TY - JOUR A1 - Hartmann, Jürgen A1 - Litorja, M. A1 - Fowler, J. A1 - Fox, N. A1 - Stock, M. A1 - Razet, A. A1 - Khlevnoy, B. A1 - Ikonen, E. A1 - Machacs, M. A1 - Doytchinov, K. T1 - Final report on the CCPR-S2 supplementary comparison of area measurements of apertures for radiometry JF - Metrologia Y1 - 2007 UR - http://permalink.bibkatalog.de/BV012573233 VL - 44 IS - 02002 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Moritz, W. A1 - Roth, U. A1 - Heyde, M. A1 - Rademann, K. A1 - Reichling, M. T1 - Submicrosecond range surface heating and temperature measurement for efficient sensor reactivation JF - Thin Solid Films Y1 - 2001 UR - http://permalink.bibkatalog.de/BV013351743 IS - 391 SP - 143 EP - 148 ER - TY - CHAP A1 - Hartmann, Jürgen A1 - Dobhan, Alexander A1 - Engelmann, Bastian A1 - Eberhardt, Lars A1 - Heusinger, Moritz A1 - Raab, C A1 - Schleif, Frank-Michael A1 - Türk, M. T1 - Optimierung von Prozessen und Werkzeugmaschinen durch Bereitstellung, Analyse und Soll-Ist-Vergleich von Produktionsdaten: Digitalkonferenz Y1 - 2020 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Thuillier, G. A1 - Foujols, T. A1 - Bolsée, D. A1 - Gillotay, D. A1 - Hersé, M. A1 - Petermanns, W. A1 - Decupyer, W. A1 - Mandel, H. A1 - Sperfeld, P. A1 - Taubert, Dieter Richard T1 - SOLAR/SOLSPEC BT - Scientific objectives, instrument performances and its absolute calibration using a blackbody as primary standard source JF - Solar Physics Y1 - 2009 UR - http://permalink.bibkatalog.de/BV021245164 IS - 257 SP - 185 EP - 213 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Anhalt, Klaus A1 - Lowe, D. A1 - Machin, Graham A1 - Sadli, M. A1 - Yamada, Y. T1 - Thermodynamic temperature determinations of Co-C, Pd-C Pt-C and Ru-C eutectic fixed-points cells JF - Metrologia Y1 - 2006 UR - http://permalink.bibkatalog.de/BV012573233 VL - 43 IS - 2 SP - 78 EP - 83 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Machin, G. A1 - Bloembergen, P. A1 - Sadli, M. A1 - Yamada, Y. T1 - A concerted international project to establish high-temperature fixed-points for primary thermometry JF - International Journal of Thermophysics Y1 - 2007 UR - http://permalink.bibkatalog.de/BV013298193 IS - 28 SP - 1976 EP - 1982 ER - TY - CHAP A1 - Hartmann, Jürgen A1 - Reichling, M. ED - Nazaré, H. ED - Neves, A.J. T1 - Thermal transport in diamond T2 - Properties and growth of diamond Y1 - 2001 UR - https://books.google.de/books?id=jtC1mUFZfQcC&printsec=frontcover PB - Institution of Electrical Engineers CY - London ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Sadli, M. A1 - Anhalt, Klaus A1 - Schiller, S. T1 - Thermal effects in the BB3200pg on M-C eutectic implementation JF - International Journal of Thermophysics Y1 - 2009 UR - http://permalink.bibkatalog.de/BV013298193 IS - 30 SP - 69 EP - 76 ER - TY - JOUR A1 - Hartmann, Jürgen T1 - New Developments in High-Temperature Measurement Techniques JF - International Journal of Electrical and Computer Engineering Systems Y1 - 2014 VL - 5 IS - 2 SP - 63 EP - 67 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Engert, J. A1 - Fellmuth, B. A1 - Fischer, Joachim A1 - Hollandt, Jörg A1 - Tegeler, E. A1 - Seidel, J. T1 - Die internationale Temperaturskalen BT - ITS-90 und PLTS-2000 JF - PTB Mitteilungen Y1 - 2007 UR - http://permalink.bibkatalog.de/BV035078972 VL - 117 IS - 3 SP - 236 EP - 242 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Fischer, J. A1 - Johannsen, U. A1 - Werner, L. T1 - Analytical model for the temperature dependence of the spectral responsivity of silicon JF - J. Opt. Soc. Am. B Y1 - 2001 IS - 18 SP - 942 EP - 947 ER - TY - JOUR A1 - Höfflin, Dennis A1 - Sauer, Christian A1 - Schiffler, Andreas A1 - Versch, Alexander A1 - Hartmann, Jürgen T1 - Active thermography for in-situ defect detection in laser powder bed fusion of metal JF - Journal of Manufacturing Processes N2 - Additive manufacturing (AM) has revolutionized production by offering design flexibility, reducing material waste, and enabling intricate geometries that are often unachievable with traditional methods. As the use of AM for metals continues to expand, it is crucial to ensure the quality and integrity of printed components. Defects can compromise the mechanical properties and performance of the final product. Non-destructive testing (NDT) techniques are necessary to detect and characterize anomalies during or post-manufacturing. Active thermography, a thermal imaging technique that uses an external energy source to induce temperature variations, has emerged as a promising tool in this field. This paper explores the potential of in-situ non-destructive testing using the processing laser of a PBF-LB/M setup as an excitation source for active thermography. With this technological approach, artificially generated internal defects underneath an intact surface can be detected down to a defect size of 350 μm – 450 μm. Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:863-opus-57601 SN - 1526-6125 VL - 131 SP - 1758 EP - 1769 PB - Elsevier BV ER - TY - JOUR A1 - Höfflin, Dennis A1 - Sauer, Christian A1 - Schiffler, Andreas A1 - Manara, Jochen A1 - Hartmann, Jürgen T1 - Pixelwise high-temperature calibration for in-situ temperature measuring in powder bed fusion of metal with laser beam JF - Heliyon N2 - High-temperature calibration methods in additive manufacturing involve the use of advanced techniques to accurately measure and control the temperature of the build material during the additive manufacturing process. Infrared cameras, blackbody radiation sources and non-linear optimization algorithms are used to correlate the temperature of the material with its emitted thermal radiation. This is essential for ensuring the quality and repeatability of the final product. This paper presents the calibration procedure of an imaging system for in-situ measurement of absolute temperatures and temperature gradients during powder bed fusion of metal with laser beam (PBF-LB/M) in the temperature range of 500 K–1500 K. It describes the design of the optical setup to meet specific requirements in this application area as well as the procedure for accounting the various factors influencing the temperature measurement. These include camera-specific effects such as varying spectral sensitivities of the individual pixels of the sensor as well as influences of the exposure time and the exposed sensor area. Furthermore, influences caused by the complex optical path, such as inhomogeneous transmission properties of the galvanometer scanner as well as angle-dependent transmission properties of the f-theta lens were considered. A two-step fitting algorithm based on Planck's law of radiation was applied to best represent the correlation. With the presented procedure the calibrated thermography system provides the ability to measure absolute temperatures under real process conditions with high accuracy. Y1 - 2024 U6 - https://doi.org/10.1016/j.heliyon.2024.e28989 SN - 2405-8440 VL - 10 IS - 7 PB - Elsevier BV ER - TY - GEN A1 - Höfflin, Dennis A1 - Schiffler, Andreas A1 - Hartmann, Jürgen A1 - Sauer, Christian T1 - Dual Scan head approach for in-situ defect detection in laser powder bed fusion of metals - Dataset N2 - This dataset contains thermographic data from a study on in-situ defect detection in the Laser Powder Bed Fusion of Metals (PBF-LB/M) process. The data was collected using a novel experimental setup named Synchronized Path Infrared Thermography (SPIT), which employs a dual scan head configuration. One scan head directs the processing laser, while the second scan head positions the measurement field of an infrared (IR) camera. This setup allows for the precise analysis of the cooling behavior of the material decoupled from the immediate laser-material interaction zone. The experiments were conducted on pre-fabricated stainless steel (EOS StainlessSteel PH1, DIN 14540) samples with embedded, cylindrical subsurface defects of varying diameters. A single layer of metal powder was applied to these samples and then fused by the laser. The dataset includes a series of measurements where process parameters, specifically the volumetric energy density and the laser scanning speed, were systematically varied to assess their influence on defect detection reliability. The provided data consists of raw thermographic recordings, which capture the surface temperature distribution in the heat-affected zone behind the melt pool. These recordings can be used to identify localized areas of elevated temperature caused by the insulating effect of the subsurface defects, which impede heat transfer into the substrate. This dataset is valuable for researchers working on process monitoring, defect detection algorithms, and the validation of thermal simulations in additive manufacturing. Y1 - 2025 U6 - https://doi.org/10.5281/zenodo.15727369 ER - TY - GEN A1 - Sauer, Christian A1 - Schiffler, Andreas A1 - Höfflin, Dennis A1 - Hartmann, Jürgen T1 - Temporally Gated Active Thermography for Defect Detection in Laser-Based Powder Bed Fusion of Metals - Dataset N2 - This HDF5-dataset contains in-situ high-speed infrared thermography data acquired during the Laser-Based Powder Bed Fusion (PBF-LB/M) process. The data was collected using a Synchronized Path Infrared Thermography (SPIT) setup, which employs a dual-scanhead configuration to guide both the processing laser and the thermal camera's field of view. The primary feature of this dataset is the application of a temporally gated acquisition strategy. The infrared camera's integration time (800 µs) was synchronized with a modulated processing laser (500 Hz) to capture thermal data exclusively during the laser-off phases. This method effectively isolates the material's thermal emission from high-intensity laser reflections. Y1 - 2025 U6 - https://doi.org/10.5281/zenodo.17747278 ER - TY - CHAP A1 - Hartmann, Jürgen A1 - Ring, E.F.J. A1 - Ammer, K. A1 - Land, D. A1 - Thomas, R. A1 - Hand, J.W. ED - Zhang, Z.M. ED - Tsai, B.K. ED - Machin, G. T1 - Infrared and Microwave Medical Thermometry in Radiometric Temperature Measurements Part II BT - Applications T2 - Experimental Methods in the Physical Sciences Y1 - 2009 UR - http://permalink.bibkatalog.de/BV010604537 SN - 978-0-12-375091-4 VL - 43 SP - 393 EP - 448 PB - Elsevier Academic Press CY - Amsterdam ER - TY - CHAP A1 - Hartmann, Jürgen A1 - Hollandt, Jörg A1 - Struß, O. A1 - Gaertner, R. A1 - Ishii, J. ED - Zhang, Z.M. ED - Tsai, B.K. ED - Machin, Graham T1 - Industrial Applications of Radiation Thermometry, in Radiometric Temperature Measurements Part II BT - Applications T2 - Experimental Methods in the Physical Sciences, Volume 43 Y1 - 2009 UR - http://permalink.bibkatalog.de/BV010604537 SN - 978-0-12-375091-4 VL - 43 SP - 1 EP - 56 PB - Elsevier Academic Press CY - Amsterdam ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Edler, F. T1 - Simultaneous contact and non-contact measurements of the melting temperature of a Ni-C fixed-point cell JF - International Journal of Thermophysics Y1 - 2007 UR - http://permalink.bibkatalog.de/BV013298193 IS - 28 SP - 2002 EP - 2008 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Hollandt, Jörg A1 - Meindl, P. A1 - Taubert, Dieter Richard A1 - Werner, L. T1 - Traceable Radiometric Calibration of Semiconductor Detectors and their Application for Thermodynamic Temperature Measurement JF - MAPAN - Journal of Metrology Society of India Y1 - 2010 VL - 25 IS - 3-10 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Edler, F. T1 - Kombi-Fixpunktzelle zur Erzielung kleinster metrologischer Unsicherheiten JF - Sensor Magazin Y1 - 2007 UR - http://permalink.bibkatalog.de/BV037313622 IS - 1 SP - 20 EP - 21 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Keawprasert, T. A1 - Anhalt, Klaus A1 - Taubert, Dieter Richard T1 - Monochromator-based Absolute Calibration of Radiation Thermometers JF - International Journal of Thermophysics Y1 - 2011 UR - http://permalink.bibkatalog.de/BV013298193 IS - 32 SP - 1697 EP - 1706 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Anhalt, Klaus A1 - Taubert, Dieter Richard A1 - Hollandt, Jörg T1 - Absolute radiometry for the MeP-K BT - The irradiance measurement method JF - International Journal of Thermophysics Y1 - 2011 UR - http://permalink.bibkatalog.de/BV013298193 IS - 32 SP - 1707 EP - 1718 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Hollandt, Jörg A1 - Friedrich, R. A1 - Gutschwager, B. A1 - Taubert, Dieter Richard T1 - High-Accuracy Radiation Thermometry at the National Metrology Institute of Germany BT - the PTB JF - High Temperatures - High Pressures Y1 - 2005 VL - 35/36 IS - 4 SP - 379 EP - 415 ER - TY - JOUR A1 - Hartmann, Jürgen T1 - High-temperature measurement techniques for the application in photometry radiometry and thermometry JF - Physics Reports Y1 - 2009 UR - http://permalink.bibkatalog.de/BV012962270 VL - 469 SP - 205 EP - 269 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Völker, S. T1 - Thermal management of light sources JF - International Journal of Thermophysics Y1 - 2011 UR - http://permalink.bibkatalog.de/BV013298193 IS - 32 SP - 513 EP - 522 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Hollandt, Jörg A1 - Gutschwager, B. A1 - Struss, O. T1 - Strahlungsthermometrie BT - Temperaturen berührungslos messen JF - Automatisierungstechnische Praxis Y1 - 2006 IS - 6 SP - 70 EP - 81 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Hollandt, Jörg A1 - Anhalt, Klaus T1 - Radiation thermometry capabilities of the PTB up to 3200 K JF - MEASURE Y1 - 2008 IS - 3 SP - 26 EP - 34 ER - TY - JOUR A1 - Hartmann, Jürgen T1 - New Developments in High-Temperature Measurement Techniques JF - International Journal of Electrical and Computer Engineering Systems Y1 - 2014 VL - 5 IS - 2 SP - 63 EP - 67 ER - TY - JOUR A1 - Blotevogel, Thomas A1 - Egermann, Jan A1 - Goldlücke, Jürgen A1 - Leipertz, Alfred A1 - Hartmann, Matthias A1 - Schenk, Martin A1 - Berckmueller, Martin T1 - Developing Planar Laser-Induced Fluorescence for the Investigation of the Mixture Formation Process in Hydrogen Engines JF - SAE Paper Y1 - 2004 UR - http://permalink.bibkatalog.de/BV013334911 IS - 2004-01-1408 ER - TY - CHAP A1 - Blotevogel, Thomas A1 - Goldlücke, Jürgen A1 - Egermann, Jan A1 - Leipertz, Alfred A1 - Hartmann, Matthias A1 - Rottengruber, Hermann ED - Eichlseder, Helmut T1 - Untersuchung der Gemischbildung von Gasmotoren mit Hilfe laseroptischer Messverfahren T2 - Der Arbeitsprozess des Verbrennungsmotors (10. Tagung) Y1 - 2005 SP - 139 EP - 166 PB - Verlag der Technischen Universität Graz CY - Graz ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Edler, F. A1 - Anhalt, Klaus T1 - Neuartige eutektische Metall-Kohlenstoff-Hochtemperaturfixpunkte für die Thermometrie JF - PTB Mitteilungen Y1 - 2007 UR - http://permalink.bibkatalog.de/BV035078972 VL - 117 IS - 3 SP - 256 EP - 260 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Taubert, Dieter Richard A1 - Monte, C. A1 - Gutschwager, B. A1 - Baltruschat, C. A1 - Hollandt, Jörg A1 - Kochems, D. A1 - Küchel, C. T1 - The Spectral Photon Flux of the Radiometric Calibration Spectral Source for the NIRSpec Instrument of the James Webb Space Telescope JF - Metrologia Y1 - 2009 UR - http://permalink.bibkatalog.de/BV012573233 IS - 46 SP - 207 EP - 212 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Thomas, R. A1 - Hill, K.D. A1 - Steele, A.G. A1 - Ma, C.K. T1 - Bilateral comparison of the NRC and PTB local realizations of the ITS-90 between the silver point and 1700 °C using vacuum tungsten strip lamps as transfer standards JF - Metrologia Y1 - 2006 UR - http://permalink.bibkatalog.de/BV012573233 VL - 43 IS - 03003 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Friedrich, R. A1 - Taubert, Dieter Richard A1 - Hollandt, Jörg T1 - Improved calibration of the spectral responsivity of interference filter radiometers in the visible and near infrared spectral range at PTB JF - Metrologia Y1 - 2003 UR - http://permalink.bibkatalog.de/BV012573233 IS - 40 SP - 35 EP - 38 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Anhalt, Klaus A1 - Zelenjuk, A. A1 - Taubert, Dieter Richard T1 - New PTB Set-up for the absolute calibration of the spectral responsivity of radiation thermometers JF - International Journal of Thermophysics Y1 - 2009 UR - http://permalink.bibkatalog.de/BV013298193 IS - 30 SP - 192 EP - 202 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Ma, C.K. A1 - Gibson, C. T1 - Decreasing dependence of the calibration of the tungsten strip lamp on the temperature of the lamp base with increasing filament length JF - Metrologia Y1 - 2005 UR - http://permalink.bibkatalog.de/BV012573233 IS - 42 SP - 383 EP - 388 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Anhalt, Klaus A1 - Wang, Y. A1 - Yamada, Y. T1 - Large and small aperture Fixed-point cells of Cu, Pt-C, and Re-C JF - International Journal of Thermophysics Y1 - 2008 UR - http://permalink.bibkatalog.de/BV013298193 IS - 29 SP - 969 EP - 983 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Werner, L. T1 - Radiation thermometry towards the triple point of water? JF - International Journal of Thermophysics Y1 - 2008 UR - http://permalink.bibkatalog.de/BV013298193 IS - 29 SP - 1052 EP - 1065 ER - TY - JOUR A1 - Hartmann, Jürgen T1 - Correct consideration of the index of refraction using blackbody radiation JF - Optics Express Y1 - 2006 UR - http://permalink.bibkatalog.de/BV013253264 VL - 14 IS - 18 SP - 8121 EP - 8126 ER - TY - JOUR A1 - Hartmann, Jürgen T1 - Advanced comparator method for measuring ultra small aperture areas JF - Meas.Sci.Techn. Y1 - 2001 IS - 12 SP - 1678 EP - 1682 ER - TY - JOUR A1 - Hartmann, Jürgen A1 - Lowe, D. A1 - Anhalt, Klaus T1 - Construction and validation of a platinum-carbon eutectic fixed-point JF - Metrologia Y1 - 2008 UR - http://permalink.bibkatalog.de/BV012573233 IS - 45 SP - 325 EP - 329 ER - TY - JOUR A1 - Höfflin, Dennis A1 - Hartmann, Jürgen A1 - Rosilius, Maximilian A1 - Seitz, Philipp A1 - Schiffler, Andreas T1 - Opto-Thermal Investigation of Additively Manufactured Steel Samples as a Function of the Hatch Distance JF - Sensors N2 - Nowadays, additive manufacturing processes are becoming more and more appealing due to their production-oriented design guidelines, especially with regard to topology optimisation and minimal downstream production depth in contrast to conventional technologies. However, a scientific path in the areas of quality assurance, material and microstructural properties, intrinsic thermal permeability and dependent stress parameters inhibits enthusiasm for the potential degrees of freedom of the direct metal laser melting process (DMLS). Especially in quality assurance, post-processing destructive measuring methods are still predominantly necessary in order to evaluate the components adequately. The overall objective of these investigations is to gain process knowledge make reliable in situ statements about component quality and material properties based on the process parameters used and emission values measured. The knowledge will then be used to develop non-destructive tools for the quality management of additively manufactured components. To assess the effectiveness of the research design in relation to the objectives for further investigations, this pre-study evaluates the dependencies between the process parameters, process emission during manufacturing and resulting thermal diffusivity and the relative density of samples fabricated by DMLS. Therefore, the approach deals with additively built metal samples made on an EOS M290 apparatus with varying hatch distances while simultaneously detecting the process emission. Afterwards, the relative density of the samples is determined optically, and thermal diffusivity is measured using the laser flash method. As a result of this pre-study, all interactions of the within factors are presented. The process variable hatch distance indicates a strong influence on the resulting material properties, as an increase in the hatch distance from 0.11 mm to 1 mm leads to a drop in relative density of 57.4%. The associated thermal diffusivity also reveals a sharp decrease from 5.3 mm2/s to 1.3 mm2/s with growing hatch distances. The variability of the material properties can also be observed in the measured process emissions. However, as various factors overlap in the thermal radiation signal, no clear assignment is possible within the scope of this work. KW - additive manufacturing processes KW - material Y1 - 2021 U6 - https://doi.org/10.3390/s22010046 SN - 1424-8220 VL - 22 IS - 1 PB - MDPI ER - TY - JOUR A1 - Wehnert, Kira-Kristin A1 - Ochs, Dennis A1 - Schmitt, Jan A1 - Hartmann, Jürgen A1 - Schiffler, Andreas T1 - Reducing Lifecycle Costs due to Profile Scanning of the Powder Bed in Metal Printing JF - Procedia CIRP 98 N2 - First time right is one major goal in powder based 3D metal printing. Reaching this goal is driven by reducing life cycle costs for quality measures, to minimize scrap rate and to increase productivity under optimal resource efficiency. Therefore, monitoring the state of the powder bed for each printed layer is state of the art in selective laser melting. In the most modern approaches the quality monitoring is done by computer vision systems working with an interference on trained neural networks with images taken after exposure and after recoating. There are two drawbacks of this monitoring method: First, the sensor signals - the image of the powder bed - give no direct height information. Second, the application of this method needs to be trained and labeled with reference images for several cases. The novel approach presented in this paper uses a laser line scanner attached to the recoating machine. With this new concept, a direct threshold measure can be applied during the recoating process to detect deviations in height level without prior knowledge. The evaluation can be done online during recoating and feedback to the controller to monitor each individual layer. Hence, in case of deviations the location in the printing plane is an inherent measurement and will be used to decide which severity of error is reported. The signal is used to control the process, either by starting the recoating process again or stopping the printing process. With this approach, the sources of error for each layer can be evaluated with deep information to evaluate the cause of the error. This allows a reduction of failure in the future, which saves material costs, reduces running time of the machine life cycle phase in serial production and results in less rework for manufactured parts. Also a shorter throughput time per print job results, which means that the employee can spent more time to other print jobs and making efficient use of the employee’s work force. In summary, this novel approach will not only reduce material costs but also operating costs and thus optimize the entire life cycle cost structure. The paper presents a first feasibility and application of the described approach for test workpieces in comparison to conventional monitoring systems on an EOS M290 machine. Y1 - 2021 UR - 10.1016/j.procir.2021.01.175 VL - 98 SP - 684 EP - 689 PB - Elsevir ER - TY - JOUR A1 - Hay, Bruno A1 - Beaumont, Oliver A1 - Lambeng, Nora A1 - Cataldi, Michel A1 - Lorrette, Christophe A1 - Knopp, Kevin A1 - Hartmann, Jürgen A1 - Beckstein, Fabia A1 - Stobitzer, Dorothea A1 - Milošević, Nenad A1 - Stepanic, Nenad A1 - Wu, Jiyu A1 - Mildeova, Petra T1 - Inter‑laboratory Comparison on Thermal Diffusivity Measurements by the Laser Flash Method at Ultra‑high Temperature JF - International Journal of Thermophysics N2 - thermal diffusivity measurements by the laser flash method in the temperature range from 23 °C to 3000 °C. The main objective was to assess the variability and coherency of thermal diffusivity measurements performed at ultra-high temperatures at the European level. Three refractory materials (molybdenum, tungsten and isotropic graphite IG210) were selected for this inter-laboratory comparison, due to their high melting point. The disk-shaped specimens needed were machined from the same blocks of materials in order to reduce any potential scattering of results between participants due to inhomogeneity effects. The homogeneity of the sets of specimens was studied by the pilot laboratory (LNE) before launching the comparison process. Thermal diffusivity measurements were then carried out by the seven participants on the three materials during two successive thermal cycles up to the maximum temperatures that can be reached by the devices used. The analysis of results showed a good agreement between the participants for temperatures above 400 °C, with relative deviations within the uncertainties of measurement and lower than ± 4 % for molybdenum, ± 5 % for isotropic graphite and ± 9 % for tungsten. Y1 - 2023 UR - https://doi.org/10.1007/s10765-023-03159-5 VL - 2023 SP - 44 EP - 48 ER - TY - JOUR A1 - Manara, Jochen A1 - Hartmann, Jürgen A1 - Kerwagen, Fabian A1 - Maak, Christoph A1 - Muscio, Albert A1 - Paeth, Heiko A1 - Ebert, Hans-Peter T1 - Passive Radiative Cooling Materials with Special Focus on the Reduction of Urban Heat Island Effect: A Current Summarized Classification of Need, Approaches and Characterization Methods JF - International Journal of Thermophysics N2 - Rapidly rising global temperatures and the intensification of the urban heat island (UHI) effect necessitate new, energy-efficient solutions to mitigate heat stress in cities. Passive radiative cooling (PRC) offers a highly promising, low-energy pathway to achieve sub-ambient temperatures by reflecting incoming solar radiation while emitting long-wave infrared radiation through the atmospheric infrared window. This review summarizes key aspects of PRC and its role in reducing UHI impacts. Furthermore the fundamental physics of heat transfer and radiative heat exchange, including the materials properties such as solar reflectance and thermal emissivity which are correlated with the figures of merit, temperature drop below ambient temperature and cooling power. A comprehensive classification of current PRC materials is presented based on both structural architectures and physical effects. Additionally an overview on measurement techniques are employed to determine the performance of PRC materials, focusing on the key performance indicators. For this purpose in-field as wells as laboratory measurement techniques are introduced and opportunities in standardizing testing protocols are highlighted. Finally, future research directions are outlined, focusing on novel material development, theoretical advancements, scalable fabrication processes, and integration strategies within urban infrastructures. These innovations are important for enhancing building energy efficiency, reducing urban heat stress, and promoting sustainable urban development in the face of climate change. Y1 - 2025 U6 - https://doi.org/10.1007/s10765-025-03529-1 VL - 46 IS - 58 ER - TY - CHAP A1 - Blotevogel, Thomas A1 - Goldlücke, Jürgen A1 - Egermann, Jan A1 - Leipertz, Alfred A1 - Hartmann, Matthias A1 - Schenk, Martin A1 - Berckmüller, Martin ED - Dingel, Oliver T1 - Gemischbildungsuntersuchung in Gasmotoren mittels optischer Messverfahren, speziell in Wasserstoffmotoren T2 - Gasfahrzeuge N2 - Planar laser-induced fluorescence (PLIF) has been successfully used for the investigation of the mixture formation process in hydrogen engines for passenger cars. Detailed information has been obtained about process development (qualitative measurement) and on fuel/air-ratio (quantitative measurement) inside the combustion chamber. These results can be used for further optimization of mixture formation and combustion process concerning emissions and fuel consumption. The measurement technique used is not only limited to hydrogen or to passenger car engines, but can also be applied to other fuel gases like natural gas or to other engine sizes like bus engines. The main topic of this paper is the experimental verification of the procedure which was executed by simultaneous PLIF and Raman scattering measurements. By Raman scattering the fuel/air-ratio can directly be determined from direct concentration measurements of the different gas species. The fuel/air-ratios determined by PLIF and Raman measurements are in good agreement indicating that a quantitative fuel/air-ratio measurement during the mixture formation process of gas and hydrogen engines is possible by PLIF. This fact is also confirmed by other measurements, e.g., global fuel/air-ratio calculated from measured intake air and fuel gas flow. KW - Wasserstoff Gasmotor Laser Optische Messtechnik Y1 - 2004 SN - 3816924395 SP - 205 EP - 229 PB - expert verlag CY - Renningen ER - TY - JOUR A1 - Strasser, Claire A1 - Moukhina, Elena A1 - Hartmann, Jürgen T1 - Time–Temperature-Transformation (TTT) Cure Diagram of an Epoxy–Amine System JF - Macromolecular Theory and Simulations Y1 - 2024 UR - https://doi.org/10.1002/mats.202400039 VL - 33 IS - 6 SP - 2400039 ER -