TY - JOUR A1 - Berretz, Frank A1 - Skorupa, Sascha A1 - Sander, Volker A1 - Belloum, Adam A1 - Bubak, Marian T1 - Actor-Driven Workflow Execution in Distributed Environments JF - Euro-Par 2010 Parallel Processing Workshops : HeteroPAR, HPCC, HiBB, CoreGrid, UCHPC, HPCF, PROPER, CCPI, VHPC ; Ischia, Italy, August 31 - September 3, 2010 ; revised selected papers / Mario R. Guarracino ... (eds.) Y1 - 2011 SN - 978-3-642-21877-4 N1 - Lecture Notes in Computer Science ; 6586 SP - 287 EP - 294 PB - Springer CY - Berlin ER - TY - JOUR A1 - Gerhards, M. A1 - Skorupa, Sascha A1 - Sander, Volker A1 - Pfeiffer, P. A1 - Belloum, Adam T1 - Towards a security framework for a WS-HumanTask processor JF - 7th International Conference on Network and Service Management (CNSM), 2011 Paris Y1 - 2011 SN - 978-3-901882-44-9 SP - 1 EP - 5 PB - IEEE CY - New York ER - TY - JOUR A1 - Gerhards, M. A1 - Skorupa, Sascha A1 - Sander, Volker A1 - Belloum, Adam A1 - Vesunin, D. A1 - Benabdelkader, A. T1 - HisT/PLIER : A Two-Fold Provenance Approach for Grid-Enabled Scientific Workflows Using WS-VLAM JF - 12th IEEE/ACM International Conference on Grid Computing (GRID), 2011 Y1 - 2011 U6 - https://doi.org/10.1109/Grid.2011.39 SP - 224 EP - 225 PB - IEEE CY - New York ER - TY - JOUR A1 - Hirschfeld, Julian A. A1 - Lustfeld, Hans A1 - Reißel, Martin A1 - Steffen, Bernhard T1 - A novel scheme for precise diagnostics and effective stabilization of currents in a fuel cell stack JF - International Journal of Energy Research N2 - A novel scheme for detecting inhomogeneous internal currents in a fuel cell stack is presented. In this paper the scheme is investigated for the case that the flow field plates consist of graphite. Then plates of high conductivity, e.g. aluminium between the flow field plates together with small slits in these plates have three effects: (a) Whenever a local inhomogeneity of the electric current occurs at a particular cell in the stack, this will induce a surface current close to that cell perpendicular to the averaged current. This current can be detected. (b) The plates of high conductivity completely prevent the inhomogeneities from spreading to neighbouring cells. (c) Even at the particular cell the inhomogeneity is suppressed as far as possible. Thus this scheme leads to much better diagnostic possibilities and at the same time reduces electric instabilities to an extent, where they probably become harmless. This scheme will first be explained for a simple model to clarify the idea. However, very precise three dimensional computations using realistic parameters are presented, corroborating the results of the simple model. Y1 - 2010 U6 - https://doi.org/10.1002/er.1662 SN - 0363-907X VL - 34 IS - 3 SP - 293 EP - 301 PB - Wiley CY - London ER - TY - JOUR A1 - Hirschfeld, Julian A. A1 - Lustfeld, Hans A1 - Reißel, Martin A1 - Steffen, Bernhard T1 - Tomographic diagnostics of current distributions in a fuel cell stack JF - International Journal of Energy Research N2 - A novel tomographic scheme for analysing the state of any single membrane electrode assembly (MEA) in a stack is suggested. Plates of very high conductivity placed between every fuel cell and slitted in an appropriate manner cause surface currents at well-defined locations of the stack. We show that knowing these surface currents, information about anomalies of the currents in a MEA can be obtained using the methods of tomography. The results are mathematically not unique. However, when assuming plausible defect structures, one can exclude improbable deficiencies by applying a special form of simulated annealing. We present numerical calculations of typical examples demonstrating that the essential defects of the MEA in any single cell of the stack can be detected and their extent can be determined. Y1 - 2010 U6 - https://doi.org/10.1002/er.1634 SN - 0363-907X VL - 34 IS - 3 SP - 284 EP - 292 PB - Wiley CY - London ER - TY - JOUR A1 - Heinrichs, U. A1 - Pietrzyk, Uwe A1 - Ziemons, Karl T1 - Design optimization of the PMT-ClearPET prototypes based on simulation studies with GEANT3 JF - IEEE Transactions on Nuclear Science N2 - Within the Crystal Clear Collaboration (CCC), four centers are developing second generation high performance small animal positron emission tomography (PET) scanners for different kinds of animals and medical applications. The first prototypes are photomultiplier tube (PMT)-based systems including depth of interaction (DOI) detection by using a phoswich layer of lutetium oxyorthosilicate (LSO) and lutetium yttrium aluminum perovskite (LuYAP). The aim of these simulation studies is to optimize sensitivity and spatial resolution of given designs, which vary in fields of view (FOVs) caused by different detector configurations (ring/octagon) and sizes. For this purpose the simulation tool GEANT3 (CERN, Geneva, Switzerland) was used. Y1 - 2003 SN - 0018-9499 VL - 50 IS - 5 SP - 1428 EP - 1432 ER - TY - JOUR A1 - Müller, Martin A1 - Hirschfeld, Julian A. A1 - Lambertz, Rita A1 - Schulze Lohoff, Andreas A1 - Lustfeld, Hans A1 - Pfeifer, Heinz A1 - Reißel, Martin T1 - Validation of a novel method for detecting and stabilizing malfunctioning areas in fuel cell stacks JF - Journal of power sources N2 - In this paper a setup for detecting malfunctioning areas of MEAs in fuel cell stacks is described. Malfunctioning areas generate electric cross currents inside bipolar plates. To exploit this we suggest bipolar plates consisting not of two but of three layers. The third one is a highly conducting layer and segmented such that the cross currents move along the segments to the surface of the stack where they can be measured by an inductive sensor. With this information a realistic model can be used to detect the malfunctioning area. Furthermore the third layer will prevent any current inhomogeneity of a malfunctioning cell to spread to neighbouring cells in the stack. In this work the results of measurements in a realistic cell setup will be compared with the results obtained in simulation studies with the same configuration. The basis for the comparison is the reliable characterisation of the electrical properties of the cell components and the implication of these results into the simulation model. The experimental studies will also show the limits in the maximum number of segments, which can be used for a reliable detection of cross currents. Y1 - 2014 U6 - https://doi.org/10.1016/j.jpowsour.2014.08.045 SN - 1873-2755 (E-Journal); 0378-7753 (Print) VL - 272 SP - 225 EP - 232 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Reißel, Martin A1 - Lustfeld, Hans A1 - Hirschfeld, Julian A. A1 - Steffen, Bernhard T1 - Uniqueness of magnetotomography for fuel cells and fuel cell stacks / Lustfeld, H. ; Hirschfeld, J. ; Reißel, M ; Steffen, B. JF - Journal of Physics A: Mathematical and Theoretical. 42 (2009), H. 495205 Y1 - 2009 SN - 0022-3689 SP - 9 S. ER - TY - JOUR A1 - Reißel, Martin A1 - Lustfeld, Hans A1 - Steffen, Bernhard A1 - Schmidt, U. T1 - Reconstruction of Electric Currents in a Fuel Cell by Magnetic Field Measurements / Lustfeld, H. ; Reißel, M. ; Steffen, B. ; Schmidt, U. JF - Journal of fuel cell science and technology Y1 - 2009 SN - 1550-624X VL - Vol. 6 IS - Iss. 2 SP - 021012-1 EP - 021012-8 ER - TY - JOUR A1 - Reißel, Martin A1 - Hirschfeld, Julian A. A1 - Lustfeld, Hans A1 - Steffen, Bernhard T1 - Magnetotomography and Electric Currents in a Fuel Cell / Lustfeld, H. ; Reißel, M. ; Steffen, B. JF - Fuel Cells. 9 (2009), H. 4 Y1 - 2009 SN - 1615-6854 SP - 474 EP - 481 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Lustfeld, Hans A1 - Hirschfeld, Julian A. A1 - Reißel, Martin A1 - Steffen, Bernhard T1 - Enhancement of precision and reduction of measuring points in tomographic reconstructions JF - Physics Letters A Y1 - 2011 SN - 0375-9601 VL - 375 IS - 8 SP - 1167 EP - 1171 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Ortner, Marion A1 - Hauser, Christine A1 - Schmaderer, Christoph A1 - Muggenthaler, Claudia A1 - Hapfelmeier, Alexander A1 - Sorg, Christian A1 - Diehl-Schmid, Janine A1 - Kurz, Alexander A1 - Förstl, Hans A1 - Ikenberg, Benno A1 - Kotliar, Konstantin A1 - Holger, Poppert A1 - Grimmer, Timo T1 - Decreased vascular pulsatility in Alzheimer’s disease dementia measured by transcranial color-coded duplex sonography JF - Neuropsychiatric disease and treatment N2 - Purpose: Impaired paravascular drainage of β-Amyloid (Aβ) has been proposed as a contributing cause for sporadic Alzheimer’s disease (AD), as decreased cerebral blood vessel pulsatility and subsequently reduced propulsion in this pathway could lead to the accumulation and deposition of Aβ in the brain. Therefore, we hypothesized that there is an increased impairment in pulsatility across AD spectrum. Patients and Methods: Using transcranial color-coded duplex sonography (TCCS) the resistance and pulsatility index (RI; PI) of the middle cerebral artery (MCA) in healthy controls (HC, n=14) and patients with AD dementia (ADD, n=12) were measured. In a second step, we extended the sample by adding patients with mild cognitive impairment (MCI) stratified by the presence (MCI-AD, n=8) or absence of biomarkers (MCI-nonAD, n=8) indicative for underlying AD pathology, and compared RI and PI across the groups. To control for atherosclerosis as a confounder, we measured the arteriolar-venular-ratio of retinal vessels. Results: Left and right RI (p=0.020; p=0.027) and left PI (p=0.034) differed between HC and ADD controlled for atherosclerosis with AUCs of 0.776, 0.763, and 0.718, respectively. The RI and PI of MCI-AD tended towards ADD, of MCI-nonAD towards HC, respectively. RIs and PIs were associated with disease severity (p=0.010, p=0.023). Conclusion: Our results strengthen the hypothesis that impaired pulsatility could cause impaired amyloid clearance from the brain and thereby might contribute to the development of AD. However, further studies considering other factors possibly influencing amyloid clearance as well as larger sample sizes are needed. Y1 - 2019 U6 - https://doi.org/10.2147/NDT.S225754 SN - 1178-2021 IS - 15 SP - 3487 EP - 3499 PB - Dove Medical Press CY - Albany, Auckland ER - TY - JOUR A1 - Bandlitz, Stefan A1 - Nakhoul, Makram A1 - Kotliar, Konstantin T1 - Daily variations of corneal white-to-white diameter measured with different methods JF - Clinical and experimental optometry N2 - Purpose: A precise determination of the corneal diameter is essential for the diagnosis of various ocular diseases, cataract and refractive surgery as well as for the selection and fitting of contact lenses. The aim of this study was to investigate the agreement between two automatic and one manual method for corneal diameter determination and to evaluate possible diurnal variations in corneal diameter. Patients and Methods: Horizontal white-to-white corneal diameter of 20 volunteers was measured at three different fixed times of a day with three methods: Scheimpflug method (Pentacam HR, Oculus), placido based topography (Keratograph 5M, Oculus) and manual method using an image analysis software at a slitlamp (BQ900, Haag-Streit). Results: The two-factorial analysis of variance could not show a significant effect of the different instruments (p = 0.117), the different time points (p = 0.506) and the interaction between instrument and time point (p = 0.182). Very good repeatability (intraclass correlation coefficient ICC, quartile coefficient of dispersion QCD) was found for all three devices. However, manual slitlamp measurements showed a higher QCD than the automatic measurements with the Keratograph 5M and the Pentacam HR at all measurement times. Conclusion: The manual and automated methods used in the study to determine corneal diameter showed good agreement and repeatability. No significant diurnal variations of corneal diameter were observed during the period of time studied. Y1 - 2022 U6 - https://doi.org/10.2147/OPTO.S360651 SN - 0816-4622 IS - 14 SP - 173 EP - 181 PB - Taylor & Francis CY - London ER - TY - JOUR A1 - Lustfeld, Hans A1 - Pithan, C. A1 - Reißel, Martin T1 - Metallic electrolyte composites in the framework of the brick-layer model JF - Journal of the European Ceramic Society N2 - 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. Y1 - 2012 U6 - https://doi.org/10.1016/j.jeurceramsoc.2011.10.017 SN - 0955-2219 VL - 32 IS - 4 SP - 859 EP - 864 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Staat, Manfred A1 - Sponagel, Stefan A1 - Nguyen, Nhu Huynh T1 - Experiment and material model for soft tissue materials JF - Constitutive models for rubber VI N2 - Biomechanics studies biological soft tissue materials (growth, remodeling) in vivo. For this objective, the detailed information of material properties must be well defined to construct reliable constitutive models. In the paper, the bulge test is carried out with elastomers in order to develop a test method. Then, application of the test for soft tissue materials is straightforward due to the similarities between elastomers with soft tissue materials as proved in Holzapfel 2005, Ogden 2009. It means, after the preliminary experiments and parameter identification with rubber materials has been setup, experiments on soft tissue materials can be similarly carried out. Elastomers have a complex behavior which strongly depends on the largest previous load cycle. For simplicity we consider only the first loading. Y1 - 2010 SN - 9780429206597 (eBook) U6 - https://doi.org/10.1201/NOE0415563277-90 PB - Taylor & Francis CY - London ER - TY - JOUR A1 - Murgan, Ilina A1 - Beyer, Sonja A1 - Kotliar, Konstantin A1 - Weber, Lutz A1 - Bechtold-Dalla Pozza, Susanne A1 - Dalla Pozza, Robert A1 - Wegner, Aharon A1 - Sitnikova, Diana A1 - Stock, Konrad A1 - Heemann, Uwe A1 - Schmaderer, Christoph A1 - Baumann, Marcus T1 - Arterial and Retinal Vascular Changes in Hypertensive and Prehypertensive Adolescents JF - American Journal of Hypertension Y1 - 2013 SN - 1941-7225 VL - 26 IS - 3 SP - 400 EP - 408 PB - Oxford University Press CY - Oxford ER - TY - RPRT A1 - Blandford, Daniel A1 - Dachwald, Bernd A1 - Digel, Ilya A1 - Espe, Clemens A1 - Feldmann, Marco A1 - Francke, Gero A1 - Hiecke, Hannah A1 - Kowalski, Julia A1 - Lindner, Peter A1 - Plescher, Engelbert A1 - Schöngarth, Sarah T1 - Enceladus Explorer : Schlussbericht — Version: 1.0 Y1 - 2015 U6 - https://doi.org/10.2314/GBV:86319950X N1 - Förderkennzeichen BMWi 50NA1206 PB - FH Aachen CY - Aachen ER - TY - JOUR A1 - Röth, Anjali A. A1 - Slabu, Ioana A1 - Kolvenbach, K. A1 - Engelmann, Ulrich M. A1 - Baumann, Martin A1 - Schmitz-Rode, T. A1 - Trahms, L. A1 - Neumann, U. T1 - Aufnahmekinetik von magnetischen Nanopartikeln zur Tumortherapie in humanen Pankreaskarzinomzelllinien JF - Zeitschrift für Gastroenterologie Y1 - 2015 U6 - https://doi.org/10.1055/s-0035-1559529 SN - 1439-7803 VL - 53 IS - 8 SP - KC139 PB - Thieme CY - Stuttgart ER - TY - JOUR A1 - Kotliar, Konstantin A1 - Hanssen, Henner A1 - Eberhardt, Karla A1 - Vilser, Walthard A1 - Schmaderer, Christoph A1 - Halle, Martin A1 - Heemann, Uwe A1 - Baumann, Marcus T1 - Retinal pulse wave velocity in young male normotensive and mildly hypertensive subjects JF - Microcirculation Y1 - 2013 SN - 1549-8719 N1 - Accepted Article (Accepted, unedited articles published online and citable. The final edited and typeset version of record will appear in future.) PB - Wiley CY - Malden ER - TY - JOUR A1 - Kowalski, Julia A1 - Linder, Peter A1 - Zierke, S. A1 - Wulfen, B. van A1 - Clemens, J. A1 - Konstantinidis, K. A1 - Ameres, G. A1 - Hoffmann, R. A1 - Mikucki, J. A1 - Tulaczyk, S. A1 - Funke, O. A1 - Blandfort, D. A1 - Espe, Clemens A1 - Feldmann, Marco A1 - Francke, Gero A1 - Hiecker, S. A1 - Plescher, Engelbert A1 - Schöngarth, Sarah A1 - Dachwald, Bernd A1 - Digel, Ilya A1 - Artmann, Gerhard A1 - Eliseev, D. A1 - Heinen, D. A1 - Scholz, F. A1 - Wiebusch, C. A1 - Macht, S. A1 - Bestmann, U. A1 - Reineking, T. A1 - Zetzsche, C. A1 - Schill, K. A1 - Förstner, R. A1 - Niedermeier, H. A1 - Szumski, A. A1 - Eissfeller, B. A1 - Naumann, U. A1 - Helbing, K. T1 - Navigation technology for exploration of glacier ice with maneuverable melting probes JF - Cold Regions Science and Technology N2 - The Saturnian moon Enceladus with its extensive water bodies underneath a thick ice sheet cover is a potential candidate for extraterrestrial life. Direct exploration of such extraterrestrial aquatic ecosystems requires advanced access and sampling technologies with a high level of autonomy. A new technological approach has been developed as part of the collaborative research project Enceladus Explorer (EnEx). The concept is based upon a minimally invasive melting probe called the IceMole. The force-regulated, heater-controlled IceMole is able to travel along a curved trajectory as well as upwards. Hence, it allows maneuvers which may be necessary for obstacle avoidance or target selection. Maneuverability, however, necessitates a sophisticated on-board navigation system capable of autonomous operations. The development of such a navigational system has been the focal part of the EnEx project. The original IceMole has been further developed to include relative positioning based on in-ice attitude determination, acoustic positioning, ultrasonic obstacle and target detection integrated through a high-level sensor fusion. This paper describes the EnEx technology and discusses implications for an actual extraterrestrial mission concept. Y1 - 2016 U6 - https://doi.org/10.1016/j.coldregions.2015.11.006 SN - 0165-232X IS - 123 SP - 53 EP - 70 PB - Elsevier CY - Amsterdam ER -