@article{ReisgenSchleserMokrovetal.2012, author = {Reisgen, Uwe and Schleser, Markus and Mokrov, Oleg and Ahmed, Essam}, title = {Statistical modeling of laser welding of DP/TRIP steel sheets}, series = {Optics and laser technology}, volume = {44}, journal = {Optics and laser technology}, number = {1}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1879-2545 (E-Journal); 0030-3992 (Print); 0308-4280 (Print)}, doi = {10.1016/j.optlastec.2011.05.025}, pages = {92 -- 101}, year = {2012}, abstract = {In this research work, a statistical analysis of the CO2 laser beam welding of dual phase (DP600)/transformation induced plasticity (TRIP700) steel sheets was done using response surface methodology. The analysis considered the effect of laser power (2-2.2 kW), welding speed (40-50 mm/s) and focus position (-1 to 0 mm) on the heat input, the weld bead geometry, uniaxial tensile strength, formability limited dome height and welding operation cost. The experimental design was based on Box-Behnken design using linear and quadratic polynomial equations for predicting the mathematical models. The results indicate that the proposed models predict the responses adequately within the limits of welding parameters being used and the welding speed is the most significant parameter during the welding process.}, language = {en} } @article{ReisgenSchleserMokrovetal.2012, author = {Reisgen, Uwe and Schleser, Markus and Mokrov, Oleg and Ahmed, Essam}, title = {Optimization of laser welding of DP/TRIP steel sheets using statistical approach}, series = {Optics and laser technology}, volume = {44}, journal = {Optics and laser technology}, number = {1}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1879-2545 (E-Journal); 0030-3992 (Print); 0308-4280 (Print)}, doi = {10.1016/j.optlastec.2011.06.028}, pages = {255 -- 262}, year = {2012}, abstract = {Generally, the quality of a weld joint is directly influenced by the welding input parameter settings. Selection of proper process parameters is important to obtain the desired weld bead profile and quality. In this research work, numerical and graphical optimization techniques of the CO2 laser beam welding of dual phase (DP600)/transformation induced plasticity (TRIP700) steel sheets were carried out using response surface methodology (RSM) based on Box-Behnken design. The procedure was established to improve the weld quality, increase the productivity and minimize the total operation cost by considering the welding parameters range of laser power (2-2.2 kW), welding speed (40-50 mm/s) and focus position (-1 to 0 mm). It was found that, RSM can be considered as a powerful tool in experimental welding optimization, even when the experimenter does not have a model for the process. Strong, efficient and low cost weld joints could be achieved using the optimum welding conditions.}, language = {en} } @article{ReisgenSchleserAbdurakhmanovetal.2012, author = {Reisgen, Uwe and Schleser, Markus and Abdurakhmanov, Aydemir and Turichin, Gleb and Valdaitseva, Elena and Bach, Friedrich-Wilhelm and Hassel, Thomas and Beniyashi, Alexander}, title = {Investigation of factors influencing the formation of weld defects in non-vacuum electron beam welding}, series = {The Paton welding journal}, volume = {2012}, journal = {The Paton welding journal}, number = {2}, publisher = {Paton Publishing House}, address = {Kiev}, issn = {0957-798X}, pages = {11 -- 18}, year = {2012}, abstract = {The influence of welding condition parameters and properties of material on formation of defects, such as humping and undercuts, in non-vacuum electron beam welding was investigated. The influence of separate welding parameters on the quality of welds was determined.}, language = {en} } @article{ReisgenSchleserAbdurakhmanovetal.2012, author = {Reisgen, Uwe and Schleser, Markus and Abdurakhmanov, Aydemir and Gumenyuk, Andrey}, title = {Measuring of plasma properties induced by non-vacuum electron beam welding}, series = {Physics of plasma}, volume = {19}, journal = {Physics of plasma}, number = {1}, publisher = {AIP Publishing}, address = {Melville, NY}, issn = {1089-7674 (E-Journal); 1070-664X (Print)}, doi = {10.1063/1.3675874}, pages = {1 -- 7}, year = {2012}, abstract = {Electron beam plasma measurement was realised by means of DIABEAM system invented by ISF RWTH Aachen. The Langmuir probe method is used for measurement. The relative simplicity of the method and the possibility of dispersion of high power on the probe allow its application for the investigation of high-power electron beams. The key element of the method is a rotating thin tungsten wire, which intersects the beam transversely on its axis and collects part of the current by itself. The signals, which are registered in the DIABEAM as a voltage, were taken in the form of amplitude. The conversion of the probe current into the distribution along the beam radius was realised using the Abel's method. A voltage-current characteristic was built for the beam current. The local electron density as well as the electron temperature, the floating potential and the plasma potential were measured and calculated by means of this characteristic.}, language = {en} } @inproceedings{ReisgenSchleserAbdurakhmanovetal.2012, author = {Reisgen, Uwe and Schleser, Markus and Abdurakhmanov, Aydemir and Gumenyuk, Andrej}, title = {Application of electron beam welding to fabrication of steel-aluminium dissimilar joint}, series = {Beam technologies \& laser application : proceedings of the VII international conference, Saint Petersburg, Sept. 18-21, 2012}, booktitle = {Beam technologies \& laser application : proceedings of the VII international conference, Saint Petersburg, Sept. 18-21, 2012}, publisher = {Publ. House}, address = {Saint Petersburg}, pages = {265 -- 279}, year = {2012}, language = {en} } @article{ReisgenOlschokJakobsetal.2012, author = {Reisgen, Uwe and Olschok, Simon and Jakobs, Stefan and Schleser, Markus and Mokrov, Oleg and Rossiter, Eduardo}, title = {Laser beam submerged arc hybrid welding}, series = {Physics procedia}, volume = {39}, journal = {Physics procedia}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1875-3892}, doi = {10.1016/j.phpro.2012.10.016}, pages = {75 -- 83}, year = {2012}, abstract = {The laser beam-submerged arc hybrid welding method originates from the knowledge that, with increasing penetration depth, the laser beam process has a tendency to pore formation in the lower weld regions. The coupling with the energy-efficient submerged-arc process improves degassing and reduces the tendency to pore formation. The high deposition rate of the SA process in combination with the laser beam process offers, providing the appropriate choice of weld preparation, the possibility of welding plates with a thickness larger than 20° mm in a single pass, and also of welding thicker plates with the double-sided single pass technique.}, language = {en} } @inproceedings{ReisertGeisslerFloerkeetal.2012, author = {Reisert, Steffen and Geissler, H. and Fl{\"o}rke, R. and Weiler, C. and Wagner, P. and Sch{\"o}ning, Michael Josef}, title = {Characterisation of aseptic sterilisation processes using an electronic nose}, series = {Nanoscale Science and Technology (NS\&T´12) : Proceedings Book Humboldt Kolleg ; Tunisia, 17-19 March, 2012}, booktitle = {Nanoscale Science and Technology (NS\&T´12) : Proceedings Book Humboldt Kolleg ; Tunisia, 17-19 March, 2012}, editor = {Abdelghani, Adnane and Sch{\"o}ning, Michael Josef}, pages = {45 -- 45}, year = {2012}, language = {en} } @inproceedings{QuadfliegSchoeneSchleseretal.2012, author = {Quadflieg, Till and Schoene, Jens and Schleser, Markus and Jockenh{\"o}vel, Stefan and Reisgen, Uwe and Gries, Thomas}, title = {Shear connectors for hybrid joints of metal and FRP}, series = {Diversity in composites : conference proceedings : Composites Australia and CRC-ACS 2012 conference}, booktitle = {Diversity in composites : conference proceedings : Composites Australia and CRC-ACS 2012 conference}, editor = {Heslehurst, Rikard Benton}, publisher = {Composites Australia}, address = {Hawthorne}, isbn = {978-0-9873285-0-2}, pages = {[152] -- [160]}, year = {2012}, language = {en} } @article{PoghossianWeilBaeckeretal.2012, author = {Poghossian, Arshak and Weil, M. H. and B{\"a}cker, Matthias and Mayer, D. and Sch{\"o}ning, Michael Josef}, title = {Field-effect Devices Functionalised with Gold-Nanoparticle/Macromolecule Hybrids: New Opportunities for a Label-Free Biosensing}, series = {Procedia Engineering}, journal = {Procedia Engineering}, number = {47}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1877-7058}, doi = {10.1016/j.proeng.2012.09.136}, pages = {273 -- 276}, year = {2012}, abstract = {Field-effect capacitive electrolyte-insulator-semiconductor (EIS) sensors functionalised with citrate-capped gold nanoparticles (AuNP) have been used for the electrostatic detection of macromolecules by their intrinsic molecular charge. The EIS sensor detects the charge changes in the AuNP/macromolecule hybrids induced by the adsorption or binding events. A feasibility of the proposed detection scheme has been exemplary demonstrated by realising EIS sensors for the detection of poly-D-lysine molecules.}, language = {en} } @inproceedings{PoghossianAbouzarSchoening2012, author = {Poghossian, Arshak and Abouzar, Maryam H. and Sch{\"o}ning, Michael Josef}, title = {(Bio-­)chemical sensor array based on nanoplate SOI capacitors}, series = {Nanoscale Science and Technology (NS\&T´12) : Proceedings Book Humboldt Kolleg ; Tunisia, 17-19 March, 2012}, booktitle = {Nanoscale Science and Technology (NS\&T´12) : Proceedings Book Humboldt Kolleg ; Tunisia, 17-19 March, 2012}, editor = {Abdelghani, Adnane and Sch{\"o}ning, Michael Josef}, pages = {31 -- 31}, year = {2012}, language = {en} } @article{PieperKlein2012, author = {Pieper, Martin and Klein, Peter}, title = {Application of simple, periodic homogenization techniques to non-linear heat conduction problems in non-periodic, porous media}, series = {Heat mass transfer}, volume = {48}, journal = {Heat mass transfer}, number = {2}, publisher = {Springer}, address = {Berlin}, issn = {0947-7411}, doi = {10.1007/s00231-011-0879-4}, pages = {291 -- 300}, year = {2012}, abstract = {Often, detailed simulations of heat conduction in complicated, porous media have large runtimes. Then homogenization is a powerful tool to speed up the calculations by preserving accurate solutions at the same time. Unfortunately real structures are generally non-periodic, which requires unpractical, complicated homogenization techniques. We demonstrate in this paper, that the application of simple, periodic techniques to realistic media, that are just close to periodic, gives accurate, approximative solutions. In order to obtain effective parameters for the homogenized heat equation, we have to solve a so called "cell problem". In contrast to periodic structures it is not trivial to determine a suitable unit cell, which represents a non-periodic media. To overcome this problem, we give a rule of thumb on how to choose a good cell. Finally we demonstrate the efficiency of our method for virtually generated foams as well as real foams and compare these results to periodic structures.}, language = {en} } @inproceedings{PhamNguyenStaat2012, author = {Pham, Phu Tinh and Nguyen, Thanh Ngoc and Staat, Manfred}, title = {FEM based shakedown analysis of hardening structures}, series = {Proceedings International Conference on Advances in Computational Mechanics (ACOME)}, booktitle = {Proceedings International Conference on Advances in Computational Mechanics (ACOME)}, pages = {870 -- 882}, year = {2012}, language = {en} } @article{PaulssenNgyugenKahlckeetal.2012, author = {Paulßen, Elisabeth and Ngyugen, Hung Huy and Kahlcke, Nils and Deflon, Victor M. and Abram, Ulrich}, title = {Tricarbonyltechnetium(I) and -rhenium(I) complexes with N′-thiocarbamoylpicolylbenzamidines}, series = {Polyhedron}, volume = {40}, journal = {Polyhedron}, number = {1}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0277-5387}, doi = {10.1016/j.poly.2012.04.008}, pages = {153 -- 158}, year = {2012}, abstract = {N,N-Dialkylamino(thiocarbonyl)-N′-picolylbenzamidines react with (NEt4)2[M(CO)3X3] (M = Re, X = Br; M = Tc, X = Cl) under formation of neutral [M(CO)3L] complexes in high yields. The monoanionic NNS ligands bind in a facial coordination mode and can readily be modified at the (CS)NR1R2 moiety. The complexes [99Tc(CO)3(LPyMor)] and [Re(CO)3(L)] (L = LPyMor, LPyEt) were characterized by X-ray diffraction. Reactions of [99mTc(CO)3(H2O)3]+ with the N′-thiocarbamoylpicolylbenzamidines give the corresponding 99mTc complexes. The ester group in HLPyCOOEt allows linkage between biomolecules and the metal core.}, language = {en} } @article{PaulssenKongArciszewskietal.2012, author = {Paulßen, Elisabeth and Kong, Shushu and Arciszewski, Pawel and Wielbalck, Swantje and Abram, Ulrich}, title = {Aryl and NHC Compounds of Technetium and Rhenium}, series = {Journal of the American Chemical Society}, volume = {134}, journal = {Journal of the American Chemical Society}, number = {22}, publisher = {ACS Publications}, address = {Washington, DC}, issn = {1520-5126}, doi = {10.1021/ja3033718}, pages = {9118 -- 9121}, year = {2012}, abstract = {Air- and water-stable phenyl complexes with nitridotechnetium(V) cores can be prepared by straightforward procedures. [TcNPh2(PPh3)2] is formed by the reaction of [TcNCl2(PPh3)2] with PhLi. The analogous N-heterocyclic carbene (NHC) compound [TcNPh2(HLPh)2], where HLPh is 1,3,4-triphenyl-1,2,4-triazol-5-ylidene, is available from (NBu4)[TcNCl4] and HLPh or its methoxo-protected form. The latter compound allows the comparison of different Tc-C bonds within one compound. Surprisingly, the Tc chemistry with such NHCs does not resemble that of corresponding Re complexes, where CH activation and orthometalation dominate.}, language = {en} } @article{OrzadaMaderwaldPoseretal.2012, author = {Orzada, S. and Maderwald, S. and Poser, B. A. and Johst, S. and Kannengiesser, S. and Ladd, M. E. and Bitz, Andreas}, title = {Time-interleaved acquisition of modes: an analysis of SAR and image contrast implications}, series = {Magnetic Resonance in Medicine}, volume = {67}, journal = {Magnetic Resonance in Medicine}, number = {4}, publisher = {Wiley-Liss}, address = {New York}, issn = {1522-2594}, doi = {10.1002/mrm.23081}, pages = {1033 -- 1041}, year = {2012}, abstract = {s the magnetic field strength and therefore the operational frequency in MRI are increased, the radiofrequency wavelength approaches the size of the human head/body, resulting in wave effects which cause signal decreases and dropouts. Especially, whole-body imaging at 7 T and higher is therefore challenging. Recently, an acquisition scheme called time-interleaved acquisition of modes has been proposed to tackle the inhomogeneity problems in high-field MRI. The basic premise is to excite two (or more) different Burn:x-wiley:07403194:media:MRM23081:tex2gif-stack-1 modes using static radiofrequency shimming in an interleaved acquisition, where the complementary radiofrequency patterns of the two modes can be exploited to improve overall signal homogeneity. In this work, the impact of time-interleaved acquisition of mode on image contrast as well as on time-averaged specific absorption rate is addressed in detail. Time-interleaved acquisition of mode is superior in Burn:x-wiley:07403194:media:MRM23081:tex2gif-stack-2 homogeneity compared with conventional radiofrequency shimming while being highly specific absorption rate efficient. Time-interleaved acquisition of modes can enable almost homogeneous high-field imaging throughout the entire field of view in PD, T2, and T2*-weighted imaging and, if a specified homogeneity criterion is met, in T1-weighted imaging as well.}, language = {en} } @article{OlaruKowalskiSethietal.2012, author = {Olaru, Alexandra Maria and Kowalski, Julia and Sethi, Vaishali and Bl{\"u}mich, Bernhard}, title = {Exchange relaxometry of flow at small P{\´e}clet numbers in a glass bead pack}, series = {Journal of Magnetic Resonance (JMR)}, volume = {220}, journal = {Journal of Magnetic Resonance (JMR)}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1096-0856}, doi = {10.1016/j.jmr.2012.04.015}, pages = {32 -- 44}, year = {2012}, abstract = {In this paper we consider low P{\´e}clet number flow in bead packs. A series of relaxation exchange experiments has been conducted and evaluated by ILT analysis. In the resulting correlation maps, we observed a collapse of the signal and a translation towards smaller relaxation times with increasing flow rates, as well as a signal tilt with respect to the diagonal. In the discussion of the phenomena we present a mathematical theory for relaxation exchange experiments that considers both diffusive and advective transport. We perform simulations based on this theory and discuss them with respect to the conducted experiments.}, language = {en} } @phdthesis{Oflaz2012, author = {Oflaz, Hakan}, title = {Entwicklung eines Prototypen zur Prognose von Fr{\"u}hgeburten : ein biomedizintechnischer Ansatz}, publisher = {Deutsche Zentralbibliothek f{\"u}r Medizin}, address = {K{\"o}ln}, doi = {10.4126/38m-004639208}, year = {2012}, language = {en} } @article{OertelBung2012, author = {Oertel, Mario and Bung, Daniel Bernhard}, title = {Initial stage of two-dimensional dam-break waves: laboratory versus VOF}, series = {Journal of hydraulic research}, volume = {50}, journal = {Journal of hydraulic research}, number = {1}, publisher = {Taylor \& Francis}, address = {London}, issn = {1814-2079 (E-Journal); 0022-1686 (Print)}, doi = {10.1080/00221686.2011.639981}, pages = {89 -- 97}, year = {2012}, abstract = {Since several decades, dam-break waves have been of main research interest. Mathematical approaches have been developed by analytical, physical and numerical models within the past 120 years. During the past 10 years, the number of research investigations has increased due to improved measurement techniques as well as significantly increased computer memories and performances. In this context, the present research deals with the initial stage of two-dimensional dam-break waves by comparing physical and numerical model results as well as analytical approaches. High-speed images and resulting particle image velocimetry calculations are thereby compared with the numerical volume-of-fluid (VOF) method, included in the commercial code FLOW-3D. Wave profiles and drag forces on placed obstacles are analysed in detail. Generally, a good agreement between the laboratory and VOF results is found.}, language = {en} } @inproceedings{OertelBung2012, author = {Oertel, Mario and Bung, Daniel Bernhard}, title = {Characteristics of cross-bar block ramp flows}, series = {Hydraulic structures into the 21st century : 4th IAHR International Symposium on Hydraulic Structures : 9.-11.2.2012, Porto}, booktitle = {Hydraulic structures into the 21st century : 4th IAHR International Symposium on Hydraulic Structures : 9.-11.2.2012, Porto}, organization = {International Symposium on Hydraulic Structures <4, 2012, Porto>}, isbn = {978-989-8509-01-7}, pages = {Elektronisch publiziert}, year = {2012}, language = {en} } @inproceedings{NoetzoldUphuesWegeneretal.2012, author = {N{\"o}tzold, K. and Uphues, A. and Wegener, R. and Soter, S. and Fink, K. and Bragard, Michael and Griessel, R.}, title = {Inverter based test setup for LVRT verification of a full-scale 2 MW wind power converter}, series = {EPE Joint Wind Energy and T\&D Chapters Seminar : 28th and 29th of June 2012, in the Utzon Centre, Aalborg, Denmark ; papers, posters, presentations. - Session 2: Grid connection, compliance}, booktitle = {EPE Joint Wind Energy and T\&D Chapters Seminar : 28th and 29th of June 2012, in the Utzon Centre, Aalborg, Denmark ; papers, posters, presentations. - Session 2: Grid connection, compliance}, publisher = {EPE Association}, address = {Brussels}, year = {2012}, language = {en} } @article{NovacekTranKlingeetal.2012, author = {Novacek, V. and Tran, Thanh Ngoc and Klinge, U. and Tolba, R. H. and Staat, Manfred and Bronson, D. G. and Miesse, A. M. and Whiffen, J. and Turquier, F.}, title = {Finite element modelling of stapled colorectal end-to-end anastomosis : Advantages of variable height stapler design}, series = {Journal of Biomechanics}, volume = {45}, journal = {Journal of Biomechanics}, number = {115}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1873-2380}, doi = {10.1016/j.jbiomech.2012.07.021}, pages = {2693 -- 2697}, year = {2012}, abstract = {The impact of surgical staplers on tissues has been studied mostly in an empirical manner. In this paper, finite element method was used to clarify the mechanics of tissue stapling and associated phenomena. Various stapling modalities and several designs of circular staplers were investigated to evaluate the impact of the device on tissues and mechanical performance of the end-to-end colorectal anastomosis. Numerical simulations demonstrated that a single row of staples is not adequate to resist leakage due to non-linear buckling and opening of the tissue layers between two adjacent staples. Compared to the single staple row configuration, significant increase in stress experienced by the tissue at the inner staple rows was observed in two and three rows designs. On the other hand, adding second and/or third staple row had no effect on strain in the tissue inside the staples. Variable height design with higher staples in outer rows significantly reduced the stresses and strains in outer rows when compared to the same configuration with flat cartridge.}, language = {en} } @article{NomdedeuWillenSchiefferetal.2012, author = {Nomdedeu, Mar Monsonis and Willen, Christine and Schieffer, Andre and Arndt, Hartmut}, title = {Temperature-dependent ranges of coexistence in a model of a two-prey-one-predator microbial food web}, series = {Marine Biology}, volume = {159}, journal = {Marine Biology}, number = {11}, publisher = {Springer}, address = {Berlin}, issn = {1432-1793}, doi = {10.1007/s00227-012-1966-x}, pages = {2423 -- 2430}, year = {2012}, abstract = {The objective of our study was to analyze the effects of temperature on the population dynamics of a three-species food web consisting of two prey bacteria (Pedobacter sp. and Acinetobacter johnsonii) and a protozoan predator (Tetrahymena pyriformis) as model organisms. We assessed the effects of temperature on the growth rates of all three species with the objective of developing a model with four differential equations based on the experimental data. The following hypotheses were tested at a theoretical level: Firstly, temperature changes can affect the dynamic behavior of a system by temperature-dependent parameters and interactions and secondly, food web response to temperature cannot be derived from the single species temperature response. The main outcome of the study is that temperature changes affect the parameter range where coexistence is possible within all three species. This has significant consequences on our ideas regarding the evaluation of effects of global warming.}, language = {en} } @inproceedings{NixFrotscherStaat2012, author = {Nix, Yvonne and Frotscher, Ralf and Staat, Manfred}, title = {Implementation of the edge-based smoothed extended finite element method}, series = {Proceedings 6th European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2012) Vienna, Austria, September 10-14, 2012}, booktitle = {Proceedings 6th European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2012) Vienna, Austria, September 10-14, 2012}, editor = {Eberhardsteiner, J.}, year = {2012}, language = {en} } @incollection{NiendorfWinterFrauenrath2012, author = {Niendorf, Thoralf and Winter, Lukas and Frauenrath, Tobias}, title = {Electrocardiogram in an MRI environment: Clinical needs, practical considerations, safety implications, technical solutions and fFuture directions}, series = {Advances in Electrocardiograms - Methods and Analysis}, booktitle = {Advances in Electrocardiograms - Methods and Analysis}, editor = {Millis, Richard}, publisher = {IntechOpen}, address = {London}, isbn = {978-953-307-923-3 (print)}, doi = {10.5772/24340}, pages = {309 -- 324}, year = {2012}, language = {en} } @article{NguyenDuongTranetal.2012, author = {Nguyen, Nhu Huynh and Duong, Minh Tuan and Tran, Thanh Ngoc and Pham, Phu Tinh and Grottke, O. and Tolba, R. and Staat, Manfred}, title = {Influence of a freeze-thaw cycle on the stress-stretch curves of tissues of porcine abdominal organs}, series = {Journal of Biomechanics}, volume = {45}, journal = {Journal of Biomechanics}, number = {14}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1873-2380}, doi = {10.1016/j.jbiomech.2012.07.008}, pages = {2382 -- 2386}, year = {2012}, abstract = {The paper investigates both fresh porcine spleen and liver and the possible decomposition of these organs under a freeze-thaw cycle. The effect of tissue preservation condition is an important factor which should be taken into account for protracted biomechanical tests. In this work, tension tests were conducted for a large number of tissue specimens from twenty pigs divided into two groups of 10. Concretely, the first group was tested in fresh state; the other one was tested after a freeze-thaw cycle which simulates the conservation conditions before biomechanical experiments. A modified Fung model for isotropic behavior was adopted for the curve fitting of each kind of tissues. Experimental results show strong effects of the realistic freeze-thaw cycle on the capsule of elastin-rich spleen but negligible effects on the liver which virtually contains no elastin. This different behavior could be explained by the autolysis of elastin by elastolytic enzymes during the warmer period after thawing. Realistic biomechanical properties of elastin-rich organs can only be expected if really fresh tissue is tested. The observations are supported by tests of intestines.}, language = {en} } @article{MuribTranCeunincketal.2012, author = {Murib, Mohammed S. and Tran, Anh Quang and Ceuninck, Ward de and Sch{\"o}ning, Michael Josef and Nesladek, Milos and Serpeng{\"u}zel, Ali and Wagner, Patrick}, title = {Analysis of an optical biosensor based on elastic light scattering from diamond-, glass-, and sapphire microspheres}, series = {Physica Status Solidi A}, volume = {209}, journal = {Physica Status Solidi A}, number = {9}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1862-6319}, doi = {10.1002/pssa.201100795}, pages = {1804 -- 1810}, year = {2012}, abstract = {Deoxyribonucleic acid (DNA) and protein recognition are now standard tools in biology. In addition, the special optical properties of microsphere resonators expressed by the high quality factor (Q-factor) of whispering gallery modes (WGMs) or morphology dependent resonances (MDRs) have attracted the attention of the biophotonic community. Microsphere-based biosensors are considered as powerful candidates to achieve label-free recognition of single molecules due to the high sensitivity of their WGMs. When the microsphere surface is modified with biomolecules, the effective refractive index and the effective size of the microsphere change resulting in a resonant wavelength shift. The transverse electric (TE) and the transverse magnetic (TM) elastic light scattering intensity of electromagnetic waves at 600 and 1400 nm are numerically calculated for DNA and unspecific binding of proteins to the microsphere surface. The effect of changing the optical properties was studied for diamond (refractive index 2.34), glass (refractive index 1.50), and sapphire (refractive index 1.75) microspheres with a 50 µm radius. The mode spacing, the linewidth of WGMs, and the shift of resonant wavelength due to the change in radius and refractive index, were analyzed by numerical simulations. Preliminary results of unspecific binding of biomolecules are presented. The calculated shift in WGMs can be used for biomolecules detection.}, language = {en} } @article{MottaghyDijkshoorn2012, author = {Mottaghy, Darius and Dijkshoorn, Lydia}, title = {Implementing an effective finite difference formulation for borehole heat exchangers into a heat and mass transport code}, series = {Renewable Energy}, volume = {45}, journal = {Renewable Energy}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0960-1481}, doi = {10.1016/j.renene.2012.02.013}, pages = {59 -- 71}, year = {2012}, abstract = {We present an effective finite difference formulation for implementing and modeling multiple borehole heat exchangers (BHE) in the general 3-D coupled heat and flow transport code SHEMAT. The BHE with arbitrary length can be either coaxial or double U-shaped. It is particularly suitable for modeling deep BHEs which contain varying pipe diameters and materials. Usually, in numerical simulations, a fine discretization of the BHE assemblage is required, due to the large geometric aspect ratios involved. This yields large models and long simulation times. The approach avoids this problem by considering heat transport between fluid and the soil through pipes and grout via thermal resistances. Therefore, the simulation time can be significantly reduced. The coupling with SHEMAT is realized by introducing an effective heat generation. Due to this connection, it is possible to consider heterogeneous geological models, as well as the influence of groundwater flow. This is particularly interesting when studying the long term behavior of a single BHE or a BHE field. Heating and cooling loads can enter the model with an arbitrary interval, e.g. from hourly to monthly values. When dealing with large BHE fields, computing times can be further significantly reduced by focusing on the temperature field around the BHEs, without explicitly modeling inlet and outlet temperatures. This allows to determine the possible migration of cold and warm plumes due to groundwater flow, which is of particular importance in urban areas with a high BHE installation density. The model is validated against the existing BHE modeling codes EWS and EED. A comparison with monitoring data from a deep BHE in Switzerland shows a good agreement. Synthetic examples demonstrate the field of application of this model.}, language = {en} } @article{MiyamotoKanekoMatsuoetal.2012, author = {Miyamoto, Ko-ichiro and Kaneko, Kazumi and Matsuo, Akira and Wagner, Torsten and Kanoh, Shin{\´i}chiro and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo}, title = {Miniaturized chemical imaging sensor system using an OLED display panel}, series = {Sensors and Actuators B: Chemical}, volume = {170}, journal = {Sensors and Actuators B: Chemical}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0925-4005}, doi = {10.1016/j.snb.2011.02.029}, pages = {82 -- 87}, year = {2012}, abstract = {The chemical imaging sensor is a semiconductor-based chemical sensor that can visualize the two-dimensional distribution of specific ions or molecules in the solution. In this study, we developed a miniaturized chemical imaging sensor system with an OLED display panel as a light source that scans the sensor plate. In the proposed configuration, the display panel is placed directly below the sensor plate and illuminates the back surface. The measured area defined by illumination can be arbitrarily customized to fit the size and the shape of the sample to be measured. The waveform of the generated photocurrent, the current-voltage characteristics and the pH sensitivity were investigated and pH imaging with this miniaturized system was demonstrated.}, language = {en} } @article{MiyamotoIchimuraWagneretal.2012, author = {Miyamoto, K. and Ichimura, H. and Wagner, Torsten and Yoshinobu, T. and Sch{\"o}ning, Michael Josef}, title = {Chemical Imaging of ion Diffusion in a Microfluidic Channel}, series = {Procedia Engineering}, journal = {Procedia Engineering}, number = {47}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1877-7058}, doi = {10.1016/j.proeng.2012.09.289}, pages = {886 -- 889}, year = {2012}, abstract = {The chemical imaging sensor is a chemical sensor which is capable of visualizing the spatial distribution of chemical species in sample solution. In this study, a novel measurement system based on the chemical imaging sensor was developed to observe the inside of a Y-shaped microfluidic channel while injecting two sample solutions from two branches. From the collected chemical images, it was clearly observed that the injected solutions formed laminar flows in the microfluidic channel. In addition, ion diffusion across the laminar flows was observed. This label-free method can acquire quantitative data of ion distribution and diffusion in microfluidic devices, which can be used to determine the diffusion coefficients, and therefore, the molecular weights of chemical species in the sample solution.}, language = {en} } @article{MansurovDigelBiisenbaevetal.2012, author = {Mansurov, Z. and Digel, Ilya and Biisenbaev, M. and Savistkaya, I. and Kistaubaeva, A. and Akimbekov, Nuraly S. and Zhubanova, A.}, title = {Bio-composite material on the basis of carbonized rice husk in biomedicine and environmental applications}, series = {Eurasian Chemico-Technological Journal}, volume = {14}, journal = {Eurasian Chemico-Technological Journal}, number = {2}, publisher = {Institute of Combustion Problems}, address = {Almaty}, issn = {2522-4867}, doi = {10.18321/ectj105}, pages = {115 -- 131}, year = {2012}, language = {en} } @article{LustfeldPithanReissel2012, author = {Lustfeld, H. and Pithan, C. and Reißel, Martin}, title = {Metallic electrolyte composites in the framework of the brick-layer model}, series = {Journal of the European Ceramic Society}, volume = {32}, journal = {Journal of the European Ceramic Society}, number = {4}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0955-2219}, doi = {10.1016/j.jeurceramsoc.2011.10.017}, pages = {859 -- 864}, year = {2012}, abstract = {It is well known that the already large dielectric constants of some electrolytes like BaTiO₃ can be enhanced further by adding metallic (e.g. Ni, Cu or Ag) nanoparticles. The enhancement can be quite large, a factor of more than 1000 is possible. The consequences for the properties will be discussed in the present paper applying a brick-layer model (BLM) for calculating dc-resistivities of thin layers and a modified one (PBLM) that includes percolation for calculating dielectric properties of these materials. The PBLM results in an at least qualitative description and understanding of the physical phenomena: This model gives an explanation for the steep increase of the dielectric constant below the percolation threshold and why this increase is connected to a dramatic decrease of the breakdown voltage as well as the ability of storing electrical energy. We conclude that metallic electrolyte composites like BaTiO₃ are not appropriate for energy storage.}, language = {en} } @inproceedings{LogenHoefkenSchuba2012, author = {Logen, Steffen and H{\"o}fken, Hans and Schuba, Marko}, title = {Simplifying RAM Forensics : A GUI and Extensions for the Volatility Framework}, series = {2012 Seventh International Conference on Availability, Reliability and Security (ARES), 20-24 August 2012, Prague, Czech Republic}, booktitle = {2012 Seventh International Conference on Availability, Reliability and Security (ARES), 20-24 August 2012, Prague, Czech Republic}, publisher = {IEEE}, address = {New York}, isbn = {978-1-4673-2244-7}, doi = {10.1109/ARES.2012.12}, pages = {620 -- 624}, year = {2012}, abstract = {The Volatility Framework is a collection of tools for the analysis of computer RAM. The framework offers a multitude of analysis options and is used by many investigators worldwide. Volatility currently comes with a command line interface only, which might be a hinderer for some investigators to use the tool. In this paper we present a GUI and extensions for the Volatility Framework, which on the one hand simplify the usage of the tool and on the other hand offer additional functionality like storage of results in a database, shortcuts for long Volatility Framework command sequences, and entirely new commands based on correlation of data stored in the database.}, language = {en} } @article{LoebSchartnerDachwaldetal.2012, author = {Loeb, Horst Wolfgang and Schartner, Karl-Heinz and Dachwald, Bernd and Ohndorf, Andreas and Seboldt, Wolfgang}, title = {Interstellar heliopause probe}, series = {Труды МАИ}, journal = {Труды МАИ}, number = {60}, publisher = {Moskauer Staatliches Luftfahrtinstitut (МАИ)}, address = {Moskau}, pages = {2 -- 2}, year = {2012}, abstract = {There is common agreement within the scientific community that in order to understand our local galactic environment it will be necessary to send a spacecraft into the region beyond the solar wind termination shock. Considering distances of 200 AU for a new mission, one needs a spacecraft traveling at a speed of close to 10 AU/yr in order to keep the mission duration in the range of less than 25 yrs, a transfer time postulated by European Space Agency (ESA). Two propulsion options for the mission have been proposed and discussed so far: the solar sail propulsion and the ballistic/radioisotope-electric propulsion (REP). As a further alternative, we here investigate a combination of solar-electric propulsion (SEP) and REP. The SEP stage consists of six 22-cms diameter RIT-22 ion thrusters working with a high specific impulse of 7377 s corresponding to a positive grid voltage of 5 kV. Solar power of 53 kW at begin of mission (BOM) is provided by a lightweight solar array.}, language = {en} } @inproceedings{LoPiparoKernMazzetti2012, author = {Lo Piparo, G. B. and Kern, Alexander and Mazzetti, C.}, title = {Some masterpoints about risk due to lightning}, series = {International Conference on Lightning Protection (ICLP) : 2 - 7 Sept. 2012, Vienna}, booktitle = {International Conference on Lightning Protection (ICLP) : 2 - 7 Sept. 2012, Vienna}, publisher = {IEEE}, address = {Piscataway, NJ}, organization = {International Conference on Lightning Protection <2012, Wien>}, isbn = {978-1-4673-1896-9 (E-Book) ; 978-1-4673-1898-3 (Print)}, pages = {1 -- 6}, year = {2012}, language = {en} } @misc{LindelGreiserWaxmanetal.2012, author = {Lindel, Tomasz Dawid and Greiser, Andreas and Waxman, Patrick and Dietterle, Martin and Seifert, Frank and Fontius, Ulrich and Renz, Wolfgang and Dieringer, Matthias A. and Frauenrath, Tobias and Schulz-Menger, Jeanette and Niendorf, Thoralf and Ittermann, Bernd}, title = {Cardiac CINE MRI at 7 T using a transmit array}, series = {2012 ISMRM Annual Meeting Proceedings}, journal = {2012 ISMRM Annual Meeting Proceedings}, issn = {1545-4428}, year = {2012}, abstract = {With its need for high SNR and short acquisition times, Cardiac MRI (CMR) is an intriguing target application for ultrahigh field MRI. Due to the sheer size of the upper torso, however, the known RF issues of 7T MRI are also most prominent in CMR. Recent years brought substantial progress but the full potential of the ultrahigh field for CMR is yet to be exploited. Parallel transmission (pTx) is a promising approach in this context and several groups have already reported B1 shimming for 7T CMR. In such a static pTx application amplitudes and phases of all Tx channels are adjusted individually but otherwise imaging techniques established in current clinical practice 1.5 T and 3 T are applied. More advanced forms of pTx as spatially selective excitation (SSE) using Transmit SENSE promise additional benefits like faster imaging with reduced fields of view or improved SAR control. SSE requires the full dynamic capabilities of pTx, however, and for the majority of today's implemented pTx hardware the internal synchronization of the Tx array does not easily permit external triggering as needed for CMR. Here we report a software solution to this problem and demonstrate the feasibility of CINE CMR at 7 T using a Tx array.}, language = {en} } @article{LeursMezoOehlschlaegeretal.2012, author = {Leurs, Ulrike and Mezo, Gabor and {\"O}hlschl{\"a}ger, Peter and Orban, Erika and Marquard, Andrea and Manea, Marilena}, title = {Design, synthesis, in vitro stability and cytostatic effect of multifunctional anticancer drug-bioconjugates containing GnRH-III as a targeting moiety}, series = {Peptide Science}, volume = {98}, journal = {Peptide Science}, number = {1}, publisher = {Wiley}, address = {New York, NY}, issn = {1097-0282}, doi = {10.1002/bip.21640}, pages = {1 -- 10}, year = {2012}, abstract = {Bioconjugates containing the GnRH-III hormone decapeptide as a targeting moiety are able to deliver chemotherapeutic agents specifically to cancer cells expressing GnRH receptors, thereby increasing their local efficacy while limiting the peripheral toxicity. However, the number of GnRH receptors on cancer cells is limited and they desensitize under continuous hormone treatment. A possible approach to increase the receptor mediated tumor targeting and consequently the cytostatic effect of the bioconjugates would be the attachment of more than one chemotherapeutic agent to one GnRH-III molecule. Here we report on the design, synthesis and biochemical characterization of multifunctional bioconjugates containing GnRH-III as a targeting moiety and daunorubicin as a chemotherapeutic agent. Two different drug design approaches were pursued. The first one was based on the bifunctional [4Lys]-GnRH-III (Glp-His-Trp-Lys-His-Asp-Trp-Lys-Pro-Gly-NH2) containing two lysine residues in positions 4 and 8, whose ϵ-amino groups were used for the coupling of daunorubicin. In the second drug design, the native GnRH-III (Glp-His-Trp-Ser-His-Asp-Trp-Lys-Pro-Gly-NH2) was used as a scaffold; an additional lysine residue was coupled to the ϵ-amino group of 8Lys in order to generate two free amino groups available for conjugation of daunorubicin. The in vitro stability/degradation of all synthesized compounds was investigated in human serum, as well as in the presence of rat liver lysosomal homogenate. Their cellular uptake was determined on human breast cancer cells and the cytostatic effect was evaluated on human breast, colon and prostate cancer cell lines. Compared with a monofunctional compound, both drug design approaches resulted in multifunctional bioconjugates with increased cytostatic effect.}, language = {en} } @article{LempiaeinenCouttetBolognanietal.2012, author = {Lempi{\"a}inen, Harri and Couttet, Philippe and Bolognani, Federico and M{\"u}ller, Arne and Dubost, Val{\´e}rie and Luisier, Rapha{\"e}lle and Rio-Espinola, Alberto del and Vitry, Veronique and Unterberger, Elif B. and Thomson, John P. and Treindl, Fridolin and Metzger, Ute and Wrzodek, Clemens and Hahne, Florian and Zollinger, Tulipan and Brasa, Sarah and Kalteis, Magdalena and Marcellin, Magali and Giudicelli, Fanny and Braeuning, Albert and Morawiec, Laurent and Zamurovic, Natasa and L{\"a}ngle, Ulrich and Scheer, Nico and Sch{\"u}beler, Dirk and Goodman, Jay and Chibout, Salah-Dine and Marlowe, Jennifer and Theil, Dietlinde and Heard, David J. and Grenet, Olivier and Zell, Andreas and Templin, Markus F. and Meehan, Richard R. and Wolf, Roland C. and Elcombe, Clifford R. and Schwarz, Michael and Moulin, Pierre and Terranova, R{\´e}mi and Moggs, Jonathan G.}, title = {Identification of Dlk1-Dio3 imprinted gene cluster non-coding RNAs as novel candidate biomarkers for liver tumor promotion}, series = {Toxicological Sciences}, volume = {131}, journal = {Toxicological Sciences}, number = {2}, publisher = {Oxford University Press}, address = {Oxford}, issn = {1094-2025}, doi = {10.1093/toxsci/kfs303}, pages = {375 -- 386}, year = {2012}, abstract = {The molecular events during nongenotoxic carcinogenesis and their temporal order are poorly understood but thought to include long-lasting perturbations of gene expression. Here, we have investigated the temporal sequence of molecular and pathological perturbations at early stages of phenobarbital (PB) mediated liver tumor promotion in vivo. Molecular profiling (mRNA, microRNA [miRNA], DNA methylation, and proteins) of mouse liver during 13 weeks of PB treatment revealed progressive increases in hepatic expression of long noncoding RNAs and miRNAs originating from the Dlk1-Dio3 imprinted gene cluster, a locus that has recently been associated with stem cell pluripotency in mice and various neoplasms in humans. PB induction of the Dlk1-Dio3 cluster noncoding RNA (ncRNA) Meg3 was localized to glutamine synthetase-positive hypertrophic perivenous hepatocytes, sug- gesting a role for β-catenin signaling in the dysregulation of Dlk1-Dio3 ncRNAs. The carcinogenic relevance of Dlk1-Dio3 locus ncRNA induction was further supported by in vivo genetic dependence on constitutive androstane receptor and β-catenin pathways. Our data identify Dlk1-Dio3 ncRNAs as novel candidate early biomarkers for mouse liver tumor promotion and provide new opportunities for assessing the carcinogenic potential of novel compounds.}, language = {en} } @article{LeidingerNoistenWollert2012, author = {Leidinger, Rafael and Noisten, Thomas and Wollert, J{\"o}rg}, title = {Realtime automation networks in moVing industrial environments}, series = {Journal of systemics, cybernetics and informatics}, volume = {Vol. 10}, journal = {Journal of systemics, cybernetics and informatics}, number = {Iss. 2}, publisher = {IIIC}, address = {Orlando}, issn = {1690-4532}, pages = {52 -- 56}, year = {2012}, abstract = {The radio-based wireless data communication has made the realization of new technical solutions possible in many fields of the automation technology (AT). For about ten years, a constant disproportionate growth of wireless technologies can be observed in the automation technology. However, it shows that especially for the AT, conventional technologies of office automation are unsuitable and/or not manageable. The employment of mobile services in the industrial automation technology has the potential of significant cost and time savings. This leads to an increased productivity in various fields of the AT, for example in the factory and process automation or in production logistics. In this paper technologies and solutions for an automation-suited supply of mobile wireless services will be introduced under the criteria of real time suitability, IT-security and service orientation. Emphasis will be put on the investigation and development of wireless convergence layers for different radio technologies, on the central provision of support services for an easy-to-use, central, backup enabled management of combined wired / wireless networks and on the study on integrability in a Profinet real-time Ethernet network.}, language = {en} } @inproceedings{KoetterDeckerDetzleretal.2012, author = {K{\"o}tter, Jens and Decker, Stefan and Detzler, Raphael and Sch{\"a}fer, Jochen and Schmitz, Mark and Herrmann, Ulf}, title = {Cost Reduction of Solar Fields with HelioTrough Collector}, publisher = {FLAGSOL}, address = {K{\"o}ln}, pages = {9 S. : Ill., graph. Darst.}, year = {2012}, language = {en} } @article{KurulganDemirciDemirciLinderetal.2012, author = {Kurulgan Demirci, Eylem and Demirci, Taylan and Linder, Peter and Trzewik, J{\"u}rgen and Gierkowski, Jessica Ricarda and Gossmann, Matthias and Kayser, Peter and Porst, Dariusz and Digel, Ilya and Artmann, Gerhard and Temiz Artmann, Ayseg{\"u}l}, title = {rhAPC reduces the endothelial cell permeability via a decrease of contractile tensions induced by endothelial cells}, series = {Journal of Bioscience and Bioengineering}, volume = {113}, journal = {Journal of Bioscience and Bioengineering}, number = {2}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1347-4421}, doi = {10.1016/j.jbiosc.2012.03.019}, pages = {212 -- 219}, year = {2012}, abstract = {All cells generate contractile tension. This strain is crucial for mechanically controlling the cell shape, function and survival. In this study, the CellDrum technology quantifying cell's (the cellular) mechanical tension on a pico-scale was used to investigate the effect of lipopolysaccharide (LPS) on human aortic endothelial cell (HAoEC) tension. The LPS effect during gram-negative sepsis on endothelial cells is cell contraction causing endothelium permeability increase. The aim was to finding out whether recombinant activated protein C (rhAPC) would reverse the endothelial cell response in an in-vitro sepsis model. In this study, the established in-vitro sepsis model was confirmed by interleukin 6 (IL-6) levels at the proteomic and genomic levels by ELISA, real time-PCR and reactive oxygen species (ROS) activation by florescence staining. The thrombin cellular contraction effect on endothelial cells was used as a positive control when the CellDrum technology was applied. Additionally, the Ras homolog gene family, member A (RhoA) mRNA expression level was checked by real time-PCR to support contractile tension results. According to contractile tension results, the mechanical predominance of actin stress fibers was a reason of the increased endothelial contractile tension leading to enhanced endothelium contractility and thus permeability enhancement. The originality of this data supports firstly the basic measurement principles of the CellDrum technology and secondly that rhAPC has a beneficial effect on sepsis influenced cellular tension. The technology presented here is promising for future high-throughput cellular tension analysis that will help identify pathological contractile tension responses of cells and prove further cell in-vitro models.}, language = {en} } @phdthesis{KurulganDemirci2012, author = {Kurulgan Demirci, Eylem}, title = {The effect of rhAPC on contractile tension : an in-vitro sepsis model of cardiomyocytes and endothelial cells}, year = {2012}, language = {en} } @inproceedings{KuhnhenneDoeringPyschnyetal.2012, author = {Kuhnhenne, Markus and D{\"o}ring, Bernd and Pyschny, Dominik and Feldmann, Markus}, title = {Energy efficient sandwich construction}, series = {Proceedings of the VI International Congress on Architectural Envelopes : 20.6. - 22.6.2012, San Sebastian, Spain}, booktitle = {Proceedings of the VI International Congress on Architectural Envelopes : 20.6. - 22.6.2012, San Sebastian, Spain}, publisher = {ICAE}, organization = {International Congress on Architectural Envelopes <6, 2012, San Sebastian>}, pages = {277 -- 285}, year = {2012}, language = {en} } @article{KotliarLanzlHanssenetal.2012, author = {Kotliar, Konstantin and Lanzl, Ines M. and Hanssen, Henner and Eberhardt, Karla and Vilser, Walthard and Halle, Martin and Heemann, Uwe and Schmidt-Trucks{\"a}ss, Arno and Baumann, Marcus}, title = {Does increased blood pressure rather than aging influence retinal pulse wave velocity?}, series = {Investigative Ophthalmology \& Visual Science, IOVS}, volume = {53}, journal = {Investigative Ophthalmology \& Visual Science, IOVS}, number = {4}, publisher = {ARVO}, address = {Rockville, Md.}, issn = {0146-0404}, doi = {10.1167/iovs.11-8815}, pages = {2119 -- 2126}, year = {2012}, abstract = {Purpose: It was demonstrated previously that retinal pulse wave velocity (rPWV) as a measure of retinal arterial stiffness is increased in aged anamnestically healthy volunteers compared with young healthy subjects. Using novel methodology of rPWV assessment this finding was confirmed and investigated whether it might relate to the increased blood pressure usually accompanying the aging process, rather than to the aging itself. Methods: A total of 12 young 25.5-year-old (24.0-28.8) [median(1st quartile-3rd quartile)] and 12 senior 68.5-year-old (63.8-71.8) anamnestically healthy volunteers; and 12 senior 63.0-year-old (60.8-65.0) validated healthy volunteers and 12 young 33.0-year-old (29.5-35.0) hypertensive patients were examined. Time-dependent alterations of vessel diameter were assessed by the Dynamic Vessel Analyzer in a retinal artery of each subject. The data were filtered and processed using mathematical signal analysis and rPWVs were calculated. Results: rPWV amounted to 1200 (990-1470) RU (relative units)/s in the hypertensive group and to 1040 (700-2230) RU/s in anamnestically healthy seniors. These differed significantly from rPWVs in young healthy group (410 [280-500] RU/s) and in validated healthy seniors (400 [320-510] RU/s). rPWV associated with age and mean arterial pressure (MAP) in the pooled cohort excluded validated healthy seniors. In a regression model these associations remain when alternately adjusted for MAP and age. When including validated healthy seniors in the pooled cohort only association with MAP remains. Conclusions: Both aging (with not excluded cardiovascular risk factors) and mild hypertension are associated with elevated rPWV. rPWV increases to a similar extent both in young mildly hypertensive subjects and in aged anamnestically healthy persons. Healthy aging is not associated with increased rPWV.}, language = {en} } @article{KobusBitzUdenetal.2012, author = {Kobus, Thiele and Bitz, Andreas and Uden, Mark J. van and Lagemaat, Miram W. and Rothgang, Eva and Orzada, Stephan and Heerschap, Arend and Scheenen, Tom W. J.}, title = {In vivo 31P MR spectroscopic imaging of the human prostate at 7 T: safety and feasibility}, series = {Magnetic Resonance in Medicine}, volume = {68}, journal = {Magnetic Resonance in Medicine}, number = {6}, publisher = {Wiley-Liss}, address = {New York}, issn = {1522-2594}, doi = {10.1002/mrm.24175}, pages = {1683 -- 1695}, year = {2012}, abstract = {31P MR spectroscopic imaging of the human prostate provides information about phosphorylated metabolites that could be used for prostate cancer characterization. The sensitivity of a magnetic field strength of 7 T might enable 3D 31P MR spectroscopic imaging with relevant spatial resolution in a clinically acceptable measurement time. To this end, a 31P endorectal coil was developed and combined with an eight-channel 1H body-array coil to relate metabolic information to anatomical location. An extensive safety validation was performed to evaluate the specific absorption rate, the radiofrequency field distribution, and the temperature distribution of both coils. This validation consisted of detailed Finite Integration Technique simulations, confirmed by MR thermometry and Burn:x-wiley:07403194:media:MRM24175:tex2gif-stack-1 measurements in a phantom and in vivo temperature measurements. The safety studies demonstrated that the presence of the 31P endorectal coil had no influence on the specific absorption rate levels and temperature distribution of the external eight-channel 1H array coil. To stay within a 10 g averaged local specific absorption rate of 10 W/kg, a maximum time-averaged input power of 33 W for the 1H array coil was allowed. For transmitting with the 31P endorectal coil, our safety limit of less than 1°C temperature increase in vivo during a 15-min MR spectroscopic imaging experiment was reached at a time-averaged input power of 1.9 W. With this power setting, a second in vivo measurement was performed on a healthy volunteer. Using adiabatic excitation, 3D 31P MR spectroscopic imaging produced spectra from the entire prostate in 18 min with a spatial resolution of 4 cm3. The spectral resolution enabled the separate detection of phosphocholine, phosphoethanolamine, inorganic phosphate, and other metabolites that could play an important role in the characterization of prostate cancer.}, language = {en} } @inproceedings{KnackstedtEggertFleischer2012, author = {Knackstedt, Ralf and Eggert, Mathias and Fleischer, Stefan}, title = {The Legal Perspective on Business to Government Reporting - A Conceptual Modeling Approach and Its Application in the Financial Sector}, series = {45th Hawaii International Conference on System Sciences 2012}, booktitle = {45th Hawaii International Conference on System Sciences 2012}, isbn = {978-0-7695-4525-7}, doi = {10.1109/HICSS.2012.576}, pages = {2309 -- 2318}, year = {2012}, language = {en} } @article{KirsteinMuellerWaleckiMingersetal.2012, author = {Kirstein, Simon and M{\"u}ller, Karsten and Walecki-Mingers, Mark and Deserno, Thomas M.}, title = {Robust adaptive flow line detection in sewer pipes}, series = {Automation in construction}, journal = {Automation in construction}, number = {21}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1872-7891 (E-Journal) ; 0926-5805 (Print)}, doi = {10.1016/j.autcon.2011.05.009}, pages = {24 -- 31}, year = {2012}, abstract = {As part of a novel approach to automatic sewer inspection, this paper presents a robust algorithm for automatic flow line detection. A large image repository is obtained from about 50,000 m sewers to represent the high variability of real world sewer systems. Automatic image processing combines Canny edge detection, Hough transform for straight lines and cost minimization using Dijkstra's shortest path algorithm. Assuming that flow lines are mostly smoothly connected horizontal structures, piecewise flow line delineation is reduced to a process of selecting adjacent line candidates. Costs are derived from the gap between adjacent candidates and their reliability. A single parameter α enables simple control of the algorithm. The detected flow line may precisely follow the segmented edges (α = 0.0) or minimize gaps at joints (α = 1.0). Both, manual and ground truth-based analysis indicate that α = 0.8 is optimal and independent of the sewer's material. The algorithm forms an essential step to further automation of sewer inspection.}, language = {en} } @article{KirchnerReisertPuetzetal.2012, author = {Kirchner, Patrick and Reisert, Steffen and P{\"u}tz, Patrick and Keusgen, Michael and Sch{\"o}ning, Michael Josef}, title = {Characterisation of polymeric materials as passivation layer for calorimetric H2O2 gas sensors}, series = {Physica Status Solidi (a)}, volume = {209}, journal = {Physica Status Solidi (a)}, number = {5}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1862-6319}, doi = {10.1002/pssa.201100773}, pages = {859 -- 863}, year = {2012}, abstract = {Calorimetric gas sensors for monitoring the H₂O₂ concentration at elevated temperatures in industrial sterilisation processes have been presented in previous works. These sensors are built up in form of a differential set-up of a catalytically active and passive temperature-sensitive structure. Although, various types of catalytically active dispersions have been studied, the passivation layer has to be established and therefore, chemically as well as physically characterised. In the present work, fluorinated ethylene propylene (FEP), perfluoralkoxy (PFA) and epoxy-based SU-8 photoresist as temperature-stable polymeric materials have been investigated for sensor passivation in terms of their chemical inertness against H₂O₂, their hygroscopic properties as well as their morphology. The polymeric materials were deposited via spin-coating on the temperature-sensitive structure, wherein spin-coated FEP and PFA show slight agglomerates. However, they possess a low absorption of humidity due to their hydrophobic surface, whereas the SU-8 layer has a closed surface but shows a slightly higher absorption of water. All of them were inert against gaseous H₂O₂ during the characterisation in H₂O₂ atmosphere that demonstrates their suitability as passivation layer for calorimetric H₂O₂ gas sensors.}, language = {en} } @article{KirchnerOberlaenderFriedrichetal.2012, author = {Kirchner, Patrick and Oberl{\"a}nder, Jan and Friedrich, Peter and Berger, J{\"o}rg and Rysstad, Gunnar and Sch{\"o}ning, Michael Josef and Keusgen, Michael}, title = {Realisation of a calorimetric gas sensor on polyimide foil for applications in aseptic food industry}, series = {Sensors and Actuators B: Chemical}, volume = {170}, journal = {Sensors and Actuators B: Chemical}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0925-4005}, doi = {10.1016/j.snb.2011.01.032}, pages = {60 -- 66}, year = {2012}, abstract = {A calorimetric gas sensor is presented for the monitoring of vapour-phase H2O2 at elevated temperature during sterilisation processes in aseptic food industry. The sensor was built up on a flexible polyimide foil (thickness: 25 μm) that has been chosen due to its thermal stability and low thermal conductivity. The sensor set-up consists of two temperature-sensitive platinum thin-film resistances passivated by a layer of SU-8 photo resist and catalytically activated by manganese(IV) oxide. Instead of an active heating structure, the calorimetric sensor utilises the elevated temperature of the evaporated H2O2 aerosol. In an experimental test rig, the sensor has shown a sensitivity of 4.78 °C/(\%, v/v) in a H2O2 concentration range of 0\%, v/v to 8\%, v/v. Furthermore, the sensor possesses the same, unchanged sensor signal even at varied medium temperatures between 210 °C and 270 °C of the gas stream. At flow rates of the gas stream from 8 m3/h to 12 m3/h, the sensor has shown only a slightly reduced sensitivity at a low flow rate of 8 m3/h. The sensor characterisation demonstrates the suitability of the calorimetric gas sensor for monitoring the efficiency of industrial sterilisation processes.}, language = {en} } @inproceedings{KernSchelthoffMathieu2012, author = {Kern, Alexander and Schelthoff, Christof and Mathieu, Moritz}, title = {Calculation of interception efficiencies for mesh-type air-terminations according to IEC 62305-3 using a dynamic electro-geometrical model}, series = {International Conference on Lightning Protection (ICLP) : 2 - 7 Sept. 2012, Vienna}, booktitle = {International Conference on Lightning Protection (ICLP) : 2 - 7 Sept. 2012, Vienna}, publisher = {IEEE}, address = {Piscataway, NJ}, organization = {International Conference on Lightning Protection <2012, Wien>}, isbn = {978-1-4673-1896-9 (E-Book) ; 978-1-4673-1898-3 (Print)}, pages = {1 -- 6}, year = {2012}, language = {en} } @book{JanserHavermann2012, author = {Janser, Frank and Havermann, Marc}, title = {Inkompressible Str{\"o}mungen}, publisher = {Mainz}, address = {Aachen}, isbn = {978-3-86130-446-3}, pages = {189 S. : Ill., graph. Darst.}, year = {2012}, language = {en} } @article{ImmelGruetzkeSpaeteetal.2012, author = {Immel, Timo and Gr{\"u}tzke, Martin and Sp{\"a}te, Anne-Katrin and Groth, Ulrich and {\"O}hlschl{\"a}ger, Peter and Huhn, Thomas}, title = {Synthesis and X-ray structure analysis of a heptacoordinate titanium(IV)-bis-chelate with enhanced in vivo antitumor efficacy}, series = {Chemical Communications}, volume = {48}, journal = {Chemical Communications}, number = {46}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1364-548X}, doi = {10.1039/C2CC31624B}, pages = {5790 -- 5792}, year = {2012}, abstract = {Chelate stabilization of a titanium(IV)-salan alkoxide by ligand exchange with 2,6-pyridinedicarboxylic acid (dipic) resulted in heptacoordinate complex 3 which is not redox-active, stable on silica gel and has increased aqueous stability. 3 is highly toxic in HeLa S3 and Hep G2 and has enhanced antitumor efficacy in a mouse cervical-cancer model.}, language = {en} } @article{IkenKirsanovLeginetal.2012, author = {Iken, Heiko and Kirsanov, D. and Legin, A. and Sch{\"o}ning, Michael Josef}, title = {Novel Thin-Film Polymeric Materials for the Detection of Heavy Metals}, series = {Procedia Engineering}, journal = {Procedia Engineering}, number = {47}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1877-7058}, doi = {10.1016/j.proeng.2012.09.148}, pages = {322 -- 325}, year = {2012}, abstract = {A variety of transition metals, e.g., copper, zinc, cadmium, lead, etc. are widely used in industry as components for wires, coatings, alloys, batteries, paints and so on. The inevitable presence of transition metals in industrial processes implies the ambition of developing a proper analytical technique for their adequate monitoring. Most of these elements, especially lead and cadmium, are acutely toxic for biological organisms. Quantitative determination of these metals at low activity levels in different environmental and industrial samples is therefore a vital task. A promising approach to achieve an at-side or on-line monitoring on a miniaturized and cost efficient way is the combination of a common potentiometric sensor array with heavy metal-sensitive thin-film materials, like chalcogenide glasses and polymeric materials, respectively.}, language = {en} } @article{Huening2012, author = {H{\"u}ning, Felix}, title = {Using Trench PowerMOSFETs in Linear Mode}, series = {Power Electronics Europe (2012)}, journal = {Power Electronics Europe (2012)}, publisher = {DFA Media}, address = {Tonbridge}, issn = {1748-3530}, pages = {27 -- 29}, year = {2012}, abstract = {If we think about applications for modern Power MOSFETs using trench technology, running them in linear mode may not be top of the priority list. Yet there are multiple uses for Trench Power MOSFETs in linear mode. In fact, even turning the device on and off in switching applications is a form of linear operation. Also, these components can be run in linear mode to protect the device against voltage surges. This article will illustrate the factors that need to be considered for linear operation and show how Trench Power MOSFETs are suited to it.}, language = {en} } @article{HoetterFateriGebhardt2012, author = {H{\"o}tter, Jan-Steffen and Fateri, Miranda and Gebhardt, Andreas}, title = {Selective laser melting of metals: desktop machines open up new chances even for small companies}, series = {Advanced materials research}, volume = {622-623}, journal = {Advanced materials research}, publisher = {Trans Tech Publ.}, address = {Baech}, issn = {1662-8985 (E-Journal); 1022-6680 (Print)}, doi = {10.4028/www.scientific.net/AMR.622-623.461}, pages = {461 -- 465}, year = {2012}, abstract = {Additive manufacturing (AM) of metal parts by using Selective Laser Melting (SLM) has become a powerful tool mostly in the area of automotive, aerospace engineering and others. Especially in the field of dentistry, jewelry and related branches that require individualized or even one-of-a-kind products, the direct digital manufacturing process opens up new ways of design and manufacturing. In these fields, mostly small and medium sized businesses (SME) are operating which do not have sufficient human and economic resources to invest in this technology. But to stay competitive, the application of AM can be regarded as a necessity. In this situation a new desktop machine (Realizer SLM 50) was introduced that cost about 1/3 of a shop floor SLM machine and promises small quality parts. To find out whether the machine really is an alternative for SMEs the University of Applied Science, Aachen, Germany, designed, build and optimized typical parts from the dentistry and the jewelry branches using CoCr and silver material, the latter being new with this application. The paper describes the SLM procedure and how to find and optimize the most important parameters. The test is accompanied by digital simulation in order to verify the build parameters and to plan future builds. The procedure is shown as well as the resulting parts made from CoCr and silver material.}, language = {en} } @article{HuckPoghossianWagneretal.2012, author = {Huck, Christina and Poghossian, Arshak and Wagner, Patrick and Sch{\"o}ning, Michael Josef}, title = {Combined amperometric/field-effect sensor for the detection of dissolved hydrogen}, series = {Sensors and actuators B: Chemical}, volume = {187}, journal = {Sensors and actuators B: Chemical}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0925-4005}, doi = {10.1016/j.snb.2012.10.050}, pages = {168 -- 173}, year = {2012}, abstract = {Real-time and reliable monitoring of the biogas process is crucial for a stable and efficient operation of biogas production in order to avoid digester breakdowns. The concentration of dissolved hydrogen (H₂) represents one of the key parameters for biogas process control. In this work, a one-chip integrated combined amperometric/field-effect sensor for monitoring the dissolved H₂ concentration has been developed for biogas applications. The combination of two different transducer principles might allow a more accurate and reliable measurement of dissolved H₂ as an early warning indicator of digester failures. The feasibility of the approach has been demonstrated by simultaneous amperometric/field-effect measurements of dissolved H₂ concentrations in electrolyte solutions. Both, the amperometric and the field-effect transducer show a linear response behaviour in the H₂ concentration range from 0.1 to 3\% (v/v) with a slope of 198.4 ± 13.7 nA/\% (v/v) and 14.9 ± 0.5 mV/\% (v/v), respectively.}, language = {en} } @incollection{HoffschmidtAlexopoulosRauetal.2012, author = {Hoffschmidt, Bernhard and Alexopoulos, Spiros and Rau, Christoph and Sattler, Johannes Christoph and Anthrakidis, Anette and Teixeira Boura, Cristiano Jos{\´e} and O'Connor, P. and Hilger, Patrick}, title = {Concentrating solar power}, series = {Comprehensive renewable energy / ed. Ali Sayigh. Vol. 3: Solar thermal systems: components and applications}, volume = {3}, booktitle = {Comprehensive renewable energy / ed. Ali Sayigh. Vol. 3: Solar thermal systems: components and applications}, publisher = {Elsevier}, address = {Amsterdam}, isbn = {978-0-08-087872-0}, doi = {10.1016/B978-0-08-087872-0.00319-X}, pages = {595 -- 636}, year = {2012}, language = {en} } @incollection{HoffschmidtAlexopoulosGoettscheetal.2012, author = {Hoffschmidt, Bernhard and Alexopoulos, Spiros and G{\"o}ttsche, Joachim and Sauerborn, Markus}, title = {High concentration solar collectors}, series = {Comprehensive renewable energy / ed. Ali Sayigh. Vol. 3: Solar thermal systems: components and applications}, volume = {3}, booktitle = {Comprehensive renewable energy / ed. Ali Sayigh. Vol. 3: Solar thermal systems: components and applications}, publisher = {Elsevier}, address = {Amsterdam}, isbn = {978-0-08-087873-7}, doi = {10.1016/B978-0-08-087872-0.00306-1}, pages = {165 -- 209}, year = {2012}, abstract = {Solar thermal concentrated power is an emerging technology that provides clean electricity for the growing energy market. To the solar thermal concentrated power plant systems belong the parabolic trough, the Fresnel collector, the solar dish, and the central receiver system. For high-concentration solar collector systems, optical and thermal analysis is essential. There exist a number of measurement techniques and systems for the optical and thermal characterization of the efficiency of solar thermal concentrated systems. For each system, structure, components, and specific characteristics types are described. The chapter presents additionally an outline for the calculation of system performance and operation and maintenance topics. One main focus is set to the models of components and their construction details as well as different types on the market. In the later part of this chapter, different criteria for the choice of technology are analyzed in detail.}, language = {en} } @article{HerzwurmKramsPietschetal.2012, author = {Herzwurm, Georg and Krams, Benedikt and Pietsch, Wolfram and Schockert, Sixten}, title = {Report from the 3rd international workshop on requirements prioritization for customer oriented software development (RePriCo'12)}, series = {ACM SIGSOFT Software Engineering Notes}, volume = {37}, journal = {ACM SIGSOFT Software Engineering Notes}, number = {4}, publisher = {Association for Computing Machinery}, address = {New York}, issn = {0163-5948}, doi = {10.1145/2237796.2237817}, pages = {32 -- 34}, year = {2012}, abstract = {Prioritization is an essential task within requirements engineering to cope with complexity and to establish focus properly. The 3rd Workshop on Requirements Prioritization for customer oriented Software Development (RePriCo'12) focused on requirements prioritization and adjacent themes in the context of customer oriented development of bespoke and standard software. Five submissions have been accepted for the proceedings and for presentation. The report summarizes and points out key findings.}, language = {en} } @article{HenkenOosterhuisOehlschlaegeretal.2012, author = {Henken, F. E. and Oosterhuis, K. and {\"O}hlschl{\"a}ger, Peter and Bosch, L. and Hooijberg, E. and Haanen, J. B. A. G. and Steenbergen, R. D. M.}, title = {Preclinical safety evaluation of DNA vaccines encoding modified HPV16 E6 and E7}, series = {Vaccine}, volume = {30}, journal = {Vaccine}, number = {28}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0264-410X}, doi = {10.1016/j.vaccine.2012.04.013}, pages = {4259 -- 4266}, year = {2012}, abstract = {Persistent infection with high-risk human papillomaviruses (hrHPV) can result in the formation of anogenital cancers. As hrHPV proteins E6 and E7 are required for cancer initiation and maintenance, they are ideal targets for immunotherapeutic interventions. Previously, we have described the development of DNA vaccines for the induction of HPV16 E6 and E7 specific T cell immunity. These vaccines consist of 'gene-shuffled' (SH) versions of HPV16 E6 and E7 that were fused to Tetanus Toxin Fragment C domain 1 (TTFC) and were named TTFC-E6SH and TTFC-E7SH. Gene-shuffling was performed to avoid the risk of inducing malignant transformation at the vaccination site. Here, we describe the preclinical safety evaluation of these candidate vaccines by analysis of their transforming capacity in vitro using established murine fibroblasts (NIH 3T3 cells) and primary human foreskin keratinocytes (HFKs). We demonstrate that neither ectopic expression of TTFC-E6SH and TTFC-E7SH alone or in combination enabled NIH 3T3 cells to form colonies in soft agar. In contrast, expression of HPV16 E6WT and E7WT alone or in combination resulted in effective transformation. Similarly, retroviral transduction of HFKs from three independent donors with both TTFC-E6SH and TTFC-E7SH alone or in combination did not show any signs of immortalization. In contrast, the combined expression of E6WT and E7WT induced immortalization in HFKs from all donors. Based on these results we consider it justified to proceed to clinical evaluation of DNA vaccines encoding TTFC-E6SH and TTFC-E7SH in patients with HPV16 associated (pre)malignancies.}, language = {en} } @article{HasanKeilStaatetal.2012, author = {Hasan, Istabrak and Keil, Ludger and Staat, Manfred and Wahl, Gerhard and Bourauel, Christoph}, title = {Determination of the frictional coefficient of the implant-antler interface : experimental approach}, series = {Biomedical Engineering / Biomedizinische Technik}, volume = {57}, journal = {Biomedical Engineering / Biomedizinische Technik}, number = {5}, publisher = {De Gruyter}, address = {Berlin}, issn = {1862-278X}, pages = {359 -- 363}, year = {2012}, abstract = {The similar bone structure of reindeer antler to human bone permits studying the osseointegration of dental implants in the jawbone. As the friction is one of the major factors that have a significant influence on the initial stability of immediately loaded dental implants, it is essential to define the frictional coefficient of the implant-antler interface. In this study, the kinetic frictional forces at the implant-antler interface were measured experimentally using an optomechanical setup and a stepping motor controller under different axial loads and sliding velocities. The corresponding mean values of the static and kinetic frictional coefficients were within the range of 0.5-0.7 and 0.3-0.5, respectively. An increase in the frictional forces with increasing applied axial loads was registered. The measurements showed an evidence of a decrease in the magnitude of the frictional coefficient with increasing sliding velocity. The results of this study provide a considerable assessment to clarify the suitable frictional coefficient to be used in the finite element contact analysis of antler specimens.}, language = {en} } @inproceedings{HartmannKallweitFeldusenetal.2012, author = {Hartmann, Axel and Kallweit, Stephan and Feldusen, Antje and Schr{\"o}der, Wolfgang}, title = {Detection of upstream propagating sound waves at buffet flow using high-speed PIV}, pages = {14 S. : graph. Darst.}, year = {2012}, language = {en} } @article{GutheilBergGrotendorst2012, author = {Gutheil, Inge and Berg, Tommy and Grotendorst, Johannes}, title = {Performance Analysis of Parallel Eigensolvers of two Libraries on BlueGene/P}, series = {Journal of Mathematics and Systems Science}, volume = {2}, journal = {Journal of Mathematics and Systems Science}, number = {4}, publisher = {David Publishing}, address = {Libertyville}, issn = {2159-5291}, doi = {10.17265/2159-5291/2012.04.003}, pages = {231 -- 236}, year = {2012}, abstract = {Many applications in computational science and engineering require the computation of eigenvalues and vectors of dense symmetric or Hermitian matrices. For example, in DFT (density functional theory) calculations on modern supercomputers 10\% to 30\% of the eigenvalues and eigenvectors of huge dense matrices have to be calculated. Therefore, performance and parallel scaling of the used eigensolvers is of upmost interest. In this article different routines of the linear algebra packages ScaLAPACK and Elemental for parallel solution of the symmetric eigenvalue problem are compared concerning their performance on the BlueGene/P supercomputer. Parameters for performance optimization are adjusted for the different data distribution methods used in the two libraries. It is found that for all test cases the new library Elemental which uses a two-dimensional element by element distribution of the matrices to the processors shows better performance than the old ScaLAPACK library which uses a block-cyclic distribution.}, language = {en} } @misc{GraesslRenzHezeletal.2012, author = {Gr{\"a}ßl, Andreas and Renz, Wolfgang and Hezel, Fabian and Frauenrath, Tobias and Pfeiffer, Harald and Hoffmann, Werner and Kellmann, Peter and Martin, Conrad and Niendorf, Thoralf}, title = {Design, evaluation and application of a modular 32 channel transmit/receive surface coil array for cardiac MRI at 7T}, series = {2012 ISMRM Annual Meeting Proceedings}, journal = {2012 ISMRM Annual Meeting Proceedings}, issn = {1545-4428}, year = {2012}, abstract = {Cardiac MR (CMR) at ultrahigh (≥7.0 T) fields is regarded as one of the most challenging MRI applications. At 7.0 T image quality is not always exclusively defined by signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Detrimental effects bear the potential to spoil the signal-to-noise (SNR) and contrast-to-noise (CNR) benefits of cardiac MR (CMR) at 7.0 T. B₁⁺-inhomogeneities and signal voids represent the main challenges. Various pioneering coil concepts have been proposed to tackle these issues, enabling cardiac MRI at 7.0 T. This includes a trend towards an ever larger number of transmit and receive channels. This approach affords multi-dimensional B₁⁺ modulations to improve B₁⁺ shimming performance and to enhance RF efficiency. Also, parallel imaging benefits from a high number of receive channels enabling two-dimensional acceleration. Realizing the limitations of existing coil designs tailored for UHF CMR and recognizing the opportunities of a many element TX/RX channel architecture this work proposes a modular, two dimensional 32-channel transmit and receive array using loop elements and examines its efficacy for enhanced B¹+ homogeneity and improved parallel imaging performance.}, language = {en} } @book{Grotendorst2012, author = {Grotendorst, Johannes}, title = {Hierarchical methods for dynamics in complex molecular systems : IAS Winter School, 5 - 9 March 2012, Forschungszentrum J{\"u}lich GmbH ; lecture notes / ed. by Johannes Grotendorst, Godehard Sutmann, Gerhard Gompper, Dominik Marx}, publisher = {Forschungszentrum J{\"u}lich}, address = {J{\"u}lich}, isbn = {978-3-89336-768-9}, pages = {VI, 540 S. zahlr. Ill. u. graph. Darst.}, year = {2012}, language = {en} } @article{Grotendorst2012, author = {Grotendorst, Johannes}, title = {IAS Winter School: Hierarchical Methods for Dynamics in Complex Molecular Systems}, series = {Innovatives Supercomputing in Deutschland : inSiDE. 10 (2012), H. 1}, journal = {Innovatives Supercomputing in Deutschland : inSiDE. 10 (2012), H. 1}, publisher = {-}, pages = {104}, year = {2012}, language = {en} } @article{GrinsvenBonStrauvenetal.2012, author = {Grinsven, Bart van and Bon, Natalie vanden and Strauven, Hannelore and Grieten, Lars and Murib, Mohammed and Jim{\´e}nez Monroy, Kathia L. and Janssens, Stoffel D. and Haenen, Ken and Sch{\"o}ning, Michael Josef and Vermeeren, Veronique and Ameloot, Marcel and Michiels, Luc and Thoelen, Ronald and Ceuninck, Ward de and Wagner, Patrick}, title = {Heat-Transfer Resistance at Solid-Liquid Interfaces: A Tool for The Detection of Single Nucleotide Polymorphisms in DNA.}, series = {ACS Nano}, volume = {6}, journal = {ACS Nano}, number = {3}, publisher = {ACS Publications}, address = {Washington, DC}, issn = {1936-086X}, doi = {10.1021/nn300147e}, pages = {2712 -- 2721}, year = {2012}, abstract = {In this article, we report on the heat-transfer resistance at interfaces as a novel, denaturation-based method to detect single-nucleotide polymorphisms in DNA. We observed that a molecular brush of double-stranded DNA grafted onto synthetic diamond surfaces does not notably affect the heat-transfer resistance at the solid-to-liquid interface. In contrast to this, molecular brushes of single-stranded DNA cause, surprisingly, a substantially higher heat-transfer resistance and behave like a thermally insulating layer. This effect can be utilized to identify ds-DNA melting temperatures via the switching from low- to high heat-transfer resistance. The melting temperatures identified with this method for different DNA duplexes (29 base pairs without and with built-in mutations) correlate nicely with data calculated by modeling. The method is fast, label-free (without the need for fluorescent or radioactive markers), allows for repetitive measurements, and can also be extended toward array formats. Reference measurements by confocal fluorescence microscopy and impedance spectroscopy confirm that the switching of heat-transfer resistance upon denaturation is indeed related to the thermal on-chip denaturation of DNA.}, language = {en} } @article{GrandeMeffertSchoenbergeretal.2012, author = {Grande, Marion and Meffert, Elisabeth and Schoenberger, Eva and Jung, Stefanie and Frauenrath, Tobias and Huber, Walter and Hussmann, Katja and Moormann, Mareike and Heim, Stefan}, title = {From a concept to a word in a syntactically complete sentence: An fMRI study on spontaneous language production in an overt picture description task}, series = {NeuroImage}, volume = {61}, journal = {NeuroImage}, number = {3}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1522-2586}, doi = {10.1016/j.neuroimage.2012.03.087}, pages = {702 -- 714}, year = {2012}, abstract = {Spontaneous language has rarely been subjected to neuroimaging studies. This study therefore introduces a newly developed method for the analysis of linguistic phenomena observed in continuous language production during fMRI. Most neuroimaging studies investigating language have so far focussed on single word or — to a smaller extent — sentence processing, mostly due to methodological considerations. Natural language production, however, is far more than the mere combination of words to larger units. Therefore, the present study aimed at relating brain activation to linguistic phenomena like word-finding difficulties or syntactic completeness in a continuous language fMRI paradigm. A picture description task with special constraints was used to provoke hesitation phenomena and speech errors. The transcribed speech sample was segmented into events of one second and each event was assigned to one category of a complex schema especially developed for this purpose. The main results were: conceptual planning engages bilateral activation of the precuneus. Successful lexical retrieval is accompanied - particularly in comparison to unsolved word-finding difficulties - by the left middle and superior temporal gyrus. Syntactic completeness is reflected in activation of the left inferior frontal gyrus (IFG) (area 44). In sum, the method has proven to be useful for investigating the neural correlates of lexical and syntactic phenomena in an overt picture description task. This opens up new prospects for the analysis of spontaneous language production during fMRI.}, language = {en} } @inproceedings{GerhardsSanderBelloum2012, author = {Gerhards, Michael and Sander, Volker and Belloum, Adam}, title = {About the flexible Migration of Workflow Tasks to Clouds : Combining on- and off-premise Executions of Applications}, series = {CLOUD COMPUTING 2012 : The Third International Conference on Cloud Computing, GRIDs, and Virtualization ; July 22-27, 2012 - Nice, France}, booktitle = {CLOUD COMPUTING 2012 : The Third International Conference on Cloud Computing, GRIDs, and Virtualization ; July 22-27, 2012 - Nice, France}, editor = {Zimmermann, Wolf and Lee, Yong Woo and Demchenko, Yuri}, publisher = {IARIA Journals}, isbn = {978-1-61208-216-5}, pages = {82 -- 87}, year = {2012}, abstract = {An increasing number of applications target their executions on specific hardware like general purpose Graphics Processing Units. Some Cloud Computing providers offer this specific hardware so that organizations can rent such resources. However, outsourcing the whole application to the Cloud causes avoidable costs if only some parts of the application benefit from the specific expensive hardware. A partial execution of applications in the Cloud is a tradeoff between costs and efficiency. This paper addresses the demand for a consistent framework that allows for a mixture of on- and off-premise calculations by migrating only specific parts to a Cloud. It uses the concept of workflows to present how individual workflow tasks can be migrated to the Cloud whereas the remaining tasks are executed on-premise.}, language = {en} } @book{Gell2012, author = {Gell, Sebastian}, title = {Determinants of earnings forecast error, earnings forecast revision and earnings forecast accuracy}, publisher = {Springer Gabler}, address = {Wiesbaden}, isbn = {978-3-8349-3936-4}, doi = {10.1007/978-3-8349-3937-1}, pages = {XXIV, 125 Seiten}, year = {2012}, abstract = {​Earnings forecasts are ubiquitous in today's financial markets. They are essential indicators of future firm performance and a starting point for firm valuation. Extremely inaccurate and overoptimistic forecasts during the most recent financial crisis have raised serious doubts regarding the reliability of such forecasts. This thesis therefore investigates new determinants of forecast errors and accuracy. In addition, new determinants of forecast revisions are examined. More specifically, the thesis answers the following questions: 1) How do analyst incentives lead to forecast errors? 2) How do changes in analyst incentives lead to forecast revisions?, and 3) What factors drive differences in forecast accuracy?}, language = {en} } @inproceedings{GanegedaraAlahakoonMashfordetal.2012, author = {Ganegedara, H. and Alahakoon, D. and Mashford, J. and Paplinski, A. and M{\"u}ller, Karsten and Deserno, T. M.}, title = {Self organising map based region of interest labelling for automated defect identification in large sewer pipe image collections}, series = {The 2012 International Joint Conference on Neural Networks (IJCNN) : 10 - 15 June 2012, Brisbane, Australia ; [part of the] 2012 IEEE World Congress on Computational Intelligence (IEEE-WCCI 2012)}, booktitle = {The 2012 International Joint Conference on Neural Networks (IJCNN) : 10 - 15 June 2012, Brisbane, Australia ; [part of the] 2012 IEEE World Congress on Computational Intelligence (IEEE-WCCI 2012)}, publisher = {IEEE}, address = {Piscataway, NJ}, organization = {IEEE Computational Intelligence Society (IEEE-CIS)}, isbn = {978-1-4673-1490-9}, pages = {8 S.}, year = {2012}, language = {en} } @inproceedings{FunkeBoernerKeinzetal.2012, author = {Funke, Harald and B{\"o}rner, Sebastian and Keinz, Jan and Kusterer, K. and Kroninger, D. and Kitajima, J. and Kazari, M. and Horikama, A.}, title = {Numerical and experimental characterization of low NOx Micromix combustion principle for industrial hydrogen gas turbine applications}, series = {Proceedings of ASME Turbo Expo 2012}, booktitle = {Proceedings of ASME Turbo Expo 2012}, pages = {11}, year = {2012}, language = {en} } @inproceedings{FunkeBoernerKeinzetal.2012, author = {Funke, Harald and B{\"o}rner, Sebastian and Keinz, Jan and Hendrick, P. and Recker, E.}, title = {Low NOx Hydrogen combustion chamber for industrial gas turbine applications", 14th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery}, series = {ISROMAC-14 : the Forteenth International Symposium on Transport Phenomena and Dynamics of Rotating Machinery ; Honolulu, Hawaii, February 27 - March 02nd, 2012}, booktitle = {ISROMAC-14 : the Forteenth International Symposium on Transport Phenomena and Dynamics of Rotating Machinery ; Honolulu, Hawaii, February 27 - March 02nd, 2012}, year = {2012}, language = {en} } @inproceedings{FuchsRitzStrauch2012, author = {Fuchs, Britta and Ritz, Thomas and Strauch, Jakob}, title = {Usability of mobile applications : dissemination of usability engineering in small and medium enterprises}, series = {Proceedings of the International Conference on Data Communication Networking, e-Business and Optical Communication Systems : Rome, Italy, 24 - 27 July, 2012 ; [integrated in the ICETE (International Conference on e-Business and Telecommunications)]}, booktitle = {Proceedings of the International Conference on Data Communication Networking, e-Business and Optical Communication Systems : Rome, Italy, 24 - 27 July, 2012 ; [integrated in the ICETE (International Conference on e-Business and Telecommunications)]}, editor = {Obaidat, Mohammad S.}, publisher = {SciTePress}, address = {[Lissabon]}, isbn = {978-989-8565-23-5}, pages = {272 -- 277}, year = {2012}, language = {en} } @inproceedings{FrotscherRaatschenStaat2012, author = {Frotscher, Ralf and Raatschen, Hans-J{\"u}rgen and Staat, Manfred}, title = {Application of an edge-based smoothed finite element method on geometrically non-linear plates of non-linear material}, series = {Proceedings European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2012)}, booktitle = {Proceedings European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2012)}, editor = {Eberhardsteiner, J.}, year = {2012}, language = {en} } @inproceedings{FrotscherRaatschenStaat2012, author = {Frotscher, Ralf and Raatschen, Hans-J{\"u}rgen and Staat, Manfred}, title = {Effectiveness of the edge-based smoothed finite element method applied to soft biological tissues}, series = {ESMC-2012 - 8th European Solid Mechanics Conference, Graz, Austria, July 9-13, 2012}, booktitle = {ESMC-2012 - 8th European Solid Mechanics Conference, Graz, Austria, July 9-13, 2012}, editor = {Holzapfel, Gerhard A.}, publisher = {Verlag d. Technischen Universit{\"a}t Graz}, address = {Graz}, isbn = {978-3-85125-223-1}, year = {2012}, language = {en} } @inproceedings{FrickeZiolkoAnthrakidisetal.2012, author = {Fricke, Barbara and Ziolko, C. and Anthrakidis, Anette and Alexopoulos, Spiros and Hoffschmidt, Bernhard and Giese, F. and Dillig, M.}, title = {InnoSol - environmental aspects of the open volumetric receiver technology}, series = {30th ISES Biennial Solar World Congress 2011 : : Kassel, Germany, 28 August - 2 September 2011. Vol. 5}, booktitle = {30th ISES Biennial Solar World Congress 2011 : : Kassel, Germany, 28 August - 2 September 2011. Vol. 5}, publisher = {Curran}, address = {Red Hook, NY}, organization = {International Solar Energy Society}, pages = {3895 -- 3900}, year = {2012}, language = {en} } @inproceedings{FredebeulKreinSteingroever2012, author = {Fredebeul-Krein, Markus and Steingr{\"o}ver, Markus}, title = {Wholesale Broadband Access to IPTV in an NGA environment : how to deal with it from a regulatory perspective?}, pages = {1 -- 16}, year = {2012}, language = {en} } @misc{FrauenrathPfeifferHezeletal.2012, author = {Frauenrath, Tobias and Pfeiffer, Harald and Hezel, Fabian and Dieringer, Matthias A. and Winter, Lukas and Gr{\"a}ßl, Andreas and Santoro, Davide and {\"O}zerdem, Celal and Renz, Wolfgang and Greiser, Andreas and Niendorf, Thoralf}, title = {Lessons learned from cardiac MRI at 7.0 T: LV function assessment at 3.0 T using local multi-channel transceiver coil arrays}, series = {2012 ISMRM Annual Meeting Proceedings}, journal = {2012 ISMRM Annual Meeting Proceedings}, issn = {1545-4428}, year = {2012}, abstract = {Cardiac MR (CMR) is of proven clinical value but also an area of vigorous ongoing research since image quality is not always exclusively defined by signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Recent developments of CMR at 7.0 T have been driven by pioneering explorations into novel multichannel transmit and receive coil array technology to tackle the challenges B1+-field inhomogeneities, to offset specific-absorption rate (SAR) constraints and to reduce banding artifacts in SSFP imaging. For this study, recognition of the benefits and performance of local surface Tx/Rx-array structures recently established at 7.0 T inspired migration to 3.0 T, where RF inhomogeneities and SAR limitations encountered in routine clinical CMR, though somewhat reduced versus the 7.0 T situation, remain significant. For all these reasons, this study was designed to build and examine the feasibility of a local four channel Tx/Rx cardiac coil array for anatomical and functional cardiac imaging at 3.0 T. For comparison, a homebuilt 4 channel Rx cardiac coil array exhibiting the same geometry as the Tx/Rx coil and a Rx surface coil array were used.}, language = {en} } @misc{FrauenrathFuchsHezeletal.2012, author = {Frauenrath, Tobias and Fuchs, Katharina and Hezel, Fabian and Dieringer, Matthias A. and Rieger, Jan and Niendorf, Thoralf}, title = {Improved cardiac triggering by combining multiple physiological signals: a cardiac MR feasibility study at 7.0 T}, series = {2012 ISMRM Annual Meeting Proceedings}, journal = {2012 ISMRM Annual Meeting Proceedings}, issn = {1545-4428}, year = {2012}, abstract = {In current clinical cardiovascular MR (CMR) practice cardiac motion is commonly dealt with using ECG based synchronization. However, ECG is corrupted by magneto-hydrodynamic (MHD) effects in magnetic fields. This leads to artifacts in the ECG trace and evokes severe T-wave elevations, which might be misinterpreted as R-waves resulting in erroneous triggering. At (ultra)high field strengths, the propensity of ECG recordings to MHD effects is further pronounced. Pulse oximetry (POX) being inherently sensitive to blood oxygenation provides an alternative approach for cardiac gating. However, due to the travel time of the blood the peak of maximum oxygenation and hence the trigger is delayed by approx. 300 ms with respect to the ECG's R-wave. Also the peak of maximum oxygenation shows a jitter of up to 65 ms. Alternative triggering approaches include acoustic cardiac triggering (ACT). In current clinical practice cardiac gating / triggering commonly relies on using single physiological signals only. Realizing this limitation this study proposes a combined triggering approach which exploits multiple physiological signals including ECG, POX or ACT to track cardiac activity. The feasibility of the coupled approach is examined for LV function assessment at 7.0 T. For this purpose, breath-held 2D-CINE imaging in conjunction with cardiac synchronization was performed paralleled by real time logging of physiological waveforms to track (mis)synchronization between the cardiac cycle and data acquisition. Combinations of the ECG, POX and ACT signals were evaluated and processed in real time to facilitate reliable trigger information.}, language = {en} } @article{FrauenrathFuchsDieringeretal.2012, author = {Frauenrath, Tobias and Fuchs, Katharina and Dieringer, Matthias A. and {\"O}zerdem, Celal and Patel, Nishan and Renz, Wolfgang and Greiser, Andreas and Elgeti, Thomas and Niendorf, Thoralf}, title = {Detailing the use of magnetohydrodynamic effects for synchronization of MRI with the cardiac cycle: A feasibility study}, series = {Journal of Magnetic Resonance Imaging}, volume = {36}, journal = {Journal of Magnetic Resonance Imaging}, number = {2}, publisher = {Wiley-Liss}, address = {New York}, issn = {1522-2586}, doi = {10.1002/jmri.23634}, pages = {364 -- 372}, year = {2012}, abstract = {Purpose: To investigate the feasibility of using magnetohydrodynamic (MHD) effects for synchronization of magnetic resonance imaging (MRI) with the cardiac cycle. Materials and Methods: The MHD effect was scrutinized using a pulsatile flow phantom at B0 = 7.0 T. MHD effects were examined in vivo in healthy volunteers (n = 10) for B0 ranging from 0.05-7.0 T. Noncontrast-enhanced MR angiography (MRA) of the carotids was performed using a gated steady-state free-precession (SSFP) imaging technique in conjunction with electrocardiogram (ECG) and MHD synchronization. Results: The MHD potential correlates with flow velocities derived from phase contrast MRI. MHD voltages depend on the orientation between B0 and the flow of a conductive fluid. An increase in the interelectrode spacing along the flow increases the MHD potential. In vivo measurement of the MHD effect provides peak voltages of 1.5 mV for surface areas close to the common carotid artery at B0 = 7.0 T. Synchronization of MRI with the cardiac cycle using MHD triggering is feasible. MHD triggered MRA of the carotids at 3.0 T showed an overall image quality and richness of anatomic detail, which is comparable to ECG-triggered MRAs. Conclusion: This feasibility study demonstrates the use of MHD effects for synchronization of MR acquisitions with the cardiac cycle. J. Magn. Reson. Imaging 2012;36:364-372. © 2012 Wiley Periodicals, Inc.}, language = {en} } @article{FischerKowalskiPudasaini2012, author = {Fischer, Jan-Thomas and Kowalski, Julia and Pudasaini, Shiva P.}, title = {Topographic curvature effects in applied avalanche modelling}, series = {Cold Regions Science and Technology}, volume = {74-75}, journal = {Cold Regions Science and Technology}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1872-7441}, doi = {10.1016/j.coldregions.2012.01.005}, pages = {21 -- 30}, year = {2012}, abstract = {This paper describes the implementation of topographic curvature effects within the RApid Mass MovementS (RAMMS) snow avalanche simulation toolbox. RAMMS is based on a model similar to shallow water equations with a Coulomb friction relation and the velocity dependent Voellmy drag. It is used for snow avalanche risk assessment in Switzerland. The snow avalanche simulation relies on back calculation of observed avalanches. The calibration of the friction parameters depends on characteristics of the avalanche track. The topographic curvature terms are not yet included in the above mentioned classical model. Here, we fundamentally improve this model by mathematically and physically including the topographic curvature effects. By decomposing the velocity dependent friction into a topography dependent term that accounts for a curvature enhancement in the Coulomb friction, and a topography independent contribution similar to the classical Voellmy drag, we construct a general curvature dependent frictional resistance, and thus propose new extended model equations. With three site-specific examples, we compare the apparent frictional resistance of the new approach, which includes topographic curvature effects, to the classical one. Our simulation results demonstrate substantial effects of the curvature on the flow dynamics e.g., the dynamic pressure distribution along the slope. The comparison of resistance coefficients between the two models demonstrates that the physically based extension presents an improvement to the classical approach. Furthermore a practical example highlights its influence on the pressure outline in the run out zone of the avalanche. Snow avalanche dynamics modeling natural terrain curvature centrifugal force friction coefficients.}, language = {en} } @article{FerreinSteinbauerVassos2012, author = {Ferrein, Alexander and Steinbauer, Gerald and Vassos, Stavros}, title = {Action-Based Imperative Programming with YAGI}, pages = {24 -- 31}, year = {2012}, abstract = {Many tasks for autonomous agents or robots are best described by a specification of the environment and a specification of the available actions the agent or robot can perform. Combining such a specification with the possibility to imperatively program a robot or agent is what we call the actionbased imperative programming. One of the most successful such approaches is Golog. In this paper, we draft a proposal for a new robot programming language YAGI, which is based on the action-based imperative programming paradigm. Our goal is to design a small, portable stand-alone YAGI interpreter. We combine the benefits of a principled domain specification with a clean, small and simple programming language, which does not exploit any side-effects from the implementation language. We discuss general requirements of action-based programming languages and outline YAGI, our action-based language approach which particularly aims at embeddability.}, language = {en} } @article{FerreinMeyer2012, author = {Ferrein, Alexander and Meyer, Thomas}, title = {A Brief Overview of Artificial Intelligence in South Africa}, series = {AI Magazine}, volume = {33}, journal = {AI Magazine}, number = {1}, publisher = {AAAI}, address = {Menlo Park}, issn = {0738-4602}, doi = {10.1609/aimag.v33i1.2357}, pages = {99 -- 101}, year = {2012}, abstract = {South Africa in recent years is the establishment of a number of research hubs involved in AI activities ranging from mobile robotics and computational intelligence, to knowledge representation and reasoning, and human language technologies. In this survey we take the reader through a quick tour of the research being conducted at these hubs, and touch on an initiative to maintain and extend the current level of interest in AI research in the country.}, language = {en} } @inproceedings{FerreinKallweitLautermann2012, author = {Ferrein, Alexander and Kallweit, Stephan and Lautermann, Mark}, title = {Towards an autonomous pilot system for a tunnel boring machine}, series = {5th Robotics and Mechatronics Conference of South Africa (ROBMECH) : 26 - 27 November 2012 ; CSIR International Conference Centre Gauteng South Africa}, booktitle = {5th Robotics and Mechatronics Conference of South Africa (ROBMECH) : 26 - 27 November 2012 ; CSIR International Conference Centre Gauteng South Africa}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-4673-5183-6}, year = {2012}, language = {en} } @inproceedings{FeldmannPyschnyDoeringetal.2012, author = {Feldmann, Markus and Pyschny, D. and D{\"o}ring, Bernd and Kuhnhenne, Markus}, title = {Life cycle assessment of steel constructions}, series = {Life-cycle and sustainability of civil infrastructure systems : proceedings of the Third International Symposium on Life-Cycle Civil Engineering (IALCCE'12) : Vienna, Austria, October 3-6, 2012}, booktitle = {Life-cycle and sustainability of civil infrastructure systems : proceedings of the Third International Symposium on Life-Cycle Civil Engineering (IALCCE'12) : Vienna, Austria, October 3-6, 2012}, publisher = {Taylor and Francis}, address = {Hoboken}, organization = {International Symposium on Life-Cycle Civil Engineering <3, 2012, Wien>}, isbn = {978-0-203-10336-4}, pages = {321}, year = {2012}, language = {en} } @article{FateriHoetterGebhardt2012, author = {Fateri, Miranda and H{\"o}tter, Jan-Steffen and Gebhardt, Andreas}, title = {Experimental and Theoretical Investigation of Buckling Deformation of Fabricated Objects by Selective Laser Melting}, series = {Physics Procedia}, volume = {39}, journal = {Physics Procedia}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1875-3892}, doi = {10.1016/j.phpro.2012.10.062}, pages = {464 -- 470}, year = {2012}, abstract = {Although Selective Laser Melting (SLM) process is an innovative manufacturing method, there are challenges such as inferior mechanical properties of fabricated objects. Regarding this, buckling deformation which is caused by thermal stress is one of the undesired mechanical properties which must be alleviated. As buckling deformation is more observable in hard to process materials, silver is selected to be studied theoretically and experimentally for this paper. Different scanning strategies are utilized and a Finite Element Method (FEM) is applied to calculate the temperature gradient in order to determine its effect on the buckling deformation of the objects from experiments.}, language = {en} } @inproceedings{EngelsSchnabel2012, author = {Engels, Elmar and Schnabel, Holger}, title = {Rapid-control-prototyping of industrial drives for the sercos automation bus}, series = {13th International Workshop on Mechatronics (MECATRONICS), 2012 9th France-Japan \& 7th Europe-Asia Congress on and Research and Education in Mechatronics (REM)}, booktitle = {13th International Workshop on Mechatronics (MECATRONICS), 2012 9th France-Japan \& 7th Europe-Asia Congress on and Research and Education in Mechatronics (REM)}, isbn = {978-1-4673-4771-6}, pages = {177 -- 181}, year = {2012}, abstract = {This article describes the functionality of a MATLAB® library that can be used to develop motion-logic applications in MATLAB programming language for industrial drive and control systems using the well known sercos automation bus. Therewith MATLAB's functionality is extended to designing automation applications from single axis machines up to multi-kinematic robots.}, language = {en} } @article{EilmannRigling2012, author = {Eilmann, Britta and Rigling, Andreas}, title = {Tree-growth analyses to estimate tree species' drought tolerance}, series = {Tree Physiology}, volume = {32}, journal = {Tree Physiology}, number = {2}, editor = {Abrams, Marc}, publisher = {Oxford University Press}, address = {Oxford}, issn = {0829-318X (Print)}, doi = {10.1093/treephys/tps004}, pages = {178 -- 187}, year = {2012}, abstract = {Climate change is challenging forestry management and practices. Among other things, tree species with the ability to cope with more extreme climate conditions have to be identified. However, while environmental factors may severely limit tree growth or even cause tree death, assessing a tree species' potential for surviving future aggravated environmental conditions is rather demanding. The aim of this study was to find a tree-ring-based method suitable for identifying very drought-tolerant species, particularly potential substitute species for Scots pine (Pinus sylvestris L.) in Valais. In this inner-Alpine valley, Scots pine used to be the dominating species for dry forests, but today it suffers from high drought-induced mortality. We investigate the growth response of two native tree species, Scots pine and European larch (Larix decidua Mill.), and two non-native species, black pine (Pinus nigra Arnold) and Douglas fir (Pseudotsuga menziesii Mirb. var. menziesii), to drought. This involved analysing how the radial increment of these species responded to increasing water shortage (abandonment of irrigation) and to increasingly frequent drought years. Black pine and Douglas fir are able to cope with drought better than Scots pine and larch, as they show relatively high radial growth even after irrigation has been stopped and a plastic growth response to drought years. European larch does not seem to be able to cope with these dry conditions as it lacks the ability to recover from drought years. The analysis of trees' short-term response to extreme climate events seems to be the most promising and suitable method for detecting how tolerant a tree species is towards drought. However, combining all the methods used in this study provides a complete picture of how water shortage could limit species.}, language = {en} } @inproceedings{DuongNguyenStaat2012, author = {Duong, Minh Tuan and Nguyen, Nhu Huynh and Staat, Manfred}, title = {Numerical stability enhancement of modeling hyperelastic materials}, series = {Proceedings European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2012)}, booktitle = {Proceedings European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2012)}, editor = {Eberhardsteiner, J.}, year = {2012}, language = {en} } @inproceedings{DuongNguyenStaat2012, author = {Duong, Minh Tuan and Nguyen, Nhu Hunyh and Staat, Manfred}, title = {Finite Element Implementation of a 3D Fung-type Model}, series = {ESMC-2012 - 8th European Solid Mechanics Conference, Graz, Austria, July 9-13, 2012}, booktitle = {ESMC-2012 - 8th European Solid Mechanics Conference, Graz, Austria, July 9-13, 2012}, publisher = {Verlag d. Technischen Universit{\"a}t Graz}, address = {Graz}, isbn = {978-3-85125-223-1}, year = {2012}, language = {en} } @book{DigelZhubanovaAkimbekov2012, author = {Digel, Ilya and Zhubanova, Azhar Ahmetovna and Akimbekov, Nuraly S.}, title = {Visual Virology}, address = {Almaty}, isbn = {978-601-247-298-1}, pages = {144 S. : zahlr. Ill.}, year = {2012}, language = {en} } @incollection{DigelMansurovBiisenbaevetal.2012, author = {Digel, Ilya and Mansurov, Zulkhair and Biisenbaev, Makhmut and Savitskaya, Irina and Kistaubaeva, Aida and Akimbekov, Nuraly S. and Zhubanova, Azhar}, title = {Heterogeneous Composites on the Basis of Microbial Cells and Nanostructured Carbonized Sorbents}, series = {Composites and Their Applications}, booktitle = {Composites and Their Applications}, editor = {Hu, Ning}, publisher = {Intech}, address = {London}, isbn = {978-953-51-0706-4}, doi = {10.5772/47796}, pages = {249 -- 272}, year = {2012}, abstract = {The fact that microorganisms prefer to grow on liquid/solid phase surfaces rather than in the surrounding aqueous phase was noticed long time ago [1]. Virtually any surface - animal, mineral, or vegetable - is a subject for microbial colonization and subsequent biofilm formation. It would be adequate to name just a few notorious examples on microbial colonization of contact lenses, ship hulls, petroleum pipelines, rocks in streams and all kinds of biomedical implants. The propensity of microorganisms to become surface-bound is so profound and ubiquitous that it vindicates the advantages for attached forms over their free-ranging counterparts [2]. Indeed, from ecological and evolutionary standpoints, for many microorganisms the surface-bound state means dwelling in nutritionally favorable, non-hostile environments [3]. Therefore, in most of natural and artificial ecosystems surface-associated microorganisms vastly outnumber organisms in suspension and often organize into complex communities with features that differ dramatically from those of free cells [4].}, language = {en} } @inproceedings{DachwaldMikuckiTulaczyketal.2012, author = {Dachwald, Bernd and Mikucki, Jill A. and Tulaczyk, Slawek and Digel, Ilya and Feldmann, Marco and Espe, Clemens and Plescher, Engelbert and Xu, Changsheng}, title = {IceMole - a maneuverable probe for clean in-situ analysis and sampling of subsurface ice and subglacial aquatic ecosystems : extended abstract / SCAR Open Science Conference 2012, Session 29: Advancing Clean Technologies for Exploration of Glacial Aquatic Ecosystems}, year = {2012}, abstract = {The "IceMole" is a novel maneuverable subsurface ice probe for clean in-situ analysis and sampling of subsurface ice and subglacial water/brine. It is developed and build at FH Aachen University of Applied Sciences' Astronautical Laboratory. A first prototype was successfully tested on the Swiss Morteratsch glacier in 2010. Clean sampling is achieved with a hollow ice screw (as it is used in mountaineering) at the tip of the probe. Maneuverability is achieved with a differentially heated melting head. Funded by the German Space Agency (DLR), a consortium led by FH Aachen currently develops a much more advanced IceMole probe, which includes a sophisticated system for obstacle avoidance, target detection, and navigation in the ice. We intend to use this probe for taking clean samples of subglacial brine at the Blood Falls (McMurdo Dry Valleys, East Antarctica) for chemical and microbiological analysis. In our conference contribution, we 1) describe the IceMole design, 2) report the results of the field tests of the first prototype on the Morteratsch glacier, 3) discuss the probe's potential for the clean in-situ analysis and sampling of subsurface ice and subglacial liquids, and 4) outline the way ahead in the development of this technology.}, subject = {Eisschicht}, language = {en} } @inproceedings{DachwaldFeldmannEspeetal.2012, author = {Dachwald, Bernd and Feldmann, Marco and Espe, Clemens and Plescher, Engelbert and Konstantinidis, K. and Forstner, R.}, title = {Enceladus explorer - A maneuverable subsurface probe for autonomous navigation through deep ice}, series = {63rd International Astronautical Congress 2012, IAC 2012; Naples; Italy; 1 October 2012 through 5 October 2012. (Proceedings of the International Astronautical Congress, IAC ; 3)}, booktitle = {63rd International Astronautical Congress 2012, IAC 2012; Naples; Italy; 1 October 2012 through 5 October 2012. (Proceedings of the International Astronautical Congress, IAC ; 3)}, publisher = {Curran}, address = {Red Hook, NY}, organization = {International Astronautical Congress <63, 2012, Napoli>}, isbn = {978-1-62276-979-7}, pages = {1756 -- 1766}, year = {2012}, language = {en} } @article{CzarneckiSpiliopoulou2012, author = {Czarnecki, Christian and Spiliopoulou, Myra}, title = {A holistic framework for the implementation of a next generation network}, series = {International Journal of Business Information Systems}, volume = {9}, journal = {International Journal of Business Information Systems}, number = {4}, publisher = {Inderscience Enterprises}, address = {Olney, Bucks}, issn = {1746-0972}, doi = {10.1504/IJBIS.2012.046291}, pages = {385 -- 401}, year = {2012}, abstract = {As the potential of a next generation network (NGN) is recognised, telecommunication companies consider switching to it. Although the implementation of an NGN seems to be merely a modification of the network infrastructure, it may trigger or require changes in the whole company, because it builds upon the separation between service and transport, a flexible bundling of services to products and the streamlining of the IT infrastructure. We propose a holistic framework, structured into the layers 'strategy', 'processes' and 'information systems' and incorporate into each layer all concepts necessary for the implementation of an NGN, as well as the alignment of these concepts. As a first proof-of-concept for our framework we have performed a case study on the introduction of NGN in a large telecommunication company; we show that our framework captures all topics that are affected by an NGN implementation.}, language = {en} } @article{BaeckerRaueSchusseretal.2012, author = {B{\"a}cker, Matthias and Raue, Markus and Schusser, Sebastian and Jeitner, C. and Breuer, L. and Wagner, P. and Poghossian, Arshak and F{\"o}rster, Arnold and Mang, Thomas and Sch{\"o}ning, Michael Josef}, title = {Microfluidic chip with integrated microvalves based on temperature- and pH-responsive hydrogel thin films}, series = {Physica Status Solidi (a)}, volume = {209}, journal = {Physica Status Solidi (a)}, number = {5}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1862-6319}, doi = {10.1002/pssa.201100763}, pages = {839 -- 845}, year = {2012}, abstract = {Two types of microvalves based on temperature-responsive poly(N-isopropylacrylamide) (PNIPAAm) and pH-responsive poly(sodium acrylate) (PSA) hydrogel films have been developed and tested. The PNIPAAm and PSA hydrogel films were prepared by means of in situ photopolymerization directly inside the fluidic channel of a microfluidic chip fabricated by combining Si and SU-8 technologies. The swelling/shrinking properties and height changes of the PNIPAAm and PSA films inside the fluidic channel were studied at temperatures of deionized water from 14 to 36 °C and different pH values (pH 3-12) of Titrisol buffer, respectively. Additionally, in separate experiments, the lower critical solution temperature (LCST) of the PNIPAAm hydrogel was investigated by means of a differential scanning calorimetry (DSC) and a surface plasmon resonance (SPR) method. Mass-flow measurements have shown the feasibility of the prepared hydrogel films to work as an on-chip integrated temperature- or pH-responsive microvalve capable to switch the flow channel on/off.}, language = {en} } @inproceedings{BungSunMeirelesetal.2012, author = {Bung, Daniel Bernhard and Sun, Q. and Meireles, I. and Matos, J. and Viseu, T.}, title = {USBR type III stilling basin performance for steep stepped spillways}, series = {Hydraulic structures into the 21st century : 4th IAHR International Symposium on Hydraulic Structures : 9.-11.2.2012, Porto}, booktitle = {Hydraulic structures into the 21st century : 4th IAHR International Symposium on Hydraulic Structures : 9.-11.2.2012, Porto}, organization = {International Symposium on Hydraulic Structures <4, 2012, Porto>}, isbn = {978-989-8509-01-7}, pages = {Elektronisch publiziert}, year = {2012}, language = {en} } @inproceedings{Bung2012, author = {Bung, Daniel Bernhard}, title = {Sensitivity of phase detection techniques in aerated chute flows to hydraulic design parameters}, series = {2nd European IAHR congress : 27. - 29. June 2012, M{\"u}nchen}, booktitle = {2nd European IAHR congress : 27. - 29. June 2012, M{\"u}nchen}, publisher = {Lehrstuhl u. Versuchsanst. f{\"u}r Wasserbau u. Wasserwirtschaft d. TU M{\"u}nchen}, address = {M{\"u}nchen}, organization = {International Association for Hydraulic Engineering and Research}, isbn = {978-3-943683-03-5}, pages = {Artikelkennnummer: B15}, year = {2012}, language = {en} } @article{BragardvanHoekDeDoncker2012, author = {Bragard, Michael and van Hoek, H. and De Doncker, R. W.}, title = {A major design step in IETO concept realization that allows overcurrent protection and pushes limits of switching performance}, series = {IEEE transactions on power electronics}, volume = {27}, journal = {IEEE transactions on power electronics}, number = {9}, publisher = {IEEE}, address = {New York}, issn = {0885-8993}, doi = {10.1109/TPEL.2012.2189136}, pages = {4163 -- 4171}, year = {2012}, abstract = {This paper presents the latest prototype of the integrated emitter turn-off thyristor concept, which potentially ranks among thyristor high-power devices like the gate turn-off thyristor and the integrated gate-commutated thyristor (IGCT). Due to modifications of the external driver stage and mechanical press-pack design optimization, this prototype allows for full device characterization. The turn-off capability was increased to 1600 A with an active silicon area of 823mm2 . This leads to a transient peak power of 672.1kW/cm² . Within this paper, measurements and concept assessment are presented and a comparison to state-of-the-art IGCT devices is provided.}, language = {en} } @phdthesis{Bragard2012, author = {Bragard, Michael}, title = {The integrated emitter turn-off thyristor : an innovative MOS-gated high-power device. - (Aachener Beitr{\"a}ge des ISEA ; 62)}, publisher = {Shaker}, address = {Aachen}, isbn = {978-3-8440-1152-4}, pages = {III, 164 S. : Ill., graph. Darst.}, year = {2012}, abstract = {This thesis introduces the Integrated Emitter Turn-Off (IETO) Thyristor as a new high-power device. Known state-of-the-art research activities like the Dual GCT, the ETO thyristor and the ICT were presented and critically reviewed. A comparison with commercialized solutions identifies the pros and cons of each type of device family. Based on this analysis, the IETO structure is proposed, covering most benefits of each device class. In particular the combination of a MOS-assisted turn-off with a thyristor-based device allows a voltage-controlled MOS switching and the low on-state voltage of the thyristors. The following synthesis of an IETO device stands on a three-dimensional field of optimization spanned by electric, mechanical and thermal aspects. From an electric point of view, the lowest possible parasitic inductance and resistance within the commutation path are optimization criteria. The mechanical construction has to withstand the required contact pressure of multiple kilo Newtons. Finally, thermal borders limit the maximum average current of the device. FEM simulations covering these three aspects are performed for several design proposals. An IETO prototype is constructed and measurements on various test benches attest thermal, mechanical and electric performance. A local decoupling of the external driver stage and the presspack housing is presented by a cable connection. This separation enables a thermal and mechanical independence, which is advantageous in terms of vibrations and thermal cycles including increased reliability. The electric pulse performance of the prototype device is a factor of 3.1 above today''s solutions. In single-pulse measurements, a current up to 1600 A was successfully turned off at 115°C with an active silicon area of 823 mm². One reason for this increased turn-off capability is the extremely low-inductive construction. Additional functionality of the IETO thyristor like over-current self-protection and defined short-circuit failure state are successfully verified.}, language = {en} }