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423 results on '"Obermeier, F."'

4. Present Status of the Fractesus Project: Round Robin on Unirradiated Materials

Author

Bonny, G., additional, Altstadt, E., additional, Arffman, P., additional, Cicero, S., additional, Obermeier, F., additional, Petit, T., additional, Swan, H., additional, Chaouadi, R., additional, Gaganidze, E., additional, Hargitai, B., additional, Kolluri, M., additional, Kopriva, R., additional, Rozsahegyi, P., additional, Serrano, M., additional, Spätig, P., additional, Uytdenhouwen, I., additional, Wilcox, H., additional, and Yamamoto, M., additional

Published
2023
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8. Fluglärm

Author

Delfs, J., Dobrzynski, W., Heller, H., Isermann, U., Michel, U., Splettstösser, W., Obermeier, F., Müller, Gerhard, editor, and Möser, Michael, editor

Published
2004
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9. Fracture Mechanics Testing of Neutron Irradiated RPV Steels using Mini-C(T) Specimens

Author

Das, A., Chekhonin, P., Houska, M., Obermeier, F., and Altstadt, E.

Subjects
Fracture mechanics testing, neutron-irradiation, Master Curve, sub-sized specimen, transition temperature, reactor pressure vessel steels
Abstract

Neutron irradiation induced embrittlement of the reactor pressure vessel (RPV) reduces the operating lifetime of nuclear reactors and leads to an increase in the transition temperature T0. Fracture mechanics testing of RPV steels before and after neutron irradiation, which reveals the shift in T0, is often limited by the shortage of irradiated material. To solve this, we tested sub-sized 0.16T C(T) specimens manufactured from already tested SE(B) standard Charpy sized specimens using the Master Curve concept. The transferability of fracture mechanics data from small to standard sized specimens forms a key part of this study. To investigate the effect of chemical composition on neutron irradiation, four western RPV steels are chosen in this study, three base and one weld metal. Fractography is performed on broken mini-C(T) specimens using scanning electron microscopy in order to determine the location of the fracture initiating particles as well as the mode of fracture. In order to make the testing procedure simpler, based on large statistical data, we studied the impact of the slow stable crack growth censoring criterion on the determination of T0. We found that the results from the small specimens are comparable to the standard specimens. RPV steels containing higher amounts of Cu, Ni and P exhibit a higher increase in T0 after irradiation. The fracture initiating particles were located at greater distances from the crack front in irradiated specimens of the weld material as compared to the unirradiated specimens. The fracture toughness of all materials remained constant for similar test temperatures irrespective of their irradiation state. Furthermore, we found that the stable crack growth censoring criterion did not influence the T0 significantly. Our results demonstrate the validity of small specimen testing and confirms the role of the impurity elements Cu and P in neutron embrittlement.

Published
2022

10. P587 Disease severity in the INFLAMMATORY BOWEL DISEASES: Do patients and physicians agree?

Author

Timmer, A, primary, de Sordi, D, additional, Neuser, J, additional, Seibel, K, additional, Hensel, A, additional, Schmidt-Lauber, M, additional, Allgayer, H, additional, Klebl, F, additional, Obermeier, F, additional, Jessen, P, additional, Schnoy, E, additional, Helwig, U, additional, Morgenstern, J, additional, Leifeld, L, additional, Schmidt, S, additional, Meinhardt, C, additional, Maaser, C, additional, Bästlein, E, additional, Bokemeyer, A, additional, Graefe, U, additional, Kühbacher, T, additional, Kaltz, B, additional, Sander, C, additional, and Wolfgang, K, additional

Published
2022
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14. Fluglärm

Author

Dobrzynski, W., Heller, H., Matschat, K., Müller, E.-A., Neuwerth, G., Obermeier, F., Schultz, K.-J., Splettstößer, W., Heckl, Manfred, editor, and Müller, Helmut A., editor

Published
1994
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19. Anti-inflammatory role of sympathetic nerves in chronic intestinal inflammation

Author

Straub, R.H., Grum, F., Strauch, U., Capellino, S., Bataille, F., Bleich, A., Falk, W., Scholmerich, J., and Obermeier, F.

Subjects
Nervous system, Sympathetic -- Physiological aspects, Nervous system, Sympathetic -- Research, Crohn's disease -- Development and progression, Crohn's disease -- Research, Health
Published
2008

21. Influence of intestinal bacteria on induction of regulatory T cells: lessons from a transfer model of colitis

Author

Strauch, U.G., Obermeier, F., Grunwald, N., Gurster, S., Dunger, N., Schultz, M., Griese, D.P., Mahler, M., Scholmerich, J., and Rath, H.C.

Subjects
CD4 lymphocytes -- Analysis, Colitis -- Development and progression, Host-bacteria relationships -- Health aspects, Host-bacteria relationships -- Research, Intestines -- Microbiology, Intestines -- Research, Health
Published
2005

22. In vivo CpG DNA/toll-like receptor 9 interaction induces regulatory properties in CD4+CD62L+ T cells which prevent intestinal inflammation in the SCID transfer model of colitis

Author

Obermeier, F., Strauch, U.G., Dunger, N., Grunwald, N., Rath, H.C., Herfarth, H., Scholmerich, J., and Falk, W.

Subjects
Inflammatory bowel diseases -- Genetic aspects, Inflammatory bowel diseases -- Development and progression, CD4 lymphocytes -- Research, Cytosine -- Research, Guanosine -- Research, Health
Published
2005

41. Interferometric tomography for flow visualization of density fields in supersonic jets and convective flow

Author

Soller, C., Wenskus, R., Middendorf, P., Meier, G.E.A., and Obermeier, F.

Subjects
Optical tomography -- Usage, Holography -- Usage, Flow visualization -- Methods, Jets -- Research, Astronomy, Physics
Abstract

Tomographic methods are used for the investigation of three-dimensional compressible flow fields by means of interferometric methods. A modified algebraic reconstruction technique algorithm is applied. The algorithm proved to give reliable reconstructions from experimentally measured projection data in the case of an unrestricted angular view. The method was used for the reconstruction of density distributions of weakly perturbed supersonic free jets exiting from a deformed Laval nozzle. Even small perturbations of the jet resulted in significant three-dimensional effects. Reconstruction of a multiple system of jets emanating from a sievelike nozzle showed mutual interactions between the constituent jets. For the investigation of unsteady flows a setup for the recording of holographic interferograms was designed. Here, because of experimental restrictions, only a limited angular range of views was accessible. In the context of this limited-view geometry, reconstructions revealed considerable distortions for objects containing steep gradients.

Published
1994

42. Mechanisms of transonic blade-vortex interaction noise

Author

Lent, H.M., Meier, G.E.A., Muller, K.J., Obermeier, F., Schievelbusch, U., and Schurmann,O.

Subjects
Airplanes -- Noise, Rotors (Helicopters) -- Research, Aerospace and defense industries, Business, Science and technology
Abstract

Studies were conducted on the aerodynamic sound generation of helicopter blades resulting from vortex-airfoilinteraction in a two-dimensional transonic flow. Experiments were conducted in a vacuum operated transonic wind tunnel and a shock tube. The primary goal of the study was to determine the important parameters which affect the blade-vortex interaction (BVI) noise of helicopter blades. Results of the experiments led to the discovery of two new mechanisms of aerodynamic sound generation by BVI which were previously not considered, compressibility and transonic waves.

Published
1993

43. Sound generation by rotor-vortex interaction in low Mach number flow

Author

Obermeier, F. and Zhu, K.Q.

Subjects
Airplanes -- Noise, Rotors (Helicopters) -- Research, Aerospace and defense industries, Business, Science and technology
Abstract

The factors involved in predicting aerodynamic sound generation of helicopter blades were analyzed. The effects of the unsteady separation of vortex sheets at sharp trailing edges on blade-vortex interaction noise and predicted sound field as aresult of simplifications of the description of the motion of vorticity were also studied. Results indicate that the radiated sound field is dependent on fulfillment of the Kutta condition at the trailing edge of the airfoil.

Published
1993

49. The role of domestic hygiene in inflammatory bowel diseases: hepatitis A and worm infestations

Author

Hafner, S, Timmer, A, Herfarth, H, Rogler, G, Schölmerich, J, Schäffler, A, Ehrenstein, B, Jilg, W, Ott, C, Strauch, U G, Obermeier, F, University of Zurich, and Obermeier, F

Subjects
10219 Clinic for Gastroenterology and Hepatology, 10076 Center for Integrative Human Physiology, 570 Life sciences, biology, 610 Medicine & health, 2721 Hepatology, 2715 Gastroenterology
Published
2008

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