170,679 research outputs found
Die Arbeiten des Schlossers : Zweite Folge. Der Kunstschlosser : Vorbilder für Bauschlosserei, Gebrauchsartikel, Hausgeräte und Beleuchtungsgegenstände, sowie Einzelheiten und Verzierungen, welche der Ornamentik des Schlossers angehören : enthaltend Lappen-, Scharnier- und Fischbänder, Drücker, Handhaben und Thorklopfer, Schlüsselschilder, Schliessbleche, Schlossplatten, Schlüssel und Schlüsselbärte; Kamingeräte, Kandelaber, Lampen, Ampelarme und Körbe, Kronenleuchter, Leuchter und Laternen; Konsolen, Zunftzeichen, Grabkreuze, Wetterfahnen und Spitzen, Kassetten, Ofenschirme, Waschtische und Gestelle, Blumentische, Kleiderhalter und Garderobenständer, Bügeleisen, Abstreifeisen, Brotschneidebeschlag nebst Messer, Wappen, Monogramme und Einzelheiten
No full textunter Mitwirkung von C. A. Böttger ; im herrschenden Stil und gangbarsten Verhältnissen, nach genauem Mass entworfen und gezeichnet von A. Graef sen. und M. Graef jun.Exlibrisetikette: "Geschenk aus dem Nachlass von August Waldner." 002230265_0001 Exemplar der ETH-BIBExlibrisstempel: "Verlagsbuchhandlung B.F. Voigt Weimar" 002230400_0001 Exemplar der ETH-BI
Vector field electron tomography of magnetic materials: Theoretical development
No full textThe theory of vector field electron tomography, the reconstruction of the three-dimensional magnetic induction around a magnetized object, is derived within the framework of Lorentz transmission electron microscopy. The tomographic reconstruction method uses as input two orthogonal tilt series of magnetic phase maps and is based on the vector slice theorem. An analytical reconstruction of the magnetic induction of a single magnetic dipole is presented as a proof-of-concept. The method is compared to two previously reported approaches: a reconstruction starting from the gradient of the magnetic phase maps, and a direct reconstruction of the magnetic vector potential. Numerical examples as well as estimates of the reconstruction errors for a range of magnetic particle shapes are reported. (c) 2007 Elsevier B.V. All rights reserved
On the magnetostatics of chains of magnetic nanoparticles
No full textA novel approach is presented for the computation of the magnetostatic energy of straight and bent chains of identical, uniformly magnetized particles of arbitrary shape. The formalism relies on the concept of the magnetometric tensor field, and allows for closed form expressions for the magnetostatic energy, demagnetization factor, Young's modulus, and bending modulus of chains in terms of the shape amplitude of the particles. Analytical solutions are presented for straight chains of spheres, cubes, and cylinders, and for bent chains of spheres. Numerical results include chains of octahedra, tetrahedra, cuboctahedra, and bi-cones. The axial demagnetization factor for the bi-cone shape is derived in analytical form. An approximate energy expression, using the full shape-dependent interaction formalism for short separation distances, and the standard dipolar interaction expression for larger distances, is introduced
On the computation of the demagnetization tensor field for an arbitrary particle shape using a Fourier space approach
No full textA method is presented to compute the demagnetization tensor field for uniformly magnetized particles of arbitrary shape. By means of a Fourier space approach it is possible to compute analytically the Fourier representation of the demagnetization tensor field for a given shape. Then, specifying the direction of the uniform magnetization, the demagnetizing field and the magnetostatic energy associated with the particle can be evaluated. In some particular cases, the real space representation is computable analytically. In general, a numerical inverse fast Fourier transform is required to perform the inversion. As an example, the demagnetization tensor field for the tetrahedron will be given. (C) 2003 Elsevier Science B.V. All rights reserved
General magnetostatic shape-shape interactions
No full textThe magnetostatic interaction energy between two magnetic elements of arbitrary,7 Shape is presented as a convolution between the cross-correlation of the particle shapes and the dipolar tensor field. A generalized dipole-dipole interaction is derived, where the magnetic moments associated with the two particles interact through a magnetometric tensor field. carrying all the shape information. Example computations are given in order to verify the correctness of the formalism The well-known result of the interaction between prisms, employed in most micromagnetic simulations. is correctly retrieved. The numerical accuracy of the method is also compared to a simple analytical result. Finally, one additional example computation, two interlaced interacting rings, is presented to show the generality of the formalism. (C) 2004 Elsevier B.V. All rights reserved
The fluxgate ring-core demagnetization field
No full textThe local demagnetization factor for the ring-core flux gate is derived analytically, based on a tangential magnetization model. The results are in good agreement with experimental data for a wide range of ring shape parameters. Approximate expressions in the limit of a narrow, thin ring are obtained, and indicate that the local demagnetization factor scales with the ratio of the cross-sectional area to the total area of the ring. Analytical modeling of the demagnetization factors for a uniform magnetization state results in an underestimate of the local cross-section averaged demagnetization factors by 50% or more. (C) 2006 Elsevier B.V. All rights reserved
General magnetostatic shape-shape interaction forces and torques
No full textExpressions for the magnetostatic interaction force and torque between two magnetic objects of arbitrary shape are derived within the shape amplitude formalism. A generalized force is derived as the gradient of the magnetometric tensor field, which is the convolution of the cross-correlation of the object shapes with the dipolar tensor fields. Expressions for the mechanical and magnetic torques are also derived in terms of the magnetometric tensor field. Expressions suitable for numerical evaluation are given as finite Fourier summations. Example computations are given for the interactions between pairs of uniformly magnetized spheres (for which analytical results are compared to numerical results), cubes, octahedra, tetrahedra, and cuboctahedra. The accuracy of the derived numerical relations for energy, force, and torques is of the order of 0.1% for object spacings smaller than the object dimensions. (C) 2009 Elsevier B.V. All rights reserved
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Theoretical study of ferroelectric nanoparticles using phase reconstructed electron microscopy
No full textFerroelectric nanostructures are important for a variety of applications in electronic and electro-optical devices, including nonvolatile memories and thin-film capacitors. These applications involve stability and switching of polarization using external stimuli, such as electric fields. We present a theoretical model describing how the shape of a nanoparticle affects its polarization in the absence of screening charges, and quantify the electron-optical phase shift for detecting ferroelectric signals with phase-sensitive techniques in a transmission electron microscope. We provide an example phase shift computation for a uniformly polarized prolate ellipsoid with varying aspect ratio in the absence of screening charges
Demagnetization factors for cylindrical shells and related shapes
No full textMagnetostatic self and interaction energies can be computed via demagnetization factors whenever the magnetic state is close to a uniform state, e. g. in the presence of a strong applied field, or when the dimensions involved are within the single-domain limit. We derive analytical expressions for the demagnetization factors of cylindrical shells and rings with rectangular and square cross-sections. The factors are given either as a combination of elliptic integrals or as a series expansion in powers of the dimensionless ratio between inner and outer radii. Limiting cases are analysed for particular ranges of the shape parameters. We also investigate the ring with a square cross-section, and the elliptic ring, where analytical expressions are provided only for small eccentricity. Finally, we introduce the dipolar coupling integral encoding magnetostatic interactions between a magnetized cylinder and a thin coating on its lateral surface. (C) 2008 Elsevier B.V. All rights reserved
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