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101.
Guglielmo DAmico Montserrat Guillen Raimondo Manca 《Insurance: Mathematics and Economics》2009,45(2):173-179
In this paper a stochastic model for disability insurance contracts is presented. The model is based on a discrete time non-homogeneous semi-Markov process to which the backward recurrence time process is joined. This permits us to study in a more complete way the disability evolution and to face the duration problem in a more effective way. The model is applied to a sample of contracts drawn at random from a mutual insurance company. 相似文献
102.
Nestor Zouain Ivaldo Pontes Jean Vaunat 《European Journal of Mechanics - A/Solids》2010,29(3):327-336
Energy and dissipation pseudo-potentials are employed to derive constitutive relationships, in the context of thermodynamic concepts, for the widely used Modified Cam-Clay (MCC) model for soil mechanics. A variational formulation of the MCC evolution equations is proposed in this paper. Since plastic collapse of MCC soils cannot be embedded in the classical limit analysis theory, finding the critical amplification of the load that produces plastic collapse is formulated in the form of a system of equations and inequalities. Then, a mixed minimization principle is proposed for the plastic collapse analysis of MCC soils. This principle is obtained by the application of the variational formulation for the flow law introduced in the first part of the article. 相似文献
103.
Anabel Gonzalez Guillen Marcin Oszajca Katarzyna Luberda-Durna Wieslaw Lasocha 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(11):1502-1508
Two organic–inorganic hybrid layered materials, namely poly[(μ‐1,4‐diaminobenzene‐κ2N:N′)[μ3‐sulfato(VI)‐κ4O:O′:O′′,O′′′]manganese], [Mn(SO4)(C6H8N2)]n, 1 , and poly[(μ‐1,4‐diaminobenzene‐κ2N:N′)[μ3‐sulfato(VI)‐κ4O:O′:O′′,O′′′]copper], [Cu(SO4)(C6H8N2)]n, 2 , have been synthesized using 1,4‐phenylenediamine (PPD) as an organic template and component (linker). Both materials form three‐dimensional frameworks. The crystal structures were determined using data from powder X‐ray diffraction measurements. The purity and morphology of the compounds were studied by elemental analyses and SEM investigations, and their thermal stabilities were determined by thermogravimetric and nonambient powder X‐ray diffraction measurements, which indicated that 1 is stable up to 537 K and 2 is stable up to 437 K. 相似文献
104.
Ruairi M. Nestor Mihai Basa Martin Lastiwka Nathan J. Quinlan 《Journal of computational physics》2009,228(5):1733-1749
The finite volume particle method (FVPM) is a mesh-free method for fluid dynamics which allows simple and accurate implementation of boundary conditions and retains the conservation and consistency properties of classical finite volume methods. In this article, the FVPM is extended to viscous flows using a consistency-corrected smoothed particle hydrodynamics (SPH) approximation to evaluate velocity gradients. The accuracy of the viscous FVPM is improved by a higher-order discretisation of the inviscid flux combined with a second-order temporal discretisation. The higher-order inviscid FVPM is validated for a 1-D shock tube problem, in which it demonstrates an enhanced shock capturing ability. For two-dimensional simulations, a small arbitrary Lagrange–Euler correction to fully Lagrangian particle motion is beneficial in maintaining a favourable particle distribution over long simulation times. The viscous FVPM is validated for two-dimensional Poiseuille, Taylor–Green and lid-driven cavity flows, and good agreement is achieved with analytic or reference numerical solutions. These results establish the viability of FVPM as a tool for mesh-free simulation of viscous flows in engineering. 相似文献
105.
Experimental and theoretical study of the structure and vibrational spectra of valpromide,C7H15CONH2
Nieves C. Comelli Nestor E. Massa Eduardo A. Castro Luis Bruno Blanch Alicia H. Jubert 《Journal of Raman spectroscopy : JRS》2009,40(1):6-17
In this work, we present results of the conformational and vibrational properties of valpromide (Vpd), an amide with antiepileptic activity, studied by IR and Raman spectroscopy at 300 and 77 K, and 300 K, respectively. Experimental data are compared against ab initio calculations performed at B3LYP level with the inclusion of solvatation effects. Experimental results, reinforced by theoretical calculations, point out that Vpd has three conformers on the potential energy surface, with different structures that can be identified in the CO and NH spectral regions. These conformers are defined by different angular arrays of the dihedral angles formed with the CO, C N and C〈 H, C C of the aliphatic chain bonds. The existence of different conformations and structures are discussed on the basis of results derived from electronic localization function (ELF) and natural orbital bond (NBO) analysis. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
106.
107.
The spectroscopic study of trivalent ytterbium doped Li6Y(BO3)3 is conducted in the UV-visible and infrared range. An excitation in the charge transfer band of ytterbium has been selected in order to reduce the reabsorption effect on the IR emission intensity. The maximum of the emission is located at 972 nm for an excitation at 230 nm. The energy level assignment has been successfully conducted using vibrational spectroscopy to distinguish the pure electronic transitions from the phonon-assisted ones. The splitting of the 2F5/2 and 2F7/2 components is equal to 523 cm−1 and 676 cm−1, respectively. The decay time dependence as a function of the concentration is also reported. The calculated value τrad is about (1.03 ± 0.01) ms for the 1% doped material. For the highest concentration, an IR excitation gives rise to the observation of a blue-green luminescence caused by two mechanisms: an erbium emission at 550 nm after upconversion and a cooperative luminescence of ytterbium ions. 相似文献
108.
109.
Guang-Lei Zuo Hyun Yong Kim Yanymee N. Guillen Quispe Zhi-Qiang Wang Seung Hwan Hwang Kyong-Oh Shin Soon Sung Lim 《Molecules (Basel, Switzerland)》2021,26(1)
Muehlenbeckia volcanica (Benth.) Endl. (M. volcanica), native to South America, is a traditional Peruvian medicinal plant that has multi-therapeutic properties; however, no phytochemicals have been identified from it yet. In this study, a five-step polarity-stepwise elution counter-current chromatography (CCC) was developed using methanol/water (1:5, v/v) as the stationary phase and different ratios of n-hexane, ethyl acetate, and n-butanol as mobile phases to separate the compounds from the 70% methanol extract of M. volcanica, by which six compounds with a wide range of polarities were separated in a single run of CCC and were identified as gallic acid, protocatechuic acid, 4,4′-dihydroxy-3,3′-imino-di-benzoic acid, rutin, quercitrin, and quercetin. Then, two compounds from the fractions of stepwise elution CCC were separated using conventional high-speed CCC, pH-zone-refining CCC, and preparative high-performance liquid chromatography, and identified as shikimic acid and miquelianin. These compounds are reported from M. volcanica for the first time. Notably, except for shikimic acid, all other compounds showed anti-diabetic potentials via antioxidant, antiglycation, and aldose reductase inhibition. The results suggest that the polarity-stepwise elution CCC can be used to efficiently separate or fractionate compounds with a wide range of polarities from natural products. Moreover, M. volcanica and its bioactive compounds are potent anti-diabetic agents. 相似文献
110.
Castro K Pérez-Alonso M Rodríguez-Laso MD Etxebarria N Madariaga JM 《Analytical and bioanalytical chemistry》2007,387(3):847-860
Non-destructive and non-invasive micro-Raman fibre optic and micro-XRF analyses were performed to study a wallpaper from the
beginning of the 19th century. The complementarity of these two non-destructive techniques is shown in this work. The analysed
artwork is considered one of the most beautiful wallpapers ever manufactured according to the catalogues and books; it is
known as Chasse de Compiègne, manufactured by Jacquemart, Paris, in 1812. During the analysis, an unexpected pigment was detected by both analytical techniques:
lead-tin yellow type II. This pigment was used until ca. 1750, when other yellow pigments replaced it, thus it is very difficult
to find it in paintings afterwards. Together with this pigment, red lead, Prussian blue, brochantite, yellow iron oxide, calcium
carbonate, vermilion, carbon black of animal origin (bone black), lead white, and raw and burnt sienna were also determined
by combining the analytical information provided by both techniques. A possible degradation of brochantite to antlerite is
also discussed. 相似文献