Henrik Kjeldsen

Dr. Henrik Kjeldsen

orcid

Research Focus & Metrics

Academic Career Length

16Years (2011-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 June 2015 in Review of Scientific Instruments
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HPH. B. Pedersen
H. B. Pedersen
ASA. Svendsen
A. Svendsen
LHL. S. Harbo
L. S. Harbo
HKH. V. Kiefer
H. V. Kiefer
HKHenrik Kjeldsen
Henrik Kjeldsen
LAL. H. Andersen
L. H. Andersen
We describe the design of and the first commissioning experiments with a newly constructed electrostatic storage ring named SAPHIRA (Storage Ring in Aarhus for PHoton-Ion Reaction Analysis). With an intense beam of Cu− at 4 keV, the storage ring is characterized in terms of the stored ion beam decay rate, the longitudinal spreading of an injected ion bunch, as well as the direct measurements of the transverse spatial distributions under different conditions of storage. The ion storage stability in SAPHIRA was investigated systematically in a selected region of its electrical configuration space.

15 November 2011 in The Astrophysical Journal
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CJChen Jiang
Chen Jiang
BJB. W. Jiang
B. W. Jiang
JCJ. Christensen-Dalsgaard
J. Christensen-Dalsgaard
TBT. R. Bedding
T. R. Bedding
DSD. Stello
D. Stello
FMF. Mullally
F. Mullally
We have analyzed oscillations of the red giant star HD 186355 observed by the NASA Kepler satellite. The data consist of the first five quarters of science operations of Kepler, which cover about 13 months. The high-precision time-series data allow us to accurately extract the oscillation frequencies from the power spectrum. We find that the frequency of the maximum oscillation power, νmax, and the mean large frequency separation, Δν, are around 106 and 9.4 μHz, respectively. A regular pattern of radial and non-radial oscillation modes is identified by stacking the power spectra in an echelle diagram. We use the scaling relations of Δν and νmax to estimate the preliminary asteroseismic mass, which is confirmed with the modeling result (M = 1.45 ± 0.05 M ☉) using the Yale Rotating stellar Evolution Code (YREC7). In addition, we constrain the effective temperature, luminosity, and radius from comparisons between observational constraints and models. A number of mixed l = 1 modes are also detected and taken into account in our model comparisons. We find a mean observational period spacing for these mixed modes of about 58 s, suggesting that this red giant branch star is in the shell hydrogen-burning phase.

25 August 2022 in Sensors
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QBQuentin Baire
Quentin Baire
MDMiruna Dobre
Miruna Dobre
APAnne-Sophie Piette
Anne-Sophie Piette
Luca Giovanni LanzaLuca Giovanni Lanza
Luca Giovanni Lanza
Arianna CauteruccioArianna Cauteruccio
Arianna Cauteruccio
CICarmen Garcia Izquierdo
Carmen Garcia Izquierdo
Precipitation is among the most important meteorological variables for, e.g., meteorological, hydrological, water management and climate studies. In recent years, non-catching precipitation gauges are increasingly adopted in meteorological networks. Despite such growing diffusion, calibration procedures and associated uncertainty budget are not yet standardized or prescribed in best practice documents and standards. This paper reports a metrological study aimed at proposing calibration procedures and completing the uncertainty budgets, to make non-catching precipitation gauge measurements traceable to primary standards. The study is based on the preliminary characterization of different rain drop generators, specifically developed for the investigation. Characterization of different models of non-catching rain gauges is also included.

7 July 2023 in Energies
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CSCamelia Stratulat
Camelia Stratulat
RGRaluca Elena Ginghina
Raluca Elena Ginghina
ABAdriana Elena Bratu
Adriana Elena Bratu
AIAlper Isleyen
Alper Isleyen
MTMurat Tunc
Murat Tunc
Jochen VoglJochen Vogl
Jochen Vogl
In this study, five laboratories, namely, BRML (Romania), TUBITAK UME (Turkey), IMBIH (Bosnia and Herzegovina), BAM (Germany), and DTI (Denmark), developed and validated analytical procedures by ICP-MS, ICP-OES, MWP-AES, WD-XRF, and ID-MS for the determination of inorganic impurities in solid and liquid biofuels, established the budget of uncertainties, and developed the method for determining the amount of ash in the measurement range 0–1.2% with absolute repeatability less than 0.1% and absolute reproducibility of 0.2% (according to EN ISO 18122). In order to create homogeneous certified reference materials, improved methodologies for the measurement and characterization of solid and liquid biofuels were developed. Thus, information regarding the precision, accuracy, and bias of the method, and identifying the factors that intervened in the measurement of uncertainty were experimentally determined, supplementing the information from the existing standards in the field.

28 January 2024 in Energies
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HKHenrik Kjeldsen
Henrik Kjeldsen
PØPeter Friis Østergaard
Peter Friis Østergaard
HSHelena Strauss
Helena Strauss
JNJan Nielsen
Jan Nielsen
BTBayan TALLAWI
Bayan TALLAWI
JHJens Ole Hougaard
Jens Ole Hougaard
This paper presents methodologies and equipment for SI-traceable inline measurements of water content (a critical quality parameter) in solid biofuels. Inline measurement systems for water content are commonly used at CHP plants, providing continuous real-time data. However, the accuracy of these systems is in most cases unsatisfactory, mainly because the systems are not calibrated representatively for the relevant material, and until now, calibrations traceable to the SI system have not been available. To provide reliable and accurate inline water content data, new procedures and equipment for calibrating measurement systems were developed. Two reference methods for the determination of water content were developed; one measures the airflow and dewpoint of desorbed water in the air passing a test sample, while the other uses a P2O₅-sensor. Additionally, a transfer standard based on a cavity resonance sensor was developed for fast onsite calibration of the inline sensor at the power plant. This new instrument allows for quick and accurate measurements. The transfer standard is made metrologically traceable to the primary measurement standards. The entire system was demonstrated by calibrating an inline microwave-based (MW) sensor at the CHP plant of VERDO in Randers, Denmark. Thus, a complete metrological traceability chain was established from an industrial to a primary standard.

8 July 2025 in TM - Technisches Messen
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SKStephan Krenek
Stephan Krenek
RERené Eisermann
René Eisermann
GFGuillaume Failleau
Guillaume Failleau
XLXin Lu
Xin Lu
PTPeter Thomas
Peter Thomas
KAKlaus Anhalt
Klaus Anhalt
The measurement and control of temperature plays a key role in achieving the European Green Deal targets for a low carbon energy system. Fibre-optic thermometry is an emerging technology that can improve temperature measurement in extreme environments for energy providers and industry due to its distributed sensing and immunity to electromagnetic fields. Various applications for optimisation and monitoring in the energy sector are described, covering the whole range from energy generation to transmission and consumption. However, fibre-optic thermometers have cross sensitivities to other quantities (e.g., strain and humidity) and ageing effects that need to be investigated, quantified and minimised to obtain traceable and reliable measurements. This is particularly important so that applications in critical infrastructure can benefit from future measurements that are not possible with conventional sensors. The European INFOTherm project aims to overcome the limitations that currently prevent the widespread use of fibre-optic thermometry by creating a dedicated European metrology infrastructure for research, development and calibration. First results on measurement uncertainty, improvement of measurement techniques and practical field tests are presented.