measurement uncertainties
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2022 ◽  
Vol 2149 (1) ◽  
pp. 012008
Author(s):  
Philipp Schneider ◽  
Saulius Nevas ◽  
Detlef Lindner ◽  
Lutz Werner ◽  
Ulrike Linke ◽  
...  

Abstract A modular photometric trap detector system has recently been developed at Physikalisch-Technische Bundesanstalt (PTB). All parts of the detector are now completely calibrated. The new planned traceability chain for the realisation of luminous intensity unit can therefore be established for the first time. This contribution shows the results of the individual calibration steps including the associated measurement uncertainties and correlations. A major part of the calibrations along the traceability chain is done at the upgraded measurement setup TULIP (TUnable Lasers In Photometry). The improvements of the TULIP setup are presented and the effects on the measurement uncertainty are shown. The result of the first complete calibration according to the new traceability chain is compared to previous calibration results both in terms of spectral irradiance responsivity and luminous responsivity. The further steps required towards implementing the new traceability chain and the possible implications are discussed.


Robotica ◽  
2021 ◽  
pp. 1-16
Author(s):  
B. V. Vidyadhara ◽  
Lima Agnel Tony ◽  
Mohitvishnu S. Gadde ◽  
Shuvrangshu Jana ◽  
V. P. Varun ◽  
...  

SUMMARY In this paper, we present a novel passive single degree-of-freedom (DoF) manipulator design and its integration on an autonomous drone to capture a moving target. The end-effector is designed to be passive, to disengage the moving target from a flying UAV and capture it efficiently in the presence of disturbances, with minimal energy usage. It is also designed to handle target sway and the effect of downwash. The passive manipulator is integrated with the drone through a single DoF arm, and experiments are carried out in an outdoor environment. The rack-and-pinion mechanism incorporated for this manipulator ensures safety by extending the manipulator beyond the body of the drone to capture the target. The autonomous capturing experiments are conducted using a red ball hanging from a stationary drone and subsequently from a moving drone. The experiments show that the manipulator captures the target with a success rate of 70% even under environmental/measurement uncertainties and errors.


2021 ◽  
Author(s):  
Philipp Schneider ◽  
Thorsten Gerloff ◽  
Armin Sperling

In this contribution a framework is presented that aims to help for handling correlations within measurement uncertainty calculations for spectral quantities. Taking correlations for spectral quantities into account is necessary as they directly influence the measurement uncertainties especially for integral quantities. Therefore, determination of correlations within traceability chains at national metrology institutes (NMIs) and disseminations of correlated data to test laboratory level is encouraged and a major goal of the EMPIR project 19NRM02 “Revision and extension of standards for test methods for LED lamps, luminaires and modules” (RevStdLED). The presented python-based analysis framework is used in photometry and spectroradiometry at PTB to calculate the results and associated measurement uncertainty for spectral irradiance, spectral irradiance responsivity and luminous responsivity based on spectral calibrations.


2021 ◽  
Author(s):  
P. Kliment ◽  
M. Šmíd ◽  
G. Porrovecchio

LED-based light sources have replaced massively traditional sources. The metrology traceability chains realised in leading European NMIs utilise the absolutely calibrated broadband radiometers (three-element silicon trap detectors) for calibrating primary photometers. Specific spectral properties of white LED allow to apply the trap detectors directly as new primary photometers. The unfiltered technique (Dӧnsberg at al., 2014) is used and the calibration of spectral irradiance responsivity is needed. We have a long experience in detector-based spectral irradiance responsivity calibrations declared by particular CMC’s published in BIPM KCDB. The aim of this work was to revise the uncertainty budget in order to reduce the measurement uncertainties for specific application of calibration of the trap-based unfiltered primary photometers UPP. The two calibration methods were used to analyse the occasional back-reflection effect of the UPP front aperture. The measurement was performed using our reference spectral responsivity facility in spectral range 350 nm – 900 nm.


2021 ◽  
Vol 18 ◽  
pp. 100296
Author(s):  
Gustavo Esteves Coelho ◽  
Álvaro Ribeiro ◽  
Maria Graça Neves ◽  
António Pascoal

2021 ◽  
Author(s):  
◽  
Dominic Francesco Ferretti

<p>A new GC-IRMS technique has been developed for isotopic and mixing ratio analysis of atmospheric CO2. The technique offers for the first time, N2O-free, high precision (<0.05 [per mil]) analysis of d13C and d18O from small whole-air samples. On-line GC separation of CO2 and N2O from these small samples is combined with IRMS under elevated ion source pressures. A specialised open split interface is an integral part of the inlet system and ensures a continuous flow of either sample gas or pure helium to the IRMS. The analysis, including all flushing, uses a total of 45 ml of an air sample collected at ambient pressure. Of this, three 0.5 ml aliquots are injected onto the GC column, each providing [approximately] 0.8 nmol CO2 in the IRMS source. At this sample size, d13C precision obtained is at the theoretical shot-noise limit. Demonstrated precisions for d13C, d18O, and CO2 mixing ratio (all measured simultaneously)are 0.02 [per mil], 0.04 [per mil] and 0.4 ppm respectively. The initial results from an inter calibration exercise with Atmospheric Research at the Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australia achieved the International Atomic Energy Agency (IAEA) target precision for d13C. During this exercise, agreement for d18O and CO2 mixing ratio was outside the IAEA and World Meteorological Organization (WMO) target precisions for these species, however, when the measurement uncertainties of the two laboratories were considered, the differences were not significant. An inter comparison program using air samples collected at Baring Head, New Zealand and Cape Grim, Australia was also established with CSIRO and d13C, d18O and CO2 mixing ratio showed excellent agreement when combined measurement uncertainties were considered. Further inter comparisons with the Carbon Cycle Group at the National Oceanic and Atmospheric Administration Climate Monitoring and Diagnostics Laboratory (NOAA CMDL), the Institute of Arctic and Alpine Research (INSTAAR), and Scripps Institution of Oceanography (SIO) were also established. No significant differences for d13C were observed during these inter comparison programs. Therefore, these preliminary measurements suggest that the current situation between these laboratories for d13C comparisons from whole-air in glass flasks may be improved compared to the 1995 IAEA inter comparison from whole-air in high-pressure cylinders. Following these inter calibration and inter comparison exercises, temporal and spatial variations in the mixing ratio and isotopic composition of atmospheric CO2 were determined over a large region of the Pacific Ocean to demonstrate the successful use of the GC-IRMS technique. Temporal variations were observed at long-term monitoring sites in the Southern Hemisphere (Baring Head, Cape Grim, and Arrival Heights, Ross Island, Antarctica). Seasonal cycles of CO2 mixing ratio and d13C, with amplitudes of [approximately] 1 ppm and [approximately] 0.05 [per mil] respectively, were measured at Baring Head. A decline in d13C of [approximately] -0.1 [per mil]/year was observed at Arrival Heights between 1997 and 1999. Spatial variations in the Pacific Ocean were investigated by shipboard sampling programs between [approximately] 62 degrees S and [approximately] 32 degrees N. These data were consistent with a Southern Ocean sink between [approximately] 43 degrees S and [approximately] 57 degrees S. In addition, inter hemispheric gradients of d13C and CO2 mixing ratio in March and September 1998 were determined and the position and intensity of the SPCZ and ITCZ were important for the strength of these inter hemispheric gradients. Measurements performed during an upper tropospheric flight from New Zealand, to Antarctica show elevated CO2 levels and depleted d13C compared to samples obtained in the marine boundary layer over this region. A small-scale application of the technique measured soil-respired CO2 in a New Zealand Mountain Beech forest from 150 ml sample flasks that were filled to ambient pressure. These measurements determined a difference between the d13C source signature from the young and old trees of [approximately] 0.3 [per mil], which was in the correct direction but of smaller magnitude than that expected. The small sample requirements of the GC-IRMS technique ease sample collection logistics for varied research. Since initial results from an inter calibration exercise with CSIRO obtain the IAEA target precision for d13C and the technique has demonstrated its ability to successfully monitor atmospheric CO2 species from small whole-air samples, without contamination by atmospheric N2O or the use of cryogen, the technique will be a powerful tool in global carbon cycle research.</p>


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