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981.
Diego Álvarez Oliver Dorn Natalia Irishina Miguel Moscoso 《Journal of computational physics》2009,228(16):5710-5721
We present a level-set based technique to recover key characteristics of a defect or crack (e.g. location, length and shape) in a two-dimensional material from boundary electrical measurements. The key feature of this work is to extend the usual level-set technique for modeling volumetric objects to very thin objects. Two level-set functions are employed: the first one models the location and form of the crack, and the second one models its length and connectivity. An efficient gradient based method is derived in order to define evolution laws for these two level-set functions which minimize the least squares data misfit. Numerical experiments show the utility of this method even in the presence of a significant noise level in the measurements. A finite element method is used to simulate the electric field behavior in the presence of very thin objects. 相似文献
982.
We propose an annular-aperture-based defocusing technique for three-dimensional (3D) particle metrology from a single camera view. This simple configuration has high optical efficiency and the ability to deal with overlapped defocused images. Initial results show that an uncertainty in depth of 23 microm can be achieved over a range of 10 mm for macroscopic systems. This method can also be applied in microscopy for the measurement of fluorescently doped microparticles, thus providing a promising solution for 3D flow metrology at both macroscales and microscales. 相似文献
983.
Marina V. Chirskaya Natalia L. Sergovskaya Sergey I. Sviridov 《Tetrahedron letters》2004,45(48):8811-8813
Substituted 3-bromotetrahydrofurans were prepared from homoallylic alcohols via bromination and cyclization in methanol in the presence of potassium carbonate. 相似文献
984.
Natalia Berruti Onesti 《Annali di Matematica Pura ed Applicata》1960,52(1):79-106
Sunto Nel presente lavoro l' A. stabilisce le equazioni di Eulero relative agli integrali curvilinei
e rileva alcune proprietà delle estremali relative alla funzione F, occupandosi in particolare dell'esistenza delle derivate
successive delle funzioni da cui le estremali sono definite. 相似文献
985.
The focus of this article is the investigation of the electrical behavior of the normal myocardium following the delivery of high-strength defibrillation shocks. To achieve its goal, the study employs a complex three-dimensional defibrillation model of a slice of the canine heart characterized with realistic geometry and fiber architecture. Defibrillation shocks of various strengths and electrode configurations are delivered to the model preparation in which a sustained ventricular tachycardia is induced. Instead of analyzing the post-shock electrical events as progressions of transmembrane potential maps, the study examines the evolution of the postshock phase singularities (PSs) which represent the organizing centers of reentry. The simulation results demonstrate that the shock induces numerous PSs the majority of which vanish before the reentrant wavefronts associated with them complete half of a single rotation. Failed shocks are characterized with one or more PSs that survive the initial period of PS annihilation to establish a new postshock arrhythmia. The increase in shock strength results in an overall decrease of the number of PSs that survive over 200 ms after the end of the shock; however, the exact behavior of the PSs is strongly dependent on the shock electrode configuration. (c) 2002 American Institute of Physics. 相似文献
986.
Propranolol was imprinted using noncovalent interactions in the shell of core-shell nanoparticles prepared by aqueous emulsion polymerization in the presence and absence of toluene. The imprinted particles were characterized, and their capacity to rebind propranolol from both organic and aqueous media was analyzed. Results showed that the amount of template incorporated into the polymer and the presence of toluene as a "porogenic" agent influenced the ability of the nanoparticles obtained to rebind propranolol. The presence of toluene during imprinting increased rebinding by about 2-fold in buffer and by 3-fold in toluene, compared with similar materials made in the absence of toluene during imprinting. It also influenced the final surface area of the particles. Binding site affinity, assessed by radioligand displacement, was measured as IC50 values of about 1-10 microM. This compares with about 3 microM for bulk polymer made with a similar composition. Finally, to demonstrate the advantages of structured particles for analytical applications a new property, fluorescence, was incorporated into the core of the particles without interfering with the imprinted shell and its ability to rebind propranolol. 相似文献
987.
Spectral-luminescence characteristics of Yb3+ and Nd3+ ions in water solutions of their complexes with some organic dyes of sulfophenylphthalexones group have been considered. Complexes can be efficiently excited with visible light (exc = 532 nm). 4f-Luminescence as a result of energy transfer from the dye moiety to the lanthanide ion was shown. Complexation of new polydentate ligand L of sulfophenylphthalexones type increases the luminescence lifetimes because of the reduced solvation of the ion by water. They were determined as 12.60 s for complex Yb-L and 1.45 s for Nd-L. 相似文献
988.
989.
990.
Controlled incorporation of water molecules into carboxy hydrogen-bond networks: a designed approach
Pérez C Rodríguez ML Foces-Foces C Pérez-Hernández N Pérez R Martín JD 《Organic letters》2003,5(5):641-644
The incorporation of water molecules into the hydrogen-bonded pattern of condensed organic materials implies an unfavorable entropic tradeoff resulting from water ordering. Here we show for a family of diacids of general structure (+/-)-1 that extended chains of anhydrous or hydrated structures can be prepared by controlling the steric factors that lead to the closest packing of individual components. 相似文献