TY - BOOK A1 - Stuhlsatz, André T1 - Hybride Spracherkennung Eine HMM/SVM-Systemintegration Y1 - 2008 SN - 9783639100624 PB - VDM Verlag CY - Saarbrücken ER - TY - CHAP A1 - Stuhlsatz, André A1 - Meier, Hans-Günter A1 - Katz, M. A1 - Krüger, S. E. A1 - Wendemuth, Andreas ED - Wendemuth, Andreas T1 - Classification of Speech Recognition Hypotheses with Support Vector Machines T2 - Proceedings of the Speech Processing Workshop: Magdeburg, Germany, September 09, 2003 ; in connection with the symposium of the German Association for Pattern Recognition (DAGM) 2003 Y1 - 2003 SN - 9783929757590 PB - Otto-von-Guericke-Universität Magdeburg CY - Magdeburg ER - TY - CHAP A1 - Stuhlsatz, André T1 - Recognition of ultrasonic multi-echo sequences for autonomous symbolic indoor tracking T2 - Sixth International Conference on Machine Learning and Applications (ICMLA 2007), 13-15 December 2007, Cincinnati Y1 - 2007 SN - 978-0-7695-3069-7 U6 - https://doi.org/10.1109/ICMLA.2007.30 SP - 178 EP - 185 PB - IEEE ER - TY - CHAP A1 - Stuhlsatz, André A1 - Meier, Hans-Günter A1 - Wendemuth, Andreas ED - Kurzynski, Marek ED - Puchala, Edward ED - Wozniak, Michal ED - Zolnierek, Andrzej T1 - Maximum Margin Classification on Convex Euclidean Metric Spaces T2 - Advances in Soft Computing Y1 - 2007 SN - 9783540751748 U6 - https://doi.org/10.1007/978-3-540-75175-5_27 SN - 1867-5662 VL - AINSC,volume 45 SP - 216 EP - 223 PB - Springer Nature CY - Berlin, Heidelberg ER - TY - CHAP A1 - Stuhlsatz, André A1 - Meier, Hans-Günter A1 - Wendemuth, Andreas T1 - Making the Lipschitz Classifier Practical via Semi-infinite Programming T2 - 2008 Seventh International Conference on Machine Learning and Applications, 11-13 December 2008, San Diego Y1 - 2008 SN - 978-0-7695-3495-4 U6 - https://doi.org/10.1109/ICMLA.2008.26 SP - 40 EP - 47 PB - IEEE ER - TY - JOUR A1 - Benim, Ali Cemal A1 - Neuhoff, H. G. T1 - Analysis of erosion behaviour in a turbocharger radial turbine JF - International Journal for Numerical Methods in Fluids N2 - An analysis of the erosion behaviour of a turbocharger radial turbine is presented. The solution domain includes both sides of the radial turbine scroll with double intake and the rotor channel. In the analysis a dilute gas‐particle flow assumption is employed. The gas turbulence is defined by the k‐ε model. In solving the gas phase equation, the computer code Harwell‐FLOW3D is employed, which is based on a finite volume formulation using non‐orthogonal body‐fitted structured gridding and a pressure correction method. The particle phase is described by a Lagrangian approach, while particle paths are computed deterministically, neglecting the turbulent dispersion. For the computation of particle trajectories the code PTRACK is employed, which has been developed at ABB. Computations are carried out for several particle size classes. The results show that particles are thrown back into the scroll by the rotor at high rates. This seems to be the main source of erosion effects in the scroll. It has been observed that particles are unequally distributed between the scroll sides on their re‐entry, resulting in greater erosion on one of the scroll sides. The maximum erosion along the scroll is found to be likely to occur near the scroll end. KW - Erosion KW - Abgasturbolader KW - Radialturbine Y1 - 1993 U6 - https://doi.org/10.1002/fld.1650160402 SN - 0271-2091 VL - 16 IS - 4 SP - 259 EP - 285 PB - Wiley ER - TY - JOUR A1 - Benim, Ali Cemal T1 - Finite element analysis of confined turbulent swirling flows JF - International Journal for Numerical Methods in Fluids N2 - The finite element method is applied to incompressible and statistically steady confined turbulent swirling flows. A velocity–pressure formulation is employed. The momentum and continuity equations are solved using a segregated algorithm. Two turbulence models, namely the standard κ–ε model and the algebraic stress model, are considered. It is shown that the algebraic stress model leads to significantly more accurate results in swirling flows compared to the κ–ε model. A novel way of implementing the algebraic stress model is presented in which the stresses are coupled to the Navier–Stokes equations in such a way that they ‘correct’ the effective viscosity hypothesis. This formulation seems to provide a convenient approach for finite elements. In deriving the discretization equations, a streamline‐upwind/Petrov–Galerkin method is employed. Comparisons performed between various upwind schemes show that the numerical solution may be substantially affected by the particular upwind procedure used. The analysis is extended to the prediction of particle motion in turbulent swirling flow fields. Here the fluid turbulence is modelled adopting a stochastic approach. The influence of turbulence modelling on particle movement is investigated. KW - Finite-Elemente-Methode KW - Turbulente Strömung KW - Navier-Stokes-Gleichung KW - Numerische Strömungssimulation Y1 - 1990 U6 - https://doi.org/10.1002/fld.1650110602 SN - 0271-2091 VL - 11 IS - 6 SP - 697 EP - 717 PB - Wiley ER - TY - JOUR A1 - Suh, S.-H. A1 - Benim, Ali Cemal T1 - The primitive variables formulation of the Navier-Stokes equations using the finite analytic method JF - Applied Mathematical Modelling KW - Navier-Stokes-Gleichung KW - Finite analytische Methode KW - Numerische Strömungssimulation Y1 - 1989 U6 - https://doi.org/10.1016/0307-904X(89)90066-8 SN - 0307-904X VL - 13 IS - 9 SP - 550 EP - 554 PB - Elsevier ER - TY - JOUR A1 - Benim, Ali Cemal A1 - Zinser, Walter A1 - Schnell, Uwe T1 - Investigation into the finite element analysis of enclosed turbulent diffusion flames JF - Applied Mathematical Modelling KW - Finite-Elemente-Methode KW - Turbulente Diffusionsflamme KW - Navier-Stokes-Gleichung KW - Numerische Strömungssimulation Y1 - 1989 U6 - https://doi.org/10.1016/0307-904X(89)90069-3 SN - 0307-904X VL - 13 IS - 5 SP - 258 EP - 267 PB - Elsevier ER - TY - JOUR A1 - Benim, Ali Cemal T1 - Finite element solution of an enclosed turbulent diffusion flame JF - International Journal for Numerical Methods in Fluids N2 - A finite element formulation of enclosed turbulent diffusion flames is presented. A primitive variables approach is preferred in the analysis. A mixed interpolation is employed for the velocity and pressure. In the solution of the Navier‐Stokes equations, a segregated formulation is adopted, where the pressure discretization equation is obtained directly from the discretized continuity equation, considering the velocity‐pressure relationships in the discretized momentum equations. The state of turbulence is defined by a κ–ϵ model. Near solid boundaries, a wall function approach is employed. The combustion rates are estimated using the eddy dissipation concept. The expensive direct treatment of the integrodifferential equations of radiation is avoided by employing the moment method, which allows the derivation of an approximate local field equation for the radiation intensity. The proposed finite element model is verified by investigating a technical turbulent diffusion flame of semi‐industrial size, and comparing the results with experiments and finite difference predictions. KW - Finite-Elemente-Methode KW - Turbulente Diffusionsflamme KW - Navier-Stokes-Gleichung KW - Numerische Strömungssimulation Y1 - 1989 U6 - https://doi.org/10.1002/fld.1650090305 SN - 0271-2091 VL - 9 IS - 3 SP - 289 EP - 303 PB - Wiley ER - TY - JOUR A1 - Benim, Ali Cemal T1 - A finite element solution of radiative heat transfer in participating media utilizing the moment method JF - Computer Methods in Applied Mechanics and Engineering KW - Finite-Elemente-Methode KW - Wärmeübertragung KW - Wärmestrahlung KW - Momentenmethode KW - Numerische Strömungssimulation Y1 - 1988 U6 - https://doi.org/10.1016/0045-7825(88)90065-5 SN - 0045-7825 VL - 67 IS - 1 SP - 1 EP - 14 PB - Elsevier ER - TY - JOUR A1 - Benim, Ali Cemal A1 - Zinser, Walter T1 - A segregated formulation of Navier-Stokes equations with finite elements JF - Computer Methods in Applied Mechanics and Engineering KW - Navier-Stokes-Gleichung KW - Turbulente Strömung KW - Finite-Elemente-Methode KW - Numerische Strömungssimulation Y1 - 1986 U6 - https://doi.org/10.1016/0045-7825(86)90015-0 SN - 0045-7825 VL - 57 IS - 2 SP - 223 EP - 237 PB - Elsevier ER - TY - JOUR A1 - Benim, Ali Cemal A1 - Zinser, Walter T1 - Investigation into the finite element analysis of confined turbulent flows using a κ-ε model of turbulence JF - Computer Methods in Applied Mechanics and Engineering KW - Finite-Elemente-Methode KW - Turbulente Strömung KW - Numerische Strömungssimulation Y1 - 1985 U6 - https://doi.org/10.1016/0045-7825(85)90045-3 SN - 0045-7825 VL - 51 IS - 1-3 SP - 507 EP - 523 PB - Elsevier ER - TY - JOUR A1 - Wannek, C. A1 - Nehr, Sascha A1 - Vahlenkamp, M. A1 - Mergel, J. A1 - Stolten, D. T1 - Pseudo-half-cell measurements on symmetrical catalyst-coated membranes and their relevance for optimizing DMFC anodes JF - Journal of Applied Electrochemistry KW - Luftreinhaltung Y1 - 2009 U6 - https://doi.org/10.1007/s10800-009-9960-9 SN - 0021-891X VL - 40 IS - 1 SP - 29 EP - 38 PB - Springer Nature ER - TY - JOUR A1 - Nehr, Sascha A1 - Bohn, Birger A1 - Fuchs, Hendrik A1 - Hofzumahaus, Andreas A1 - Wahner, Andreas T1 - HO2 formation from the OH + benzene reaction in the presence of O2 JF - Physical Chemistry Chemical Physics KW - Luftreinhaltung Y1 - 2011 U6 - https://doi.org/10.1039/c1cp20334g SN - 1463-9076 VL - 13 IS - 22 PB - Royal Society of Chemistry (RSC) ER - TY - JOUR A1 - Fuchs, H. A1 - Bohn, Birger A1 - Hofzumahaus, A. A1 - Holland, F. A1 - Lu, K. D. A1 - Nehr, Sascha A1 - Rohrer, F. A1 - Wahner, A. T1 - Detection of HO2 by laser-induced fluorescence: calibration and interferences from RO2 radicals JF - Atmospheric Measurement Techniques N2 - Abstract. HO2 concentration measurements are widely accomplished by chemical conversion of HO2 to OH including reaction with NO and subsequent detection of OH by laser-induced fluorescence. RO2 radicals can be converted to OH via a similar radical reaction sequence including reaction with NO, so that they are potential interferences for HO2 measurements. Here, the conversion efficiency of various RO2 species to HO2 is investigated. Experiments were conducted with a radical source that produces OH and HO2 by water photolysis at 185 nm, which is frequently used for calibration of LIF instruments. The ratio of HO2 and the sum of OH and HO2 concentrations provided by the radical source was investigated and was found to be 0.50 ± 0.02. RO2 radicals are produced by the reaction of various organic compounds with OH in the radical source. Interferences via chemical conversion from RO2 radicals produced by the reaction of OH with methane and ethane (H-atom abstraction) are negligible consistent with measurements in the past. However, RO2 radicals from OH plus alkene- and aromatic-precursors including isoprene (mainly OH-addition) are detected with a relative sensitivity larger than 80 % with respect to that for HO2 for the configuration of the instrument with which it was operated during field campaigns. Also RO2 from OH plus methyl vinyl ketone and methacrolein exhibit a relative detection sensitivity of 60 %. Thus, previous measurements of HO2 radical concentrations with this instrument were biased in the presence of high RO2 radical concentrations from isoprene, alkenes or aromatics, but were not affected by interferences in remote clean environment with no significant emissions of biogenic VOCs, when the OH reactivity was dominated by small alkanes. By reducing the NO concentration and/or the transport time between NO addition and OH detection, interference from these RO2 species are suppressed to values below 20 % relative to the HO2 detection sensitivity. The HO2 conversion efficiency is also smaller by a factor of four, but this is still sufficient for atmospheric HO2 concentration measurements for a wide range of conditions. KW - Luftreinhaltung Y1 - 2011 U6 - https://doi.org/10.5194/amt-4-1209-2011 SN - 1867-8548 VL - 4 IS - 6 SP - 1209 EP - 1225 PB - Copernicus ER - TY - JOUR A1 - Nehr, Sascha A1 - Bohn, Birger A1 - Wahner, Andreas T1 - Prompt HO2Formation Following the Reaction of OH with Aromatic Compounds under Atmospheric Conditions JF - The Journal of Physical Chemistry A KW - Luftreinhaltung Y1 - 2012 U6 - https://doi.org/10.1021/jp210946y SN - 1089-5639 VL - 116 IS - 24 SP - 6015 EP - 6026 PB - American Chemical Society (ACS) ER - TY - JOUR A1 - Lu, K. D. A1 - Rohrer, F. A1 - Holland, F. A1 - Fuchs, H. A1 - Bohn, Birger A1 - Brauers, Theo A1 - Chang, C. C. A1 - Häseler, R. A1 - Hu, M. A1 - Kita, K. A1 - Kondo, Y. A1 - Li, X. A1 - Lou, S. R. A1 - Nehr, Sascha A1 - Shao, M. A1 - Zeng, L. M. A1 - Wahner, A. A1 - Zhang, Y. H. A1 - Hofzumahaus, A. T1 - Observation and modelling of OH and HO2 concentrations in the Pearl River Delta 2006: a missing OH source in a VOC rich atmosphere JF - Atmospheric Chemistry and Physics N2 - Abstract. Ambient OH and HO2 concentrations were measured by laser induced fluorescence (LIF) during the PRIDE-PRD2006 (Program of Regional Integrated Experiments of Air Quality over the Pearl River Delta, 2006) campaign at a rural site downwind of the megacity of Guangzhou in Southern China. The observed OH concentrations reached daily peak values of (15–26) × 106 cm−3 which are among the highest values so far reported for urban and suburban areas. The observed OH shows a consistent high correlation with j(O1D) over a broad range of NOx conditions. The correlation cannot be reproduced by model simulations, indicating that OH stabilizing processes are missing in current models. The observed OH exhibited a weak dependence on NOx in contrast to model predictions. While modelled and measured OH agree well at NO mixing ratios above 1 ppb, a continuously increasing underprediction of the observed OH is found towards lower NO concentrations, reaching a factor of 8 at 0.02 ppb NO. A dependence of the modelled-to-measured OH ratio on isoprene cannot be concluded from the PRD data. However, the magnitude of the ratio fits into the isoprene dependent trend that was reported from other campaigns in forested regions. Hofzumahaus et al. (2009) proposed an unknown OH recycling process without NO, in order to explain the high OH levels at PRD in the presence of high VOC reactivity and low NO. Taking a recently discovered interference in the LIF measurement of HO2 into account, the need for an additional HO2 → OH recycling process persists, but the required source strength may be up to 20% larger than previously determined. Recently postulated isoprene mechanisms by Lelieveld et al. (2008) and Peeters and Müller (2010) lead to significant enhancements of OH expected for PRD, but an underprediction of the observed OH by a factor of two remains at low NO (0.1–0.2 ppb). If the photolysis of hydroperoxy aldehydes from isoprene is as efficient as proposed by Peeters and Müller (2010), the corresponding OH formation at PRD would be more important than the primary OH production from ozone and HONO. While the new isoprene mechanisms need to be confirmed by laboratory experiments, there is probably need for other, so far unidentified chemical processes to explain entirely the high OH levels observed in Southern China. KW - Luftreinhaltung Y1 - 2012 U6 - https://doi.org/10.5194/acp-12-1541-2012 SN - 1680-7324 VL - 12 IS - 3 SP - 1541 EP - 1569 PB - Copernicus ER - TY - JOUR A1 - Fuchs, H. A1 - Dorn, Hans-Peter A1 - Bachner, M. A1 - Bohn, Birger A1 - Brauers, Theo A1 - Gomm, S. A1 - Hofzumahaus, A. A1 - Holland, F. A1 - Nehr, Sascha A1 - Rohrer, F. A1 - Tillmann, R. A1 - Wahner, A. T1 - Comparison of OH concentration measurements by DOAS and LIF during SAPHIR chamber experiments at high OH reactivity and low NO concentration JF - Atmospheric Measurement Techniques N2 - Abstract. During recent field campaigns, hydroxyl radical (OH) concentrations that were measured by laser-induced fluorescence (LIF) were up to a factor of ten larger than predicted by current chemical models for conditions of high OH reactivity and low NO concentration. These discrepancies, which were observed in forests and urban-influenced rural environments, are so far not entirely understood. In summer 2011, a series of experiments was carried out in the atmosphere simulation chamber SAPHIR in Jülich, Germany, in order to investigate the photochemical degradation of isoprene, methyl-vinyl ketone (MVK), methacrolein (MACR) and aromatic compounds by OH. Conditions were similar to those experienced during the PRIDE-PRD2006 campaign in the Pearl River Delta (PRD), China, in 2006, where a large difference between OH measurements and model predictions was found. During experiments in SAPHIR, OH was simultaneously detected by two independent instruments: LIF and differential optical absorption spectroscopy (DOAS). Because DOAS is an inherently calibration-free technique, DOAS measurements are regarded as a reference standard. The comparison of the two techniques was used to investigate potential artifacts in the LIF measurements for PRD-like conditions of OH reactivities of 10 to 30 s−1 and NO mixing ratios of 0.1 to 0.3 ppbv. The analysis of twenty experiment days shows good agreement. The linear regression of the combined data set (averaged to the DOAS time resolution, 2495 data points) yields a slope of 1.02 ± 0.01 with an intercept of (0.10 ± 0.03) × 106 cm−3 and a linear correlation coefficient of R2 = 0.86. This indicates that the sensitivity of the LIF instrument is well-defined by its calibration procedure. No hints for artifacts are observed for isoprene, MACR, and different aromatic compounds. LIF measurements were approximately 30–40% (median) larger than those by DOAS after MVK (20 ppbv) and toluene (90 ppbv) had been added. However, this discrepancy has a large uncertainty and requires further laboratory investigation. Observed differences between LIF and DOAS measurements are far too small to explain the unexpected high OH concentrations during the PRIDE-PRD2006 campaign. KW - Luftreinhaltung Y1 - 2012 U6 - https://doi.org/10.5194/amt-5-1611-2012 SN - 1867-8548 VL - 5 IS - 7 SP - 1611 EP - 1626 PB - Copernicus ER - TY - JOUR A1 - Emanuelsson, E. U. A1 - Hallquist, M. A1 - Kristensen, K. A1 - Glasius, M. A1 - Bohn, Birger A1 - Fuchs, H. A1 - Kammer, B. A1 - Kiendler-Scharr, A. A1 - Nehr, Sascha A1 - Rubach, F. A1 - Tillmann, R. A1 - Wahner, A. A1 - Wu, H.-C. A1 - Mentel, Th. F. T1 - Formation of anthropogenic secondary organic aerosol (SOA) and its influence on biogenic SOA properties JF - Atmospheric Chemistry and Physics N2 - Abstract. Secondary organic aerosol (SOA) formation from mixed anthropogenic and biogenic precursors has been studied exposing reaction mixtures to natural sunlight in the SAPHIR chamber in Jülich, Germany. In this study aromatic compounds served as examples of anthropogenic volatile organic compound (VOC) and a mixture of α-pinene and limonene as an example for biogenic VOC. Several experiments with exclusively aromatic precursors were performed to establish a relationship between yield and organic aerosol mass loading for the atmospheric relevant range of aerosol loads of 0.01 to 10 μg m−3. The yields (0.5 to 9%) were comparable to previous data and further used for the detailed evaluation of the mixed biogenic and anthropogenic experiments. For the mixed experiments a number of different oxidation schemes were addressed. The reactivity, the sequence of addition, and the amount of the precursors influenced the SOA properties. Monoterpene oxidation products, including carboxylic acids and dimer esters were identified in the aged aerosol at levels comparable to ambient air. OH radicals were measured by Laser Induced Fluorescence, which allowed for establishing relations of aerosol properties and composition to the experimental OH dose. Furthermore, the OH measurements in combination with the derived yields for aromatic SOA enabled application of a simplified model to calculate the chemical turnover of the aromatic precursor and corresponding anthropogenic contribution to the mixed aerosol. The estimated anthropogenic contributions were ranging from small (≈8%) up to significant fraction (50%) providing a suitable range to study the effect of aerosol composition on the aerosol volatility (volume fraction remaining (VFR) at 343 K: 0.86–0.94). The aromatic aerosol had higher oxygen to carbon ratio O/C and was less volatile than the biogenic fraction. However, in order to produce significant amount of aromatic SOA the reaction mixtures needed a higher OH dose that also increased O/C and provided a less volatile aerosol. The SOA yields, O/C, and f44 (the mass fraction of CO2+ ions in the mass spectra which can be considered as a measure of carboxylic groups) in the mixed photo-chemical experiments could be described as linear combinations of the corresponding properties of the pure systems. For VFR there was in addition an enhancement effect, making the mixed aerosol significantly less volatile than what could be predicted from the pure systems. A strong positive correlation was found between changes in volatility and O/C with the exception during dark hours where the SOA volatility decreased while O/C did not change significantly. Thus, this change in volatility under dark conditions as well as the anthropogenic enhancement is due to chemical or morphological changes not affecting O/C. KW - Luftreinhaltung Y1 - 2013 U6 - https://doi.org/10.5194/acp-13-2837-2013 SN - 1680-7324 VL - 13 IS - 5 SP - 2837 EP - 2855 PB - Copernicus ER - TY - JOUR A1 - Fuchs, H. A1 - Hofzumahaus, A. A1 - Rohrer, F. A1 - Bohn, Birger A1 - Brauers, Theo A1 - Dorn, Hans-Peter A1 - Häseler, R. A1 - Holland, F. A1 - Kaminski, M. A1 - Li, X. A1 - Lu, K. A1 - Nehr, Sascha A1 - Tillmann, R. A1 - Wegener, R. A1 - Wahner, A. T1 - Experimental evidence for efficient hydroxyl radical regeneration in isoprene oxidation JF - Nature Geoscience KW - Luftreinhaltung Y1 - 2013 U6 - https://doi.org/10.1038/NGEO1964 SN - 1752-0894 VL - 6 IS - 12 SP - 1023 EP - 1026 PB - Springer Nature ER - TY - JOUR A1 - Fuchs, H. A1 - Acir, Ismail-Hakki A1 - Bohn, Birger A1 - Brauers, Theo A1 - Dorn, Hans-Peter A1 - Häseler, R. A1 - Hofzumahaus, A. A1 - Holland, F. A1 - Kaminski, M. A1 - Li, X. A1 - Lu, K. A1 - Lutz, A. A1 - Nehr, Sascha A1 - Rohrer, F. A1 - Tillmann, R. A1 - Wegener, R. A1 - Wahner, A. T1 - OH regeneration from methacrolein oxidation investigated in the atmosphere simulation chamber SAPHIR JF - Atmospheric Chemistry and Physics N2 - Abstract. Hydroxyl radicals (OH) are the most important reagent for the oxidation of trace gases in the atmosphere. OH concentrations measured during recent field campaigns in isoprene-rich environments were unexpectedly large. A number of studies showed that unimolecular reactions of organic peroxy radicals (RO2) formed in the initial reaction step of isoprene with OH play an important role for the OH budget in the atmosphere at low mixing ratios of nitrogen monoxide (NO) of less than 100 pptv. It has also been suggested that similar reactions potentially play an important role for RO2 from other compounds. Here, we investigate the oxidation of methacrolein (MACR), one major oxidation product of isoprene, by OH in experiments in the simulation chamber SAPHIR under controlled atmospheric conditions. The experiments show that measured OH concentrations are approximately 50% larger than calculated by the Master Chemical Mechanism (MCM) for conditions of the experiments (NO mixing ratio of 90 pptv). The analysis of the OH budget reveals an OH source that is not accounted for in MCM, which is correlated with the production rate of RO2 radicals from MACR. In order to balance the measured OH destruction rate, 0.77 OH radicals (1σ error: ± 0.31) need to be additionally reformed from each reaction of OH with MACR. The strong correlation of the missing OH source with the production of RO2 radicals is consistent with the concept of OH formation from unimolecular isomerization and decomposition reactions of RO2. The comparison of observations with model calculations gives a lower limit of 0.03 s−1 for the reaction rate constant if the OH source is attributed to an isomerization reaction of MACR-1-OH-2-OO and MACR-2-OH-2-OO formed in the MACR + OH reaction as suggested in the literature (Crounse et al., 2012). This fast isomerization reaction would be a competitor to the reaction of this RO2 species with a minimum of 150 pptv NO. The isomerization reaction would be the dominant reaction pathway for this specific RO2 radical in forested regions, where NO mixing ratios are typically much smaller. KW - Luftreinhaltung Y1 - 2014 U6 - https://doi.org/10.5194/acp-14-7895-2014 SN - 1680-7324 VL - 14 IS - 15 SP - 7895 EP - 7908 PB - Copernicus ER - TY - CHAP A1 - Nehr, Sascha A1 - Tanabe, Shin-ichi T1 - ISO/TC 146/SC 6 - Setting international standards for the assessment of indoor air quality T2 - Indoor Air 2014 - 13th International Conference on Indoor Air Quality and Climate, Hong Kong KW - Luftreinhaltung Y1 - 2014 CY - Hong Kong ER - TY - JOUR A1 - Nehr, Sascha A1 - Bohn, Birger A1 - Dorn, Hans-Peter A1 - Fuchs, H. A1 - Häseler, R. A1 - Hofzumahaus, A. A1 - Li, X. A1 - Rohrer, F. A1 - Tillmann, R. A1 - Wahner, A. T1 - Atmospheric photochemistry of aromatic hydrocarbons: OH budgets during SAPHIR chamber experiments JF - Atmospheric Chemistry and Physics N2 - Abstract. Current photochemical models developed to simulate the atmospheric degradation of aromatic hydrocarbons tend to underestimate OH radical concentrations. In order to analyse OH budgets, we performed experiments with benzene, toluene, p-xylene and 1,3,5-trimethylbenzene in the atmosphere simulation chamber SAPHIR. Experiments were conducted under low-NO conditions (typically 0.1–0.2 ppb) and high-NO conditions (typically 7–8 ppb), and starting concentrations of 6–250 ppb of aromatics, dependent on OH rate constants. For the OH budget analysis a steady-state approach was applied in which OH production and destruction rates (POH and DOH) have to be equal. The POH were determined from measurements of HO2, NO, HONO, and O3 concentrations, considering OH formation by photolysis and recycling from HO2. The DOH were calculated from measurements of the OH concentrations and total OH reactivities. The OH budgets were determined from DOH/POH ratios. The accuracy and reproducibility of the approach were assessed in several experiments using CO as a reference compound where an average ratio DOH/POH = 1.13 ± 0.19 was obtained. In experiments with aromatics, these ratios ranged within 1.1–1.6 under low-NO conditions and 0.9–1.2 under high-NO conditions. The results indicate that OH budgets during photo-oxidation experiments with aromatics are balanced within experimental accuracies. Inclusion of a further, recently proposed OH production via HO2 + RO2 reactions led to improvements under low-NO conditions but the differences were small and insignificant within the experimental errors. KW - Luftreinhaltung Y1 - 2014 U6 - https://doi.org/10.5194/acp-14-6941-2014 SN - 1680-7324 VL - 14 IS - 13 SP - 6941 EP - 6952 PB - Copernicus ER - TY - JOUR A1 - Zellner, R. A1 - Herrmann, H. A1 - Wiesen, P. A1 - Nehr, Sascha T1 - New and Emerging Technologies of Societal Relevance: Impact on Air Quality and Climate JF - Chemie Ingenieur Technik KW - Luftreinhaltung Y1 - 2016 U6 - https://doi.org/10.1002/cite.201650083 SN - 0009-286X VL - 88 IS - 9 SP - 1257 EP - 1258 PB - Wiley ER - TY - JOUR A1 - Nehr, Sascha A1 - Franzen-Reuter, Isabelle A1 - Kucejko, Catharina T1 - New directions: Future approaches to the standardized assessment of airborne pollutants affecting environmental quality JF - Atmospheric Environment KW - Luftreinhaltung Y1 - 2017 U6 - https://doi.org/10.1016/j.atmosenv.2017.06.051 SN - 1352-2310 VL - 166 SP - 570 EP - 572 PB - Elsevier ER - TY - JOUR A1 - Kaminski, Martin A1 - Fuchs, Hendrik A1 - Acir, Ismail-Hakki A1 - Bohn, Birger A1 - Brauers, Theo A1 - Dorn, Hans-Peter A1 - Häseler, Rolf A1 - Hofzumahaus, Andreas A1 - Li, Xin A1 - Lutz, Anna A1 - Nehr, Sascha A1 - Rohrer, Franz A1 - Tillmann, Ralf A1 - Vereecken, Luc A1 - Wegener, Robert A1 - Wahner, Andreas T1 - Investigation of the β-pinene photooxidation by OH in the atmosphere simulation chamber SAPHIR JF - Atmospheric Chemistry and Physics N2 - Abstract. Besides isoprene, monoterpenes are the non-methane volatile organic compounds (VOCs) with the highest global emission rates. Due to their high reactivity towards OH, monoterpenes can dominate the radical chemistry of the atmosphere in forested areas. In the present study the photochemical degradation mechanism of β-pinene was investigated in the Jülich atmosphere simulation chamber SAPHIR (Simulation of Atmospheric PHotochemistry In a large Reaction Chamber). One focus of this study is on the OH budget in the degradation process. Therefore, the SAPHIR chamber was equipped with instrumentation to measure radicals (OH, HO2, RO2), the total OH reactivity, important OH precursors (O3, HONO, HCHO), the parent VOC β-pinene, its main oxidation products, acetone and nopinone and photolysis frequencies. All experiments were carried out under low-NO conditions ( ≤  300 ppt) and at atmospheric β-pinene concentrations ( ≤  5 ppb) with and without addition of ozone. For the investigation of the OH budget, the OH production and destruction rates were calculated from measured quantities. Within the limits of accuracy of the instruments, the OH budget was balanced in all β-pinene oxidation experiments. However, even though the OH budget was closed, simulation results from the Master Chemical Mechanism (MCM) 3.2 showed that the OH production and destruction rates were underestimated by the model. The measured OH and HO2 concentrations were underestimated by up to a factor of 2, whereas the total OH reactivity was slightly overestimated because the model predicted a nopinone mixing ratio which was 3 times higher than measured. A new, theory-derived, first-generation product distribution by Vereecken and Peeters (2012) was able to reproduce the measured nopinone time series and the total OH reactivity. Nevertheless, the measured OH and HO2 concentrations remained underestimated by the numerical simulations. These observations together with the fact that the measured OH budget was closed suggest the existence of unaccounted sources of HO2. Although the mechanism of additional HO2 formation could not be resolved, our model studies suggest that an activated alkoxy radical intermediate proposed in the model of Vereecken and Peeters (2012) generates HO2 in a new pathway, whose importance has been underestimated so far. The proposed reaction path involves unimolecular rearrangement and decomposition reactions and photolysis of dicarbonyl products, yielding additional HO2 and CO. Further experiments and quantum chemical calculations have to be made to completely unravel the pathway of HO2 formation. KW - Luftreinhaltung Y1 - 2017 U6 - https://doi.org/10.5194/acp-17-6631-2017 SN - 1680-7324 VL - 17 IS - 11 SP - 6631 EP - 6650 PB - Copernicus ER - TY - JOUR A1 - Nehr, Sascha A1 - Hösen, Elisabeth A1 - Tanabe, Shin-ichi T1 - Emerging developments in the standardized chemical characterization of indoor air quality JF - Environment International KW - Indoor air quality KW - Indoor air chemistry KW - Online-measurement KW - Non-target-screening KW - Indoor air quality management KW - Luftreinhaltung Y1 - 2017 U6 - https://doi.org/10.1016/j.envint.2016.09.020 SN - 0160-4120 VL - 98 SP - 233 EP - 237 PB - Elsevier ER - TY - JOUR A1 - Novelli, Anna A1 - Kaminski, Martin A1 - Rolletter, Michael A1 - Acir, Ismail-Hakki A1 - Bohn, Birger A1 - Dorn, Hans-Peter A1 - Li, Xin A1 - Lutz, Anna A1 - Nehr, Sascha A1 - Rohrer, Franz A1 - Tillmann, Ralf A1 - Wegener, Robert A1 - Holland, Frank A1 - Hofzumahaus, Andreas A1 - Kiendler-Scharr, Astrid A1 - Wahner, Andreas A1 - Fuchs, Hendrik T1 - Evaluation of OH and HO2 concentrations and their budgets during photooxidation of 2-methyl-3-butene-2-ol (MBO) in the atmospheric simulation chamber SAPHIR JF - Atmospheric Chemistry and Physics N2 - Several previous field studies have reported unexpectedly large concentrations of hydroxyl and hydroperoxyl radicals (OH and HO2, respectively) in forested environments that could not be explained by the traditional oxidation mechanisms that largely underestimated the observations. These environments were characterized by large concentrations of biogenic volatile organic compounds (BVOC) and low nitrogen oxide concentration. In isoprene-dominated environments, models developed to simulate atmospheric photochemistry generally underestimated the observed OH radical concentrations. In contrast, HO2 radical concentration showed large discrepancies with model simulations mainly in non-isoprene-dominated forested environments. An abundant BVOC emitted by lodgepole and ponderosa pines is 2-methyl-3-butene-2-ol (MBO), observed in large concentrations for studies where the HO2 concentration was poorly described by model simulations. In this work, the photooxidation of MBO by OH was investigated for NO concentrations lower than 200 pptv in the atmospheric simulation chamber SAPHIR at Forschungszentrum Jülich. Measurements of OH and HO2 radicals, OH reactivity (kOH), MBO, OH precursors, and organic products (acetone and formaldehyde) were used to test our current understanding of the OH-oxidation mechanisms for MBO by comparing measurements with model calculations. All the measured trace gases agreed well with the model results (within 15 %) indicating a well understood mechanism for the MBO oxidation by OH. Therefore, the oxidation of MBO cannot contribute to reconciling the unexplained high OH and HO2 radical concentrations found in previous field studies. KW - Luftreinhaltung Y1 - 2018 U6 - https://doi.org/10.5194/acp-18-11409-2018 SN - 1680-7324 N1 - Code and data availability The data from the experiments in the SAPHIR chamber used in this work are available on the EUROCHAMP data home page (https://data.eurochamp.org/, last access: 1 October 2019, EUROCHAMP, 2019). Supplement The supplement related to this article is available online at: https://doi.org/10.5194/acp-20-3333-2020-supplement. VL - 18 IS - 15 SP - 11409 EP - 11422 PB - Copernicus ER - TY - JOUR A1 - Rolletter, Michael A1 - Kaminski, Martin A1 - Acir, Ismail-Hakki A1 - Bohn, Birger A1 - Dorn, Hans-Peter A1 - Li, Xin A1 - Lutz, Anna A1 - Nehr, Sascha A1 - Rohrer, Franz A1 - Tillmann, Ralf A1 - Wegener, Robert A1 - Hofzumahaus, Andreas A1 - Kiendler-Scharr, Astrid A1 - Wahner, Andreas A1 - Fuchs, Hendrik T1 - Investigation of the α-pinene photooxidation by OH in the atmospheric simulation chamber SAPHIR JF - Atmospheric Chemistry and Physics N2 - Abstract. The photooxidation of the most abundant monoterpene, α-pinene, by the hydroxyl radical (OH) was investigated at atmospheric concentrations in the atmospheric simulation chamber SAPHIR. Concentrations of nitric oxide (NO) were below 120 pptv. Yields of organic oxidation products are determined from measured time series giving values of 0.11±0.05, 0.19±0.06, and 0.05±0.03 for formaldehyde, acetone, and pinonaldehyde, respectively. The pinonaldehyde yield is at the low side of yields measured in previous laboratory studies, ranging from 0.06 to 0.87. These studies were mostly performed at reactant concentrations much higher than observed in the atmosphere. Time series of measured radical and trace-gas concentrations are compared to results from model calculations applying the Master Chemical Mechanism (MCM) 3.3.1. The model predicts pinonaldehyde mixing ratios that are at least a factor of 4 higher than measured values. At the same time, modeled hydroxyl and hydroperoxy (HO2) radical concentrations are approximately 25 % lower than measured values. Vereecken et al. (2007) suggested a shift of the initial organic peroxy radical (RO2) distribution towards RO2 species that do not yield pinonaldehyde but produce other organic products. Implementing these modifications reduces the model–measurement gap of pinonaldehyde by 20 % and also improves the agreement in modeled and measured radical concentrations by 10 %. However, the chemical oxidation mechanism needs further adjustment to explain observed radical and pinonaldehyde concentrations. This could be achieved by adjusting the initial RO2 distribution, but could also be done by implementing alternative reaction channels of RO2 species that currently lead to the formation of pinonaldehyde in the model. KW - Luftreinhaltung Y1 - 2019 U6 - https://doi.org/10.5194/acp-19-11635-2019 SN - 1680-7324 N1 - Data availability Data of the experiments in the SAPHIR chamber used in this work are available on the EUROCHAMP data home page (https://data.eurochamp.org/, last access: 28 April 2019, Eurochamp, 2019). Supplement The supplement related to this article is available online at: https://doi.org/10.5194/acp-19-11635-2019-supplement. VL - 19 IS - 18 SP - 11635 EP - 11649 PB - Copernicus ER - TY - JOUR A1 - Bekö, Gabriel A1 - Carslaw, Nicola A1 - Fauser, Patrik A1 - Kauneliene, Violeta A1 - Nehr, Sascha A1 - Phillips, Gavin A1 - Saraga, Dikaia A1 - Schoemaecker, Coralie A1 - Wierzbicka, Aneta A1 - Querol, Xavier T1 - The past, present, and future of indoor air chemistry JF - Indoor Air KW - Luftreinhaltung Y1 - 2020 U6 - https://doi.org/10.1111/ina.12634 SN - 0905-6947 VL - 30 IS - 3 SP - 373 EP - 376 PB - Wiley ER - TY - JOUR A1 - Bergmann, Karl-Christian A1 - Klimek, Ludger A1 - Nehr, Sascha A1 - Straff, Wolfgang A1 - Werchan, Barbora T1 - Allergenic pollen: is it also an indoor problem? JF - Allergo Journal International KW - Luftreinhaltung Y1 - 2021 U6 - https://doi.org/10.1007/s40629-020-00161-3 SN - 2197-0378 VL - 30 IS - 6 SP - 207 EP - 208 PB - Springer Nature ER - TY - JOUR A1 - Tan, Zhaofeng A1 - Hantschke, Luisa A1 - Kaminski, Martin A1 - Acir, Ismail-Hakki A1 - Bohn, Birger A1 - Cho, Changmin A1 - Dorn, Hans-Peter A1 - Li, Xin A1 - Novelli, Anna A1 - Nehr, Sascha A1 - Rohrer, Franz A1 - Tillmann, Ralf A1 - Wegener, Robert A1 - Hofzumahaus, Andreas A1 - Kiendler-Scharr, Astrid A1 - Wahner, Andreas A1 - Fuchs, Hendrik T1 - Atmospheric photo-oxidation of myrcene: OH reaction rate constant, gas-phase oxidation products and radical budgets JF - Atmospheric Chemistry and Physics N2 - Abstract. The photo-oxidation of myrcene, a monoterpene species emitted by plants, was investigated at atmospheric conditions in the outdoor simulation chamber SAPHIR (Simulation of Atmospheric PHotochemistry In a Large Reaction Chamber). The chemical structure of myrcene consists of one moiety that is a conjugated π system (similar to isoprene) and another moiety that is a triple-substituted olefinic unit (similar to 2-methyl-2-butene). Hydrogen shift reactions of organic peroxy radicals (RO2) formed in the reaction of isoprene with atmospheric OH radicals are known to be of importance for the regeneration of OH. Structure–activity relationships (SARs) suggest that similar hydrogen shift reactions like in isoprene may apply to the isoprenyl part of RO2 radicals formed during the OH oxidation of myrcene. In addition, SAR predicts further isomerization reactions that would be competitive with bimolecular RO2 reactions for chemical conditions that are typical for forested environments with low concentrations of nitric oxide. Assuming that OH peroxy radicals can rapidly interconvert by addition and elimination of O2 like in isoprene, bulk isomerization rate constants of 0.21 and 0.097 s−1 (T=298 K) for the three isomers resulting from the 3′-OH and 1-OH addition, respectively, can be derived from SAR. Measurements of radicals and trace gases in the experiments allowed us to calculate radical production and destruction rates, which are expected to be balanced. The largest discrepancies between production and destruction rates were found for RO2. Additional loss of organic peroxy radicals due to isomerization reactions could explain the observed discrepancies. The uncertainty of the total radical (ROx=OH+HO2+RO2) production rates was high due to the uncertainty in the yield of radicals from myrcene ozonolysis. However, results indicate that radical production can only be balanced if the reaction rate constant of the reaction between hydroperoxy (HO2) and RO2 radicals derived from myrcene is lower (0.9 to 1.6×10-11 cm3 s−1) than predicted by SAR. Another explanation of the discrepancies would be that a significant fraction of products (yield: 0.3 to 0.6) from these reactions include OH and HO2 radicals instead of radical-terminating organic peroxides. Experiments also allowed us to determine the yields of organic oxidation products acetone (yield: 0.45±0.08) and formaldehyde (yield: 0.35±0.08). Acetone and formaldehyde are produced from different oxidation pathways, so that yields of these compounds reflect the branching ratios of the initial OH addition to myrcene. Yields determined in the experiments are consistent with branching ratios expected from SAR. The yield of organic nitrate was determined from the gas-phase budget analysis of reactive oxidized nitrogen in the chamber, giving a value of 0.13±0.03. In addition, the reaction rate constant for myrcene + OH was determined from the measured myrcene concentration, yielding a value of (2.3±0.3)×10-10 cm3 s−1. KW - Luftreinhaltung Y1 - 2021 U6 - https://doi.org/10.5194/acp-21-16067-2021 SN - 1680-7324 VL - 21 IS - 20 SP - 16067 EP - 16091 PB - Copernicus GmbH ER - TY - CHAP A1 - Sturtevant, Cove A1 - Metzger, Stefan A1 - Nehr, Sascha A1 - Foken, Thomas ED - Foken, Thomas T1 - Quality Assurance and Control T2 - Springer Handbook of Atmospheric Measurements KW - quality assurance KW - quality control KW - quality management KW - calibration KW - certification KW - data quality KW - data processing KW - instrument characteristics KW - instrument requirements KW - site requirements KW - Luftreinhaltung Y1 - 2021 SN - 9783030521707 U6 - https://doi.org/10.1007/978-3-030-52171-4_3 SN - 2522-8692 SP - 49 EP - 92 PB - Springer Nature CY - Cham ER - TY - JOUR A1 - Baus, Lukas A1 - Nehr, Sascha T1 - Potentials and limitations of direct air capturing in the built environment JF - Building and Environment N2 - This concept study presents an approach for resolving the trade-off between energy-efficient building operation and the provision of hygienically harmless indoor air quality. A novel coupling of HVAC-systems (heating, ventilation and air conditioning systems) with DAC-technology (direct air capturing technology) is proposed to separate CO2 in the exhaust air of buildings and recirculate the CO2-depleted air back into the building. In a mainly theoretical approach, the corresponding potentials and limitations of the novel HVAC/DAC-coupling in recirculation mode are evaluated. For that purpose, CO2-loads in the feed and exhaust air of four buildings located in Germany were measured using calibrated non-dispersive infrared (NDIR) sensors with pyroelectric detection principle. Subsequent numerical model simulations resort to typical meteorological data as well as building operation parameters grouped in different scenarios. The measurement and simulation results were assessed with regard to: (i) the unique possibilities of a HVAC/DAC-coupling in recirculation mode for the improvement of indoor air quality, (ii) the energy saving potentials through reduced air conditioning requirements enabled by a HVAC/DAC-coupling in recirculation mode, and (iii) the potential allocation of CO2 separated from building exhaust air for energetic and/or material reutilization in decentralized systems. In conclusion, a HVAC/DAC-coupling in recirculation mode can not only reduce the energy demand of buildings but also facilitates access to unutilized CO2-resources transported in the built environment and additionally offers the potential to improve indoor air quality. However, a suitable DAC module for operation in indoor air is not yet commercially available. KW - Direct air capturing KW - Indoor air quality KW - Energy-efficient ventilation KW - CO 2-Separation KW - HVAC KW - Circular economy KW - Luftreinhaltung Y1 - 2022 U6 - https://doi.org/10.1016/j.buildenv.2021.108629 SN - 0360-1323 VL - 208 PB - Elsevier ER - TY - JOUR A1 - Alvarez, Elena Gómez A1 - Carslaw, Nicola A1 - Dusanter, Sébastien A1 - Edwards, Pete A1 - Gábor Mihucz, Viktor A1 - Heard, Dwayne A1 - Kleffmann, Jörg A1 - Nehr, Sascha A1 - Schoemacker, Coralie A1 - Venables, Dean T1 - Techniques for measuring indoor radicals and radical precursors JF - Applied Spectroscopy Reviews N2 - Radicals and their precursors play a central role in the chemical transformations occurring in indoor air and on indoor surfaces. Such species include OH, HO2, peroxy radicals, nitrous acid, reactive chlorine species, NO3, N2O5, Criegee intermediates, and glyoxal and methylglyoxal. Recent advances on instrumental analysis and modeling studies have demonstrated the need for a wider range of measurements of radical species and their precursors in indoor air. This work reviews measurement techniques and provides considerations for indoor measurements of several radicals and their precursors. Techniques to determine the actinic flux are also presented owing to the relevance of photolytically-initiated processes indoors. This review is also intended to provide pointers for those wanting to learn more about measurements of radicals indoors. KW - Criegee KW - peroxy KW - HONO KW - FAGE KW - CIMS KW - Laser-induced fluorescence KW - Luftreinhaltung Y1 - 2022 U6 - https://doi.org/10.1080/05704928.2022.2087666 SN - 0570-4928 VL - 57 IS - 7 SP - 580 EP - 624 PB - Informa UK Limited ER - TY - JOUR A1 - Pang, Jacky Yat Sing A1 - Novelli, Anna A1 - Kaminski, Martin A1 - Acir, Ismail-Hakki A1 - Bohn, Birger A1 - Carlsson, Philip T. M. A1 - Cho, Changmin A1 - Dorn, Hans-Peter A1 - Hofzumahaus, Andreas A1 - Li, Xin A1 - Lutz, Anna A1 - Nehr, Sascha A1 - Reimer, David A1 - Rohrer, Franz A1 - Tillmann, Ralf A1 - Wegener, Robert A1 - Kiendler-Scharr, Astrid A1 - Wahner, Andreas A1 - Fuchs, Hendrik T1 - Investigation of the limonene photooxidation by OH at different NO concentrations in the atmospheric simulation chamber SAPHIR (Simulation of Atmospheric PHotochemistry In a large Reaction Chamber) JF - Atmospheric Chemistry and Physics N2 - Abstract. The oxidation of limonene by the hydroxyl (OH) radical and ozone (O3) was investigated in the atmospheric simulation chamber SAPHIR (Simulation of Atmospheric PHotochemistry In a large Reaction Chamber) in experiments performed at different nitric oxide (NO) mixing ratios from nearly 0 up to 10 ppbv. For the experiments dominated by OH oxidation, the formaldehyde (HCHO) yield was experimentally determined and found to be (12 ± 3), (13 ± 3), and (32 ± 5) % for experiments with low (∼ 0.1 ppbv), medium (∼ 0.3 ppbv), and high NO (5 to 10 ppbv), respectively. The yield in an ozonolysis-only experiment was (10 ± 1) %, which agrees with previous laboratory studies. The experimental yield of the first-generation organic nitrates from limonene–OH oxidation is calculated as (34 ± 5) %, about 11 % higher than the value in the Master Chemical Mechanism (MCM), which is derived from structure–activity relationships (SARs). Time series of measured radicals, trace-gas concentrations, and OH reactivity are compared to results from zero-dimensional chemical box model calculations applying MCM v3.3.1. Modeled OH reactivity is 5 to 10 s−1 (25 % to 33 % of the OH reactivity at the start of the experiment) higher than measured values at the end of the experiments under all chemical conditions investigated, suggesting either that there are unaccounted loss processes of limonene oxidation products or that products are less reactive toward OH. In addition, model calculations underestimate measured hydroperoxyl radical (HO2) concentrations by 20 % to 90 % and overestimate organic peroxyl radical (RO2) concentrations by 50 % to 300 %. The largest deviations are found in low-NO experiments and in the ozonolysis experiment. An OH radical budget analysis, which uses only measured quantities, shows that the budget is closed in most of the experiments. A similar budget analysis for RO2 radicals suggests that an additional RO2 loss rate constant of about (1–6) × 10−2 s−1 for first-generation RO2 is required to match the measured RO2 concentrations in all experiments. Sensitivity model runs indicate that additional reactions converting RO2 to HO2 at a rate constant of about (1.7–3.0) × 10−2 s−1 would improve the model–measurement agreement of NOx, HO2, and RO2 concentrations and OH reactivity. Reaction pathways that could lead to the production of additional OH and HO2 are discussed, which include isomerization reactions of RO2 from the oxidation of limonene, different branching ratios for the reaction of RO2 with HO2, and a faster rate constant for RO2 recombination reactions. As the exact chemical mechanisms of the additional HO2 and OH sources could not be identified, further work needs to focus on quantifying organic product species and organic peroxy radicals from limonene oxidation. KW - Luftreinhaltung Y1 - 2022 U6 - https://doi.org/10.5194/acp-22-8497-2022 SN - 1680-7324 VL - 22 IS - 13 SP - 8497 EP - 8527 PB - Copernicus ER - TY - JOUR A1 - Nehr, Sascha A1 - Jäckel, Simon T1 - Successful Innovation Transfer through Pre-Standardization: A Case Study JF - Standards N2 - This study presents an approach to structure, analyze and evaluate corporate standardization processes using the example of pre-standardization for the reduction of environmental impacts in product design and development. For this purpose, we give a detailed description of the evolution of the European Standard EN 16524 entitled “Mechanical products—Methodology for reduction of environmental impacts in product design and development”. The standardization strategy behind the evolution of EN 16524 is analyzed using the approach of a Business Model Canvas combined with an evaluation using pre-defined success factors. Moreover, we derive general recommendations for corporate standardization professionals in checklists for each field of the underlying Business Model Canvas. With regard to the case study depicted here, we come to the conclusion that pre-standards are especially suited for innovation transfer in the field of emerging and rapidly evolving scientific and technical results. KW - standardization strategies KW - pre-standards KW - success factors KW - Business Model Canvas KW - environmental impact KW - Luftreinhaltung Y1 - 2023 U6 - https://doi.org/10.3390/standards3010004 SN - 2305-6703 VL - 3 IS - 1 SP - 31 EP - 42 PB - MDPI ER - TY - JOUR A1 - Nehr, Sascha A1 - Duarte, Regina M. B. O. A1 - Almeida, Antoine S. A1 - Baus, Lukas A1 - Bergmann, Karl-Christian T1 - Assessing the relevance of allergenic pollen in indoor environments—current knowledge base and research needs JF - Allergo Journal International N2 - SummaryAirborne pollen allergens—a relevant component of bioaerosols and, therefore, of airborne particulate matter—are considered an important metric in air quality assessments. Although the measurement of airborne pollen allergen concentrations in outdoor environments (namely, in urban areas) has been recognized as a key environmental health indicator, no such obligation exists for indoor environments (dwellings or occupational settings). However, people spend most of their daily time (80–90%) indoors, where the majority of their exposure to air pollution, including pollen allergens, occurs. Nonetheless, the relative importance of airborne pollen allergen exposure indoors differs from outdoors because of differences in pollen loads, sources, dispersion, and degree of penetration from the outdoor surroundings, as well as the differences in the allergenic pollen profiles. In this brief review, we mined the literature over the last 10 years to summarize what existing measurements reveal about the relevance of airborne allergenic pollen in indoor environments. The research priorities on this topic are presented, highlighting the challenges and the motivations for obtaining pollen data in built environments which are key to understand the extent and mechanisms of human exposure to airborne pollen allergens. Thus, we provide a comprehensive assessment of the relevance of airborne allergenic pollen in indoor environments, highlighting knowledge gaps and research needs related to their health effects. KW - standardization strategies KW - pre-standards KW - success factors KW - Business Model Canvas KW - environmental impact KW - Luftreinhaltung Y1 - 2023 U6 - https://doi.org/10.1007/s40629-023-00251-y SN - 2197-0378 VL - 32 IS - 6 SP - 167 EP - 175 PB - Springer Nature ER - TY - JOUR A1 - Saffell, John A1 - Nehr, Sascha T1 - Improving Indoor Air Quality through Standardization JF - Standards N2 - Human beings experience a large fraction of their exposure to air pollutants in indoor environments. Air pollution is a large environmental health risk, and exposure to ambient air pollution and indoor air pollution contribute equally to the total number of fatalities worldwide. Although legislative authorities have established limit values for ambient outdoor air and stack emissions, there are inconsistent and variable national and regional limit values for gaseous substances and airborne particulate matter in the built environment (schools, homes, healthcare facilities, offices, and other public spaces). This lack of regulation is unsurprising, because indoor spaces are characterized by complex air chemistry, and their construction materials and types of activities vary significantly. The current understanding of indoor pollutants, including short-lived oxidants, degradation of VOCs, particle formation, and particle composition, is incomplete. It is necessary to identify and assess emerging pollutants and their toxicity, and to consider new consumer products and green construction materials and their impact on indoor air quality (IAQ). Learning from IAQ surveys and audit protocols, research methodologies should be regularized for cross-research comparisons. Some indoor air quality guidance and standards have been written, and several more are in development, with the international ISO 16000 series of indoor standards leading the way for improving indoor air data quality. The WHO has established some ambient air limit values which can mostly be translated into indoor limit values. The built environment needs to harmonize energy efficiency, thermal comfort and air quality standards and guidance. In this review, we discuss the next steps for improving international, regional and national standards and guidance, leading to better and more complete indoor air quality regulations. KW - indoor air quality KW - IAQ KW - air quality standards KW - air quality regulations KW - air quality guidance KW - indoor pollutants KW - IAQ survey KW - indoor air data quality KW - limit value KW - Luftreinhaltung Y1 - 2023 U6 - https://doi.org/10.3390/standards3030019 SN - 2305-6703 VL - 3 IS - 3 SP - 240 EP - 267 PB - MDPI ER - TY - JOUR A1 - Baus, Lukas A1 - Nehr, Sascha A1 - Maeda, Nobutaka ED - Ming, Ting Zhen T1 - Investigation of CO2-Sorption Characteristics of Readily Available Solid Materials for Indoor Direct Air Capturing JF - Indoor Air N2 - Direct air capturing (DAC) is an energy demanding process for CO2-removal from air. Ongoing research focuses on the potential of indoor air as DAC-feed to profit from currently unused energetic synergies between DAC and the built environment. In this work, we investigated the performance of three different readily available, solid DAC-adsorbers under typical indoor environmental conditions of 16-25°C, 25-60% relative humidity (RH), and CO2-concentrations of less than 800 ppm above atmospheric concentrations. The measured mass-specific CO2-adsorption capacities of K2CO3-impregnated activated carbon, polyethylenimine-snow (PEI-snow), and polyethylenimine (PEI) on silica a amount to 6.5 ± 0.3 mg g−1, 52.9 ± 4.9 mg g−1, and 56.9 ± 4.2 mg g−1, respectively. Among the three investigated adsorber materials, PEI on silica is the most promising candidate for DAC-applications as its synthesis is rather simple, the CO2-desorption is feasible at moderate conditions of about 80°C at 100 mbar, and the competing co-adsorption of water does not strongly affect the CO2-adsorption under the investigated experimental conditions. KW - Luftreinhaltung Y1 - 2023 U6 - https://doi.org/10.1155/2023/8821044 SN - 1600-0668 VL - 2023 SP - 1 EP - 8 PB - Wiley ER - TY - CHAP A1 - Nehr, Sascha A1 - Simmler, Walter T1 - Air, 6. Photochemical Degradation T2 - Ullmann's Encyclopedia of Industrial Chemistry KW - Luftreinhaltung Y1 - 2023 SN - 9783527303854 U6 - https://doi.org/10.1002/14356007.o02_o06.pub2 SP - 1 EP - 11 PB - Wiley ET - 1 ER - TY - JOUR A1 - Nehr, Sascha A1 - Baus, Lukas A1 - Çınar, Hasan A1 - Elsen, Ingo A1 - Frauenrath, Tobias T1 - Indoor environmental quality assessment in passively ventilated classrooms in Germany and estimation of ventilation energy losses JF - Journal of Building Engineering KW - Indoor air quality KW - Indoor environmental quality KW - Energy-efficient ventilation KW - CO2 KW - PM2.5 KW - TVOC KW - Passive ventilation KW - Luftreinhaltung Y1 - 2024 U6 - https://doi.org/10.1016/j.jobe.2024.110937 SN - 2352-7102 VL - 97 PB - Elsevier ER - TY - JOUR A1 - Uffmann, Kai A1 - Abicht, Claus A1 - Grote, Wolfgang A1 - Quick, Harald H. A1 - Ladd, Mark E. T1 - Design of an MR-compatible piezoelectric actuator for MR elastography JF - Concepts in Magnetic Resonance Part A: Bridging Education and Research N2 - Magnetic Resonance (MR) elastography is a method for measuring tissue elasticity via phase images acquired with an MR scanner. The propagation of periodic mechanical waves through the tissue can be captured by means of a modified phase contrast sequence. These waves are generated with a mechanical oscillator (actuator) and coupled into the tissue through the skin. The actuator must be capable of generating a sinusoidal excitation with excellent phase and amplitude stability, while not disturbing the MR imaging process. In this work, an actuator based on a piezoelectric principle was developed. Based on the imaging evaluation of several material samples, the housing for the piezoelectric ceramic was constructed of aluminum. Smaller parts of the housing were manufactured from brass and titanium to fulfill the mechanical constraints. A lever was used to transfer the oscillation generated by the piezoelectric ceramic to the point of excitation. The lever amplifies the piezoelectric motion, allowing for a more compact design. Three different lever designs were characterized by an acceleration sensor both outside and inside the magnet. It was shown that the rigidity of the lever, as determined by its material and form, was decisive in determining the resonant frequency of the system and therefore the maximum practical frequency of operation. It was also shown that the motion of the oscillator is unaffected by the electromagnetic fields of the MR imager. The final design can be placed directly in the magnet bore within a few centimeters of the tissue volume to be imaged without generating significant artifacts. An amplitude range of 0–1 mm in the frequency range from 0 to over 300 Hz was achieved, sufficient for performing most MR elastography applications. © 2002 Wiley Periodicals, Inc. Concepts in Magnetic Resonance (Magn Reson Engineering) 15: 239–254, 2002 KW - Elasticity KW - Elastography KW - Actuator KW - MRI KW - Piezoelectric Y1 - 2002 UR - 1552-5023 U6 - https://doi.org/https://doi.org/10.1002/cmr.10045 VL - 15 IS - 4 SP - 239 EP - 254 PB - Wiley ER - TY - JOUR A1 - Galban, Craig A1 - Maderwald, Stefan A1 - Herrmann, Burkhard A1 - Brauck, K. A1 - Grote, Wolfgang A1 - de Greiff, A. A1 - Uffmann, K. A1 - Ladd, M. T1 - Measuring Skeletal Muscle Elasticity in Patients with Hypogonadism by MR Elastography JF - Proc. Intl. Soc. Mag. Reson. Med. N2 - Men afflicted with hypogonadism have reduced fat-free mass and in some cases a loss in muscle strength. We hypothesize that muscle elasticity of the lower extremities differs between patients with hypogonadism and healthy controls. The shear modulus of the soleus muscle was measured non-invasively using MR elastography (MRE) at 0%, 5%, 10%, 15%, and 20% of the subject’s maximum applied force. The results from this study showed statistical differences between the patients and controls, even though there were no statistical differences in applied force. Y1 - 2005 UR - https://cds.ismrm.org/protected/05MProceedings/PDFfiles/02016.pdf VL - 13 SP - 2016 ER - TY - JOUR A1 - Galban, Craig A1 - Maderwald, Stefan A1 - Eggebrecht, Holger A1 - Grote, Wolfgang A1 - de Greiff, A. A1 - Uffmann, K. A1 - Ladd, M. E. T1 - Monitoring the Effects of Chronic Obstructive Pulmonary Disease on Muscle Elasticity by MR Elastography JF - Proc. Intl. Soc. Mag. Reson. Med. N2 - Men afflicted with chronic obstructive pulmonary disease (COPD) show signs of muscle dysfunction, such as increased muscle fatigue and acidosis during exercise. We hypothesize that muscle elasticity of the lower extremities differs between patients with COPD and age-related controls. The shear modulus of the soleus muscle was measured non-invasively using MR elastography (MRE) at 0%, 5%, 10%, 15%, and 20% of the subject’s maximum applied force. The results from this study showed statistical differences between the patients and controls, even though there were no statistical differences in the maximum applied force. Y1 - 2005 UR - https://cds.ismrm.org/protected/05MProceedings/PDFfiles/02015.pdf VL - 13 SP - 2015 ER - TY - JOUR A1 - Beyer, Marc-André A1 - Grote, Wolfgang A1 - Reinig, Gunter T1 - Adaptive exact linearization control of batch polymerization reactors using a Sigma-Point Kalman Filter JF - Journal of Process Control N2 - The Chylla–Haase polymerization reactor is widely accepted as a benchmark process for the evaluation of control strategies for batch reactors. In this contribution a control concept based on Exact I/O-Linearization is proposed and compared to a conventional cascade control structure. In order to adapt the exact linearization control strategy to various polymerization products and batch conditions, an advanced probabilistic inference algorithm (Sigma-Point Kalman Filter) is applied and investigated. Sigma-Point Kalman Filters have the major improvement of simplified implementation compared to local linearization methods (i.e. Extended Kalman Filter) because no analytical Jacobians are required. Stochastic simulation studies are introduced and show the effectiveness, accuracy and benefit of the control concept. Within several scenarios a satisfying robustness against structural errors in the underlying model equations for the nonlinear control law and the inference algorithm is demonstrated. Furthermore it is pointed out, that with little effort in reassembling the plant design, control performance can be improved significantly. KW - Batch process operation KW - Exact I/O-Linearization control KW - Online parameter estimation KW - Sigma-Point Kalman Filter Y1 - 2008 UR - 1873-2771 U6 - https://doi.org/10.1016/j.jprocont.2007.12.002 VL - 18 IS - 7-8 SP - 663 EP - 675 PB - Elsevier ER - TY - CHAP A1 - Grote, Wolfgang A1 - Kastsian, Darya A1 - Mönnigmann, Martin T1 - Optimal power system unit commitment with guaranteed local stability T2 - Proceedings of the 2011 American Control Conference N2 - This article deals with the cost optimal commitment of power systems. System stability is often only considered after solving the commitment problem. We show by example that a cost optimization may result in a mode of operation that, while economically optimal, is unstable or has otherwise unacceptable dynamics. As a remedy, we propose to use the so-called normal vector method, which has been developed for the optimization of nonlinear dynamical systems with stability boundaries and uncertain parameters. We apply the method to a small sample power grid, where the optimization goal is to minimize the energy production costs for a given power consumption. KW - Optimization KW - Power system stability KW - Robustness Y1 - 2011 U6 - https://doi.org/10.1109/ACC.2011.5991058 SN - 2378-5861 SP - 4526 EP - 4531 PB - IEEE ER - TY - JOUR A1 - Grote, Wolfgang A1 - Kastsian, Darya A1 - Mönnigmann, Martin T1 - Guaranteed stability in optimal power generation dispatching under uncertainty JF - IEEE Transactions on Power Systems N2 - Stability and cost optimality of power generation and supply systems must not be considered independently from one another. Simple examples show that optimizing cost without considering stability may result in modes of operation that, while economically optimal, are unstable. We demonstrate that stability, robustness, and optimality can be considered systematically and simultaneously by combining bifurcation theory and nonlinear optimization. Essentially, the proposed method enforces a backoff distance between the optimal point of operation and operational or stability boundaries in the space of the optimization variables, where bifurcation theory is used to describe nonlinear stability boundaries. KW - Normal vector method KW - Power dispatch KW - Robust optimization KW - Stability KW - Unit commitment Y1 - 2013 U6 - https://doi.org/10.1109/TPWRS.2012.2207970 SN - 1558-0679 VL - 28 IS - 2 SP - 1103 EP - 1112 PB - IEEE ER - TY - JOUR A1 - Jost, Michael A1 - Grote, Wolfgang A1 - Möllenbruck, Florian A1 - Mönnigmann, Martin T1 - Plant-wide control of a parabolic trough power plant with thermal energy storage JF - IFAC Proceedings Volumes N2 - We present a control scheme for a parabolic trough power plant that is equipped with a molten salt thermal energy storage system. We show that the multivariable control problem for the solar field can be decoupled by controlling the three way valve that splits the heat transfer fluid between the storage system and the steam generator. The steam generation cycle is regulated with inlet pressure control. The subsystems of the plant are modeled based on first principles, where we focus on the steam generation cycle. A multi-group extraction turbine with pre- and reheater is considered, which is suitable for solar power plants. We demonstrate the benefits of the proposed control scheme with a day-to-day simulation. KW - Control of power plants KW - Solar power plants KW - Thermal energy storage KW - Decoupling control Y1 - 2014 U6 - https://doi.org/10.3182/20140824-6-ZA-1003.00879 SN - 2589-3653 VL - 47 IS - 3 SP - 419 EP - 425 PB - Elsevier ER - TY - JOUR A1 - Mier, Dominik A1 - Möllenbruck, Florian A1 - Jost, Michael A1 - Grote, Wolfgang A1 - Mönnigmann, Martin T1 - Model predictive control of the steam cycle in a solar power plant JF - IFAC-PapersOnLine N2 - We derive a nonlinear model of the steam cycle of a solar power plant, estimate its unknown parameters with measured data, and design a linear model predictive controller based on the resulting model. Simulations show that the linear model predictive controller is able to regulate the electrical power of the nonlinear steam process of the plant to a given reference trajectory very well. Moreover, it results in very good disturbance rejection. KW - Power plant control KW - solar power KW - model predictive control Y1 - 2015 U6 - https://doi.org/10.1016/j.ifacol.2015.09.052 SN - 2405-8963 VL - 48 IS - 8 SP - 710 EP - 715 PB - Elsevier ER - TY - CHAP A1 - Spiegel, Thomas ED - The International Centre for Sustainable Development of Energy, Water and Environment Systems, T1 - Imbalance reduction of energy balancing groups as a means of renewable energy expansion - Optiosn for an active energy balancing group management T2 - 12th Conference on Sustainable Development of Energy, Water and Environment Systems, 04.-08.10.2017, Dubrovnik Y1 - 2017 ER - TY - CHAP A1 - Rödder, Maximilian A1 - Frank, Lena A1 - Kirschner, Daniel A1 - Neef, Matthias A1 - Adam, Mario ED - The International Centre for Sustainable Development of Energy, Water and Environment Systems, T1 - EnergiBUS4home – Sustainable energy resourcing in low-energy buildings T2 - 12th Conference on Sustainable Development of Energy, Water and Environment Systems, 04.-08.10.2017, Dubrovnik KW - energiBUS4home Y1 - 2017 ER - TY - CHAP A1 - Reich, Marius A1 - Adam, Mario A1 - Lambach, Stefan T1 - Comparison of different Methods for Approximating Models of Energy Supply Systems and Polyoptimising the Systems-Structure and Components-Dimension T2 - 30th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (ECOS 2017), San Diego, California, USA, 2-6 July 2017 KW - Fast-Energy-Design Y1 - 2018 SN - 9781510862562 SP - 2921 EP - 2933 PB - Curran Associates Inc CY - Red Hook, NY ER - TY - CHAP A1 - Helbig, Sonja A1 - Eggert, Daniel A1 - Adam, Mario ED - Romero, Manuel ED - Mugnier, Daniel ED - Renné, David ED - Guthrie, Ken ED - Griffiths, Steven T1 - Energetic and Economic Efficiency Evaluation of Solar Assisted Heating Systems for Multi-Family Houses T2 - Proceedings of SWC2017/SHC2017, 29.10.-02.11.2017, Abu Dhabi KW - SUW-MFH Y1 - 2017 UR - http://proceedings.ises.org/swc2017 SN - 978-3-9814659-7-6 U6 - https://doi.org/10.18086/swc.2017.29.04 SP - 1 EP - 10 PB - International Solar Energy Society CY - Freiburg ER - TY - JOUR A1 - Wiesmann, Thomas A1 - Hamel, Christian A1 - Kaluza, Stefan T1 - Techniques to Remove Traces of Oxygen by Catalytic Conversion from Gas Mixtures JF - Chemie Ingenieur Technik Y1 - 2018 U6 - https://doi.org/10.1002/cite.201800022 SN - 1522-2640 VL - 90 IS - 10 SP - 1446 EP - 1452 PB - Wiley ER - TY - JOUR A1 - Weide, Philipp A1 - Schulz, Katharina A1 - Kaluza, Stefan A1 - Rohe, Markus A1 - Beranek, Radim A1 - Muhler, Martin T1 - Controlling the Photocorrosion of Zinc Sulfide Nanoparticles in Water by Doping with Chloride and Cobalt Ions JF - Langmuir Y1 - 2016 UR - http://www.ncbi.nlm.nih.gov/pubmed/27934521 U6 - https://doi.org/10.1021/acs.langmuir.6b03385 SN - 1520-5827 VL - 32 IS - 48 SP - 12641 EP - 12649 PB - ACS Publ. ER - TY - JOUR A1 - Titus, Juliane A1 - Kaluza, Stefan A1 - Marschall, Roland T1 - German Catalysis on an International Scale in Weimar JF - ChemCatChem Y1 - 2014 U6 - https://doi.org/10.1002/cctc.201402266 SN - 1867-3899 VL - 6 IS - 6 SP - 1523 EP - 1525 PB - Wiley ER - TY - JOUR A1 - Schulzke, Tim A1 - Conrad, Stefan A1 - Kaluza, Stefan A1 - van Loo, Tom T1 - Upgrading of fast pyrolysis condensates via esterification with higher alcohols JF - Biomass and Bioenergy Y1 - 2017 U6 - https://doi.org/10.1016/j.biombioe.2017.05.010 SN - 0961-9534 N1 - Postprint ist veröffentlicht unter: http://publica.fraunhofer.de/dokumente/N-446003.html VL - 103 SP - 11 EP - 20 PB - Elsevier ER - TY - JOUR A1 - Schmidt, Stefan A1 - Göbel, Christoph A1 - Nebel, Janine A1 - Wiesmann, Thomas A1 - Hamel, Christian A1 - Reinsdorf, Arne A1 - Wolf, Dorit A1 - Gehrmann, Stefan A1 - Tenhumberg, Nils A1 - Muhler, Martin A1 - Kaluza, Stefan T1 - Recent Developments in the Conversion of Synthesis Gas to Short-Chain Alcohols over Cu-Co-Based Catalysts JF - Chemie Ingenieur Technik Y1 - 2018 U6 - https://doi.org/10.1002/cite.201800023 SN - 1522-2640 VL - 90 IS - 10 SP - 1465 EP - 1475 PB - Wiley ER - TY - JOUR A1 - Schittkowski, Julian A1 - Ruland, Holger A1 - Laudenschleger, Daniel A1 - Girod, Kai A1 - Kähler, Kevin A1 - Kaluza, Stefan A1 - Muhler, Martin A1 - Schlögl, Robert T1 - Methanol Synthesis from Steel Mill Exhaust Gases: Challenges for the Industrial Cu/ZnO/Al 2 O 3 Catalyst JF - Chemie Ingenieur Technik Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-34526 SN - 1522-2640 N1 - We gratefully appreciate the support received from the Federal Ministry of Education and Research (Bundesministerium für Bildung und Forschung, BMBF, Verbundvorhaben Carbon2Chem®). VL - 90 IS - 10 SP - 1419 EP - 1429 PB - Wiley ER - TY - JOUR A1 - Peter, Maximilian A1 - Fichtl, Matthias B. A1 - Ruland, Holger A1 - Kaluza, Stefan A1 - Muhler, Martin A1 - Hinrichsen, Olaf T1 - Detailed kinetic modeling of methanol synthesis over a ternary copper catalyst JF - Chemical Engineering Journal Y1 - 2012 U6 - https://doi.org/10.1016/j.cej.2012.06.066 SN - 0009-2509 VL - 203 SP - 480 EP - 491 PB - Elsevier ER - TY - JOUR A1 - Nebel, Janine A1 - Schmidt, Stefan A1 - Pan, Qiushi A1 - Lotz, Katrin A1 - Kaluza, Stefan A1 - Muhler, Martin T1 - On the role of cobalt carbidization in higher alcohol synthesis over hydrotalcite-based Co-Cu catalysts JF - Chinese Journal of Catalysis Y1 - 2019 U6 - https://doi.org/10.1016/S1872-2067(19)63344-9 SN - 1872-2067 N1 - The research project is funded by the Federal Ministry of Education and Research (Bundesministerium für Bildung und Forschung, BMBF, Verbundvorhaben Carbon2Chem®, FKZ: 03EK3041). VL - 40 IS - 11 SP - 1731 EP - 1740 PB - Elsevier ER - TY - JOUR A1 - Mei, Bastian A1 - Sánchez, Miguel D. A1 - Reinecke, Thomas A1 - Kaluza, Stefan A1 - Xia, Wei A1 - Muhler, Martin T1 - The synthesis of Nb-doped TiO2 nanoparticles by spray drying: an efficient and scalable method JF - Journal of Materials Chemistry Y1 - 2011 U6 - https://doi.org/10.1039/c1jm11431j SN - 1364-5501 VL - 21 IS - 32 SP - 11781 EP - 11790 PB - Royal Society of Chemistry (RSC) ER - TY - CHAP A1 - Kaluza, Stefan A1 - Muhler, Martin ED - Gaigneaux, E. M. ED - Devillers, M. ED - Hermans, S. ED - Jacobs, P. A. ED - Martens, J. A. ED - Ruiz, P. T1 - A novel continuous approach for the synthesis and characterization of pure and mixed metal oxide systems applied in heterogeneous catalysis T2 - Scientific Bases for the Preparation of Heterogeneous Catalysts Y1 - 2010 SN - 978-0-444-53601-3 U6 - https://doi.org/10.1016/S0167-2991(10)75027-8 VL - Studies in Surface Science and Catalysis, 175 SP - 217 EP - 220 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kaluza, Stefan A1 - Schröter, Marie Katrin A1 - Naumann d'Alnoncourt, Raoul A1 - Reinecke, Thomas A1 - Muhler, Martin T1 - High Surface Area ZnO Nanoparticles via a Novel Continuous Precipitation Route JF - Advanced Functional Materials Y1 - 2008 U6 - https://doi.org/10.1002/adfm.200800457 SN - 1616-3028 N1 - The authors gratefully acknowledge fruitful discussions with Malte Behrens and Robert Schlögl, and financial support by the BMBF (Bundesministerium für Bildung und Forschung, project 01RI05028 “Entwicklung von Methanolsynthesekatalysatoren als Basis für nachhaltige Ressourcennutzung”). Supporting Information is available online from Wiley InterScience or from the author. VL - 18 IS - 22 SP - 3670 EP - 3677 ER - TY - JOUR A1 - Kaluza, Stefan A1 - Muhler, Martin T1 - On the Role of Aging, Washing, and Drying in the Synthesis of Polycrystalline Zinc Oxide by Precipitation: Combining Fast Continuous Mixing, Spray Drying and Freeze Drying to Unravel the Solid-State Transformations of the Precipitate JF - Catalysis Letters Y1 - 2009 UR - 1572-879X U6 - https://doi.org/10.1007/s10562-008-9818-5 N1 - The authors gratefully acknowledge fruitful discussions with Malte Behrens and Robert Schlögl, and the financial support by the BMBF (Bundesministerium für Bildung und Forschung) within the scope of the project 01RI05028 “Entwicklung von Methanolsynthesekatalysatoren als Basis für nachhaltige Ressourcennutzung” VL - 129 IS - 3-4 SP - 287 EP - 292 PB - Springer ER - TY - JOUR A1 - Kaluza, Stefan A1 - Muhler, Martin T1 - On the precipitation mechanism and the role of the post-precipitation steps during the synthesis of binary ZnO–Al2O3 composites with high specific surface area JF - Journal of Materials Chemistry KW - FBMV Y1 - 2009 U6 - https://doi.org/10.1039/b902004g SN - 1364-5501 VL - 19 IS - 23 SP - 3914 EP - 3922 PB - Royal Society of Chemistry (RSC) ER - TY - JOUR A1 - Kaluza, Stefan A1 - Behrens, Malte A1 - Schiefenhövel, Nora A1 - Kniep, Benjamin A1 - Fischer, Richard A1 - Schlögl, Robert A1 - Muhler, Martin T1 - A Novel Synthesis Route for Cu/ZnO/Al2O3 Catalysts used in Methanol Synthesis: Combining Continuous Consecutive Precipitation with Continuous Aging of the Precipitate JF - ChemCatChem Y1 - 2011 U6 - https://doi.org/10.1002/cctc.201000329 SN - 1867-3899 VL - 3 IS - 1 SP - 189 EP - 199 PB - Wiley ER - TY - JOUR A1 - Junge Puring, Kai A1 - Piontek, Stefan A1 - Smialkowski, Mathias A1 - Burfeind, Jens A1 - Kaluza, Stefan A1 - Doetsch, Christian A1 - Apfel, Ulf-Peter T1 - Simple Methods for the Preparation of Non-noble Metal Bulk-electrodes for Electrocatalytic Applications JF - Journal of visualized experiments : JoVE N2 - The rock material pentlandite with the composition Fe4.5Ni4.5S8 was synthesized via high temperature synthesis from the elements. The structure and composition of the material was characterized via powder X-ray diffraction (PXRD), Mössbauer spectroscopy (MB), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and energy dispersive X-ray spectroscopy (EDX). Two preparation methods of pentlandite bulk electrodes are presented. In the first approach a piece of synthetic pentlandite rock is directly contacted via a wire ferrule. The second approach utilizes pentlandite pellets, pressed from finely ground powder, which is immobilized in a Teflon casing. Both electrodes, whilst being prepared by an additive-free method, reveal high durability during electrocatalytic conversions in comparison to common drop-coating methods. We herein showcase the striking performance of such electrodes to accomplish the hydrogen evolution reaction (HER) and present a standardized method to evaluate the electrocatalytic performance by electrochemical and gas chromatographic methods. Furthermore, we report stability tests via potentiostatic methods at an overpotential of 0.6 V to explore the material limitations of the electrodes during electrolysis under industrial relevant conditions. Y1 - 2017 UR - http://www.ncbi.nlm.nih.gov/pubmed/28671654 U6 - https://doi.org/10.3791/56087 SN - 1940-087X IS - 124 PB - JoVE ER - TY - JOUR A1 - Heeskens, Denise A1 - Aghaei, Pedram A1 - Kaluza, Stefan A1 - Strunk, Jennifer A1 - Muhler, Martin T1 - Selective oxidation of ethanol in the liquid phase over Au/TiO 2 JF - physica status solidi (b) Y1 - 2013 U6 - https://doi.org/10.1002/pssb.201248440 SN - 1521-3951 VL - 250 IS - 6 SP - 1107 EP - 1118 PB - Wiley ER - TY - CHAP A1 - Hamel, Christian A1 - Kaluza, Stefan A1 - Unger, Christoph ED - Ernst, Stefan T1 - Catalytic tar reforming of biomass-derived synthesis gas: Influence of the catalyst, gas composition and sulfur poisoning T2 - Preprints of the DGMK-Conference "Synthesis Gas Chemistry",October 7 - 9, 2015, Dresden Y1 - 2015 SN - 978-3-941721-56-2 VL - DGMK Tagungsbericht, 2015,2 SP - 139 EP - 146 PB - DGMK CY - Hamburg ER - TY - JOUR A1 - Girod, Kai A1 - Breitkreuz, Klaas A1 - Gerstner, Andrea A1 - Marzi, Thomas A1 - Schulzke, Tim A1 - Kaluza, Stefan T1 - Close‐to‐Practice Investigations of Heterogeneously Catalyzed Syngas Conversions in Slurry and Fixed‐Bed Reactor Systems JF - Chemie Ingenieur Technik Y1 - 2018 U6 - https://doi.org/10.1002/cite.201700143 SN - 1522-2640 VL - 90 IS - 5 SP - 690 EP - 695 PB - Wiley ER - TY - JOUR A1 - Engeldahl, Barthel A1 - Özaslan, Mehtap A1 - Marschall, Roland A1 - Rose, Marcus A1 - Kaluza, Stefan A1 - Titus, Juliane A1 - Sprung, Christoph T1 - Weimar 2015: Catalysing Tomorrow’s Solutions JF - ChemCatChem Y1 - 2015 U6 - https://doi.org/10.1002/cctc.201500435 SN - 1867-3899 VL - 7 IS - 12 SP - 1794 EP - 1796 PB - Wiley ER - TY - JOUR A1 - Engel, Rebecca V. A1 - Kaluza, Stefan A1 - Oezaslan, Mehtap A1 - Peitz, Stephan T1 - German Catalysis Meeting - 50 Years and as Young as Ever JF - ChemCatChem Y1 - 2017 U6 - https://doi.org/10.1002/cctc.201700683 SN - 1867-3899 VL - 9 IS - 11 SP - 2018 EP - 2020 PB - Wiley ER - TY - JOUR A1 - Boz, İsmail A1 - Kaluza, Stefan A1 - Boroğlu, Mehtap Şafak A1 - Muhler, Martin T1 - Synthesis of high surface area ZnO powder by continuous precipitation JF - Materials Research Bulletin Y1 - 2012 U6 - https://doi.org/10.1016/j.materresbull.2012.02.005 SN - 1873-4227 VL - 47 IS - 5 SP - 1185 EP - 1190 PB - Elsevier ER - TY - JOUR A1 - Bordoloi, Ankur A1 - Sanchez, Miguel A1 - Noei, Heshmat A1 - Kaluza, Stefan A1 - Großmann, Dennis A1 - Wang, Yuemin A1 - Grünert, Wolfgang A1 - Muhler, Martin T1 - Catalytic Behaviour of Mesoporous Cobalt-Aluminum Oxides for CO Oxidation JF - Journal of Catalysts Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-34344 SN - 2314-5110 SP - 1 EP - 9 PB - Hindawi ER - TY - JOUR A1 - Anton, Johan A1 - Ruland, Holger A1 - Kaluza, Stefan A1 - Muhler, Martin T1 - Fast and Reproducible Testing of Cu–Co-Based Catalysts Applied in the Conversion of Synthesis Gas to Ethanol and Higher Alcohols JF - Catalysis Letters Y1 - 2015 U6 - https://doi.org/10.1007/s10562-015-1543-2 N1 - The work was part of the project “Bioethanol from synthesis gas—BETSY”, funded by the Ministry for Economy, Energy, Building, Habitation and Transportation of Northrhine-Westphalia within the program Ziel2.NRW financed by the European Union through the European regional development fund ERDF. VL - 145 IS - 7 SP - 1374 EP - 1381 PB - Springer ER - TY - JOUR A1 - Anton, Johan A1 - Nebel, Janine A1 - Song, Huiqing A1 - Froese, Christian A1 - Weide, Philipp A1 - Ruland, Holger A1 - Muhler, Martin A1 - Kaluza, Stefan T1 - The effect of sodium on the structure–activity relationships of cobalt-modified Cu/ZnO/Al2O3 catalysts applied in the hydrogenation of carbon monoxide to higher alcohols JF - Journal of Catalysis Y1 - 2016 U6 - https://doi.org/10.1016/j.jcat.2015.12.016 SN - 0021-9517 VL - 335 SP - 175 EP - 186 PB - Elsevier ER - TY - JOUR A1 - Anton, Johan A1 - Nebel, Janine A1 - Göbel, Christoph A1 - Gabrysch, Thomas A1 - Song, Huiqing A1 - Froese, Christian A1 - Ruland, Holger A1 - Muhler, Martin A1 - Kaluza, Stefan T1 - CO Hydrogenation to Higher Alcohols over Cu–Co-Based Catalysts Derived from Hydrotalcite-Type Precursors JF - Topics in Catalysis Y1 - 2016 UR - https://doi.org/10.1007/s11244-016-0663-2 U6 - https://doi.org/10.1007/s11244-016-0663-2 VL - 59 IS - 15-16 SP - 1361 EP - 1370 PB - Springer Nature ER - TY - JOUR A1 - Anton, Johan A1 - Nebel, Janine A1 - Song, Huiqing A1 - Froese, Christian A1 - Weide, Philipp A1 - Ruland, Holger A1 - Muhler, Martin A1 - Kaluza, Stefan T1 - Structure–activity relationships of Co-modified Cu/ZnO/Al2O3 catalysts applied in the synthesis of higher alcohols from synthesis gas JF - Applied Catalysis A: General Y1 - 2015 U6 - https://doi.org/10.1016/j.apcata.2015.07.002 SN - 0926-860X VL - 505 SP - 326 EP - 333 PB - Elsevier ER - TY - CHAP A1 - Anton, Johan A1 - Nebel, Janine A1 - Froese, Christian A1 - Kleinschmidt, Ralph A1 - Quandt, Thomas A1 - Ruland, Holger A1 - Kaluza, Stefan A1 - Muhler, Martin ED - Ernst, Stefan T1 - Higher alcohol synthesis over Na-modified Co-Cu catalysts: Co2C formation and effect of surface composition T2 - Preprints of the DGMK-Conference "Synthesis Gas Chemistry", October 7 - 9, 2015, Dresden N2 - Cu–Co-based model catalysts were prepared by a sophisticated alkali-free synthesis method and tested in the conversion of synthesis gas to higher alcohols. MoO3-coated alumina was used as the support, providing both high specific surface area and strongly interacting sites for the deposition of the active metals. A bulk Cu/Co ratio of ~2 was found to be most suitable in terms of activity and product distribution. Surface enrichment of Mo for all samples was observed by XPS, which significantly influenced the performance of the catalysts. Mo was found to be both a structural and a chemical promoter. Strong metal–support interactions were further achieved by modification of alumina with magnesia. With 12 wt% Mg incorporated, the catalysts showed 40% total oxygenate selectivity including 11% selectivity to ethanol. Y1 - 2015 SN - 978-3-941721-56-2 VL - DGMK Tagungsbericht, 2015,2 PB - DGMK CY - Hamburg ER - TY - GEN A1 - Seidel, Carl Anton T1 - Jumping Humanoid Simulink Simulation With Three Hill-Type Muscle Models N2 - This paper investigates the implementation of a human body model for the simulation of a jumping motion in Simulink. It contains details to get an insight into modern biomechanics without previous experience. In the simulation, a Hill-Type muscle is used to generate joint momentum with a phenomenologically realistic relationship between muscle length and force. The simulation published with this article is one of many solutions to design a humanoid simulation. The paper guides through the implemented build and explains its range of application. KW - biomechanics KW - humanoid Simulation KW - locomotion study KW - Simulation of Mechanical Systems Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:due62-opus-33765 CY - Düsseldorf ER - TY - CHAP A1 - Biedermann, Till M. A1 - Reich, Marius A1 - Kameier, Frank A1 - Adam, Mario A1 - Paschereit, C. T1 - Assessment of Statistical Sampling Methods and Approximation Models Applied to Aeroacoustic and Vibroacoustic Problem T2 - NOVEM - 6th conference on Noise and Vibration emerging methods, 07.-09.05.2018, Ibiza / Spain Y1 - 2018 CY - Ibiza ER - TY - CHAP A1 - Wendland, André A1 - Bumann, Marc A1 - Martin, Shane A1 - Niemann, Jörg A1 - Bosman, Stephen ED - Yilmaz, Murat ED - Niemann, Jörg ED - Clarke, Paul ED - Messnarz, Richard T1 - Optimizing System Design Through Thermal Analysis with Cubesatellite as Case Study T2 - Systems, Software and Services Process Improvement Y1 - 2020 SN - 978-3-030-56440-7 U6 - https://doi.org/10.1007/978-3-030-56441-4_30 SP - 408 EP - 420 PB - Springer Nature Switzerland CY - Cham ER - TY - JOUR A1 - Ruess, Martin A1 - Pahl, P. J. T1 - An extended QR-solver for large profiled matrices JF - International Journal for Numerical Methods in Engineering Y1 - 2009 U6 - https://doi.org/10.1002/nme.2618 SN - 1097-0207 VL - 79 IS - 11 SP - 1419 EP - 1442 PB - Wiley ER - TY - JOUR A1 - Yang, Zhengxiong A1 - Kollmannsberger, Stefan A1 - Düster, Alexander A1 - Ruess, Martin A1 - Garcia, Eduardo Grande A1 - Burgkart, Rainer A1 - Rank, Ernst T1 - Non-standard bone simulation: interactive numerical analysis by computational steering JF - Computing and Visualization in Science Y1 - 2011 U6 - https://doi.org/10.1007/s00791-012-0175-y VL - 14 IS - 5 SP - 207 EP - 216 PB - Springer ER - TY - JOUR A1 - Zander, Nils A1 - Kollmannsberger, Stefan A1 - Ruess, Martin A1 - Yosibash, Z. A1 - Rank, Ernst T1 - The Finite Cell Method for linear thermoelasticity JF - Computers & Mathematics with Applications Y1 - 2012 U6 - https://doi.org/10.1016/j.camwa.2012.09.002 SN - 0898-1221 N1 - Open Archiv VL - 64 IS - 11 SP - 3527 EP - 3541 PB - Elsevier ER - TY - CHAP A1 - Ruess, Martin A1 - Mundani, Ralf-Peter A1 - Rank, Ernst T1 - Computational steering in dynamic structure simulation: An improved communication concept T2 - 2009 IEEE Toronto International Conference Science and Technology for Humanity (TIC-STH), Toronto, 26.09.2009 - 27.09.2009 Y1 - 2009 UR - http://ieeexplore.ieee.org/document/5444450/ SN - 978-1-4244-3877-8 U6 - https://doi.org/10.1109/TIC-STH.2009.5444450 SP - 497 EP - 502 PB - IEEE ER - TY - JOUR A1 - Yang, Z. A1 - Ruess, Martin A1 - Kollmannsberger, Stefan A1 - Düster, Alexander A1 - Rank, Ernst T1 - An efficient integration technique for the voxel-based finite cell method JF - International Journal for Numerical Methods in Engineering Y1 - 2012 U6 - https://doi.org/10.1002/nme.4269 SN - 1097-0207 VL - 91 IS - 5 SP - 457 EP - 471 PB - Wiley ER - TY - CHAP A1 - Ruess, Martin A1 - Varduhn, Vasco A1 - Rank, Ernst A1 - Yosibash, Zohar ED - Bader, Michael T1 - A Parallel High-Order Fictitious Domain Approach for Biomechanical Applications T2 - 11th International Symposium on Parallel and Distributed Computing (ISPDC), 2012 : 25 - 29 June 2012, Munich, Germany ; proceedings Y1 - 2012 UR - http://ieeexplore.ieee.org/document/6341523/ SN - 978-1-4673-2599-8 U6 - https://doi.org/10.1109/ISPDC.2012.45 SP - 279 EP - 285 PB - IEEE CY - Piscataway ER - TY - JOUR A1 - Schillinger, Dominik A1 - Ruess, Martin A1 - Zander, Nils A1 - Bazilevs, Yuri A1 - Düster, Alexander A1 - Rank, Ernst T1 - Small and large deformation analysis with the p- and B-spline versions of the Finite Cell Method JF - Computational Mechanics Y1 - 2012 U6 - https://doi.org/10.1007/S00466-012-0684-Z SN - 1432-0924 VL - 50 IS - 4 SP - 445 EP - 478 PB - Springer ER - TY - JOUR A1 - Ruess, Martin A1 - Schillinger, Dominik A1 - Bazilevs, Yuri A1 - Varduhn, Vasco A1 - Rank, Ernst T1 - Weakly enforced essential boundary conditions for NURBS-embedded and trimmed NURBS geometries on the basis of the finite cell method JF - International Journal for Numerical Methods in Engineering Y1 - 2013 U6 - https://doi.org/10.1002/nme.4522 SN - 1097-0207 VL - 95 IS - 10 SP - 811 EP - 846 PB - Wiley ER - TY - JOUR A1 - Ruess, Martin A1 - Tal, David A1 - Trabelsi, Nir A1 - Yosibash, Zohar A1 - Rank, Ernst T1 - The finite cell method for bone simulations: verification and validation JF - Biomechanics and modeling in mechanobiology Y1 - 2012 UR - http://www.ncbi.nlm.nih.gov/pubmed/21695444 U6 - https://doi.org/10.1007/s10237-011-0322-2 SN - 1617-7940 VL - 11 IS - 3-4 SP - 425 EP - 437 PB - Springer ER - TY - JOUR A1 - Zander, Nils A1 - Bog, Tino A1 - Elhaddad, Mohamed A1 - Espinoza, R. A1 - Hu, H. A1 - Joly, A. A1 - Wu, C. A1 - Zerbe, P. A1 - Düster, Alexander A1 - Kollmannsberger, Stefan A1 - Parvizian, J. A1 - Ruess, Martin A1 - Schillinger, Dominik A1 - Rank, Ernst T1 - FCMLab: A finite cell research toolbox for MATLAB JF - Advances in Engineering Software Y1 - 2014 U6 - https://doi.org/10.1016/j.advengsoft.2014.04.004 SN - 0965-9978 VL - 74 SP - 49 EP - 63 PB - Elsevier ER - TY - JOUR A1 - Ruess, Martin A1 - Schillinger, Dominik A1 - Özcan, Ali I. A1 - Rank, Ernst T1 - Weak coupling for isogeometric analysis of non-matching and trimmed multi-patch geometries JF - Computer Methods in Applied Mechanics and Engineering Y1 - 2014 U6 - https://doi.org/10.1016/j.cma.2013.10.009 SN - 0045-7825 VL - 269 SP - 46 EP - 71 PB - Elsevier ER - TY - JOUR A1 - Liang, Ke A1 - Ruess, Martin A1 - Abdalla, Mostafa T1 - The Koiter–Newton approach using von Kármán kinematics for buckling analyses of imperfection sensitive structures JF - Computer Methods in Applied Mechanics and Engineering Y1 - 2014 U6 - https://doi.org/10.1016/j.cma.2014.07.008 SN - 0045-7825 VL - 279 SP - 440 EP - 468 PB - Elsevier ER - TY - JOUR A1 - Schillinger, Dominik A1 - Ruess, Martin T1 - The Finite Cell Method: A Review in the Context of Higher-Order Structural Analysis of CAD and Image-Based Geometric Models JF - Archives of Computational Methods in Engineering Y1 - 2015 U6 - https://doi.org/10.1007/s11831-014-9115-y SN - 1886-1784 VL - 22 IS - 3 SP - 391 EP - 455 PB - Springer ER - TY - JOUR A1 - Liang, Ke A1 - Zhang, YongJie A1 - Sun, Qin A1 - Ruess, Martin T1 - A new robust design for imperfection sensitive stiffened cylinders used in aerospace engineering JF - Science China Technological Sciences KW - peer Y1 - 2015 U6 - https://doi.org/10.1007/s11431-015-5793-4 SN - 1869-1900 VL - 58 IS - 5 SP - 796 EP - 802 PB - Springer ER - TY - JOUR A1 - Kollmannsberger, Stefan A1 - Özcan, Ali I. A1 - Baiges, J. A1 - Ruess, Martin A1 - Rank, Ernst A1 - Reali, A. T1 - Parameter-free, weak imposition of Dirichlet boundary conditions and coupling of trimmed and non-conforming patches JF - International Journal for Numerical Methods in Engineering Y1 - 2015 U6 - https://doi.org/10.1002/nme.4817 SN - 1097-0207 VL - 101 IS - 9 SP - 670 EP - 699 PB - Wiley ER -