scholarly journals AN INDEPENDENT ASSESSMENT OF UNCERTAINTY FOR RADIOCARBON ANALYSIS WITH THE NEW GENERATION HIGH-YIELD ACCELERATOR MASS SPECTROMETERS

Radiocarbon ◽  
2020 ◽  
pp. 1-22
Author(s):  
A T Aerts-Bijma ◽  
D Paul ◽  
M W Dee ◽  
S W L Palstra ◽  
H A J Meijer
Keyword(s):  
Measurement Uncertainty ◽  
Research University ◽  
High Yield ◽  
Expanded Uncertainty ◽  
Mass Spectrometers ◽  
Actual Measurement ◽  
Measurement Results ◽  
Reference Measurements ◽  
Sample Measurement ◽  
Processing Steps

ABSTRACT The radiocarbon (14C) dating facility at the Centre for Isotope Research, University of Groningen went through a major upgrade in 2017 and this included installation of a MICADAS accelerator mass spectrometer (AMS). In the first 18 months, we performed 4000 sample and 3000 reference measurements. A careful evaluation of those measurement results is presented, to characterize the various sources of uncertainty and to ultimately assign, for every sample measurement, a realistic expanded uncertainty. This analysis was performed on the measurements of secondary references and sample duplicates in various phases of their processing steps. The final expanded uncertainty includes both the 14C measurement uncertainties and uncertainties originating from pretreatment steps. Where the 14C measurement uncertainty includes straightforward uncertainties arising from Poisson statistics, background subtraction, calibration on Oxalic Acid II and δ13C correction, the uncertainties originating from pretreatment steps are based on the spread of actual measurement results for secondary references and sample duplicates. We show that the 14C measurement uncertainty requires expansion, depending on the number of processing steps involved prior to a 14C measurement, by a maximum factor of 1.6 at our laboratory. By using these expansion (multiplication) factors, we make our reported uncertainty both more realistic and reliable.

Estimation of uncertainty in olfactometry

2009 ◽  
Vol 59 (7) ◽  
pp. 1409-1413 ◽  
Author(s):  
T. Higuchi
Keyword(s):  
Measurement Uncertainty ◽  
Interlaboratory Comparison ◽  
Collaborative Study ◽  
Estimation Procedure ◽  
Measurement Model ◽  
Standard Uncertainty ◽  
Expanded Uncertainty ◽  
Collaborative Test ◽  
Measurement Results ◽  
Estimation Of Uncertainty

Estimation of uncertainty in odour measurement is essential to the interpretation of the measurement results. The fundamental procedure for the estimation of measurement uncertainty comprises the specification of the measurement process, expression of the measurement model and all influences, evaluation of the standard uncertainty of each component, calculation of the combined standard uncertainty, determination of a coverage factor, calculation of the expanded uncertainty and reporting. Collaborative study such as interlaboratory comparison of olfactometry yields performance indicators of the measurement method including repeatability and reproducibility. Therefore, the use of collaborative test results for measurement uncertainty estimation according to ISO/TS 21748 and ISO 20988 is effective and reasonable. Measurement uncertainty of the triangular odour bag method was estimated using interlaboratory comparison data from 2003 to 2007 on the basis of the simplest model of statistical analysis, and the expanded uncertainty of odour index ranged between 3.1 and 6.7. On the basis of the establishment of the estimation procedure for uncertainty, a coherent interpretation method for the measurement results will be proposed and more effective and practical quality control of olfactometry will be available.

Evaluation of Measurement Uncertainty for Water Content Tests in Soil Samples

2013 ◽  
Vol 718-720 ◽  
pp. 984-988
Author(s):  
Zhi Qing Gao ◽  
Nai Qi Shen ◽  
Xu Li ◽  
Zong Yun Shu
Keyword(s):  
Measurement Uncertainty ◽  
Water Content ◽  
Measurement Accuracy ◽  
Soil Samples ◽  
Uncertainty Of Measurement ◽  
Expanded Uncertainty ◽  
Factors Affecting ◽  
Testing Conditions ◽  
Content Determination ◽  
Measurement Results

Measurement uncertainty in the water content test for soil samples is an index for evaluating the reliability of the experiment. It affects the accuracy of some parameters such as porosity and saturation, which are derived from water content. According to the requirements of the standard JJF 1059-1999 Uncertainty Evaluation and Denotation of the Measurement Results, the uncertainty for the measurement results of the water content in soil samples was evaluated. Concerning the characteristics of the water content determination in soil samples, a pail of soil sample was taken as specimen due to its relative homogeneity. The factors affecting the measurement accuracy were discussed. The result shows that the expanded uncertainty of measurement results of the water content in soil samples was 1.6% under the proposed testing conditions.

scholarly journals Expanded uncertainty evaluation taking into account the correlation between estimates of input quantities

2021 ◽  
pp. 4-8
Author(s):  
Igor Zakharov ◽  
Pavel Neyezhmakov ◽  
Olesia Botsiura
Keyword(s):  
Measurement Uncertainty ◽  
Correlation Coefficient ◽  
Degrees Of Freedom ◽  
Reduction Method ◽  
Standard Uncertainty ◽  
Effective Number ◽  
Expanded Uncertainty ◽  
Wide Range ◽  
Measurement Results ◽  
Processing Of Measurement Results

An expression for estimating the combined standard uncertainty taking into account the observed correlation between the estimates of the two input quantities is given. The Welch – Satterthwaite formula given in the GUM is analyzed. It is shown that the number of degrees of freedom calculated using this formula will vary over a wide range when the value of the correlation coefficient changes, and in some cases it may take an unacceptable zero value. An expression for calculating the combined standard uncertainty by the reduction method is given. It is shown that the number of degrees of freedom in this method does not depend on the value of the correlation coefficient. A formula for calculating the effective number of degrees of freedom taking into account the observed correlation is proposed. The existing expression for calculating the kurtosis of the measurand is analyzed and an expression is proposed for calculating the kurtosis of the measurand in the presence of a correlation between the input quantities. An example of estimation of expanded uncertainty when measuring the coefficient of a pressure transducer using a calibrator is considered. Estimates of the distribution of the measurand, obtained using Monte Carlo simulation, showed that they are closest to the estimates obtained by the kurtosis method. The considered example showed that taking into account the correlation in the processing of measurement results makes it possible to reduce the expanded measurement uncertainty of the converter coefficient by 1.22–1.27 times. Keywords: measurement uncertainty; correlation; effective number of degrees of freedom; method of kurtosis

scholarly journals Development of Three-Phase Permanent-Magnet Synchronous Motor Drive with Strategy to Suppress Harmonic Current

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1583
Author(s):  
Wei-Tse Kao ◽  
Jonq-Chin Hwang ◽  
Jia-En Liu
Keyword(s):  
Permanent Magnet ◽  
Electromotive Force ◽  
Permanent Magnet Synchronous Motor ◽  
Synchronous Motor ◽  
Motor Drive ◽  
Actual Measurement ◽  
Current Harmonic ◽  
Three Phase ◽  
Measurement Results ◽  
Harmonic Components

This study aimed to develop a three-phase permanent-magnet synchronous motor drive system with improvement in current harmonics. Considering the harmonic components in the induced electromotive force of a permanent-magnet synchronous motor, the offline response of the induced electromotive force (EMF) was measured for fast Fourier analysis, the main harmonic components were obtained, and the voltage required to reduce the current harmonic components in the corresponding direct (d-axis) and quadrature (q-axis) axes was calculated. In the closed-loop control of the direct axis and quadrature axis current in the rotor reference frame, the compensation amount of the induced EMF with harmonic components was added. Compared with the online adjustment of current harmonic injection, this simplifies the control strategy. The drive system used a 32-bit digital signal processor (DSP) TMS320F28069 as the control core, the control strategies were implemented in software, and a resolver with a resolver-to-digital converter (RDC) was used for the feedback of angular position and speed. The actual measurement results of the current harmonic improvement control show that the total harmonic distortion of the three-phase current was reduced from 5.30% to 2.31%, and the electromagnetic torque ripple was reduced from 15.28% to 5.98%. The actual measurement results verify the feasibility of this method.

scholarly journals Parameter Modeling Analysis and Experimental Verification on Magnetic Shielding Cylinder of All-Optical Atomic Spin Magnetometer

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Hong Zhang ◽  
Sheng Zou ◽  
Xi-Yuan Chen ◽  
Wei Quan
Keyword(s):  
Magnetic Measurement ◽  
Magnetic Shielding ◽  
Key Factors ◽  
Actual Measurement ◽  
Atomic Spin ◽  
Modeling Analysis ◽  
Measurement Results ◽  
All Optical ◽  
Ultrahigh Sensitivity ◽  
Shielding Effects

The ultrahigh sensitivity atomic spin magnetometer as the magnetic measurement sensor has received much concern. The performance of the magnetic shielding cylinder is one of the key factors constraining the atomic spin magnetometer’s sensitivity. In order to effectively improve the performances of the magnetic shielding, the parameter optimization models of the magnetic shielding cylinder were established in this paper. Under the condition of changing only one parameter while the others keeping constant, the effects of various parameters influencing the axial shielding coefficient were comprehensively analyzed, and the results showed that the smaller the innermost length, the innermost radius, and the radial spacing were, and the greater the axial spacing was, the better the shielding performance could be obtained. According to these results and the actual needs, the magnetic shielding cylinder was optimally designed, and then the shielding effects were simulated via the software Ansoft. The simulation results showed that the optimized magnetic shielding cylinder had the advantages of small size, high shielding performance, and lager uniformity than that of the nonoptimized one. The actual measurement results showed that the residual magnetism in the optimized magnetic shielding cylinder was below 0.1 nT, which was 2~4 times lower than the nonoptimized one.

scholarly journals 4 × 4 MIMO Antenna System for Smart Eyewear in Wi-Fi 5G and Wi-Fi 6e Wireless Communication Applications

Electronics ◽  
2021 ◽  
Vol 10 (23) ◽  
pp. 2936
Author(s):  
Ming-An Chung ◽  
Cheng-Wei Hsiao ◽  
Chih-Wei Yang ◽  
Bing-Ruei Chuang
Keyword(s):  
Ground Plane ◽  
Multiple Input Multiple Output ◽  
Antenna System ◽  
Slot Antenna ◽  
Actual Measurement ◽  
Antenna Efficiency ◽  
Mimo Antenna ◽  
Measurement Results ◽  
Working Frequency ◽  
Peak Gain

This paper proposes a small-slot antenna system (50 mm × 9 mm × 2.7 mm) for 4 × 4 multiple-input multiple-output (MIMO) on smart glasses devices. The antenna is set on the plastic temple, and the inverted F antenna radiates through the slot in the ground plane of the sputtered copper layer outside the temple. Two symmetrical antennas and slots on the same temple and series capacitive elements enhance the isolation between the two antenna ports. When both temples are equipped with the proposed antennas, 4 × 4 MIMO transmission can be achieved. The antenna substrate is made of polycarbonate (PC), and its thickness is 2.7 mm εr=2.85, tanδ=0.0092. According to the actual measurement results, this antenna has two working frequency bands when the reflection coefficient is lower than −10dB, its working frequency bandwidth at 4.58–5.72 GHz and 6.38–7.0 GHz. The proposed antenna has a peak gain of 4.3 dBi and antenna efficiency of 85.69% at 5.14 GHz. In addition, it also can obtain a peak gain of 3.3 dBi and antenna efficiency of 82.78% at 6.8 GHz. The measurement results show that this antenna has good performance, allowing future smart eyewear devices to be applied to Wi-Fi 5G (5.18–5.85 GHz) and Wi-Fi 6e (5.925–7.125 GHz).

Measurement Uncertainty

2007 ◽  
Author(s):  
D. Brynn Hibbert
Keyword(s):  
Measurement Uncertainty ◽  
Uncertainty Budget ◽  
Test Material ◽  
Metrology In Chemistry ◽  
Energy Agency ◽  
Long Run ◽  
Measurement Results ◽  
Trading Partners ◽  
History Of ◽  
Student’S T

One of the great revolutions in metrology in chemistry has been the understanding of the need to quote an appropriate measurement uncertainty with a result. For some time, a standard deviation determined under not particularly well-defined conditions was considered a reasonable adjunct to a measurement result, and multiplying by the appropriate Student’s t value gave the 95% confidence interval. But knowing that in a long run of experiments repeated under identical conditions 95% of the 95% confidence intervals would include the population mean did not answer the fundamental question of how good the result was. This became evident as international trade burgeoned and more and more discrepancies in measurement results and disagreements between trading partners came to light. To determine if two measurements of ostensibly the same measurand on the same material give results that are equivalent, they must be traceable to the same metrological reference and have stated measurement uncertainties. How to achieve that comparability is the subject of this chapter and the next. When making a chemical measurement by taking a certain amount of the test material, working it up in a form that can be analyzed, calibrating the instrument, and performing the measurement, analysts understand that there will be some doubt about the result. Contributions to uncertainty derive from each step in the analysis, and even from the basis on which the analysis is carried out. An uncertainty budget documents the history of the assessment of the measurement uncertainty of a result, and it is the outcome of the process of identifying and quantifying uncertainty. Although the client may only receive the fruits of this process as (value ± expanded uncertainty), accreditation to ISO/IEC 17025 requires the laboratory to document how the uncertainty is estimated. Estimates of plutonium sources highlight the importance of uncertainty. The International Atomic Energy Agency (IAEA) estimates there are about 700 tonnes of plutonium in the world. The uncertainty of measurement of plutonium is of the order of 0.1%, so even if all the plutonium were in one place, when analyzed the uncertainty would be 700 kg (1000 kg = 1 tonne). Seven kilograms of plutonium makes a reasonable bomb.

Stable Isotope Ratiometer-Multiple Ion Detector Unit for Quantitative and Qualitative Stable Isotope Studies by Gas Chromatography-Mass Spectrometry

1975 ◽  
Vol 21 (9) ◽  
pp. 1253-1257 ◽  
Author(s):  
Peter D Klein ◽  
Joseph R Haumann ◽  
David L Hachey
Keyword(s):  
Stable Isotope ◽  
Background Subtraction ◽  
Isotope Ratio ◽  
Gas Chromatography Mass Spectrometry ◽  
Gas Chromatograph ◽  
Mass Spectrometers ◽  
Isotope Studies ◽  
The Cost ◽  
Sample Measurement ◽  
Ion Detector

Abstract We have designed and constructed a stable isotope ratiometer-multipie ion detector unit, which can drive existing gas chromatograph-quadrupole or magnetic sector mass spectrometers to monitor up to six ions in turn. Each of the three pairs of ions can be selected for quantitation; thus three different or successive components can be analyzed in a single gas-chromatographic run. A background subtraction option permits the ion intensity in the absence of sample to be subtracted automatically during sample measurement. Displays of accumulated counts and isotope ratio are updated twice per second during the measurement and can be printed out at its conclusion. All six ions can be monitored in the analog mode by parallel outputs to a multipen recorder. Experience gained in the construction of this prototype indicates that such units could be commercially available for $10 000, or about a third to a sixth of the cost of even an inexpensive computer system.

Study on Design and Experiment of SAW Device Based on MSC

2011 ◽  
Vol 135-136 ◽  
pp. 954-959
Author(s):  
Chang Bao Wen ◽  
Yong Feng Ju ◽  
Li Liu ◽  
Ya Fei Jiang ◽  
Chen Zhao ◽  
...  
Keyword(s):  
Modular Design ◽  
Center Frequency ◽  
Network Analyzer ◽  
Test Results ◽  
Design Environment ◽  
Actual Measurement ◽  
Measurement Results ◽  
Data Output ◽  
Output Module ◽  
Good Agreement

In the design process of surface acoustic wave (SAW) device based on multistrip coupler (MSC), the characteristics of interdigital transducer (IDT) and device can not been directly achieved, and the layout structure of device can not be observed and checked. To solve some problems, the design platform of SAW device based MSC was realized in the Matlab design environment using the modular design. The design platform of SAW device based MSC consists of layout simulation module, characteristics simulation module and data output module. By means of realizing a SAW device based MSC with center frequency at 51.293MHz, the comparison and analysis between the design results and the actual test results are presented. Experiments results confirm that the platform can correctly design the device layout. The device characteristics achieved by the design platform are in good agreement with the actual measurement results by the network analyzer.

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