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991.
Sven Henning H. R. Imam Khasim Goerg H. Michler Jörg Brandt 《Macromolecular Symposia》2012,315(1):84-97
The contribution describes the development of a biocompatible nanocomposite material consisting of a resorbable polymeric matrix and osteoinductive nanoparticles that can be used to manufacture compact products, porous scaffolds, hybrid nanofibers, and alternating porous/compact structures. It is shown that the material has a good balance of stiffness, strength and toughness. The material supports osteoblast proliferation. Based on a modular design principle, several prototypes for hierarchical 3D constructs are proposed. 相似文献
992.
Tight-spans of metrics were first introduced by Isbell in 1964 and rediscovered and studied by others, most notably by Dress in 1984, who gave them this name. Subsequently, it has been found that tight-spans can be defined for more general maps, such as directed metrics and distances, and more recently for diversities. In this paper, we show that all of these tight-spans, as well as some related constructions, can be defined in terms of point configurations. This provides a useful way in which to study these objects in a unified and systematic way. We also show that by using point configurations we can recover results concerning one-dimensional tight-spans for all of the maps we consider, as well as extending these and other results to more general maps such as symmetric and asymmetric maps. 相似文献
993.
Chungen Shen Sven Leyffer Roger Fletcher 《Computational Optimization and Applications》2012,52(3):583-607
We propose a new nonmonotone filter method to promote global and fast local convergence for sequential quadratic programming algorithms. Our method uses two filters: a standard, global g-filter for global convergence, and a local nonmonotone l-filter that allows us to establish fast local convergence. We show how to switch between the two filters efficiently, and we prove global and superlinear local convergence. A special feature of the proposed method is that it does not require second-order correction steps. We present preliminary numerical results comparing our implementation with a classical filter SQP method. 相似文献
994.
995.
The main objective of isogeometric analysis is the use of one common data set for design and analysis. Geometrical models usually consist of multiple NURBS surface patches with non-matching parametrizations along common edges. The ability to handle non-conforming meshes is essential for isogeometric finite element systems to avoid manipulations of the geometry model. In general two possible strategies exist. The first one is to enhance the weak form of the potential with additional terms to constrain the deformations of adjacent edges to be equal, e.g. with the Lagrange Multiplier method. The second one is to establish a relation between the deformations of adjacent patches. Thus, superfluous degrees of freedom are condensated out of the system and the patches are connected naturally by shared degrees of freedom. No alteration of the weak form is necessary which simplifies the implementation in existing finite element systems. For adjacent edges with hierarchic knot vectors an analytical solution exists. In the general case of non-hierarchic knot vectors it is not possible to find an analytical solution. This contribution presents a new numerical method to establish this relation. A collocation along the connection line links the deformations of adjacent patches. A theoretical derivation of the method is given and the choice of the collocation points is investigated. Numerical studies compare the new method with the Lagrange Multiplier method and show its applicability. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
996.
Abstract A complete normal coordinate analysis has been performed for the tricyanomethanide ion C(CN)? 3 for which a planar structure of symmetry D3h was assumed. The symmetric Fand internal f valence force constant matrices were derived in the general case by using a GVFF and the results are applied to C(CN)? 3. 相似文献
997.
U. Niese J. von Borany P. Urwank S. Niese 《Isotopes in environmental and health studies》2013,49(11):401-406
In einer bestrahlten Kernbrennstofflösung wurde die Plutoniumaktivität mit Hilfe der Isotopenverdünnungsanalyse bestimmt. Dabei wurde 238Pu als Tracerisotop verwendet. Die Abtrennung des Plutoniums wurde durch Extraktion und die Aktivitätsmessung mit Hilfe der Alphaspektrometrie unter Verwendung von Si-Halbleiterdetektoren vorgenommen. Die Störung durch 241Am wurde durch gammaspektrometrische Messung berücksichtigt. Die Genauigkeit der 238Pu-Aktivitätsmessung und die der Messung der Gesamtaktivität beträgt ungefähr 1,5%. Die Bestimmung des 239Pu zu 240Pu Verhältnisses war nur mit einem groβen Fehler möglich, entsprechend der nahezu gleichen Alphaenergien dieser Isotope und der komplizierten Peakform. 241Pu wurde durch alphaspektrometrische Differenzmessung der nachgebildeten 241Am Aktivität bestimmt. In irradiated nuclear fuel solution plutonium isotops were determined with the help of isotope dilution analysis. 238Pu was used as a tracer isotope. Plutonium was separated by extraction and the activity was measured by alphaspectroscopy using silicon detectors. Interfering 241Am was recognized by gamma spectroscopic measurements. The accuracy of 238Pu determination and the determination of the total activity amounts to about 1-5%. For the 239Pu ratio we obtained a value with a large systematic error due to the similar alpha energies of these isotopes in the complicated shape of the peaks. The 241Pu activity was determined by alphaspectroscopic difference measurement, and was calculated from the ingrown of 241Am activity. 相似文献
998.
Martin Bock Julia Skibina Dorit Fischer Mario Bretschneider Reiner Wedell Rüdiger Grunwald Sven Burger Valentin Beloglazov Günter Steinmeyer 《Laser \u0026amp; Photonics Reviews》2013,7(4):566-570
A novel fiber technology is presented that enables the transmission of 200 nm wide spectra over meter‐long distances with minimal temporal reshaping and acceptable losses down to about 3 dB/m. Delivery of a 10 fs pulse over nearly meter distance is experimentally demonstrated, which sets a new standard for the fiber‐based delivery of few‐cycle pulses. Numerical simulations provide insight into the unique guiding mechanism in the novel hollow‐core fiber technology, enabling dispersion parameters that are within an order of magnitude of those available in free space propagation. 相似文献
999.
Artur Andruszkiewicz Kerstin Eckert Sven Eckert Stefan Odenbach 《The European physical journal. Special topics》2013,220(1):53-62
In this work the ultrasound-transit time technique is introduced as a versatile method to analyze the bubble dynamics in liquid-metal-gas flows. After discussing the principle of operation and the implementation of the technique, the methods used to extract the positions of the bubbles, their velocities, or their diameters are explained. Finally, the performance of the method is demonstrated for a liquid-metal-gas flow with and without a magnetic field. 相似文献
1000.