TY  - JOUR
A1  - Bragard, Michael
A1  - Soltau, N.
A1  - Thomas, S.
A1  - De Doncker, R. W.
T1  - The balance of renewable sources and user demands in grids : power electronics for modular battery energy storage systems
JF  - IEEE transactions on power electronics
N2  - The continuously growing amount of renewable sources starts compromising the stability of electrical grids. Contradictory to fossil fuel power plants, energy production of wind and photovoltaic (PV) energy is fluctuating. Although predictions have significantly improved, an outage of multi-MW offshore wind farms poses a challenging problem. One solution could be the integration of storage systems in the grid. After a short overview, this paper focuses on two exemplary battery storage systems, including the required power electronics. The grid integration, as well as the optimal usage of volatile energy reserves, is presented for a 5- kW PV system for home application, as well as for a 100- MW medium-voltage system, intended for wind farm usage. The efficiency and cost of topologies are investigated as a key parameter for large-scale integration of renewable power at medium- and low-voltage.
Y1  - 2010
U6  - https://doi.org/10.1109/TPEL.2010.2085455
SN  - 0885-8993
VL  - 25
IS  - 12
SP  - 3049
EP  - 3056
PB  - IEEE
CY  - New York
ER  - 
TY  - GEN
A1  - Tippkötter, Nils
A1  - Maurer, S.
A1  - Pasteur, A.
A1  - Kampeis, P.
A1  - Ulber, Roland
T1  - Hochgradient-Magnetseparation von Fermentationsprodukten–FEM Simulation der Filtermatrix
T2  - Chemie Ingenieur Technik
N2  - Durch den Einsatz magnetisierbarer Partikel lassen sich Stoffwechselprodukte direkt und selektiv aus feststoffreichen Fermentationssuspensionen abtrennen. Im Gegensatz zu klassischen Adsorbermaterialien können magnetisierbare Partikel mit sehr geringen Durchmessern verwendet werden. Zur deren Abtrennung ist jedoch ein hoher Magnetfeldgradient notwendig. Dieser wird in der Regel durch in der Trennkammer bzw. dem Magnetfeld eingebrachte magnetisierbare Drähte realisiert. Bei der Auslegung der Drahtgitter ist ein Kompromiss zwischen Abtrennrate und Durchlässigkeit nötig. Die Ausrichtung der Drähte in Relation zum Magnetfeld, deren Abstand sowie die geometrische Anordnung können hierbei variiert werden. Zum Verständnis der Einflüsse auf das sich ausbildende Magnetfeld und die Fluiddynamik wurden Simulationen mit der Finite-Elemente-Methode durchgeführt und experimentell überprüft. Hierfür wurden die Drähte unter Variation von Anzahl, Richtung und Anordnung in den Hochgradient-Magnetseparator eingebracht. Erste Verifizierungen der Simulationen zeigen, dass die in Magnetfeldrichtung ausgerichteten Drähte (x-Achse) über die geringste Partikelrückhaltefähigkeit verfügen. Die Drähte der y- und z-Achse halten den größten Anteil der Magnetpartikel zurück, wobei die Drähte in y-Richtung den höchsten Feldgradienten ausbilden. Des Weiteren konnte gezeigt werden, dass eine rhomboedrische Drahtanordnung der kubischen vorzuziehen ist.
Y1  - 2010
U6  - https://doi.org/10.1002/cite.201050217
SN  - 0009-286X
SN  - 1522-2640 (eISSN)
N1  - ProcessNet-Jahrestagung 2010 und 28. DECHEMA-Jahrestagung der Biotechnologen, 21. - 23. September 2010, Eurogress Aachen
VL  - 82
IS  - 9
SP  - 1361
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - CHAP
A1  - Raatschen, Hans-Jürgen
T1  - 75 Jahre Vereinsgeschichte
T2  - Ingenieurfreunde FH Aachen : 75 Jahre Förderverein; Elektrotechnik und Informationstechnik, Luft- und Raumfahrttechnik, Maschinenbau und Mechatronik
KW  - Geschichte
Y1  - 2010
SN  - 978-3-941704-03-9
SP  - 66
EP  - 72
PB  - Klinkenberg
CY  - Aachen
ER  - 
TY  - JOUR
A1  - Eilmann, Britta
A1  - Buchmann, Nina
A1  - Siegwolf, Rolf
A1  - Saurer, Matthias
A1  - Cherubini, Paolo
A1  - Rigling, Andreas
T1  - Fast response of Scots pine to improved water availability reflected in tree-ring width and δ13C
JF  - Plant, Cell and Environment
N2  - Drought-induced forest decline, like the Scots pine mortality in inner-Alpine valleys, will gain in importance as the frequency and severity of drought events are expected to increase. To understand how chronic drought affects tree growth and tree-ring δ13C values, we studied mature Scots pine in an irrigation experiment in an inner-Alpine valley. Tree growth and isotope analyses were carried out at the annual and seasonal scale. At the seasonal scale, maximum δ13C values were measured after the hottest and driest period of the year, and were associated with decreasing growth rates. Inter-annual δ13C values in early- and latewood showed a strong correlation with annual climatic conditions and an immediate decrease as a response to irrigation. This indicates a tight coupling between wood formation and the freshly produced assimilates for trees exposed to chronic drought. This rapid appearance of the isotopic signal is a strong indication for an immediate and direct transfer of newly synthesized assimilates for biomass production. The fast appearance and the distinct isotopic signal suggest a low availability of old stored carbohydrates. If this was a sign for C-storage depletion, an increasing mortality could be expected when stressors increase the need for carbohydrate for defence, repair or regeneration.
Y1  - 2010
U6  - https://doi.org/10.1111/j.1365-3040.2010.02153.x
SN  - 1365-3040 (Online)
SN  - 0140-7791 (Print)
VL  - 33
IS  - 8
SP  - 1351
EP  - 1360
PB  - Wiley-Blackwell
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Fonti, Patrick
A1  - von Arx, Georg
A1  - García-González, Ignacio
A1  - Eilmann, Britta
A1  - Sass-Klaassen, Ute G. W.
A1  - Gärtner, Holger
A1  - Eckstein, Dieter
T1  - Studying global change through investigation of the plastic responses of xylem anatomy in tree rings
JF  - New Phytologist
N2  - Variability in xylem anatomy is of interest to plant scientists because of the role water transport plays in plant performance and survival. Insights into plant adjustments to changing environmental conditions have mainly been obtained through structural and functional comparative studies between taxa or within taxa on contrasting sites or along environmental gradients. Yet, a gap exists regarding the study of hydraulic adjustments in response to environmental changes over the lifetimes of plants. In trees, dated tree-ring series are often exploited to reconstruct dynamics in ecological conditions, and recent work in which wood-anatomical variables have been used in dendrochronology has produced promising results. Environmental signals identified in water-conducting cells carry novel information reflecting changes in regional conditions and are mostly related to short, sub-annual intervals. Although the idea of investigating environmental signals through wood anatomical time series goes back to the 1960s, it is only recently that low-cost computerized image-analysis systems have enabled increased scientific output in this field. We believe that the study of tree-ring anatomy is emerging as a promising approach in tree biology and climate change research, particularly if complemented by physiological and ecological studies. This contribution presents the rationale, the potential, and the methodological challenges of this innovative approach.
Y1  - 2010
U6  - https://doi.org/10.1111/j.1469-8137.2009.03030.x
SN  - 1469-8137 (Online)
SN  - 0028-646X (Print)
VL  - 185
IS  - 1
SP  - 42
EP  - 53
PB  - Wiley-Blackwell
CY  - Oxford
ER  - 
TY  - GEN
A1  - Hezel, Fabian
A1  - Frauenrath, Tobias
A1  - Renz, Wolfgang
A1  - Schulz-Menger, Jeanette
A1  - Niendorf, Thoralf
T1  - Feasibility of CINE Myocardial T2* Mapping Using Susceptibility Weighted Gradient-Echo Imaging at 7.0 T
T2  - 2010 ISMRM-ESMRMB joint annual meeting
N2  - This study is designed to demonstrate the promise of susceptibility weighted 2D CINE FLASH and T2* Mapping of the heart at 7T.
Y1  - 2010
SN  - 1545-4428
N1  - ISMRM-ESMRMB joint annual meeting, 1 - 7 May 2010, Stockholm, Sweden
ER  - 
TY  - JOUR
A1  - Rigling, Andreas
A1  - Eilmann, Britta
A1  - Koechli, Roger
A1  - Dobbertin, Matthias
T1  - Mistletoe-induced crown degradation in Scots pine in a xeric environment
N2  - Increasing Scots pine (Pinus sylvestris L.) mortality has been recently observed in the dry inner valleys of the European Alps. Besides drought, infection with pine mistletoe (Viscum album ssp. austriacum) seems to play an important role in the mortality dynamics of Scots pines, but how mistletoes promote pine decline remains unclear. To verify whether pine mistletoe infection weakens the host via crown degradation, as observed for dwarf mistletoes, we studied the negative effects of pine mistletoe infestation on the photosynthetic tissues and branch growth of pairs of infested and non-infested branches. Pine mistletoe infection leads to crown degradation in its host by reducing the length, the radial increment, the ramification, the needle length and the number of needle years of the infested branches. This massive loss in photosynthetic tissue results in a reduction in primary production and a subsequent decrease in carbohydrate availability. The significant reduction in needle length due to mistletoe infection is an indication for a lower water and nutrient availability in infested branches. Thus, mistletoe infection might lead to a decrease in the availability of water and carbohydrates, the two most important growth factors, which are already shortened due to the chronic drought situation in the area. Therefore, pine mistletoe increases the risk of drought-induced mortality of its host when growing in a xeric environment.
Y1  - 2010
U6  - https://doi.org/10.1093/treephys/tpq038
SN  - 1758-4469  (Online)
SN  - 0829-318X (Print)
VL  - 30
IS  - 7
SP  - 845
EP  - 832
PB  - Oxford University Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Grajewski, Matthias
A1  - Köster, Michael
A1  - Turek, Stefam
T1  - Numerical analysis and implementational aspects of a new multilevel grid deformation method
JF  - Applied Numerical Mathematics
N2  - Recently, we introduced and mathematically analysed a new method for grid deformation (Grajewski et al., 2009) [15] we call basic deformation method (BDM) here. It generalises the method proposed by Liao et al. (Bochev et al., 1996; Cai et al., 2004; Liao and Anderson, 1992) [4], [6], [20]. In this article, we employ the BDM as core of a new multilevel deformation method (MDM) which leads to vast improvements regarding robustness, accuracy and speed. We achieve this by splitting up the deformation process in a sequence of easier subproblems and by exploiting grid hierarchy. Being of optimal asymptotic complexity, we experience speed-ups up to a factor of 15 in our test cases compared to the BDM. This gives our MDM the potential for tackling large grids and time-dependent problems, where possibly the grid must be dynamically deformed once per time step according to the user's needs. Moreover, we elaborate on implementational aspects, in particular efficient grid searching, which is a key ingredient of the BDM.
Y1  - 2010
U6  - https://doi.org/10.1016/j.apnum.2010.03.017
SN  - 0168-9274
VL  - 60
IS  - 8
SP  - 767
EP  - 781
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - GEN
A1  - Sieker, T.
A1  - Tippkötter, Nils
A1  - Ulber, Roland
T1  - Simultane Vorbehandlung, Hydrolyse und Fermentation bei der Nutzung von grüner Biomasse zur Produktion von Bioethanol
T2  - Chemie Ingenieur Technik
N2  - Gräser sind in der Lage, einen großen Teil der für eine biobasierte Wirtschaft benötigten Biomasse zur Verfügung zu stellen. Wie bei anderen lignocellulosehaltigen nachwachsenden Rohstoffen erfordert die Verwertung der im Gras enthaltenen Polysaccharide einen mehrstufigen Prozess aus Vorbehandlung, Hydrolyse und Fermentation. In Gräsern ist die Hemicellulose mitP henolcarbonsäuren wie Ferula- und p-Coumarsäure verestert, die die enzymatische Hydrolyse der Cellulose und Hemicellulose ebenso effektiv behindern wie Lignin. Anders als bei holzigen Rohstoffen ermöglicht dieser Aufbau aber eine enzymatische Vorbehandlung, mit der die Phenolcarbonsäuren abgespalten werden können. Da die bei der Vorbehandlung eingesetzten Enzyme in ihrer natürlichen Funktion synergistisch mit cellulytischen Enzymen zusammenarbeiten, besitzen sie ähnliche Optima wie die für die Hydrolyse der Polysaccharide eingesetzten Cellulasen und Hemicellulasen. Diese Eigenschaft ermöglicht die Integration von Vorbehandlung und Hydrolyse in einem einzigen Verfahrensschritt. Durch die Einführung der enzymatischen Vorbehandlung konnte das in der Literatur bekannte SSF-Verfahren für die Herstellung von Ethanol aus Gräsern um die Vorbehandlungsstufe erweitert werden. Das so realisierte simultaneous pretreatment, saccharification and fermentation (SPSF)-Verfahren stellt eine vollständige Integration der drei für die Nutzung von Lignocellulose nötigen Verfahrensschritte in der grünen Bioraffinerie dar.
Y1  - 2010
U6  - https://doi.org/10.1002/cite.201050319
SN  - 0009-286X
N1  - ProcessNet-Jahrestagung 2010 und 28. DECHEMA-Jahrestagung der Biotechnologen, 21. - 23. September 2010, Eurogress Aachen
VL  - 82
IS  - 9
SP  - 1601
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - CHAP
A1  - Anthrakidis, Anette
T1  - Schnelltest zur Abschätzung der Wirkungsgradkennlinie von Parabolrinnenkollektoren
T2  - Thermische Solarenergie : 20. Symposium ; 05. bis 07. Mai 2010, Kloster Banz, Bad Staffelstein
Y1  - 2010
SN  - 978-3-941785-29-8
SP  - 112
EP  - 117
PB  - OTTI
CY  - Regensburg
ER  -