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排序方式: 共有72条查询结果,搜索用时 15 毫秒
1.
Johannes Elschner Rainer Hinder Gunther Schmidt 《Advances in Computational Mathematics》2002,16(2-3):139-156
This paper is devoted to the numerical study of diffraction by periodic structures of plane waves under oblique incidence. For this situation Maxwell's equations can be reduced to a system of two Helmholtz equations in R
2 coupled via quasiperiodic transmission conditions on the piecewise smooth interfaces between different materials. The numerical analysis is based on a strongly elliptic variational formulation of the differential problem in a bounded periodic cell involving nonlocal boundary operators. We obtain existence and uniqueness results for discrete solutions and provide the corresponding error analysis. 相似文献
2.
We consider the problem of recovering a two-dimensional periodic structure from scattered waves measured above the structure. Following an approach by Kirsch and Kress, this inverse problem is reformulated as a nonlinear optimization problem. We develop a theoretical basis for the reconstruction method in the case of an arbitrary Lipschitz grating profile. The convergence analysis is based on new perturbation and stability results for the forward problem. 相似文献
3.
Zwitterionic Cellulose Carbamate with Regioselective Substitution Pattern: A Coating Material Possessing Antimicrobial Activity 下载免费PDF全文
Thomas Elschner Claudia Lüdecke Diana Kalden Martin Roth Bettina Löffler Klaus D. Jandt Thomas Heinze 《Macromolecular bioscience》2016,16(4):522-534
A polyzwitterion is synthesized by regioselective functionalization of cellulose possessing a uniform charge distribution. The positively charged ammonium group is present at position 6, while the negative charge of carboxylate is located at positions 2 and 3 of the repeating unit. The molecular structure of the biopolymer derivative is proved by NMR spectroscopy. This cellulose‐based zwitterion is applied to several support materials by spin‐coating and characterized by means of atomic force microscope, contact angle measurements, ellipsometry, and X‐ray photoelectron spectroscopy. The coatings possess antimicrobial activity depending on the support materials (glass, titanium, tissue culture poly(styrene)) as revealed by confocal laser scanning microscopy and live/dead staining.
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Carl Elschner 《Colloid and polymer science》1922,31(2):94-96
Ohne Zusammenfassung
Dem an silikatische Achate erinnernden Mineral, das in Hohlr?umen der Lava gebildet ist, und sich mit den sogenannten Schneekopfskugeln
in mancher Beziehung vergleichen l?\t, habe ich den Namen „Meyersit“ gegeben, nach Herrn H. H. Meyers, Spezialsachverst?ndiger
für Phosphate und Düngemittel am Mellon Institut der Universit?t Pittsburgh. 相似文献
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T. S. Altshuler M. S. Bresler M. Schlott B. Elschner E. Gratz 《Zeitschrift für Physik B Condensed Matter》1995,99(1):57-60
In the intermetallic compound YbInCu4 the Gd3+-ESR and the static susceptibility were measured in the temperature range 1.5K–300 K, i.e. both below and above the valence
phase transition which occurs in this material at Tph≈50 K. The Gd3+ resonance is mainly determined by exchange interaction of Gd3+ ions with fluctuating Yb3+ ions via conduction electrons (RKKY coupling) both below and above this transition. Arguments are presented that at low temperature
YbInCu4 is a dense Kondo system (mixed valent state). 相似文献
9.
Gottfried Bruckner Johannes Elschner 《Mathematical Methods in the Applied Sciences》2005,28(7):757-778
We consider the inverse problem of recovering a 2D periodic structure from scattered waves measured above and below the structure. We discuss convergence and implementation of an optimization method for solving the inverse TE transmission problem, following an approach first developed by Kirsch and Kress for acoustic obstacle scattering. The convergence analysis includes the case of Lipschitz grating profiles and relies on variational methods and solvability properties of periodic boundary integral equations. Numerical results for exact and noisy data demonstrate the practicability of the inversion algorithm. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
10.
The nuclear spin lattice relaxation timeT 1 of the23Na,85Rb,87Rb,133Cs,14N nuclei is measured in NaCN, RbCN and CsCN as a function of temperature below and above the ferroelastic phase transition temperatureT c. BelowT c the behaviour ofT 1 of the alkali nuclei renders possible to determine the flip frequency of the CN molecules and its temperature dependence. AboveT c from the14NT 1 the correlation time τc of the rotational motions of the CN molecules and its temperature dependence is determined. An empirical rule is verified demonstrating that atT c the correlation times take nearly the same values for all cyanides. For the high and low temperature phases one obtains atT c about τc=5·10?13s and τc=5·10?11s, respectively. The results are discussed with respect to the mechanism of the phase transition. 相似文献