Literatura académica sobre el tema "Magnetic inhomogeneities"
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Artículos de revistas sobre el tema "Magnetic inhomogeneities"
Rudnick, Lawrence. "Manifestations of Magnetic Field Inhomogeneities". Journal of Astrophysics and Astronomy 32, n.º 4 (diciembre de 2011): 549–55. http://dx.doi.org/10.1007/s12036-011-9113-5.
Texto completoGogola, D., A. Krafčík, O. Štrbák y I. Frollo. "Magnetic Resonance Imaging of Surgical Implants Made from Weak Magnetic Materials". Measurement Science Review 13, n.º 4 (1 de agosto de 2013): 165–68. http://dx.doi.org/10.2478/msr-2013-0026.
Texto completoWu, Huiyan, Kerong Zhu, Guoyong Xu y Hu Wang. "Magnetic inhomogeneities in electron-doped manganites ()". Physica B: Condensed Matter 407, n.º 4 (febrero de 2012): 770–73. http://dx.doi.org/10.1016/j.physb.2011.12.022.
Texto completoGaunt, Paul. "Magnetic coercivity". Canadian Journal of Physics 65, n.º 10 (1 de octubre de 1987): 1194–99. http://dx.doi.org/10.1139/p87-195.
Texto completoShcherbakov, A. G., M. J. Fernandez-Figueroa, F. Martin-Parra, E. De Castro y M. Cornide. "The HeI λ10830 Å Observations of Two Rs Cvn Systems ζ and λ And". Symposium - International Astronomical Union 157 (1993): 167–69. http://dx.doi.org/10.1017/s0074180900174054.
Texto completoMakarov, P., V. Ustyugov y V. Scheglov. "Modelling of electromagnetic wave propagation in magnetically inhomogeneous media". Proceedings of the Komi Science Centre of the Ural Division of the Russian Academy of Sciences, n.º 5 (20 de diciembre de 2022): 100–105. http://dx.doi.org/10.19110/1994-5655-2022-5-100-105.
Texto completoEkomasov, E. G. y R. R. Murtazin. "Modeling of the nucleation of magnetic inhomogeneities in ferromagnets with inhomogeneities material parameters". Letters on Materials 2, n.º 1 (2012): 9–12. http://dx.doi.org/10.22226/2410-3535-2012-1-9-12.
Texto completoMichaud, G. "Particle transport and surface abundance inhomogeneities". Symposium - International Astronomical Union 176 (1996): 321–28. http://dx.doi.org/10.1017/s0074180900083339.
Texto completoSeppenwoolde, Jan-Henry, Mathilda van Zijtveld y Chris J. G. Bakker. "Spectral characterization of local magnetic field inhomogeneities". Physics in Medicine and Biology 50, n.º 2 (7 de enero de 2005): 361–72. http://dx.doi.org/10.1088/0031-9155/50/2/013.
Texto completoLing, C. D., E. Granado, J. J. Neumeier, J. W. Lynn y D. N. Argyriou. "Magnetic inhomogeneities in electron-doped Ca1−xLaxMnO3". Journal of Magnetism and Magnetic Materials 272-276 (mayo de 2004): 246–48. http://dx.doi.org/10.1016/j.jmmm.2003.11.102.
Texto completoTesis sobre el tema "Magnetic inhomogeneities"
Pasquato, Ester. "Effects of stellar surface inhomogeneities on astrometric accuracy". Doctoral thesis, Universite Libre de Bruxelles, 2011. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209872.
Texto completoIn the case of a red supergiant star, the average photocentre shift is about 0.1 AU. Such a photocentric noise translates in a 10% inaccuracy on the parallax (independently of the distance), which becomes larger than the statistical error on the parallax derived from the data reduction for stars that are up to about 4 kpc away. For the most nearby stars, we derive an inaccuracy on the parallax that can be 10 times its statistical error. Finally we estimate that up to about 4000 stars among red supergiants and bright giants may have astrometric parameters that are inaccurate at levels bigger than expected because of the surface brightness asymmetries. In the determination of this number, a crucial role is played by the Gaia observable magnitude range. The fact that Gaia will not observe stars brighter than 5.6 in the Gaia G band means that the closest stars will not be observed. Yet, the impact of the surface brightness asymmetries is proportional to their angular size, meaning that the stars whose astrometric accuracy would be most affected are not observed.
Various non-Gaussian spot models (as applicable in the case of magnetic spots) have been implemented and analytical predictions for the effects of such magnetic spots are computed for the most representative classes of magnetic stars.
Another effect of the presence of surface brightness asymmetries is their impact on Gaia data processing flow. The quality of the fit of the data is evaluated with the F2 parameter that is a transformation of χ2 such that it has a unit normal distribution when the model is adequate and it is independent of the number of measurements. If the goodness-of-fit F2 of the single-star solution is not good enough (F2>3), a chain of solution of growing complexity is tried until a satisfactory one (with F2<3) is obtained. If no good solution is found, a so-called stochastic solution is computed where a "cosmic" error is added to the data in order to obtain a single-star solution with F2=0. We show that the photocentre noise induces an increase in the goodness-of-fit parameter, causing this chain of solutions to be entered. Depending on the characteristics of the photocentre noise, a variable fraction of the stars in our simulations end up with a non-single-star solution. Yet, we show that these (orbital) solutions are not acceptable because non-significant or non-physical. Finally, an important fraction of stars is assigned a stochastic solution with a cosmic noise matching well the photocentric noise.
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Les asymétries de brillance de surface sont une caractéristique commune des étoiles. Parmi d'autres effets, elles provoquent une différence entre la projection du centre de masse et le photocentre. L'évolution de ces structures de surface rend cette différence variable avec le temps. Dans certains cas, le déplacement du photocentre peut être une fraction non négligeable du rayon de l'étoile R et, si R>1 UA, de la parallaxe. Nous examinons l'impact des asymétries de brillance de surface sur la solution astrométrique de Gaia et sur le processus de traitement des données. En particulier nous dérivons des expressions analytiques pour le changement des paramètres astrométriques déerivées pour une étoile simple, par rapport aux paramètres pour une étoile uniformément lumineuse, en fonction des caractéristiques des asymétries de brillance de surface. Ces prévisions sont confirmées par les résultats de simulations du traitement des données astrométriques de Gaia, auxquelles des mouvements du photocentre causés par des asymétries de brillance de surface ont été ajoutés en utilisant un modèle gaussien markovien.
Dans le cas d'une étoile super-géante rouge, le décalage moyen du photocentre est d'environ 0.1 UA. Un bruit photocentrique de cette amplitude se traduit dans une imprécision de 10% sur la parallaxe (indépendamment de la distance), qui peut devenir plus grande que l'erreur statistique sur la parallaxe déerivée par la réduction des données, pour les étoiles plus proches d'environ 4 kpc. Pour les étoiles les plus proches, nous évaluons une imprécision sur la parallaxe qui peut être 10 fois leur erreur statistique. Finalement, nous estimons que jusqu'à environ 4000 étoiles parmi les super-géantes rouges et géantes brillantes peuvent avoir des paramètres astrométriques inexactes à des niveaux plus grands que prévu en raison des asymétries de brillance de surface. Dans la détermination de ce nombre, la gamme de magnitudes observables par Gaia joue un rôle crucial. Le fait que Gaia n'observera pas les étoiles plus brillantes que 5.6 mag (en bande Gaia) signifie que les étoiles les plus proches ne seront pas observées. Pourtant, l'impact des asymétries de brillance de surface est proportionnel à leur taille angulaire, ce qui signifie que les étoiles dont la précision astrométrique seraient la plus affecté ne seront pas observées.
Différents modèles de taches ont été réalisés et des prédictions analytiques pour les effets de ces taches magnétiques sont calculés pour les classes les plus représentatives des étoiles magnétiques.
Un autre effet de la présence des asymétries de brillance de surface est leur impact sur le traitement des données de Gaia. La qualité de l'ajustement des données est évaluée avec le paramètre F2 qui est une transformation de χ2 telle qu'il ait une distribution normale lorsque le modèle est adéquat. Si la qualité de l'ajustement F2 de la solution étoile-simple n'est pas acceptable (F2>3), une chaîne de solutions de complexité croissante est essayée jusqu'à ce qu'une solution satisfaisante (avec F2<3) soit obtenue. Si aucune solution satisfaisante n'est trouvée, une solution dite stochastique est calculée où une erreur "cosmique" est ajoutée aux données afin d'obtenir une solution étoile-simple avec F2=0. Nous montrons que le bruit du photocentre induit une augmentation de F2, ce qui provoque l'activation de cette chaîne de solutions. Selon les caractéristiques du bruit du photocentre, une solution étoile-non-simple est obtenue pour une fraction variable des étoiles dans nos simulations. Nous montrons que ces solutions (orbitales) ainsi obtenues ne sont pas acceptables car non significatives ou non-physiques. Enfin, une fraction importante d'étoiles se voient attribuer une solution stochastique avec un bruit cosmique correspondant au bruit photocentrique.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
Assländer, Jakob [Verfasser]. "Static Field Inhomogeneities in Magnetic Resonance Encephalography: Effects and Mitigation / Jakob Assländer". München : Verlag Dr. Hut, 2014. http://d-nb.info/1063221269/34.
Texto completoBaumann, Christoph. "Magnetic and structural inhomogeneities in single layered manganites La1-xSr1+xMnO4 : hyperfine field investigations /". Berlin : Mensch-und-Buch-Verl, 2005. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=014182273&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
Texto completoAssländer, Jakob [Verfasser] y Jürgen [Akademischer Betreuer] Hennig. "Static field inhomogeneities in magnetic resonance encephalography : : effects and mitigation = Statische Magnetfeldinhomogenitäten in der Magnetresonanzencephalographie : Effekte und Mitigation". Freiburg : Universität, 2014. http://d-nb.info/1123481458/34.
Texto completoKörzdörfer, Gregor [Verfasser], Bernhard [Akademischer Betreuer] Hensel y Bernhard [Gutachter] Hensel. "Analysis and Mitigation of the Effect of Magnetic Field Inhomogeneities and Undersampling Artifacts on Magnetic Resonance Fingerprinting / Gregor Körzdörfer ; Gutachter: Bernhard Hensel ; Betreuer: Bernhard Hensel". Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2020. http://d-nb.info/1211822125/34.
Texto completoReich, Jan Christoph [Verfasser] y G. [Akademischer Betreuer] Drexlin. "Magnetic Field Inhomogeneities and Their Influence on Transmission and Background at the KATRIN Main Spectrometer / Jan Christoph Reich. Betreuer: G. Drexlin". Karlsruhe : KIT-Bibliothek, 2013. http://d-nb.info/1031709037/34.
Texto completoBenitez, Mendieta Jessica. "An efficient and semiautomatic segmentation method for 3D surface reconstruction of the lumbar spine from Magnetic Resonance Imaging (MRI)". Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/101274/1/Jessica_Benitez%20Mendieta_Thesis.pdf.
Texto completoSplitthoff, Daniel Nicolas [Verfasser] y Jürgen [Akademischer Betreuer] Hennig. "SENSE shimming (SSH) : : fast detection of B0 field inhomogeneities in magnetic resonance imaging = SENSE Shimming (SSH) : schnelle Detektion von B0 Feldinhomogenitäten in der Magnet-Resonanz-Bildgebung". Freiburg : Universität, 2012. http://d-nb.info/1123467404/34.
Texto completoDe, Biasi Federico. "Matrix-Assisted NMR". Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3424861.
Texto completoLemarchand, Nadège. "Impacts of cosmic inhomogeneities on the CMB : primordial perturbations in two-field bouncing cosmologies and cosmic magnetism in late-time structures Secondary CMB anisotropies from magnetized haloes I. Power spectra of the Faraday rotation angle and conversion rate". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS510.
Texto completoThe Cosmic Microwave Background (CMB) is a key cosmological probe, that sets tight constraints on the CDM model of the Universe. Released 380000 years after the big bang, it exhibits tiny anisotropies in temperature and polarisation which trace the cosmic inhomogeneities at different epochs of the Universe. On the one hand, primary anisotropies give access to inflation, during which the primordial perturbations are generated. On the other hand, secondary anisotropies trace inhomogeneities in the recent Universe, which have evolved into large scale structures through gravity, starting from the primordial ones. Hence CMB anisotropies are a powerful probe of both the origin of inhomogeneities in the very early Universe, and their evolved state in the late-time Universe. This thesis deals with two aspects of inhomogeneities by first considering their production in an extension of the inflationary scenario, and second by predicting the impact of magnetic fields in large scale structures on the secondary CMB polarised anisotropies.Despite its successes, inflation does not solve the initial big bang singularity issue, where gravity might need to be quantised. In Loop Quantum Cosmology (LQC), this singularity is replaced by a quantum bounce. Single field LQC with quadratic potential has already been studied and predicts an inflation phase following the bounce. Then, primordial inhomogeneities are not only produced during inflation, but also during the bounce and the contraction preceding it. Here, I considered a multifield extension of LQC with two fields: a massive one as being the inflaton, and a massless one used as an internal clock. I first studied the background evolution of the Universe both analytically and numerically. I showed that far in the contraction, the massive field dominates the energy budget. I have also checked that inflation remains likely to happen, despite the presence of the massless field. Secondly, I investigated how perturbations are produced. Unlike the one-field case, they are now described by an isocurvature component in addition to the standard adiabatic one, the former being characteristic of multifield models, for which Planck has put upper limits. In the remote past of the contraction, these two kinds of perturbations are highly coupled. I showed how to set their initial conditions by using appropriate variables mixing both kinds of perturbations, making the coupling subdominant. These perturbations remain to be propagated through the bounce down to the end of inflation to get their primordial (cross)spectra, to be subsequently compared to observational constraints.Since its released, the CMB traveled through large scale structures before reaching us. This leads to secondary anisotropies by its interaction with these structures, like e.g. gravitational deflection or the SZ effect in clusters. Magnetic fields have been observed in galaxies and larger structures. Since these structures are also filled with free electrons, this should lead to the Faraday Rotation (FR) effect which rotates the primordial linear polarisation, turning E into B modes, and to the Faraday Conversion (FC) effect which converts linear into circular polarisation. I revisited these sources of secondary anisotropies by computing the angular power spectra of the FR angle and the FC rate by large-scale structures. I used the halo model paying special attention to the impact of magnetic field projections. I found angular power spectra peaking at multipoles 104. Assuming a mass-independent magnetic field, the angular power spectra scale with the amplitude of matter perturbations as 83. This scaling is however degenerated with the one of the magnetic field with halos’ mass. I finally detail how to compute the full angular power spectra of polarised anisotropies, starting from the FR and FC power spectra. I also show how to reconstruct the FR and FC fields from the CMB adapting the estimators developed for lensing reconstruction
Libros sobre el tema "Magnetic inhomogeneities"
Kim, Jae Koul. Static field inhomogeneities in magnetic resonance imaging. 1995.
Buscar texto completoCapítulos de libros sobre el tema "Magnetic inhomogeneities"
Ryutova, Margarita. "Effects of Flux Tube Inhomogeneities and Weak Nonlinearity". En Physics of Magnetic Flux Tubes, 75–105. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-96361-7_4.
Texto completoRyutova, Margarita. "Effects of Flux Tube Inhomogeneities and Weak Nonlinearity". En Physics of Magnetic Flux Tubes, 69–98. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-45243-1_4.
Texto completoMaceroni, C., A. Bianchini, M. Rodonó, F. van't Veer y R. Vio. "Statistics of magnetic cycles in late-type single and close binary stars". En Surface Inhomogeneities on Late-Type Stars, 303–6. Berlin, Heidelberg: Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/3-540-55310-x_177.
Texto completoKhokhlova, V. L. "Study of Inhomogeneities on the Surface of Magnetic CP Stars". En Upper Main Sequence Stars with Anomalous Abundances, 125–34. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4714-6_18.
Texto completoHubrig, S. y G. Mathys. "Mass Loss, Magnetic Field and Chemical Inhomogeneities in the He-Weak Star HD 21699". En Pulsation, Rotation and Mass Loss in Early-Type Stars, 167–68. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-1030-3_44.
Texto completoChikumoto, Noriko, Kimiyasu Furusawa y Masato Murakami. "Magneto-Optical Studies of Chemical Inhomogeneities in Bi2212 Single Crystals". En Magneto-Optical Imaging, 119–24. Dordrecht: Springer Netherlands, 2004. http://dx.doi.org/10.1007/978-94-007-1007-8_15.
Texto completoBardzokas, Demosthenis I., Michael L. Filshtinsky y Leonid A. Filshtinsky. "Scattering of a Shear Wave by Cylindrical Inhomogeneities in Piezoceramic Media of Various Configurations (Antiplane Deformation)". En Mathematical Methods in Electro-Magneto-Elasticity, 181–228. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/3-540-71031-0_5.
Texto completoNieto-Castanon, Alfonso. "FMRI minimal preprocessing pipeline". En Handbook of functional connectivity Magnetic Resonance Imaging methods in CONN, 3–16. Hilbert Press, 2020. http://dx.doi.org/10.56441/hilbertpress.2207.6599.
Texto completoSutton, Bradley P. y Fan Lam. "Imaging in the Presence of Magnetic Field Inhomogeneities". En Advances in Magnetic Resonance Technology and Applications, 327–54. Elsevier, 2022. http://dx.doi.org/10.1016/b978-0-12-822726-8.00023-3.
Texto completoCheryauka, Arvidas, Michael S. Zhdanov y Motoyuki Sato. "Chapter 5 Nonlinear approximations for electromagnetic scattering from electrical and magnetic inhomogeneities". En Methods in Geochemistry and Geophysics, 65–83. Elsevier, 2002. http://dx.doi.org/10.1016/s0076-6895(02)80087-7.
Texto completoActas de conferencias sobre el tema "Magnetic inhomogeneities"
Noterdaeme, Olivier y Michael Brady. "Correction of inhomogeneities in Magnetic Resonance Images". En 2008 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE, 2008. http://dx.doi.org/10.1109/iembs.2008.4649637.
Texto completoKrause, H. y J. Engemann. "Measurement of local material inhomogeneities in magnetic garnet films". En International Conference on Magnetics. IEEE, 1990. http://dx.doi.org/10.1109/intmag.1990.734959.
Texto completoBURGY, J., M. MAYR, V. MARTIN-MAYOR, A. MOREO y E. DAGOTTO. "COLOSSAL EFFECTS IN TRANSITION METAL OXIDES CAUSED BY INTRINSIC INHOMOGENEITIES". En Physical Phenomena at High Magnetic Fields - IV. WORLD SCIENTIFIC, 2002. http://dx.doi.org/10.1142/9789812777805_0102.
Texto completoLiebgott, Florian, Christian Wurslin y Bin Yang. "Segmentation of magnetic resonance images in presence of severe intensity inhomogeneities". En ICASSP 2013 - 2013 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP). IEEE, 2013. http://dx.doi.org/10.1109/icassp.2013.6637802.
Texto completoBaym, Gordon y Jen-Chieh Peng. "Evolution of Primordial Neutrino Helicities in Cosmic Magnetic Fields and Gravitational Inhomogeneities". En Proceedings of the 24th International Spin Symposium (SPIN2021). Journal of the Physical Society of Japan, 2022. http://dx.doi.org/10.7566/jpscp.37.020703.
Texto completoПоляков, Petr Polyakov, Акимов y M. Akimov. "The distortion of the domain structure in the presence of a local magnetic defect in the film materials with a high anisotropy". En XXIV International Conference. Москва: Infra-m, 2016. http://dx.doi.org/10.12737/23178.
Texto completoCORDERO, F., A. PAOLONE, C. CASTELLANO y R. CANTELLI. "ANELASTIC MEASUREMENTS OF THE DYNAMICS OF LATTICE, CHARGE AND MAGNETIC INHOMOGENEITIES IN CUPRATES AND MANGANITES". En Proceedings of the Workshop. WORLD SCIENTIFIC, 2003. http://dx.doi.org/10.1142/9789812705112_0016.
Texto completoChernigovskaya, M. A., B. G. Shpynev y D. S. Khabituev. "Studying Longitudinal Inhomogeneities of the Ionospheric and Geomagnetic Disturbances in the Northern Hemisphere during Magnetic Storms". En 2019 Russian Open Conference on Radio Wave Propagation (RWP). IEEE, 2019. http://dx.doi.org/10.1109/rwp.2019.8810350.
Texto completoGranado, E., P. G. Pagliuso, J. A. Sanjurjo, C. Rettori, S. B. Oseroff, M. T. Causa, A. Butera et al. "EFFECT OF INHOMOGENEITIES IN THE MAGNETIC PROPERTIES OF R1-xAxMnO3 (R = La,Pr; A = Ca, Sr)". En Proceedings of the Fifth International Workshop on Non-Crystalline Solids. WORLD SCIENTIFIC, 1998. http://dx.doi.org/10.1142/9789814447225_0015.
Texto completoRousselet-Perraut, Karine, Chantal Stehle, Thierry Lanz, Thomas Boudoyen, Slobodan Jankov, Farrokh Vakili, Martin Kilbinger, Jean-Baptiste Lebouquin y Oleg Kochukhov. "Mapping abundance inhomogeneities and magnetic fields of chemically peculiar (CP) stars with optical aperture synthesis arrays". En Astronomical Telescopes and Instrumentation, editado por Wesley A. Traub. SPIE, 2003. http://dx.doi.org/10.1117/12.458590.
Texto completoInformes sobre el tema "Magnetic inhomogeneities"
Ryutova, M., M. Kaisig y T. Tajima. Propagation of magnetoacoustic waves in the solar atmosphere with random inhomogeneities of density and magnetic fields. Office of Scientific and Technical Information (OSTI), agosto de 1990. http://dx.doi.org/10.2172/6637341.
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