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91.
Paolo De Lucia J. D. Maitland Wright 《Rendiconti del Circolo Matematico di Palermo》1991,40(3):442-452
Dopo aver dato una definizione di parte convessa di un gruppo topologico, si stabilisce una condizione affinchè il condominio
di una misura sia convesso. 相似文献
92.
93.
In the approximation of linear elliptic operators in mixed form, it is well known that the so-called inf-sup and ellipticity in the kernel properties are sufficient (and, in a sense to be made precise, necessary) in order to have good approximation properties and optimal error bounds. One might think, in the spirit of Mercier-Osborn-Rappaz-Raviart and in consideration of the good behavior of commonly used mixed elements (like Raviart-Thomas or Brezzi-Douglas-Marini elements), that these conditions are also sufficient to ensure good convergence properties for eigenvalues. In this paper we show that this is not the case. In particular we present examples of mixed finite element approximations that satisfy the above properties but exhibit spurious eigenvalues. Such bad behavior is proved analytically and demonstrated in numerical experiments. We also present additional assumptions (fulfilled by the commonly used mixed methods already mentioned) which guarantee optimal error bounds for eigenvalue approximations as well.
94.
95.
Rosa IL Filho PC Neri CR Serra OA de Figueiredo AT Varela JA Longo E 《Journal of fluorescence》2011,21(4):1575-1583
This work reports on the synthesis and characterization of a new complex of Eu3+ with the 3-hydroxypicolinamide ligand (Hhpa). Here we present an approach for obtaining bis[2-carbamoyl(κO)pyridin-3-olato(κO’)]
lanthanide complexes, which were characterized through elemental analysis, thermal analysis, infrared and photoluminescence
spectroscopies (emission, excitation, luminescence lifetimes, quantum efficiencies, Judd-Ofelt parameters and quantum yields).
Although hpa can act as a bidentate ligand in different conformations, the results attest for the occurrence of a unique coordination
site of low symmetry for the Eu3+ ions, in which two anionic hpa ligands coordinate the cations through an O/O chelating system. The phosphorescence of the
synthesized gadolinium complex provides the energy of the triplet state, which is determined to be at 20,830 cm-1 over the ground state. This makes the Hhpa ligand very adequate for sensitizing the Eu3+ luminescence, which leads to a very efficient antenna effect and opens a wide range of applications for the complex in light
emitting organic-inorganic devices. 相似文献
96.
U. Lucia G. Gervino 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(1-2):367-369
In this paper an analysis of the Stirling cycle in thermoeconomic
terms is developed using the entropy generation. In the thermoeconomic optimization of an
irreversible Stirling heat pump cycle the F function has been
introduced to evaluate the optimum for the higher and lower sources
temperature ratio in the cycle: this ratio represents the value which
optimizes the cycle itself. The variation of the function F is proportional to
the variation of the entropy generation, the maxima and minima of F has been evaluated in
a previous paper without giving the physical foundation of the method. We
investigate the groundwork of this approach: to study the
upper and lower limits of F function allows to determine the cycle stability and the
optimization conditions. The optimization consists in the best COP at
the least cost. The principle
of maximum variation for the entropy generation becomes the analytic
foundation of the optimization method in the thermoeconomic analysis
for an irreversible Stirling heat pump cycle. 相似文献
97.
Salvatore Giuffrida Guglielmo G. Condorelli Lucia L. Costanzo Giorgio Ventimiglia Raffaella Lo Nigro Maria Favazza Enrico Votrico Corrado Bongiorno Ignazio L. Fragalà 《Journal of nanoparticle research》2007,9(4):611-619
Liquid Phase Photo-Deposition (LPPD) technique has been used to obtain both colloidal particles and thin films of metallic
and chloride nickel from solutions of only precursor Ni(acac)2 (acac=2,4-pentandionato). Metallic nickel was obtained from ethanol solutions by direct nickel(II) photoreduction at 254 nm
and by acetone sensitised reaction at 300 nm. In this latter process the rate was higher than in the first one. NiCl2 was formed from CCl4 solution by a solvent-initiated reaction. TEM analysis, performed on colloidal particles of nickel, showed that their dimensions
are in the range 2–4 nm. The films did not present carbon contamination and were characterized by AFM, XPS and GIXRD. Metallic
films consisted of particles of 20–40 nm that are the result of the aggregation of smaller crystallites (4–5 nm). Larger agglomerations
(around 200 nm) have been observed for NiCl2 films. 相似文献
98.
Vladimír Petrilla Vladimíra Tomečková Vladimír Komanický Lucia Lichardusová Martina Šutorová Monika Petrillová 《光谱学快报》2014,47(1):1-5
The aim of this paper was to characterize and compare spitting cobras of Africa. The autofluorescence of Naja ashei and Naja nigricollis venoms was investigated by atomic force microscopy and fluorescence analysis. The synchronous fluorescence analysis showed higher endogenous fluorescence of Naja ashei venom in comparison with Naja nigricollis venom. The atomic force microscopy revealed different surfaces of compared venoms as a result of different amounts of proteins. Our results confirmed different structures of Naja nigricollis and Naja ashei venom. The practical advantages of selected techniques are high sensitivity, minimal quantity of venom, and capability to measure the spitting cobra by autofluorescence. 相似文献
99.
100.
In this paper, we propose a mathematical model with time delay to describe the process of diffusion of a new technology. This model is suitable for modeling diffusion processes of all those technologies that require great initial investments and public subsidies, such as technologies used for producing renewable energy. We consider external factors, such as the government policy and the production costs, that influence the decision of adoption of the new technology. We also consider the internal influence from adopters. The adoption process is described by a delay differential equation. The time delay represents the evaluation stage at which the potential consumers decide whether to adopt the new technology or not. A qualitative analysis is carried out in order to assess the stability of the equilibrium for certain parameters and to find the final level of adopters. 相似文献