and measurement methods for emissions from light-duty vehicles(CHINA 6)” (hereinafter referred to as “National standard 6th”) in 2016 based on the Euro VI standard combined with its national conditions. It will be implemented in phases from Jan. 2020, putting forward new requirements for the regulation and quality control traceability of vehicle exhaust emissions. This article mainly compares the differences in emission quality control requirements between the National Standard 5th and the National Standard 6th, and introduces the measurement methods for automobile exhaust emission such as carbon monoxide (CO), nitrogen oxides (NOx), non-methane hydrocarbons (NMHC), nitrous oxide (N2O), particle number (PN), particulate matter (PM), etc. in the updated limit emission requirements of the National Standard 6th. At the same time, from the aspects of the development of national gas standard materials, the establishment of measurement standards and the establishment of national automobile testing center, the detection and traceability technology of exhaust emissions in China are introduced. It analyzed that the existing capabilities and technical level could not meet the requirements of some emission detection in National standard 6th, and put forward the items that need to be further optimized in the current traceability technology, such as the condensation nuclear particle counter in the particle number (PN) measuring instrument, and pointed out that in next step should accelerate the research and improvement of the particle concentration attenuation coefficient, volatile particle removal efficiency, dilution ratio and other measurement indicators. In view of the requirements for the determination of methyl chloroformate and benzo [a] pyrene pollutants specified in the Euro VI standard, there is currently no standard material and traceability system in China, and it is necessary to develop standard material that meet the requirements and establish traceability standards, and we need do some job in technical reserves to cope with the increasingly updated quality control requirements at home and abroad. And it is put forward some suggestions for the release of the proposal of the European seventh emission standards (Euro Ⅶ).
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Microwave and millimeter wave power are measured by a thermistor type power meter by DC substitution. To compensation for the changes in environmental temperature, power meters usually equipped with a measurement bridge and a compensation bridge measures power in dual bridge mode. The coaxial thermistor type power sensor was calibrated with a microcalorimeter type power primary standard. Although the environmental temperature is stable, the measurement bridge can't be used alone. To ensure the validity of the primary standard calibration results, the compensation bridges are also used, it not only compensates the effects of environmental temperature, but also for the effects of the temperature variations in the ceramic core due to dual-element errors. The experiments have indicated that their deviation is 0.38% by measuring the DC substitution power of type-N coaxial thermistor sensor with single and double bridges respectively at 18 GHz frequency and 10 mW power level. For calibrating waveguide thermistor type power sensor, it was the structure of single element, so the comparisons of the results between the single and dual bridges power meter measurements are not too meaningful.
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The calibration of electromagnetic reverberation chamber is usually carried out for characteristic parameters such as field uniformity and normalized field strength under low input power. However, in practical applications such as electromagnetic compatibility immunity testing, the actual work is carried out under high input power conditions. At present, this difference is ignored in relevant international and domestic standards, and no specific theoretical or experimental proof is given. Therefore, this paper designed and carried out a specific experimental study to confirm the influence of input power on the characteristic parameters of the electromagnetic reverberation chamber. The rapid calibration technology based on 3D photoelectric field probe is adopted for calibration under low input power, and the parameter measurement under high input power is consistent with the actual working state of auto parts immunity test. The experimental results show that the influence of different input power on the characteristic parameter of field uniformity is basically within ±0.5 dB, and the influence on the normalized field strength is within 2 dB. Further, based on the analysis of the experimental results, the paper gives the corresponding suggestions for the calibration of field uniformity and normalized field strength during the calibration and testing of the electromagnetic reverberation chamber.
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Traditional stepped frequency system synthesizes a large measurement bandwidth by a series of equidistant discrete frequency signals. However, due to the limitations of the sampling theorem, the time-domain signals corresponding to fixed frequency intervals exhibit periodicity. In this case, the background and multipath interference in the field may alias into the target area, leading to adverse effects on imaging and scattering measurements. This paper explores the rapid measurement method for the frequency-stepped system and proposes a near-field scattering measurement technique based on non-uniform sampling. The paper analyzes the influence of range ambiguity on scattering measurements and designs optimization principles for the sampling function based on practical application requirements. The signal envelope is shaped through Poisson and formula-based stationary phase principles (Principle of stationary phase, POSP). To address the degradation of scattering images caused by traditional non-uniform sampling reconstruction methods, the paper proposes a weighted method that is compatible with the non-uniform sampling strategy. This method effectively suppresses aliasing interference, achieves high-resolution imaging, and improves the accuracy of Near Field to Far Field (NF-FF) transformations.
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With the support of the National Key R&D Plan projects, the National Institute of Metrology, China (NIM) has carried out the research and establishment of a new generation calculable capacitor primary standard, inductance primary standard, ac resistance standard and the enhancement capabilities of related impedance standards. With the newly established capacitance primary standard and inductance primary standard, the capacitance unit Farad and the inductance unit Henry have been reproduced at a higher level, and the traceability of dissipation factor primary standard, capacitor working standard, inductor working standard, and the ac resistance standards are all improved. At the meantime, NIM finished revising and updating the calibration system table for capacitance, inductance and dissipation factor measuring instruments, drafting and revising impedance related regulations and specifications such as standard capacitors, standard inductors, ac resistance, capacitor boxes, inductance boxes, etc. A new impedance traceability system of China based on the new generation of calculable capacitor has been established.
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The total station is a high-precision measuring instrument that integrates distance measurement, angle measurement and coordinate measurement. It plays an extensive and important role in the fields of infrastructure construction and geodetic surveying. Among them, the change in measuring scale frequency is the main source of the distance measurement scale error of the total station. It is a basic parameter related to the distance measurement characteristics of the instrument and can essentially characterize the scale error of the measuring instrument. This paper develops an automatic measurement system for the total station scale frequency and uses frequency measurement technology that can refer to a high-precision atomic clock to achieve dynamic real-time measurement of the total station scale frequency. At the same time, based on the total station scale frequency automatic measurement system, the temperature drift characteristics of the total station scale frequency were studied in detail by controlling the ambient temperature. This article is of great significance to further evaluate the distance measurement performance of the total station and to clarify the sources of distance multiplication constant errors during the calibration and calibration process of the total station.
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Separators with small working flow rates are widely used in current ambient particulate matters monitoring, while the traceability issue has not been addressed. This work focused on the separator calibration under variable flow rates. By applying customized aerosol atomizing nozzles, as well as cyclone mixing and isokinetic sampling techniques, the calibration equipment for the separators with the working flow rates within (1~16.7) L/min has been successfully established. The flow rate error between actual measurement and working point is within ±1%, and the uncertainty of Da50 is lower than 3%, k=2, which meet the requirements of corresponding standards.
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The laser multilateral coordinate measuring system has the characteristics of high coordinate measurement accuracy, which has attracted much attention from academic circles, industries and metrology institutions in various countries. However, since the accuracy of coordinate measurement in large spatial ranges is affected by various factors, and there is a lack of domestic standards related to the measurement and calibration of laser multilateral coordinate measurement systems, the development of laser multilateral coordinate measurement systems still faces many problems that need to be solved. This article focuses on the principle of laser multilateral measurement, system parameter self-calibration method, coordinate measurement traceability status and the formulation of related standards, measurement uncertainty assessment and analysis of influencing factors, the extension of laser multilateral coordinate measurement in the field of attitude measurement, and the application in the industrial field at home and abroad Extensive research and summary have been conducted on its practical applications. Among them, domestic and foreign researchers have made a variety of attempts to improve measurement accuracy, such as compensating environmental field interference, reducing ranging errors, improving system self-calibration accuracy, increasing the number of measurement stations, setting constraints, and researching the optimal layout of the system. At the same time, the establishment and improvement of relevant standards for domestic laser polygonal coordinate measurement system measurement, calibration and traceability can provide reference and basis for the manufacturing and assembly of large parts and components in industrial applications and the calibration and compensation of instruments. This article reviews the relevant literature on laser multilateral coordinate measurement systems in the field of large spatial range measurement, focusing on the principles of laser multilateral coordinate measurement, system parameter self-calibration methods, coordinate measurement uncertainty and applications, aiming to provide researchers with information on The development status and future development trends of laser multilateral coordinate measurement systems promote the development of coordinate measurement technology in large spatial ranges.
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Currently, countries around the world are paying increasing attention to the management of harmful volatile organic compounds (VOCs) in the ambient air, and harmful VOCs data is gradually becoming an important data for atmospheric environmental monitoring and control, with a significant increase in data importance. The list and information of harmful VOCs in the standards, regulations, and policy documents issued by various countries for harmful VOCs are scattered, and there is no centralized search channel or file that can fully cover the harmful VOCs data published by various countries, making it difficult to comprehensively and effectively use harmful VOCs data and information. This article designs a technical route for establishing a dataset of harmful VOCs compounds and its establishment methods based on the chemical characteristics of harmful VOCs compounds, atmospheric environment monitoring and control, and the requirements for digital calibration certification and recognition of standard reference data. The establishment process is actually completed. The reference dataset for harmful VOCs established has become a standard dataset after self-assessment, data inspection, comparison between Chinese and American datasets, and expert review. This dataset has been publicly available on the official website of the National Metrology Science Data Center, providing important data resources such as authoritative maps of harmful VOCs for scientific research and the development of the environmental protection industry. It greatly enhances scientific research autonomy and has certain reference value for the governance and research of harmful VOCs. It also lays the foundation for subsequent digital calibration certification and recognition.
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To evaluate the uncertainty of determination of the gross alpha radioactivity and the gross beta radioactivity in drinking water by thick source method. According to GB/T 5750.13-2023 "Standard Examination Methods for Drinking Water Part 13 Radioactivity Index", the gross alpha radioactivity and beta radioactivity in drinking water are measured. The measurement repeatability was regarded as type A uncertainty, and the factors introduced by the residue mass, water sample volume, instrument detection efficiency, recovery rate, etc. were regarded as type B uncertainty. The measured gross alpha and beta radioactivity concentrations were 0.66 Bq/L and 0.48 Bq/L, the relative combined uncertainties were 6.0% and 5.7%, and the expanded uncertainties were 0.08 Bq/L and 0.06 Bq/L. Uncertainty introduced by the instrument count rate (n) is the main source of uncertainty and has the greatest influence. The measurement repeatability, the counting efficiency (ε) of standard powder source and radioactivity recovery rate (F) have greater influence. The influences of total mass of the water sample residue (W), mass of the water residue weighed to prepare the sample source (m) , and the volume (V) of the water sample are less and negligible.
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A method based on microscopic imaging flow cytometry was established to measure the concentration of milk somatic cells in the standard substance for milk somatic cell count. This method labels milk somatic cells using the fluorescent dye Ethium Bromide, and the single cell multi parameter microscopic images provided by flow cytometry can effectively assist in identifying target cells in flow cytometry analysis, thereby providing the correctness and repeatability of the gate strategy. Through multiple measurements and analysis of milk somatic cell standard substance samples with different concentrations of somatic cells, it has been proven that this method has good indoor and daytime repeatability. A mathematical model for measuring the concentration of milk somatic cells in a standard substance for milk somatic cell count based on microscopic imaging flow cytometry technology was established. The analysis determined that the uncertainty of this measurement method mainly comes from measurement repeatability, sample pretreatment, reagent addition, gate operation, and measurement volume. Comprehensive evaluation, targeting the candidate V-grade (~1.0×106/mL) of the standard substance for milk somatic cell count prepared in the study, the relative uncertainty of the measurement method for milk somatic cell concentration based on microscopic imaging flow cytometry is 4.84%.
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This article studies the calibration method of ultrasonic chordal phantom, designed and developed a ultrasonic chord phantom calibration device based on intelligent technology. This device can collect the rotational speeds of the ultrasonic capstan and driven wheels of the chordal phantom through a dual channel laser velocimeter and input them into the analysis system for analysis and calculation, in order to calculate the chordal speed of the chordal phantom. And it can collect the line speeds of each point within the physiological waveform cycle and compare them with the standard physiological waveform line speeds in the database, in order to determine whether the physiological waveform curve at the setting speed meets the requirements. The experimental results indicate that compared to the existing detection methods for constant blood flow velocity, this method and device can not only conveniently and efficiently detect constant blood flow velocity, but also detect physiological waveforms intelligently, they solved the calibration and traceability problem of ultrasonic chordal phantom effectively.
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Specific Absorption Rate (SAR), as a mandatory parameter for the personal safety of electromagnetic radiation involving wireless communication products, has new requirements for the validation of the measurement system as its measurement method and measurement system need to be updated due to the change of the device under test. Based on the in-depth understanding of the validation methods in the current standard, the validation methods of the three traditional validation steps, namely, Extrapolation routine verification, Probe linearity verification and others, are measured and analyzed through electromagnetic simulation and experimental measurements, and the validation methods are extended by combining with the new requirements of the new test. The measured results show the feasibility and stability of the extended verification method. Since the reference values are obtained by the self-developed method, the validation method can be extended and the validation configurations, such as the validation points, can be customized according to the needs. This provides technical support for the study of the validation method for new and domestic SAR measurement systems.
Abstract:
Point at present situation of measuring small pulling forcegauge inmetrological service,small pulling forcegauge calibration device was developed,so some matterswhensmallpulling forcegauge is measured usingWeight,for example ,heavy working intensity,unablezeroed and full scale range cannot be measured ,can be solved.
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Digital PCR (dPCR) is an absolute quantitative technique of nucleic acid, which is widely used in transgenic and gene detection. In order to ensure the accuracy and reliability of digital PCR measurement results in China, 16 laboratories were tested using transgenic plasmid DNA samples. The comparison results showed that the difference between the ratio of foreign gene to internal copy number (<25%) to evaluate the measuring ability of the laboratories. The 16 laboratories were all within the acceptable range, and there was no significant difference among different digital PCR platforms. Due to the influence of plasmid conformation, the absolute copy number content of plasmid DNA measured in 7 laboratories was significantly lower than the reference value. It is suggested that when using digital PCR for quantitative measurement of plasmid DNA copy number, it should be confirmed whether the conformation of plasmid has an effect on amplification.
, Available online  , doi: 10.12338/j.issn.2096-9015.2020.0166
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Abstract:
In mmwave technology a low frequency is always multiplied to generate a much higher frequency. Phase noise will be also increased and phase noise test will be more important in mmwave band. It is limited with spectrum analyzer method because of some reasons. And phase noise analyzer can only cover up to 50 GHz in a single unit. After the basic introduction of phase noise test technology in mmwave band two external mixer method is provided. Result shows that with this method we can get a stable test result.