Final Uncertainty Research Articles

Production and Validation of an Alkaline Phosphatase Reference Material in Lyophilized Milk

The paper describes the characterization and evaluation of a reference material in lyophilized milk to be used for the determination of alkaline phosphatase with the reference method ISO 11816-1:2013. The reference material was produced at three levels of activity, calibrated for the determination of alkaline phosphatase activity in pasteurized (sample “60”), thermized (sample “600”), and raw milk (sample “6000”). The first assignment of the title and the uncertainties were realized through a round of 18 Italian laboratories and the EUR-MMP in 2014. In 2015, a second round was repeated with the participation of 17 expert laboratories of the net of NRLs-MMP. The first titles were confirmed, whereas the second trial succeeded in a good improvement of the final uncertainties (sample “60” = 96.10 ± 2.03; sample “600” = 775.91 ± 13.03; sample “6000” = 6040.65 ± 126.89 mU/L). The materials were fully characterized according to ISO Guide 35:2006 and proved to be highly crono and temperature stable, so these are excellent candidates to be used for internal instrumental quality control or for the organization of interlaboratory trials for alkaline phosphatase determination in milk.

Experimental study on bubble dynamics and wall heat transfer arising from a single nucleation site at subcooled flow boiling conditions – Part 1: Experimental methods and data quality verification

A novel experimental method and data acquisition/analysis strategy that ensures reliable measurements of various subcooled flow boiling parameters is discussed. In this study, all experiments were performed by keeping a single active nucleation site within the entire heated area in a square upward flow channel. This approach greatly facilitated the observation of bubble and wall heat transfer features in subcooled boiling flow.Vapor bubbles originating from the nucleation site were observed with both micro- and macroscopic views from high-speed cameras while corresponding wall temperature was measured by an infrared camera. This allowed simultaneously capturing various bubbles characteristics with multiple scales (both space and time) as well as their impact on wall heat transfer. In addition, efforts were made to characterize the observed boiling behavior with high statistical accuracy by analyzing numerous images taken at each test condition.This study proves that by taking the current strategy excellent repeatability and thus reliability can be achieved for a wide range of flow boiling parameters such as bubble size, bubble velocity, statistical distribution of bubble size and time-averaged wall heat transfer coefficients. Also, the major sources of uncertainty for each measurement are thoroughly investigated, from which the final uncertainties are determined. Overall, the present study suggests what we must concern to achieve truly reliable and useful data from any boiling experiments.

Validation of Analytical Methods for Determination of Methamphetamine Using Fourier Transform Infrared (FTIR) Spectroscopy

Validation of analytical methods for determination of methamphetamine using Fourier Transform Infrared (FTIR) Spectroscopy has been done. Parameter validation method are the repeatability of the system (precision), accuracy, linear ranges, limit of detection (LOD) and limit of quantification (LOQ). Samples was prepared by mixing a weighed portion of methamphetamine standard and alum and swirled flatly to homogeneous mixture. The mixture with total weighed of powder obtained is approximately 1.0 g. This sample was analysis using FTIR. The results of the study showed that the correlation of determination analysis methamphetamine using FTIR was R 2 =0.9998 at functional group with wave length number 698.83 cm -1 . Precision, RSD Horwitz, LOQ, LOD and recovery of the validation of analytical methods for determination of methamphetamine using FTIR were found to be 0.0087%, 2.052%, 2.3035%, 7.6786%, and 104.2%, respectively. This method have uncertainty of measurement is 0.8552%. The final result and uncertainty was (84.3334 ± 0.8552) % of methamphetamine in sample. As a conclusion, the validation of analytical methods for determination of methamphetamine using FTIR is very good method. This method is simplicity of sample preparation and low cost reagents.

Radiocarbon Analysis of Individual Amino Acids: Carbon Blank Quantification for a Small-Sample High-Pressure Liquid Chromatography Purification Method.

Compound-specific radiocarbon analysis (CSRA) of amino acids (AAs) is of great interest as a proxy for organic nitrogen (N) cycling rates, dating archeological bone collagen, and investigating processes shaping the biogeochemistry of global N reservoirs. However, recoverable quantities of individual compounds from natural samples are often insufficient for radiocarbon ((14)C) analyses (<50 μg C). Constraining procedural carbon (C) blanks and their isotopic contributions is critical for reporting of accurate CSRA measurements. Here, we report the first detailed quantification of C blanks (including sources, magnitudes, and variability) for a high-pressure liquid chromatography (HPLC) method designed to purify individual AAs from natural samples. We used pairs of AA standards with either modern (M) or dead (D) fraction modern (Fm) values to quantify MC and DC blanks within several chromatographic regions. Blanks were determined for both individual and mixed AA standard injections with peak loadings ranging from 10 to 85 μg C. We found 0.8 ± 0.4 μg of MC and 1.0 ± 0.5 μg of DC were introduced by downstream sample preparation (drying, combustion, and graphitization), which accounted for essentially the entire procedural blank for early eluting AAs. For late-eluting AAs, higher eluent organic content and fraction collected volumes contributed to total blanks of 1.5 ± 0.75 μg of MC and 3.0 ± 1.5 μg of DC. Our final measurement uncertainty for 20 μg of C of most AAs was ±0.02 Fm, although sample size requirements are larger for similar uncertainty in late-eluting AAs. These results demonstrate the first CSRA protocol for many protein AAs with uncertainties comparable to the lowest achieved in prior studies.

A Bayesian machine learning model for estimating building occupancy from open source data

Understanding building occupancy is critical to a wide array of applications including natural hazards loss analysis, green building technologies, and population distribution modeling. Due to the expense of directly monitoring buildings, scientists rely in addition on a wide and disparate array of ancillary and open source information including subject matter expertise, survey data, and remote sensing information. These data are fused using data harmonization methods, which refer to a loose collection of formal and informal techniques for fusing data together to create viable content for building occupancy estimation. In this paper, we add to the current state of the art by introducing the population data tables (PDT), a Bayesian model and informatics system for systematically arranging data and harmonization techniques into a consistent, transparent, knowledge learning framework that retains in the final estimation uncertainty emerging from data, expert judgment, and model parameterization. PDT aims to estimate ambient occupancy in units of people/1000 ft2 for a number of building types at the national and sub-national level with the goal of providing global coverage. We present the PDT model, situate the work within the larger community, and report on the progress of this multi-year project.

Evaluation of the effect of data quality on the profile uncertainty of critical dimension small angle x-ray scattering

A line grating prepared via a self-aligned quadruple patterning method was measured using critical dimension small angle x-ray scattering. A Monte Carlo Markov chain algorithm was used to analyze the uncertainty of the model fit over subsets of the full angular range and for a time series with decreasing signal-to-noise in order to determine the effect of the data quality on the final profile shape uncertainty. These results show how the total measurement time can be reduced while maintaining satisfactory profile shape uncertainty. We found that the typical measurement conditions are highly oversampled and can be reduced considerably with only marginal effect on the shape uncertainty. A comparison is made between the synchrotron measurements and a laboratory system, demonstrating that both measurements result in similar structures.

Local Neutron Flux Distribution Measurements by Wire-Dosimetry in the AMMON Experimental Program in the EOLE Reactor

Dosimetry measurements were carried out during the AMMON experimental program, in the EOLE facility. Al-0.1 wt% Au wires were positioned along curved fuel plates of JHR-type assemblies to investigate the azimuthal and axial gold capture rate profiles, directly linked to the thermal and epithermal flux. After irradiation, wires were cut into small segments (a few mm), and the gold capture rate of each part was measured by gamma spectrometry on the MADERE platform. This paper presents results in the “hafnium” configuration, and more specifically the azimuthal flux profile characterization. The final uncertainty on each measured wire lies below 1% (at 2 standard deviations). Experimental profiles are in a good agreement against Monte Carlo calculations, and the 4% capture rate increase at the plate edge is well observed. The flux dissymmetry due to assembly position in the core is also measured, and shows a 10% discrepancy between the two edges of the plate.

EURAMET.M.P-S9: comparison in the negative gauge pressure range −950 to 0 hPa

A comparison in the negative gauge pressure range was arranged in the period 2011 - 2012. A total of 14 laboratories participated in this comparison: BEV (Austria), CMI (Czech Republic), DANIAmet-FORCE (Denmark), EIM (Greece), HMI/FSB-LPM (Croatia), INM (Romania), IPQ (Portugal), LNE (France), MCCAA (Malta), METROSERT (Estonia), MIKES (Finland), MIRS/IMT/LMT (Slovenia), NSAI (Ireland) and UME (Turkey). The project was divided into two loops: Loop1, piloted by MIKES, and Loop2, piloted by LNE. The results of the two loops are reported separately: Loop1 results are presented in this paper.The transfer standard was Beamex MC5 no. 25516865 with internal pressure module INT1C, resolution 0.01 hPa. The nominal pressure range of the INT1C is −1000 hPa to +1000 hPa. The nominal pressure points for the comparison were 0 hPa, −200 hPa, −400 hPa, −600 hPa, −800 hPa and −950 hPa.The reference values and their uncertainties as well as the difference uncertainty between the laboratory results and the reference values were determined from the measurement data by Monte Carlo simulations. Stability uncertainty of the transfer standard was included in the final difference uncertainty. Degrees of equivalences and mutual equivalences between the laboratories were calculated.Each laboratory reported results for all twelve measurement points, which means that there were 168 reported values in total. Some 163 of the 168 values (97 %) agree with the reference values within the expanded uncertainties, with a coverage factor k = 2. Among the laboratories, four different methods were used to determine negative gauge pressure.It is concluded that special attention must be paid to the measurements and methods when measuring negative gauge pressures. There might be a need for a technical guide or a workshop that provides information about details and practices related to the measurements of negative gauge pressure, as well as differences between the different methods.The comparison is registered as EURAMET project no. 1170 and as a supplementary comparison EURAMET.M.P-S9 in the BIPM key comparison database.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

The influence of some relevant metallic impurities in the triple point of mercury temperature

The influence of impurities on the defined fixed points of the International Temperature Scale of 1990 is one of the most relevant sources of uncertainty in their use. Namely, the triple point of mercury is one of the fixed points most used because its assigned triple point temperature (−39,8344 °C) is within a temperature range of high interest for science and industry. Mercury can be obtained with high purity, usually better that 8N and it is realized with a high accuracy, what makes impurities a significant contributor on the final uncertainty. The best procedure to quantify this influence is by means of doping experiments which consist of the addition of a controlled amount of an impurity, determined gravimetrically, in a fixed point cell. This paper presents a summary of the results obtained from a series of doping experiments performed with some relevant metallic impurities on the triple point of mercury temperature.

Assessment of uncertainties in greenhouse gas emission profiles of livestock sectors in Africa, Latin America and Europe

The global animal food chain has a large contribution to the global anthropogenic greenhouse gas (GHG) emissions, but its share and sources vary highly across the world. However, the assessment of GHG emissions from livestock production is subject to various uncertainties, which have not yet been well quantified at large spatial scale. We assessed the uncertainties in the relations between animal production (milk, meat, egg) and the CO2, CH4, and N2O emissions in Africa, Latin America and the European Union, using the MITERRA-Global model. The uncertainties in model inputs were derived from time series of statistical data, literature review or expert knowledge. These model inputs and parameters were further divided into nine groups based on type of data and affected greenhouse gas. The final model output uncertainty and the uncertainty contribution of each group of model inputs to the uncertainty were quantified using a Monte Carlo approach, taking into account their spatial and cross-correlation. GHG emissions and their uncertainties were determined per livestock sector, per product and per emission source category. Results show large variation in the GHG emissions and their uncertainties for different continents, livestock sectors products or source categories. The uncertainty of total GHG emissions from livestock sectors is higher in Africa and Latin America than in the European Union. The uncertainty of CH4 emission is lower than that for N2O and CO2. Livestock parameters, CH4 emission factors and N emission factors contribute most to the uncertainty in the total model output. The reliability of GHG emissions from livestock sectors is relatively high (low uncertainty) at continental level, but could be lower at country level.

Submillimetre thermistors for balloon‐borne applications up to lower stratosphere: preliminary characterization with 0.02 K uncertainty

ABSTRACTThe French metrological laboratory LNE‐CNAM, in the framework of a study commissioned by the Laboratory of Dynamic Meteorology LMD, has carried out a preliminary metrological characterization of a device based on submillimetre thermistors, to be used for atmospheric temperature and humidity measurements from the ground up to the lower stratosphere.The device is a measuring system intended to perform temperature measurements between 173 K (around ‐100 °C) and 233 K (around −40 °C). It is composed of a self‐manufactured electronic device, in which submillimetre thermistors measure both air temperature and the temperature of a hygrometer sensor, in order to determine accurately water vapour concentration. Since the needed final measurement uncertainty is below 0.05 K, a comprehensive metrological characterization must be performed.One instrument prototype was supplied to the LNE‐CNAM, to be characterized between 173 K and 273 K (around 0 °C). Measurements were carried out in the quasi‐adiabatic calorimeter used by the LNE‐CNAM to realize the national temperature standard below 84 K. The calorimeter was adapted to work at temperatures up to 273 K. At any setpoint between 173 K and 273 K, the stability of the temperature was within 5 mK for several hours. The thermistors were calibrated by comparison to a calibrated reference thermometer.Preliminary results showed that calibrations with an uncertainty of around 0.02 K are possible. Tests are going to be performed in situ by the LMD, and further characterizations will be carried out to assess the obtained uncertainties and check long‐term reproducibility.

A STUDY ON THE UNCERTAINTY FOR THE ROUTINE DOSIMETRY SERVICE AT THE LEBANESE ATOMIC ENERGY COMMISSION USING HARSHAW 8814 DOSEMETERS.

The personal dosimetry service at the Lebanese Atomic Energy Commission uses Harshaw 8814 cards with LiF:Mg,Ti detectors. The dosemeters are read in a Harshaw 6600 TLD reader. In the process of accreditation for the ISO 17025 standard((1)), different influence factors are investigated and the uncertainty has been determined. The Individual Monitoring Service Laboratory-LAEC reads the dosemeters once it receives them from the customer, and new cards are immediately given for the next wearing period. The wearing period is 2 months. The dosemeter results are reported to the customers without background subtraction. Both Hp(10) and Hp(0.07) are reported. For this paper, only the uncertainty on Hp(10) will be focussed. The following factors are taken into account for the uncertainty: calibration factor, dosemeter homogeneity and repeatability, energy and angular dependence, non-linearity, temperature dependence, etc. Also the detection limit was determined. One of the important factors is the correction for fading. This fading correction depends on the procedure used such as storage temperatures, the time-temperature profile of the read-out, pre-heat and annealing conditions. Pre- and post-irradiation fading curves were measured for a storage period up to 182 d at room temperature (15-25°C). The resulting final combined standard uncertainty on the reported doses is of the order of 24 % for doses of ∼1 mSv.

Uncertainty propagation through wave optics retrieval of bending angles from GPS radio occultation: Theory and simulation results

AbstractThe wave optical technique for bending angle retrieval in processing radio occultation observations is nowadays widely used by different data processing and assimilation groups and centers. This technique uses Fourier Integral Operators that map the observed records of the amplitude and phase into the impact parameter representation, which allows for the retrieval of bending angle as a function of impact parameter. We investigate the propagation of uncertainty in the observed amplitude and excess phase to the retrieved bending angle. We construct a simple linear approximation, where the excess phase uncertainty is mapped into the bending angle uncertainty. This results in a simple analytical expression for the final uncertainty. To verify our approximation, we perform numerical Monte Carlo simulations for three example occultation events (tropical, middle, and polar latitude profiles from an atmospheric analysis). We demonstrate that our approximation basically gives good results in all cases over the entire troposphere. Exception is the narrow area near the top of the sharp boundary layer, especially in tropics, where, due to nonlinear effects, a significant systematic error arises accompanied by increased uncertainty.

Maximum Entropy를 이용한 정량적 레이더 강우추정 불확실성 분석

Abstract Existing studies on radar rainfall uncertainties were performed to reduce the uncer-tainty for each stage by using bias correction during the quantitative radar rainfall estimationprocess. However, the studies do not provide quantitative comparison with the uncertainties forall stages. Consequently, this study proposes a suitable approach that can quantify the uncer-tainties at each stage of the quantitative radar rainfall estimation process. First, the newapproach can present initial and final uncertainties, increasing or decreasing the uncertainty,and the uncertainty percentage at each stage. Furthermore, Maximum Entropy (ME) wasapplied to quantify the uncertainty in the entire process. Second, for the uncertainty quantifica-tion of radar rainfall estimation at each stage, this study used two quality control algorithms,two rainfall estimation relations, and two bias correction techniques as post-processing andprogressed through all stages of the radar rainfall estimation. For the proposed approach, thefinal uncertainty (ME = 3.81) from the ME of the bias correction stage was the smallest whilethe uncertainty of the rainfall estimation stage was higher because of the use of an unsuitablerelation. Additionally, the ME of the quality control was at 4.28 (112.34%), while that of therainfall estimation was at 4.53 (118.90%), and that of the bias correction at 3.81 (100%). How-ever, this study also determined that selecting the appropriate method for each stage wouldgradually reduce the uncertainty at each stage. Finally, the uncertainty due to natural variabil-ity was 93.70% of the final uncertainty. Thus, the results indicate that this new approach cancontribute significantly to the field of uncertainty estimation and help with estimating moreaccurate radar rainfall.Key words: Radar rainfall estimation, uncertainty quantification, uncertainty propagation,maximum entropy

Determination of zirconium isotope composition and concentration for nuclear sample analysis using Thermal Ionization Mass Spectrometry

A new Thermal Ionization Mass Spectrometry (TIMS) analytical procedure was developed to measure with high accuracy the zirconium isotope abundance and concentration without molybdenum correction in nuclear samples. A zirconium selective separation using UTEVA column was used before the TIMS measurement in order to remove all possible isobaric interferences (Mo, Y, Nb and Ru) in the solution. The separated solution was then deposited onto a filament previously outgassed for 4h to reduce the molybdenum traces in the filament. Then, the filament was introduced into the TIMS source and was maintained for 4h at a current of 5A (ionization filament) and 1.2A (evaporation filament) in order to eliminate all molybdenum trace present in the filament and in the sample. This methodology allowed the zirconium isotope abundance determination without using the molybdenum interference correction equation. The analytical results obtained with a natural solution after separation is in good accordance with the reference values: bias lower than 0.16% for the 90Zr, 91Zr, 92Zr and 94Zr isotope abundance, and a bias of ∼0.8% for the minor isotope (96Zr) were observed. This zirconium abundance determination methodology was used on three nuclear samples. Then, the calibration of a 91Zr spike solution was performed by reverse isotope dilution using a SPEX standard zirconium solution. The zirconium concentration determination was then performed on the three nuclear samples by isotope dilution using the SPEX standard zirconium solution and the 91Zr spike solution. The final uncertainties were estimated to be lower than 1%.

Event-based processing of neutron scattering data

Many of the world׳s time-of-flight spallation neutrons sources are migrating to recording individual neutron events. This provides for new opportunities in data processing, the least of which is to filter the events based on correlating them with logs of sample environment and other ancillary equipment. This paper will describe techniques for processing neutron scattering data acquired in event mode which preserve event information all the way to a final spectrum, including any necessary corrections or normalizations. This results in smaller final uncertainties compared to traditional methods, while significantly reducing processing time and memory requirements in typical experiments. Results with traditional histogramming techniques will be shown for comparison.

Development, Optimization, and Validation of a Microplate Bioassay for Relative Potency Determination of Linezolid Using a Design Space Concept, and its Measurement Uncertainty.

The aim of this study was to develop, optimize, and validate a microplate bioassay for relative potency determination of linezolid in pharmaceutical samples using quality-by-design and design space approaches. In addition, a procedure is described for estimating relative potency uncertainty based on microbiological response variability. The influence of culture media composition was studied using a factorial design and a central composite design was adopted to study the influence of inoculum proportion and triphenyltetrazolium chloride in microbial growth. The microplate bioassay was optimized regarding the responses of low, medium, and high doses of linezolid, negative and positive controls, and the slope, intercept, and correlation coefficient of dose-response curves. According to optimization results, design space ranges were established using: (a) low (1.0 μg/mL), medium (2.0 μg/mL), and high (4.0 μg/mL) doses of pharmaceutical samples and linezolid chemical reference substance; (b) Staphylococcus aureus ATCC 653 in an inoculum proportion of 10%; (c) antibiotic No. 3 culture medium pH 7.0±0.1; (d) 6 h incubation at 37.0±0.1ºC; and (e) addition of 50 μL of 0.5% (w/v) triphenyltetrazolium chloride solution. The microplate bioassay was linear (r2=0.992), specific, precise (repeatability RSD=2.3% and intermediate precision RSD=4.3%), accurate (mean recovery=101.4%), and robust. The overall measurement uncertainty was reasonable considering the increased variability inherent in microbiological response. Final uncertainty was comparable with those obtained with other microbiological assays, as well as chemical methods.

Uncertainties in nuclear decay data evaluations

Over the years, scientists have compiled and evaluated experimental results and combined these with theoretical studies with the goal of obtaining the best values, and their uncertainties, for the quantities related to radioactive decay. To meet the demand, an international group, the Decay Data Evaluation Project, was organised in 1995. The methodology adopted by this group is detailed. Some examples are given explaining how the final uncertainties are assessed from the experimental results and their uncertainties.

Influence of the physical data to calibrate TEPCs.

Tissue-equivalent proportional counters (TEPCs) measure distributions of ionisations, produced in the gas cavity by the radiation field which are afterwards converted into distributions of energy imparted by applying a calibration factor. To calibrate the pulse-height spectra, first, a marker point must be identified in the measured spectrum. Then, an accurate value of lineal energy must be assigned to this marker. A common marker that is often used for calibration is the so-called proton-edge (p-edge). It is a distinctive feature of a proton or neutron spectrum which corresponds to the maximum amount of energy that a proton can deposit in the active volume of the detector. A precise method to identify the marker point was applied to identify the p-edge with an uncertainty below 1 %. To evaluate the final uncertainty of the calibration, the uncertainty of the energy value assigned to the p-edge must also be considered. This value can be evaluated using different energy-range tables. This study investigates how the choice of different input databases for calibration purposes influences the calibration. The effect of three different frequently used sets of input data was analysed for pure propane gas and for propane-TE gas mixture.

Uncertainty analysis of an irrigation scheduling model for water management in crop production

Irrigation scheduling tools are critical to allow producers to effectively manage water resources for crop production. To be useful, these tools need to be accurate, complete, and relatively reliable. The current work presents an uncertainty analysis and its results for the Mississippi Irrigation Scheduling Tool (MIST) model, showing the margin of error (uncertainty) of the resulting irrigation advice arising solely from the propagation of measurement uncertainty through the MIST calculations. The final relative uncertainty in the water balance value from MIST was shown to be around 9% of that value, which is in the normal range of the margin of error and acceptable for agronomic systems. The results of this research also indicate that accurate measurements of irrigation and rainfall are critical to minimizing errors when using MIST and similar scheduling tools. While developed with data from Mississippi, the results of this uncertainty analysis are relevant to similar tool development efforts across the southern and southeastern United States and other high-rainfall areas, especially for locations lacking high-quality co-located weather stations.