@article{HartmannThuillierFoujolsetal., author = {Hartmann, J{\"u}rgen and Thuillier, G. and Foujols, T. and Bols{\´e}e, D. and Gillotay, D. and Hers{\´e}, M. and Petermanns, W. and Decupyer, W. and Mandel, H. and Sperfeld, P. and Taubert, Dieter Richard}, title = {SOLAR/SOLSPEC}, series = {Solar Physics}, journal = {Solar Physics}, number = {257}, pages = {185 -- 213}, language = {en} } @article{HartmannAnhaltLoweetal., author = {Hartmann, J{\"u}rgen and Anhalt, Klaus and Lowe, D. and Machin, Graham and Sadli, M. and Yamada, Y.}, title = {Thermodynamic temperature determinations of Co-C, Pd-C Pt-C and Ru-C eutectic fixed-points cells}, series = {Metrologia}, volume = {43}, journal = {Metrologia}, number = {2}, pages = {78 -- 83}, language = {en} } @article{HartmannMachinBloembergenetal., author = {Hartmann, J{\"u}rgen and Machin, G. and Bloembergen, P. and Sadli, M. and Yamada, Y.}, title = {A concerted international project to establish high-temperature fixed-points for primary thermometry}, series = {International Journal of Thermophysics}, journal = {International Journal of Thermophysics}, number = {28}, pages = {1976 -- 1982}, language = {en} } @incollection{HartmannReichling, author = {Hartmann, J{\"u}rgen and Reichling, M.}, title = {Thermal transport in diamond}, series = {Properties and growth of diamond}, booktitle = {Properties and growth of diamond}, editor = {Nazar{\´e}, H. and Neves, A.J.}, publisher = {Institution of Electrical Engineers}, address = {London}, language = {en} } @article{HartmannSadliAnhaltetal., author = {Hartmann, J{\"u}rgen and Sadli, M. and Anhalt, Klaus and Schiller, S.}, title = {Thermal effects in the BB3200pg on M-C eutectic implementation}, series = {International Journal of Thermophysics}, journal = {International Journal of Thermophysics}, number = {30}, pages = {69 -- 76}, language = {en} } @article{Hartmann, author = {Hartmann, J{\"u}rgen}, title = {New Developments in High-Temperature Measurement Techniques}, series = {International Journal of Electrical and Computer Engineering Systems}, volume = {5}, journal = {International Journal of Electrical and Computer Engineering Systems}, number = {2}, pages = {63 -- 67}, language = {en} } @article{HartmannEngertFellmuthetal., author = {Hartmann, J{\"u}rgen and Engert, J. and Fellmuth, B. and Fischer, Joachim and Hollandt, J{\"o}rg and Tegeler, E. and Seidel, J.}, title = {Die internationale Temperaturskalen}, series = {PTB Mitteilungen}, volume = {117}, journal = {PTB Mitteilungen}, number = {3}, pages = {236 -- 242}, language = {de} } @article{HartmannFischerJohannsenetal., author = {Hartmann, J{\"u}rgen and Fischer, J. and Johannsen, U. and Werner, L.}, title = {Analytical model for the temperature dependence of the spectral responsivity of silicon}, series = {J. Opt. Soc. Am. B}, journal = {J. Opt. Soc. Am. B}, number = {18}, pages = {942 -- 947}, language = {en} } @article{HoefflinSauerSchiffleretal., author = {H{\"o}fflin, Dennis and Sauer, Christian and Schiffler, Andreas and Versch, Alexander and Hartmann, J{\"u}rgen}, title = {Active thermography for in-situ defect detection in laser powder bed fusion of metal}, series = {Journal of Manufacturing Processes}, volume = {131}, journal = {Journal of Manufacturing Processes}, publisher = {Elsevier BV}, issn = {1526-6125}, doi = {10.1016/j.jmapro.2024.09.085}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:863-opus-57601}, pages = {1758 -- 1769}, abstract = {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.}, language = {en} } @article{HoefflinSauerSchiffleretal., author = {H{\"o}fflin, Dennis and Sauer, Christian and Schiffler, Andreas and Manara, Jochen and Hartmann, J{\"u}rgen}, title = {Pixelwise high-temperature calibration for in-situ temperature measuring in powder bed fusion of metal with laser beam}, series = {Heliyon}, volume = {10}, journal = {Heliyon}, number = {7}, publisher = {Elsevier BV}, issn = {2405-8440}, doi = {10.1016/j.heliyon.2024.e28989}, abstract = {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.}, language = {en} } @misc{HoefflinSchifflerHartmannetal., author = {H{\"o}fflin, Dennis and Schiffler, Andreas and Hartmann, J{\"u}rgen and Sauer, Christian}, title = {Dual Scan head approach for in-situ defect detection in laser powder bed fusion of metals - Dataset}, doi = {10.5281/zenodo.15727369}, abstract = {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.}, language = {en} } @misc{SauerSchifflerHoefflinetal., author = {Sauer, Christian and Schiffler, Andreas and H{\"o}fflin, Dennis and Hartmann, J{\"u}rgen}, title = {Temporally Gated Active Thermography for Defect Detection in Laser-Based Powder Bed Fusion of Metals - Dataset}, doi = {10.5281/zenodo.17747278}, abstract = {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.}, language = {en} } @incollection{HartmannRingAmmeretal., author = {Hartmann, J{\"u}rgen and Ring, E.F.J. and Ammer, K. and Land, D. and Thomas, R. and Hand, J.W.}, title = {Infrared and Microwave Medical Thermometry in Radiometric Temperature Measurements Part II}, series = {Experimental Methods in the Physical Sciences}, volume = {43}, booktitle = {Experimental Methods in the Physical Sciences}, editor = {Zhang, Z.M. and Tsai, B.K. and Machin, G.}, publisher = {Elsevier Academic Press}, address = {Amsterdam}, isbn = {978-0-12-375091-4}, pages = {393 -- 448}, language = {en} } @incollection{HartmannHollandtStrussetal., author = {Hartmann, J{\"u}rgen and Hollandt, J{\"o}rg and Struß, O. and Gaertner, R. and Ishii, J.}, title = {Industrial Applications of Radiation Thermometry, in Radiometric Temperature Measurements Part II}, series = {Experimental Methods in the Physical Sciences, Volume 43}, volume = {43}, booktitle = {Experimental Methods in the Physical Sciences, Volume 43}, editor = {Zhang, Z.M. and Tsai, B.K. and Machin, Graham}, publisher = {Elsevier Academic Press}, address = {Amsterdam}, isbn = {978-0-12-375091-4}, pages = {1 -- 56}, language = {en} } @article{HartmannEdler, author = {Hartmann, J{\"u}rgen and Edler, F.}, title = {Simultaneous contact and non-contact measurements of the melting temperature of a Ni-C fixed-point cell}, series = {International Journal of Thermophysics}, journal = {International Journal of Thermophysics}, number = {28}, pages = {2002 -- 2008}, language = {en} } @article{HartmannHollandtMeindletal., author = {Hartmann, J{\"u}rgen and Hollandt, J{\"o}rg and Meindl, P. and Taubert, Dieter Richard and Werner, L.}, title = {Traceable Radiometric Calibration of Semiconductor Detectors and their Application for Thermodynamic Temperature Measurement}, series = {MAPAN - Journal of Metrology Society of India}, volume = {25}, journal = {MAPAN - Journal of Metrology Society of India}, number = {3-10}, language = {de} } @article{HartmannEdler, author = {Hartmann, J{\"u}rgen and Edler, F.}, title = {Kombi-Fixpunktzelle zur Erzielung kleinster metrologischer Unsicherheiten}, series = {Sensor Magazin}, journal = {Sensor Magazin}, number = {1}, pages = {20 -- 21}, language = {de} } @article{HartmannKeawprasertAnhaltetal., author = {Hartmann, J{\"u}rgen and Keawprasert, T. and Anhalt, Klaus and Taubert, Dieter Richard}, title = {Monochromator-based Absolute Calibration of Radiation Thermometers}, series = {International Journal of Thermophysics}, journal = {International Journal of Thermophysics}, number = {32}, pages = {1697 -- 1706}, language = {en} } @article{HartmannAnhaltTaubertetal., author = {Hartmann, J{\"u}rgen and Anhalt, Klaus and Taubert, Dieter Richard and Hollandt, J{\"o}rg}, title = {Absolute radiometry for the MeP-K}, series = {International Journal of Thermophysics}, journal = {International Journal of Thermophysics}, number = {32}, pages = {1707 -- 1718}, language = {en} } @article{HartmannHollandtFriedrichetal., author = {Hartmann, J{\"u}rgen and Hollandt, J{\"o}rg and Friedrich, R. and Gutschwager, B. and Taubert, Dieter Richard}, title = {High-Accuracy Radiation Thermometry at the National Metrology Institute of Germany}, series = {High Temperatures - High Pressures}, volume = {35/36}, journal = {High Temperatures - High Pressures}, number = {4}, pages = {379 -- 415}, language = {en} } @article{Hartmann, author = {Hartmann, J{\"u}rgen}, title = {High-temperature measurement techniques for the application in photometry radiometry and thermometry}, series = {Physics Reports}, volume = {469}, journal = {Physics Reports}, pages = {205 -- 269}, language = {en} } @article{HartmannVoelker, author = {Hartmann, J{\"u}rgen and V{\"o}lker, S.}, title = {Thermal management of light sources}, series = {International Journal of Thermophysics}, journal = {International Journal of Thermophysics}, number = {32}, pages = {513 -- 522}, language = {en} } @article{HartmannHollandtGutschwageretal., author = {Hartmann, J{\"u}rgen and Hollandt, J{\"o}rg and Gutschwager, B. and Struss, O.}, title = {Strahlungsthermometrie}, series = {Automatisierungstechnische Praxis}, journal = {Automatisierungstechnische Praxis}, number = {6}, pages = {70 -- 81}, language = {de} } @article{HartmannHollandtAnhalt, author = {Hartmann, J{\"u}rgen and Hollandt, J{\"o}rg and Anhalt, Klaus}, title = {Radiation thermometry capabilities of the PTB up to 3200 K}, series = {MEASURE}, journal = {MEASURE}, number = {3}, pages = {26 -- 34}, language = {en} } @article{Hartmann, author = {Hartmann, J{\"u}rgen}, title = {New Developments in High-Temperature Measurement Techniques}, series = {International Journal of Electrical and Computer Engineering Systems}, volume = {5}, journal = {International Journal of Electrical and Computer Engineering Systems}, number = {2}, pages = {63 -- 67}, language = {en} } @article{BlotevogelEgermannGoldlueckeetal., author = {Blotevogel, Thomas and Egermann, Jan and Goldl{\"u}cke, J{\"u}rgen and Leipertz, Alfred and Hartmann, Matthias and Schenk, Martin and Berckmueller, Martin}, title = {Developing Planar Laser-Induced Fluorescence for the Investigation of the Mixture Formation Process in Hydrogen Engines}, series = {SAE Paper}, journal = {SAE Paper}, number = {2004-01-1408}, language = {en} } @incollection{BlotevogelGoldlueckeEgermannetal., author = {Blotevogel, Thomas and Goldl{\"u}cke, J{\"u}rgen and Egermann, Jan and Leipertz, Alfred and Hartmann, Matthias and Rottengruber, Hermann}, title = {Untersuchung der Gemischbildung von Gasmotoren mit Hilfe laseroptischer Messverfahren}, series = {Der Arbeitsprozess des Verbrennungsmotors (10. Tagung)}, booktitle = {Der Arbeitsprozess des Verbrennungsmotors (10. Tagung)}, editor = {Eichlseder, Helmut}, publisher = {Verlag der Technischen Universit{\"a}t Graz}, address = {Graz}, pages = {139 -- 166}, language = {de} } @article{HartmannEdlerAnhalt, author = {Hartmann, J{\"u}rgen and Edler, F. and Anhalt, Klaus}, title = {Neuartige eutektische Metall-Kohlenstoff-Hochtemperaturfixpunkte f{\"u}r die Thermometrie}, series = {PTB Mitteilungen}, volume = {117}, journal = {PTB Mitteilungen}, number = {3}, pages = {256 -- 260}, language = {de} } @article{HartmannTaubertMonteetal., author = {Hartmann, J{\"u}rgen and Taubert, Dieter Richard and Monte, C. and Gutschwager, B. and Baltruschat, C. and Hollandt, J{\"o}rg and Kochems, D. and K{\"u}chel, C.}, title = {The Spectral Photon Flux of the Radiometric Calibration Spectral Source for the NIRSpec Instrument of the James Webb Space Telescope}, series = {Metrologia}, journal = {Metrologia}, number = {46}, pages = {207 -- 212}, language = {en} } @article{HartmannThomasHilletal., author = {Hartmann, J{\"u}rgen and Thomas, R. and Hill, K.D. and Steele, A.G. and Ma, C.K.}, title = {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}, series = {Metrologia}, volume = {43}, journal = {Metrologia}, number = {03003}, language = {en} } @article{HartmannFriedrichTaubertetal., author = {Hartmann, J{\"u}rgen and Friedrich, R. and Taubert, Dieter Richard and Hollandt, J{\"o}rg}, title = {Improved calibration of the spectral responsivity of interference filter radiometers in the visible and near infrared spectral range at PTB}, series = {Metrologia}, journal = {Metrologia}, number = {40}, pages = {35 -- 38}, language = {en} } @article{HartmannAnhaltZelenjuketal., author = {Hartmann, J{\"u}rgen and Anhalt, Klaus and Zelenjuk, A. and Taubert, Dieter Richard}, title = {New PTB Set-up for the absolute calibration of the spectral responsivity of radiation thermometers}, series = {International Journal of Thermophysics}, journal = {International Journal of Thermophysics}, number = {30}, pages = {192 -- 202}, language = {en} } @article{HartmannMaGibson, author = {Hartmann, J{\"u}rgen and Ma, C.K. and Gibson, C.}, title = {Decreasing dependence of the calibration of the tungsten strip lamp on the temperature of the lamp base with increasing filament length}, series = {Metrologia}, journal = {Metrologia}, number = {42}, pages = {383 -- 388}, language = {en} } @article{HartmannAnhaltWangetal., author = {Hartmann, J{\"u}rgen and Anhalt, Klaus and Wang, Y. and Yamada, Y.}, title = {Large and small aperture Fixed-point cells of Cu, Pt-C, and Re-C}, series = {International Journal of Thermophysics}, journal = {International Journal of Thermophysics}, number = {29}, pages = {969 -- 983}, language = {en} } @article{HartmannWerner, author = {Hartmann, J{\"u}rgen and Werner, L.}, title = {Radiation thermometry towards the triple point of water?}, series = {International Journal of Thermophysics}, journal = {International Journal of Thermophysics}, number = {29}, pages = {1052 -- 1065}, language = {en} } @article{Hartmann, author = {Hartmann, J{\"u}rgen}, title = {Correct consideration of the index of refraction using blackbody radiation}, series = {Optics Express}, volume = {14}, journal = {Optics Express}, number = {18}, pages = {8121 -- 8126}, language = {en} } @article{Hartmann, author = {Hartmann, J{\"u}rgen}, title = {Advanced comparator method for measuring ultra small aperture areas}, series = {Meas.Sci.Techn.}, journal = {Meas.Sci.Techn.}, number = {12}, pages = {1678 -- 1682}, language = {en} } @article{HartmannLoweAnhalt, author = {Hartmann, J{\"u}rgen and Lowe, D. and Anhalt, Klaus}, title = {Construction and validation of a platinum-carbon eutectic fixed-point}, series = {Metrologia}, journal = {Metrologia}, number = {45}, pages = {325 -- 329}, language = {en} } @article{HoefflinHartmannRosiliusetal., author = {H{\"o}fflin, Dennis and Hartmann, J{\"u}rgen and Rosilius, Maximilian and Seitz, Philipp and Schiffler, Andreas}, title = {Opto-Thermal Investigation of Additively Manufactured Steel Samples as a Function of the Hatch Distance}, series = {Sensors}, volume = {22}, journal = {Sensors}, number = {1}, publisher = {MDPI}, issn = {1424-8220}, doi = {10.3390/s22010046}, pages = {46}, abstract = {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.}, language = {en} } @article{WehnertOchsSchmittetal., author = {Wehnert, Kira-Kristin and Ochs, Dennis and Schmitt, Jan and Hartmann, J{\"u}rgen and Schiffler, Andreas}, title = {Reducing Lifecycle Costs due to Profile Scanning of the Powder Bed in Metal Printing}, series = {Procedia CIRP 98}, volume = {98}, journal = {Procedia CIRP 98}, publisher = {Elsevir}, pages = {684 -- 689}, abstract = {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.}, language = {en} } @article{HayBeaumontLambengetal., author = {Hay, Bruno and Beaumont, Oliver and Lambeng, Nora and Cataldi, Michel and Lorrette, Christophe and Knopp, Kevin and Hartmann, J{\"u}rgen and Beckstein, Fabia and Stobitzer, Dorothea and Milošević, Nenad and Stepanic, Nenad and Wu, Jiyu and Mildeova, Petra}, title = {Inter‑laboratory Comparison on Thermal Diffusivity Measurements by the Laser Flash Method at Ultra‑high Temperature}, series = {International Journal of Thermophysics}, volume = {2023}, journal = {International Journal of Thermophysics}, pages = {44 -- 48}, abstract = {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.}, language = {en} } @article{ManaraHartmannKerwagenetal., author = {Manara, Jochen and Hartmann, J{\"u}rgen and Kerwagen, Fabian and Maak, Christoph and Muscio, Albert and Paeth, Heiko and Ebert, Hans-Peter}, title = {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}, series = {International Journal of Thermophysics}, volume = {46}, journal = {International Journal of Thermophysics}, number = {58}, doi = {10.1007/s10765-025-03529-1}, abstract = {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.}, language = {en} } @incollection{BlotevogelGoldlueckeEgermannetal., author = {Blotevogel, Thomas and Goldl{\"u}cke, J{\"u}rgen and Egermann, Jan and Leipertz, Alfred and Hartmann, Matthias and Schenk, Martin and Berckm{\"u}ller, Martin}, title = {Gemischbildungsuntersuchung in Gasmotoren mittels optischer Messverfahren, speziell in Wasserstoffmotoren}, series = {Gasfahrzeuge}, booktitle = {Gasfahrzeuge}, editor = {Dingel, Oliver}, publisher = {expert verlag}, address = {Renningen}, isbn = {3816924395}, publisher = {Hochschule f{\"u}r Angewandte Wissenschaften W{\"u}rzburg-Schweinfurt}, pages = {205 -- 229}, abstract = {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.}, language = {de} } @article{StrasserMoukhinaHartmann, author = {Strasser, Claire and Moukhina, Elena and Hartmann, J{\"u}rgen}, title = {Time-Temperature-Transformation (TTT) Cure Diagram of an Epoxy-Amine System}, series = {Macromolecular Theory and Simulations}, volume = {33}, journal = {Macromolecular Theory and Simulations}, number = {6}, pages = {2400039}, language = {en} }