@inproceedings{JahrBatosSimetal.2012, author = {Jahr, Andreas and Batos, Andrej and Sim, Hunn and Villena Mart{\´i}nez, Jose David}, title = {A New Approach for Measuring the Wear Resistance of Cutter Blades}, series = {International Conference of Agricultural Engineering - CIGR-AgEng2012, Valencia/Spanien, 8.-12.07.2012}, booktitle = {International Conference of Agricultural Engineering - CIGR-AgEng2012, Valencia/Spanien, 8.-12.07.2012}, year = {2012}, language = {en} } @article{AslanNahavandiTaymazetal.2012, author = {Aslan, Erman and Nahavandi, A. and Taymaz, I. and Benim, Ali Cemal}, title = {A note on modelling non-rectangular boundaries by the Lattice Boltzmann Method}, series = {Progress in Computational Fluid Dynamics, An International Journal}, volume = {12}, journal = {Progress in Computational Fluid Dynamics, An International Journal}, number = {6}, publisher = {inderscience}, doi = {10.1504/pcfd.2012.049815}, pages = {433 -- 438}, year = {2012}, language = {en} } @inproceedings{RuessVarduhnRanketal.2012, author = {Ruess, Martin and Varduhn, Vasco and Rank, Ernst and Yosibash, Zohar}, title = {A Parallel High-Order Fictitious Domain Approach for Biomechanical Applications}, series = {11th International Symposium on Parallel and Distributed Computing (ISPDC), 2012 : 25 - 29 June 2012, Munich, Germany ; proceedings}, booktitle = {11th International Symposium on Parallel and Distributed Computing (ISPDC), 2012 : 25 - 29 June 2012, Munich, Germany ; proceedings}, editor = {Bader, Michael}, publisher = {IEEE}, address = {Piscataway}, isbn = {978-1-4673-2599-8}, doi = {10.1109/ISPDC.2012.45}, pages = {279 -- 285}, year = {2012}, language = {en} } @article{WinklerBeckerDoolanetal.2012, author = {Winkler, Michael and Becker, Klaus and Doolan, Con and Kameier, Frank and Paschereit, Christian Oliver}, title = {Aeroacoustic Effects of a Cylinder-Plate Configuration}, series = {AIAA Journal}, volume = {50}, journal = {AIAA Journal}, number = {7}, publisher = {ARC}, doi = {10.2514/1.j051578}, pages = {1614 -- 1620}, year = {2012}, language = {en} } @inproceedings{VogelWeberEliassonetal.2012, author = {Vogel, Andreas and Weber, Konradin and Eliasson, Jonas and Palsson, Asgeir and Moser, H. M. and Palsson, Thorgeir and von L{\"o}wis, S. and Fischer, Christian}, title = {Airborne and groundbased measurements of ash particles on Iceland and over Germany during the Gr{\´i}msv{\"o}tn eruption May 2011 [Abstract]}, series = {Geophysical Research Abstracts:EGU General Assembly 2012, held 22-27 April, 2012 in Vienna, Austria}, booktitle = {Geophysical Research Abstracts:EGU General Assembly 2012, held 22-27 April, 2012 in Vienna, Austria}, publisher = {Copernicus}, address = {G{\"o}ttingen}, pages = {12854}, year = {2012}, abstract = {The eruption of the Grimsv{\"o}tn volcano in May 2010 posed with its ash plume a thread to the aviation in northern Europe. Because of ash plume forecasts of the VAAC London the airport of Keflavik in Iceland as well as airports in England, Scotland and Scandinavia were closed for some time, which caused the cancellation or change of about 500 flights in Europe. Even in Germany the airports of Bremen, Hamburg and Berlin were closed for several hours on 25 May 2011. During this eruption period in May 2011, a team of the Duesseldorf University of Applied Sciences, the University of Iceland, the University of Reykjavik and the IMO has performed airborne in-situ measurements over Iceland and Germany as well as ground based measurements in the south of Iceland. The ground based measurements were performed continuously during the whole eruption period at two significant positions (Skogar and Hvollsv{\"o}llur) with optical particle counters (OPCs). The measurement method was based on measuring the airborne concentrations of the classic aerosol components (PM10, PM2.5 and PM1) and TSP (total suspended particles) every 6 seconds. Additional measurement flights on Iceland were started already one day after the beginning of the eruption (twelve in-situ measurement flights) and marked the spatial and temporal spread of volcanic ash in the atmosphere. For the flights light slow flying piston engine powered airplanes where used. The flights over Iceland focused on the western part of Iceland in the region of Reykjavik and Keflavik and over the international airport in Keflavik and were mostly coordinated by ISAVIA. The measurement flights helped to keep Keflavik International Airport open for many additional hours despite of adverse predictions by the London VAAC model, because it was possible to observe the particle concentration on-line during the flights. In Germany a measurement flight was performed on 25 May 2012 over the northern part of Germany where the volcanic ash cloud was forecasted from the dispersion model of the London VAAC. This flight was performed on the behalf of the German Weather Service (DWD). The measurement flights revealed most time relative low airborne ash concentrations over western Iceland, although the groundbased measured ash concentrations in the south of Iceland nearer to the Grimsv{\"o}tn were very high. In Germany the measured concentrations during the flight were low enough to be consistent with the re-opening of the airports Bremen, Hamburg and Berlin, which were closed by the authorities for several hours on 25 May 2011 because of high concentration predictions by the VAAC-model. The measurement flights clearly proved that OPCs, based on slow flying piston-motor driven aircrafts, are very suitable for the determination of airborne ash particles during volcanic eruptions. This is an important issue for air traffic safety.}, language = {en} } @article{WeberEliassonVogeletal.2012, author = {Weber, Konradin and Eliasson, J. and Vogel, A. and Fischer, C. and Pohl, T. and van Haren, G. and Meier, M. and Grob{\´e}ty, B. and Dahmann, D.}, title = {Airborne in-situ investigations of the Eyjafjallaj{\"o}kull volcanic ash plume on Iceland and over north-western Germany with light aircrafts and optical particle counters}, series = {Atmospheric Environment}, volume = {48}, journal = {Atmospheric Environment}, publisher = {Elsevier}, issn = {1352-2310}, doi = {10.1016/j.atmosenv.2011.10.030}, pages = {9 -- 21}, year = {2012}, language = {en} } @inproceedings{VogelWeberFischeretal.2012, author = {Vogel, Andreas and Weber, Konradin and Fischer, Christian and Prata, A. J. and Durant, A. J.}, title = {Aircraft in situ and remote sensing measurements of emissions from Etna volcano, Sicily}, series = {Geophysical Research Abstracts: EGU General Assembly 2012}, booktitle = {Geophysical Research Abstracts: EGU General Assembly 2012}, publisher = {Copernicus}, address = {G{\"o}ttingen}, year = {2012}, abstract = {Volcanoes emit particles (silicates and sulphate aerosol) and gases (e.g., water and sulphur dioxide) which influence the radiative balance of the atmosphere. The rate at which sulphur dioxide oxidises to sulphate aerosol is poorly constrained and measurements of downwind abundance are required to quantify the rate at which this process occurs. During July and November 2011, a series of measurements were performed in emissions from Etna Volcano, Sicily, using the University of Applied Sciences (Dusseldorf) research aircraft. Both in situ and remote sensing instrumentation was simultaneously deployed to quantify the down-wind characteristics of gases and particles in the plume emitted by the volcano. In situ particle characteristics were measured using a Grimm 1.109 optical particle counter (microparticles 0.25-32 microns) and Grimm 1320 diffusion electrometer (nanoparticles 25-300 nanometers). Column abundance of sulphur dioxide was measured using a vertically-pointing differential optical absorption spectrometer (DOAS). These measurements were compared to horizontal pathlength-integrated measurements of sulphur dioxide from the Airborne Volcanic Imaging Object Detector (AVOID). Down-wind plume dispersion was discriminated through a series of aircraft transects below and through the volcanic plume. The emissions contained large amounts of nanoparticles relative to microparticles, which reflects gas-phase nucleation of sulphate aerosol. The AVOID system discriminated horizontal layering of volcanic aerosol at altitudes of up to 12,000 ft from a detection range of >50 km. Plume boundaries were discriminated using a combination of the in situ and DOAS measurements in order to compare to the pathlength-integrated measurements from AVOID.}, subject = {Forschungsflugzeug}, language = {en} } @article{YangRuessKollmannsbergeretal.2012, author = {Yang, Z. and Ruess, Martin and Kollmannsberger, Stefan and D{\"u}ster, Alexander and Rank, Ernst}, title = {An efficient integration technique for the voxel-based finite cell method}, series = {International Journal for Numerical Methods in Engineering}, volume = {91}, journal = {International Journal for Numerical Methods in Engineering}, number = {5}, publisher = {Wiley}, issn = {1097-0207}, doi = {10.1002/nme.4269}, pages = {457 -- 471}, year = {2012}, language = {en} } @article{FuchsDornBachneretal.2012, author = {Fuchs, H. and Dorn, Hans-Peter and Bachner, M. and Bohn, Birger and Brauers, Theo and Gomm, S. and Hofzumahaus, A. and Holland, F. and Nehr, Sascha and Rohrer, F. and Tillmann, R. and Wahner, A.}, title = {Comparison of OH concentration measurements by DOAS and LIF during SAPHIR chamber experiments at high OH reactivity and low NO concentration}, series = {Atmospheric Measurement Techniques}, volume = {5}, journal = {Atmospheric Measurement Techniques}, number = {7}, publisher = {Copernicus}, issn = {1867-8548}, doi = {10.5194/amt-5-1611-2012}, pages = {1611 -- 1626}, year = {2012}, abstract = {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 J{\"u}lich, 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.}, language = {en} } @inproceedings{WeberReichardtFischeretal.2012, author = {Weber, Konradin and Reichardt, R. and Fischer, Christian and Moser, H. M. and Eliasson, Jonas}, title = {Computational Visualization of Volcanic Ash Plume Concentrations Measured by light Aircrafts over Germany and Iceland during the Recent Eruptions of the Volcanoes Eyjafjallaj{\"o}kull and Grimsv{\"o}tn}, series = {Recent advances in Fluid Mechanics, Heat \& Mass Transfer, Biology and Ecology}, booktitle = {Recent advances in Fluid Mechanics, Heat \& Mass Transfer, Biology and Ecology}, editor = {Jha, Manoj K. and Lazard, Myriam and Zaharim, Azami and Sopian, Kamaruzzaman}, publisher = {WSEAS}, isbn = {978-1-61804-065-7}, pages = {236 -- 240}, year = {2012}, subject = {Vulkanasche}, language = {en} } @article{PeterFichtlRulandetal.2012, author = {Peter, Maximilian and Fichtl, Matthias B. and Ruland, Holger and Kaluza, Stefan and Muhler, Martin and Hinrichsen, Olaf}, title = {Detailed kinetic modeling of methanol synthesis over a ternary copper catalyst}, series = {Chemical Engineering Journal}, volume = {203}, journal = {Chemical Engineering Journal}, publisher = {Elsevier}, issn = {0009-2509}, doi = {10.1016/j.cej.2012.06.066}, pages = {480 -- 491}, year = {2012}, language = {en} } @inproceedings{JahrBatosPillmannetal.2012, author = {Jahr, Andreas and Batos, Andrej and Pillmann, A. and Hoppe, S. and Diett, D.}, title = {Determining the Cutting Properties of Agricultural Products}, series = {International Conference of Agricultural Engineering - CIGR-AgEng2012, Valencia/Spanien, 8.-12.07.2012}, booktitle = {International Conference of Agricultural Engineering - CIGR-AgEng2012, Valencia/Spanien, 8.-12.07.2012}, year = {2012}, language = {en} } @article{StuhlsatzLippelZielke2012, author = {Stuhlsatz, Andr{\´e} and Lippel, Jens and Zielke, Thomas}, title = {Feature extraction with deep neural networks by a generalized discriminant analysis}, series = {IEEE transactions on neural networks and learning systems}, volume = {23}, journal = {IEEE transactions on neural networks and learning systems}, number = {4}, publisher = {IEEE}, doi = {10.1109/tnnls.2012.2183645}, pages = {596 -- 608}, year = {2012}, abstract = {We present an approach to feature extraction that is a generalization of the classical linear discriminant analysis (LDA) on the basis of deep neural networks (DNNs). As for LDA, discriminative features generated from independent Gaussian class conditionals are assumed. This modeling has the advantages that the intrinsic dimensionality of the feature space is bounded by the number of classes and that the optimal discriminant function is linear. Unfortunately, linear transformations are insufficient to extract optimal discriminative features from arbitrarily distributed raw measurements. The generalized discriminant analysis (GerDA) proposed in this paper uses nonlinear transformations that are learnt by DNNs in a semisupervised fashion. We show that the feature extraction based on our approach displays excellent performance on real-world recognition and detection tasks, such as handwritten digit recognition and face detection. In a series of experiments, we evaluate GerDA features with respect to dimensionality reduction, visualization, classification, and detection. Moreover, we show that GerDA DNNs can preprocess truly high-dimensional input data to low-dimensional representations that facilitate accurate predictions even if simple linear predictors or measures of similarity are used.}, language = {en} } @article{CarapezzaBarberiRanaldietal.2012, author = {Carapezza, M. L. and Barberi, F. and Ranaldi, M. and Ricci, T. and Tarchini, L. and Barrancos, Jos{\´e} and Fischer, C. and Granieri, D. and Lucchetti, C. and Melian, G. and Perez, N. and Tuccimei, P. and Vogel, A. and Weber, Konradin}, title = {Hazardous gas emissions from the flanks of the quiescent Colli Albani volcano (Rome, Italy)}, series = {Applied Geochemistry}, volume = {27}, journal = {Applied Geochemistry}, number = {9}, publisher = {Elsevier}, doi = {10.1016/j.apgeochem.2012.02.012}, pages = {1767 -- 1782}, year = {2012}, language = {en} } @article{FleigerReichardtTreiber2012, author = {Fleiger, P. M. and Reichardt, Roland and Treiber, K.}, title = {High-Precision Power Measurement for the Grindability Test According to Zeisel}, series = {Chemical Engineering \& Technology}, volume = {35}, journal = {Chemical Engineering \& Technology}, number = {11}, publisher = {Wiley}, doi = {10.1002/ceat.201200118}, pages = {1941 -- 1948}, year = {2012}, language = {en} } @article{MaqablehAmmourahKhadrawietal.2012, author = {Maqableh, A. M. and Ammourah, S. A. and Khadrawi, A. F. and Al-Nimr, M. A. and Benim, Ali Cemal}, title = {Hydrodynamics behaviour of a fluid flow in micro-venturi}, series = {Candian Journal of Physics}, volume = {90}, journal = {Candian Journal of Physics}, number = {1}, publisher = {Canadian Science Publishing}, organization = {Canadian Science Publishing}, doi = {10.1139/p11-145}, pages = {83 -- 89}, year = {2012}, language = {en} } @article{LeadbetterHortvonLoewisetal.2012, author = {Leadbetter, S. J. and Hort, M. C. and von L{\"o}wis, S. and Weber, Konradin and Witham, C. S.}, title = {Modeling the resuspension of ash deposited during the eruption of Eyjafjallaj{\"o}kull in spring 2010}, series = {Journal of Geophysical Research: Atmospheres}, volume = {117}, journal = {Journal of Geophysical Research: Atmospheres}, number = {D20}, publisher = {American Geophysical Union (AGU)}, issn = {0148-0227}, doi = {10.1029/2011JD016802}, year = {2012}, abstract = {Eyjafjallaj{\"o}kull, a volcano in southern Iceland, erupted explosively in April and May 2010 depositing ash over a region of more than 3000 km2 to the east and southeast of the volcano. This deposited ash has been frequently remobilized by the wind causing concern for the health of Icelanders living in the region. An investigation was carried out to determine whether it would be possible to produce forecasts of days when high airborne ash concentrations were likely to occur. Information about the spatially varying surface characteristics of the region of deposited ash is not available so in the modeling approach adopted here ash is released from the surface at a rate proportional to the cube of the excess friction velocity (local friction velocity minus a threshold) only when the friction velocity exceeds a threshold. Movement of the resuspended ash is then modeled in a Lagrangian dispersion model. Modeled ash concentrations are compared to observed concentrations from two periods; PM10 observations between 23 May and 2 July 2010 and airborne particle counts between 21 September 2010 and 16 February 2011. More than 66\% of the resuspension episodes between May and July are captured by the model and the relative magnitudes of the modeled episodes in this period are in good agreement with the observations. 66\% of episodes between October and February are also captured by the model although there is an increase in the false alarm rate which appears to be due to the influence of precipitation.}, language = {en} } @article{LuRohrerHollandetal.2012, author = {Lu, K. D. and Rohrer, F. and Holland, F. and Fuchs, H. and Bohn, Birger and Brauers, Theo and Chang, C. C. and H{\"a}seler, R. and Hu, M. and Kita, K. and Kondo, Y. and Li, X. and Lou, S. R. and Nehr, Sascha and Shao, M. and Zeng, L. M. and Wahner, A. and Zhang, Y. H. and Hofzumahaus, A.}, title = {Observation and modelling of OH and HO2 concentrations in the Pearl River Delta 2006: a missing OH source in a VOC rich atmosphere}, series = {Atmospheric Chemistry and Physics}, volume = {12}, journal = {Atmospheric Chemistry and Physics}, number = {3}, publisher = {Copernicus}, issn = {1680-7324}, doi = {10.5194/acp-12-1541-2012}, pages = {1541 -- 1569}, year = {2012}, abstract = {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 M{\"u}ller (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 M{\"u}ller (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.}, language = {en} } @article{NehrBohnWahner2012, author = {Nehr, Sascha and Bohn, Birger and Wahner, Andreas}, title = {Prompt HO2Formation Following the Reaction of OH with Aromatic Compounds under Atmospheric Conditions}, series = {The Journal of Physical Chemistry A}, volume = {116}, journal = {The Journal of Physical Chemistry A}, number = {24}, publisher = {American Chemical Society (ACS)}, issn = {1089-5639}, doi = {10.1021/jp210946y}, pages = {6015 -- 6026}, year = {2012}, language = {en} } @inproceedings{WeberVogelReichardtetal.2012, author = {Weber, Konradin and Vogel, Andreas and Reichardt, Roland and Zimmermann, Thomas}, title = {Research aircraft flight for gas leakage investigation at the Elgin wellhead gas platform in the North Sea - initial results}, series = {Recent Researches in Environmental and Geological Sciences}, booktitle = {Recent Researches in Environmental and Geological Sciences}, editor = {Altawell, Najib and Konstantin, Volkov and Cristina, Matos and Fernandez de Arroyabe, Pablo}, publisher = {WSEAS}, pages = {240 -- 243}, year = {2012}, subject = {Forschungsflugzeug}, language = {en} }