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  • 1.
    Anyangwe Nwaboh, Javis
    et al.
    Physikalisch-Technische Bundesanstalt, Germany.
    Persijn, Stefan
    VSL Dutch Metrology Institute, The Netherlands.
    Arrhenius, Karine
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Bohlen, Haleh
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Werhahn, Olav
    Physikalisch-Technische Bundesanstalt, Germany.
    Ebert, Volker
    Physikalisch-Technische Bundesanstalt, Germany.
    Metrological quantification of CO in biogas using laser absorption spectroscopy and gas chromatography2018In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 29, no 9, article id 095010Article in journal (Refereed)
    Abstract [en]

    Biogas has a vital role in the future market of renewable energy. When upgraded to biomethane, it can be injected into natural gas grids if the level of certain impurities complies with the specifications in EN16723. For some of these impurities, suitable measurement methods are lacking which hampers the quality control of biomethane to be injected into natural gas networks. Here, we report the evaluation of three detection methods suitable for carbon monoxide (CO) in biogas and biomethane applications for which EN16723 specifies an upper limit of 0.1% (1000 µmol/mol). Two of these methods are based on laser absorption spectroscopy (LAS) and one on gas chromatography (GC). Both LAS spectrometers are employing direct absorption spectroscopy and operating at 4.6µm, probing a single CO absorption line in the fundamental CO band: One – called dTDLAS (direct tunable diode laser absorption spectroscopy)- is based on a new Interband Cascade Laser specially designed for biogas and biomethane applications, while the other is based on Quantum Cascade Laser Absorption Spectroscopy (QCLAS). The GC is equipped with two packed columns (Hayesep Q and Molecular Sieve 5A) and a thermal conductivity detector. Carbon monoxide amount fraction results in biogas matrices derived using these three measurement methods are compared to amount fraction values of different, gravimetrically prepared reference gas standards of CO in biogas. These were used to validate the measurement capabilities. The measured CO amount fraction results from LAS and GC covered 10 µmol/mol to 30000 µmol/mol (system measurement ranges, LAS: 3 µmol/mol - 1000 µmol/mol, GC: 500 µmol/mol - 30000 µmol/mol) and were in excellent agreement with the gravimetric values of the gas standards. At 400 µmol/mol, the guide to the expression of uncertainty in measurement (GUM) compliant relative standard uncertainties of our calibration-free dTDLAS and the gas-calibrated QCLAS systems are estimated to be 1.4 % vs 0.5 %, respectively. The relative standard uncertainty of the GC CO measurements at 5075 µmol/mol is 1.3 %. This work demonstrates that, by means of GC and LAS, relative standard uncertainties of 1.4 % and below can be reached for CO measurements in biogas and that cost-optimized calibration-free approaches not requiring frequent use of gas standards have become available.

  • 2.
    Arrhenius, Karine
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Chemistry, Biomaterials and Textiles.
    Büker, Oliver
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Fischer, Andreas
    RISE Research Institutes of Sweden, Materials and Production, Chemistry, Biomaterials and Textiles.
    Persijn, Stefan
    VSL Dutch Metrology Institute, Netherlands.
    Moore, Niamh
    NPL National Physical Laboratory, UK.
    Development and evaluation of a novel analyser for ISO14687 hydrogen purity analysis2020In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 31, no 7, article id 075010Article in journal (Refereed)
    Abstract [en]

    Standards ISO14687 and EN17124 set stringent limits for numerous gaseous impurities and particulates that may damage the fuel cell system in a hydrogen vehicle, as it is highly sensitive to the presence of even very low levels of impurities. However, performing the whole set of analyses is both technically challenging and time-consuming for any laboratory and will require a combination of several analytical techniques or instruments. In this study, we discussed the selection of analytical techniques for hydrogen purity testing in order to optimize the CAPEX (capital expenditure) and OPEX (operational expenditure), while ensuring the quality of the results and the compliance of the analytical methods with ISO21087. Among the individual impurities to be analysed in ISO14687, spectroscopy techniques are suitable for ammonia, carbon dioxide, carbon monoxide, formaldehyde, formic acid, oxygen and water. Spectroscopy techniques are even suitable for some impurities belonging to the three total species such as hydrogen sulphide, hydrogen chloride and methane. However, helium and argon, which are monoatomic, do not exhibit response in the infrared region. Therefore, any spectroscopic analysis method must be completed by another method in order to simultaneously analyse all individual gaseous impurities from ISO14687. In this study, we constructed and demonstrated the feasibility of an instrument composed of a gas chromatograph having three columns (two packed columns and a PLOT (Porous Layer Open Tubular) column and two detectors (FID and TCD) coupled in parallel to two OFCEAS instruments using reference gas mixtures. Finally, we also proposed an extended configuration that will allow performing the whole set of analyses for gaseous species from ISO14687

  • 3.
    Arrhenius, Karine
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics.
    Francini, Lorena
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics.
    Fischer, Andreas
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics.
    Büker, Oliver
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Arques, Laurent
    AP2E, France.
    Comparison of optical feedback cavity enhanced absorption spectroscopy and gas chromatography for the measurement of the main components and impurities in biogas, landfill gas, biomethane and carbon dioxide streams2023In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 34, no 9, article id 095011Article in journal (Refereed)
    Abstract [en]

    In this study, we evaluated the performances of a custom-built optical feedback cavity enhanced absorption spectroscopy (OFCEAS) instrument for the determination of the composition of energy gases, focusing on methane and carbon dioxide as main components, and carbon monoxide as impurities, in comparison with the well-established, validated, and traceable gas chromatographic method. A total of 115 real sample gases collected in biogas plants or landfills were analyzed using with both techniques over a period of 12 months. The comparison of the techniques showed that the virtual model which allows the measurement, needs to be optimized using real samples of varied compositions. The OFCEAS measurement technique was found to be capable of measuring both the main components and a trace component in different matrices; to within a 2% measurement uncertainty (higher than the gas chromatograph/thermal conductivity detector (GC/TCD) method). The OFCEAS method exhibits a very fast response, does not require daily calibration, and can be implemented online. The agreements between the OFCEAS technique and the GC/TCD method show that the drift of the OFCEAS instruments remains acceptable in the long term as long as no change is made to the virtual model. Matrix effects were observed, and those need to be taken into consideration when analyzing different types of samples. © 2023 The Author(s). Published by IOP Publishing Ltd.

  • 4.
    Colaço, Marcos
    et al.
    Rio de Janeiro State University, Brazil.
    Camara, Alexandre
    Rio de Janeiro State University, Brazil.
    Nogueira, Liebert
    University of Oslo, Norway.
    Carvalho, Isabel
    Pontifícia Universidade Católica Do Rio de Janeiro, Brazil.
    Margulis, Walter
    RISE Research Institutes of Sweden, Digital Systems, Smart Hardware. KTH Royal Institute of Technologt, Sweden.
    Barroso, Regina
    Rio de Janeiro State University, Brazil.
    Characterization of the microstructures of specialty optical fibers for electric-field sensing by propagation-based x-ray phase-contrast microtomography2021In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 32, no 6, article id 065401Article in journal (Refereed)
    Abstract [en]

    In this work, we present a quantitative (statistical) 3D morphological characterization of optical fibers used in electric-field sensing. The characterization technique employs propagation-based x-ray phase-contrast microcomputed tomography (micro-CT). In particular, we investigate specialty optical fibers that contain microstructured holes that are electro-optically modified by thermal poling to induce second-order nonlinear effects (SONE). The efficiency of the SONE is reflected in the characterization parameter, Vπ, which is highly dependent on the dimensions of the fiber. The fiber microstructures must be uniform to support the fabrication of reproducible devices. The results obtained using the micro-CT technique show that uncertainty of ±1.7% arises in the determination of the expected value of the voltage that causes a change in the phase of the electromagnetic wave equal to π rad (Vπ ), demonstrating a great advantage, compared with other techniques e.g. SEM, which would need at least 1000 images of the cross-section of an optical fiber, taken at different points, making the process more expensive and time-consuming.

  • 5.
    Dominguez, Armand
    et al.
    Lund University, Sweden.
    Borggren, Jesper
    Beamonics AB, Sweden.
    Xu, Can
    Beamonics AB, Sweden.
    Otxoterena, Paul
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Försth, Michael
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety. Luleå University of Technology, Sweden.
    Leffler, Tomas
    Vattenfall AB, Sweden; Chalmers University of Technology, Sweden.
    Bood, Joakim
    Lund University, Sweden.
    A compact Scheimpflug lidar imaging instrument for industrial diagnostics of flames2023In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 34, no 7, article id 075901Article in journal (Refereed)
    Abstract [en]

    Scheimpflug lidar is a compact alternative to traditional lidar setups. With Scheimpflug lidar it is possible to make continuous range-resolved measurements. In this study we investigate the feasibility of a Scheimpflug lidar instrument for remote sensing in pool flames, which are characterized by strong particle scattering, large temperature gradients, and substantial fluctuations in particle distribution due to turbulence. An extinction coefficient can be extracted using the information about the transmitted laser power and the spatial extent of the flame. The transmitted laser power is manifested by the intensity of the ‘echo’ from a hard-target termination of the beam located behind the flame, while the information of the spatial extent of the flame along the laser beam is provided by the range-resolved scattering signal. Measurements were performed in heptane and diesel flames, respectively. © 2023 The Author(s). 

  • 6.
    Guillory, J
    et al.
    LCM Laboratoire Commun de Métrologie, France.
    Truong, D
    LCM Laboratoire Commun de Métrologie, France.
    Wallerand, J-P
    LCM Laboratoire Commun de Métrologie, France.
    Svantesson, Claes-Göran
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Herbertsson, Magnus
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    Bergstrand, Sten
    RISE Research Institutes of Sweden, Safety and Transport, Measurement Technology.
    An SI-traceable multilateration coordinate measurement system with half the uncertainty of a laser tracker2023In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 34, no 6, article id 065016Article in journal (Refereed)
    Abstract [en]

    We have validated the performance of a prototype coordinate measurement system based on multilateration by comparing it to a laser tracker, i.e. a well-proven instrument widely used in the industry. After establishing the uncertainty budget of the different systems, we performed position measurements with both instruments on common targets. Using the estimated uncertainties associated with the measurements, we found that the multilateration system provided lower position uncertainties than the laser tracker: on average 18 µm versus 33 µm for distances up to 12 m. The uncertainties represented by confidence ellipsoids are compatible between the two systems: for confidence regions of 95% probability, they overlap as expected, i.e. in 94% of the cases. We also measured the length of a 0.8 m long reference scale bar with the multilateration system at an error of only 2 µm. This cross-comparison is a new and key step in the characterization of this SI-traceable multilateration system. © 2023 The Author(s).

  • 7.
    Haloua, Frederique
    et al.
    LNE Laboratoire national de métrologie et d'essais, France.
    Bacquart, Thomas
    NPL National Physical Laboratory, UK.
    Arrhenius, Karine
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Delobelle, Benoit
    MAHYTEC, France.
    Ent, Hugo
    VSL Van Swinden Laboratorium, The Netherlands.
    Metrology for hydrogen energy applications: a project to address normative requirements2018In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 29, no 3, article id Special Section on the 18th International Congress of Metrology (CIM 2017)Article in journal (Refereed)
    Abstract [en]

    Hydrogen represents a clean and storable energy solution that could meet worldwide energy demands and reduce greenhouse gases emission. The joint research project (JRP) ‘Metrology for sustainable hydrogen energy applications’ addresses standardisation needs through pre- and co-normative metrology research in the fast emerging sector of hydrogen fuel that meet the requirements of the European Directive 2014/94/EU by supplementing the revision of two ISO standards that are currently too generic to enable a sustainable implementation of hydrogen. The hydrogen purity dispensed at refueling points should comply with the technical specifications of ISO 14687-2 for fuel cell electric vehicles. The rapid progress of fuel cell technology now requires revising this standard towards less constraining limits for the 13 gaseous impurities. In parallel, optimized validated analytical methods are proposed to reduce the number of analyses. The study aims also at developing and validating traceable methods to assess accurately the hydrogen mass absorbed and stored in metal hydride tanks; this is a research axis for the revision of the ISO 16111 standard to develop this safe storage technique for hydrogen. The probability of hydrogen impurity presence affecting fuel cells and analytical techniques for traceable measurements of hydrogen impurities will be assessed and new data of maximum concentrations of impurities based on degradation studies will be proposed. Novel validated methods for measuring the hydrogen mass absorbed in hydrides tanks AB, AB2 and AB5 types referenced to ISO 16111 will be determined, as the methods currently available do not provide accurate results. The outputs here will have a direct impact on the standardisation works for ISO 16111 and ISO 14687-2 revisions in the relevant working groups of ISO/TC 197 ‘Hydrogen technologies’.

  • 8.
    Hessling, Peter
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Kommunikation.
    Propagation of dynamic measurement uncertainty2011In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 22, no 10, p. 105105-Article in journal (Refereed)
  • 9. Kent, M
    et al.
    Knochel, R
    Daschner, F
    Schimmer, O
    Oehlenschlager, J
    Barr, Ulla-Karin
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Intangible but not intractable: The prediction of fish 'quality' variables using dielectric spectroscopy2007In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 18, no 4, p. 1029-1037Article in journal (Refereed)
    Abstract [en]

    In many fields the concept and measurement of quality is of prime importance. The fish industry is no exception to this and many sensory approaches have been devised to quantify this rather intangible property. The EU 5th framework project 'SEQUID' has concentrated on the measurement of the dielectric properties of fish tissue as a function of time both in frozen and chilled storage. The many deteriorative biochemical and microbiological processes that take place during the gradual spoilage of such materials have a subtle influence on the dielectric properties across the spectrum but notably in the microwave frequency region. In this region the complex interactions of water, solutes and structure-forming proteins are systematically changed by death and decay. Chilling or freezing may slow these processes but such preservation techniques do not halt them entirely. The SEQUID project has shown that it is possible, using a combination of time domain reflectometry and multivariate analysis, to predict certain quality-related variables, both sensory and biochemical, with comparable accuracy to existing methods. These results are presented in this paper. © 2007 IOP Publishing Ltd.

  • 10. Kent, M.
    et al.
    Knochel, R.
    Daschner, F.
    Schimmer, O.
    Oehlenschlager, J.
    Barr, Ulla-Karin
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Intangible but not intractable: The prediction of fish 'quality' variables using dielectric spectroscopy2007In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 18, no 4, p. 1029-1037Article in journal (Refereed)
    Abstract [en]

    In many fields the concept and measurement of quality is of prime importance. The fish industry is no exception to this and many sensory approaches have been devised to quantify this rather intangible property. The EU 5th framework project 'SEQUID' has concentrated on the measurement of the dielectric properties of fish tissue as a function of time both in frozen and chilled storage. The many deteriorative biochemical and microbiological processes that take place during the gradual spoilage of such materials have a subtle influence on the dielectric properties across the spectrum but notably in the microwave frequency region. In this region the complex interactions of water, solutes and structure-forming proteins are systematically changed by death and decay. Chilling or freezing may slow these processes but such preservation techniques do not halt them entirely. The SEQUID project has shown that it is possible, using a combination of time domain reflectometry and multivariate analysis, to predict certain quality-related variables, both sensory and biochemical, with comparable accuracy to existing methods. These results are presented in this paper. © 2007 IOP Publishing Ltd.

  • 11.
    Kotze, Reinhardt
    et al.
    Cape Peninsula University of Technology, South Africa.
    Wiklund, Johan
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Ultrasound Doppler measurements inside a diaphragm valve using novel transducer technologies2014In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 25, no 10, p. 105302-Article in journal (Refereed)
    Abstract [en]

    In this project, velocity profiles were measured in a diaphragm valve using an ultrasonic velocity profiling (UVP) technique. A non-Newtonian CMC model fluid was tested in this highly complex geometry and velocity profiles were measured at four different positions at the centre (contraction) of a specially manufactured 50% open diaphragm valve. The coordinates of the complex geometry and velocity magnitudes were analysed and compared to the bulk flow rate measured using an electromagnetic flow meter. Two different ultrasonic transducers (standard and delay line) were used and results were compared in order to assess velocity data close to wall interfaces as well as the accuracy and magnitude of measured velocities. The difference between calculated and measured flow rates was 32% when using the standard ultrasonic transducers. The error difference decreased to 18% when delay line transducers were introduced to the measurements. The velocity data obtained in the diaphragm valve showed a significant improvement close to the wall interfaces when using the delay line transducers. The main limitation when using delay line transducers is that beam refraction can significantly complicate measurements in a highly complex geometry such as a diaphragm valve. A new delay line transducer with no beam refraction could provide a solution. The introduction of delay line transducers showed that UVP can be used as a powerful tool for detailed flow behaviour measurements in complex geometries.

  • 12.
    Ochoterena, Raul
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research, Branddynamik.
    Försth, Michael
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Brandteknik, material (BRm).
    Elfsberg, Mattias
    FOI Swedish Defence Research Agency, Sweden.
    Larsson, Anders
    FOI Swedish Defence Research Agency, Sweden.
    Measuring breakdown voltage for objectively detecting ignition in fire research2013In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 24, no 10, article id 105802Article in journal (Refereed)
    Abstract [en]

    This paper presents a method intended for detecting the initiation of combustion and the presence of smoke in confined or open spaces by continuously applying an intermittent high-voltage pulse between the electrodes. The method is based on an electrical circuit which generates an electrical discharge measuring simultaneously the breakdown voltage between the electrodes. It has been successfully used for the detection of particle-laden aerosols and flames. However, measurements in this study showed that detecting pyrolysis products with this methodology is challenging and arduous. The method presented here is robust and exploits the necessity of having an ignition system which at the same time can automatically discern between clean air, flames or particle-laden aerosols and can be easily implemented in the existing cone calorimeter with very minor modifications.

  • 13.
    Pendrill, Leslie
    RISE - Research Institutes of Sweden, Safety and Transport, Measurement Science and Technology.
    Assuring measurement quality in person-centred healthcare2018In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 29, no 3, p. 034003-Article in journal (Refereed)
    Abstract [en]

    Is it realistic to aspire to the same kind of quality-assurance of measurement in person-centred care, currently being implemented in healthcare globally, as is established in the physical sciences and engineering? Ensuring metrological comparability (‘traceability’) and reliably declaring measurement uncertainty when assessing patient ability or increased social capital are however challenging for subjective measurements often characterised by large dispersion. Drawing simple analogies between ‘instruments’ in the social sciences – questionnaires, ability tests, etc.–  and  engineering instruments such as thermometers does not go far enough. A possible way forward apparently equally applicable to both physical and social measurement, seems to be to model inferences in terms performance metrics of a measurement system. Person-centred care needs person-centred measurement and a full picture of the measurement process when Man acts as a measurement instrument is given in the present paper. This complements previous work by presenting the process, step by step, from the observed indication (e.g. probability of success, Psuccess, of achieving atask), through restitution with Rasch Measurement Theory, to the measurand (e.g. task difficulty). Rasch invariant measure theory can yield quantities –‘latent’ (or ‘explanatory’) variables such as task challenge or person ability – with characteristics akin to those of physical quantities. Metrological references for comparability via traceability and reliable estimates ofuncertainty and decision risks are then in reach even for perceptive measurements (and other qualitative properties). As a case study, the person-centred measurement of cognitive ability is examined, as part of the EUproject EMPIR 15HLT04 NeuroMet, for Alzheimer’s, where better analysis of correlations with brain atrophy is enabled thanks to the Rasch metrological approach.

  • 14.
    Pendrill, Leslie
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Petersson, Niclas
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Metrology of human-based and other qualitative measurements2016In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 27, no 9, article id 094003Article in journal (Refereed)
    Abstract [en]

    The metrology of human-based and other qualitative measurements is in its infancy - concepts such as traceability and uncertainty are as yet poorly developed. This paper reviews how a measurement system analysis approach, particularly invoking as performance metric the ability of a probe (such as a human being) acting as a measurement instrument to make a successful decision, can enable a more general metrological treatment of qualitative observations. Measures based on human observations are typically qualitative, not only in sectors, such as health care, services and safety, where the human factor is obvious, but also in customer perception of traditional products of all kinds. A principal challenge is that the usual tools of statistics normally employed for expressing measurement accuracy and uncertainty will probably not work reliably if relations between distances on different portions of scales are not fully known, as is typical of ordinal or other qualitative measurements. A key enabling insight is to connect the treatment of decision risks associated with measurement uncertainty to generalized linear modelling (GLM). Handling qualitative observations in this way unites information theory, the perceptive identification and choice paradigms of psychophysics. The Rasch invariant measure psychometric GLM approach in particular enables a proper treatment of ordinal data; a clear separation of probe and item attribute estimates; simple expressions for instrument sensitivity; etc. Examples include two aspects of the care of breast cancer patients, from diagnosis to rehabilitation. The Rasch approach leads in turn to opportunities of establishing metrological references for quality assurance of qualitative measurements. In psychometrics, one could imagine a certified reference for knowledge challenge, for example, a particular concept in understanding physics or for product quality of a certain health care service. Multivariate methods, such as Principal Component Regression, can also be improved by exploiting the increased resolution of the Rasch approach.

  • 15. Risman, Per O.
    et al.
    Raaholt, Birgitta
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Retro-modelling of a dual resonant applicator and accurate dielectric properties of liquid water from -20 °c to +100 °c2007In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 18, no 4, p. 959-966Article in journal (Refereed)
    Abstract [en]

    A critical analysis is made of literature reports on the dielectric properties of pure water from liquid water supercooled at -20 °C, to +100 °C, in principle in the frequency range 0 to 3 GHz. Measurements using complete multi-step numerical modelling of a dual resonant cavity at about 920 MHz and 2230 MHz are presented. The measured data at about +20 °C are used as reference for the calculation of data at other temperatures. Due to the high resolution and considerations of various error sources, the resulting accuracy becomes high and allows the construction of improved empirical formulae for the Debye relaxation behaviour. © 2007 IOP Publishing Ltd.

  • 16. Risman, Per O.
    et al.
    Raaholt, Birgitta
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Retro-modelling of a dual resonant applicator and accurate dielectric properties of liquid water from -20 °c to +100 °c2007In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 18, no 4, p. 959-966Article in journal (Refereed)
    Abstract [en]

    A critical analysis is made of literature reports on the dielectric properties of pure water from liquid water supercooled at -20 °C, to +100 °C, in principle in the frequency range 0 to 3 GHz. Measurements using complete multi-step numerical modelling of a dual resonant cavity at about 920 MHz and 2230 MHz are presented. The measured data at about +20 °C are used as reference for the calculation of data at other temperatures. Due to the high resolution and considerations of various error sources, the resulting accuracy becomes high and allows the construction of improved empirical formulae for the Debye relaxation behaviour. © 2007 IOP Publishing Ltd.

  • 17.
    Seppä, Santeri Jeremias
    et al.
    MIKES Centre for Metrology and Accreditation, Finland.
    Korpelainen, Virpi
    MIKES Centre for Metrology and Accreditation, Finland.
    Bergstrand, Sten
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Massa, kraft, längd och tryck.
    Karlsson, Helge
    Justervesenet, Norway.
    Lillepea, Lauri
    AS Metrosert, Estonia.
    Lassila, Antti
    MIKES Centre for Metrology and Accreditation, Finland.
    Intercomparison of lateral scales of scanning electron microscopes and atomic force microscopes in research institutes in Northern Europe2014In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 25, no 4, article id 44013Article in journal (Refereed)
    Abstract [en]

    An intercomparison of lateral scales of scanning electron microscopes (SEM) and atomic force microscopes (AFM) in various research laboratories in Northern Europe was organized by the local national metrology institutes. In this paper are presented the results of the comparison, with also an example uncertainty budget for AFM grating pitch measurement. Grating samples (1D) were circulated among the participating laboratories. The participating laboratories were also asked about the calibration of their instruments. The accuracy of the uncertainty estimates seemed to vary largely between the laboratories, and for some laboratories the appropriateness of the calibration procedures could be considered. Several institutes (60% of all results in terms of En value) also had good comprehension of their measurement capability. The average difference from reference value was 6.7 and 10.0 nm for calibrated instruments and 20.6 and 39.9 nm for uncalibrated instruments for 300 nm and 700 nm gratings, respectively. The correlation of the results for both nominally 300 and 700 nm gratings shows that a simple scale factor calibration would have corrected a large part of the deviations from the reference values.

  • 18.
    Silander, Isak
    et al.
    Umeå University, Sweden.
    Zelan, Martin
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Axner, Ove
    Umeå University, Sweden.
    Arrhén, Fredrik
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Pendrill, Leslie
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Foltynowicz, Aleksandra
    Umeå University, Sweden.
    Optical measurement of the gas number density in a Fabry-Perot cavity2013In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 24, no 10, article id 105207Article in journal (Refereed)
    Abstract [en]

    An optical method for measuring the gas density by monitoring the refractive index inside a high-finesse Fabry-Perot cavity is presented. The frequency of a narrow linewidth Er:fiber laser, locked to a mode of the cavity, is measured with the help of an optical frequency comb while the gas density inside the cavity changes. A resolution of 1.4 × 10-6 mol m-3 is achieved in 3 s for nitrogen, which allows measurement of a relative gas density change of 3.4 × 10-8 at atmospheric pressure.

  • 19.
    Tawackolian, Karsten
    et al.
    PTB Physikalisch-Technische Bundesanstalt, Germany.
    Büker, Oliver
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Mätteknik, Volym, flöde, temperatur o densitet.
    Hogendoorn, Jankees
    KROHNE Altometer, The Netherlands.
    Lederer, Thomas
    PTB Physikalisch-Technische Bundesanstalt, Germany.
    Investigation of a ten-path ultrasonic flow meter for accurate feedwater measurements2014In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 25, no 7, p. 75304-Article in journal (Refereed)
    Abstract [en]

    The flow instruments used in thermal power plants cannot be calibrated directly for the actual process conditions, since no traceable calibration facility with known uncertainty is available. Asystematic investigation of the relevant influence parameters is therefore needed. It was found in earlier investigations that the dominant influences on the measurement uncertainty are the flowvelocity profile and the temperature. In the present work, we report on our experimental study of the temperature and Reynolds number dependence of a new ten-path ultrasonic flow meterprototype. An improved measuring program is developed that allows for a systematic characterization. Special emphasis was placed on producing and validating well defined velocity profiles on aprecision calibration flow rig. It was also for the first time intended and validated to generate fully developed Reynolds-similar velocity profiles for different temperatures so that the two main influence parameters, namely temperature and Reynolds number, can be clearly characterized separately. Since such ideal measurement conditions are not found in practical applications, the approach is also tested for a disturbed flow condition. A well defined disturbance is generated with a new flow disturber.

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