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Marcus Wolff     Institute, Department or Faculty Head 
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Marcus Wolff published an article in November 2018.
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Henry Bruhns

5 shared publications

Hochschule für Angewandte Wissenschaften Hamburg, Fakultät Technik und Informatik, Department Maschinenbau und Produktion, Berliner Tor 21, 20099 Hamburg, Germany;(H.B.);(M.W.);(Y.S.)

Yannick Saalberg

5 shared publications

Hochschule für Angewandte Wissenschaften Hamburg, Fakultät Technik und Informatik, Department Maschinenbau und Produktion, Berliner Tor 21, 20099 Hamburg, Germany;(H.B.);(M.W.);(Y.S.)

Klaus Michael Spohr

2 shared publications

Extreme Light Infrastructure (ELI-NP) & Horia Hulubei National Institute for R & D in Physics and Nuclear Engineering (IFIN-HH), Str. Reactorului No. 30, P.O. Box MG-6, 077125 Bucharest– Măgurele, Romania

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Publication Record
Distribution of Articles published per year 
(2006 - 2018)
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15
 
Publications See all
Article 0 Reads 0 Citations Quantitative Evaluation of Broadband Photoacoustic Spectroscopy in the Infrared with an Optical Parametric Oscillator Henry Bruhns, Marcus Wolff, Yannick Saalberg, Klaus Michael ... Published: 15 November 2018
Sensors, doi: 10.3390/s18113971
DOI See at publisher website PubMed View at PubMed ABS Show/hide abstract
We evaluate the spectral resolution and the detection thresholds achievable for a photoacoustic spectroscopy (PAS) system in the broadband infrared wavelength region 3270nm≲λ≲3530nm driven by a continuous wave optical parametric oscillator (OPO) with P¯≈1.26W. The absorption spectra, IPAS(λi), for diluted propane, ethane and methane test gases at low concentrations (c∼100ppm) were measured for ∼1350 discrete wavelengths λi. The IPAS(λi) spectra were then compared to the high resolution cross section data, σFTIR, obtained by Fourier Transform Infrared Spectroscopy published in the HITRAN database. Deviations of 7.1(6)% for propane, 8.7(11)% for ethane and 15.0(14)% for methane with regard to the average uncertainty between IPAS(λi) and the expected reference values based on σFTIR were recorded. The characteristic absorption wavelengths λres can be resolved with an average resolution of δλres∼0.08nm. Detection limits range between 7.1 ppb (ethane) to 13.6 ppb (methane). In an additional step, EUREQA, an artificial intelligence (AI) program, was successfully applied to deconvolute simulated PAS spectra of mixed gas samples at low limits of detection. The results justify a further development of PAS technology to support e.g., biomedical research.
PREPRINT 0 Reads 0 Citations Photoacoustics Modelling using Amplitude Mode Expansion Method in a Multiscale T-cell Resonator Said El-Busaidy, Bernd Baumann, Marcus Wolff, Lars Duggen Published: 27 October 2018
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The photoacoustic (PA) effect consisting of the generation of an acoustic signal based on the absorption of light has already demonstrated its potential for various spectroscopic applications for both gaseous and solid samples. The signal produced during photoacoustic spectroscopy (PAS) measurement is, however, usually weak and needs to be amplified. This is achieved by using a photoacoustic cell resonator where acoustic resonances are utilized to significantly boost the signal. Therefore, a PA resonator has a significant role in PAS measurement set-ups. When designing or optimizing a new PA resonator, numerical methods are generally used to simulate the photoacoustic signal generation. In this paper, the amplitude mode expansion (AME) method is presented as a quick and accurate simulation tool. The method is used to simulate the photoacoustic signal in a multi-scale T-cell resonator over a wide frequency range. The AME method is based on eigenmode expansion and introduction of losses by quality factors. The AME simulation results are compared and analyzed against the results from the viscothermal method. Reasonably good agreement is obtained between the two methods. However, small frequency shifts in the resonances of the AME method are noted. The shifts are attributed to the location of the dominant mode within the T-cell. The viscothermal method is considered the most accurate method for simulating the photoacoustic signal in small resonators. However, it is computationally very demanding. The AME method provides a much faster simulation alternative. This is particularly useful in the design and optimization of photoacoustic resonators where numerical methods are preferred over experimental measurements due to their speed and low cost.
Article 3 Reads 0 Citations Multivariate Analysis as a Tool to Identify Concentrations from Strongly Overlapping Gas Spectra Yannick Saalberg, Marcus Wolff Published: 15 May 2018
Sensors, doi: 10.3390/s18051562
DOI See at publisher website PubMed View at PubMed ABS Show/hide abstract
We applied a multivariate analysis (MVA) to spectroscopic data of gas mixtures in the mid-IR in order to calculate the concentrations of the single components which exhibit strongly overlapping absorption spectra. This is a common challenge in broadband spectroscopy. Photoacoustic (PA) measurements of different volatile organic compounds (VOCs) in the wavelength region of 3250 nm to 3550 nm served as the exemplary detection technique. Partial least squares regression (PLS) was used to calculate concentrations from the PA spectra. After calibration, the PLS model was able to determine concentrations of single VOCs with a relative accuracy of 2.60%.
Article 2 Reads 0 Citations High-intensity discharge lamp and Duffing oscillator—Similarities and differences Bernd Baumann, Joerg Schwieger, Ulrich Stein, Sarah Hallerbe... Published: 07 December 2017
Journal of Applied Physics, doi: 10.1063/1.4999979
DOI See at publisher website
Article 5 Reads 0 Citations Multivariate Analysis as a Tool to Identify Concentrations from Strongly Overlapping Gas Spectra Yannick Saalberg, Marcus Wolff Published: 29 November 2017
Proceedings, doi: 10.3390/proceedings1080843
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Multivariate analysis (MVA) was introduced in the early 20th century and first applied in psychology under the name of Multiple Factor Analysis (MFA).
PREPRINT 0 Reads 0 Citations High-Intensity Discharge Lamp and Duffing Oscillator - Similarities and Differences Bernd Baumann, Joerg Schwieger, Ulrich Stein, Sarah Hallerbe... Published: 08 May 2017
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The processes inside the arc tube of high-intensity discharge lamps are investigated by finite element simulations. The behavior of the gas mixture inside the arc tube is governed by differential equations describing mass, energy and charge conservation as well as the Helmholtz equation for the acoustic pressure and the Navier-Stokes equation for the flow driven by the buoyancy and the acoustic streaming force. The model is highly nonlinear and requires a recursion procedure to account for the impact of acoustic streaming on the temperature and other fields. The investigations reveal the presence of a hysteresis and the corresponding jump phenomenon, quite similar to a Duffing oscillator. The similarities and, in particular, the differences of the nonlinear behavior of the high-intensity discharge lamp to that of a Duffing oscillator are discussed. For large amplitudes the high-intensity discharge lamp exhibits a stiffening effect in contrast to the Duffing oscillator.
Conferences user registered
09.05 - 11.05 2019, Physical conference 7th International Symposium on Sensor Science Chaired by Luigi Zeni , Nunzio Cennamo , Aldo Minardo
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