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91.
The aim of this paper is to model and simulate the displacement of radioactive elements in a saturated heterogeneous porous medium. New schemes are proposed to solve accurately the convection–diffusion–reaction equations including nonlinear terms in the time derivative. Numerical tests show the stability and robustness of these schemes through strong heterogeneities of the medium. Finally the COUPLEX 1 benchmark concerning the far field simulation of a polluted flow by a leak of a nuclear waste disposal is performed and compared with the results available in the literature. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
92.
93.
Germaine H. Saad 《The Journal of the Operational Research Society》1990,41(7):609-624
This paper extends earlier hierarchical production-planning approaches initiated by Hax and Meal. The proposed model incorporates both functional and hierarchical interfaces simultaneously as encountered in practice, and assures feasibility and consistency among the decisions made at the different hierarchical levels of the firm. The problem of infeasibility which arises in disaggregating the aggregate production plan into detailed schedules is solved using goal programming at the product-family disaggregation level, and using branch and bound at the item-disaggregation level. The proposed approach minimizes backlogging regardless of the underlying cost structure of the problem at hand. 相似文献
94.
The construction and performance characteristics of a novel chromate ion-selective membrane sensor are described and used for determining chromium(III) and chromium(VI) ions. The sensor is based on the use of a rhodamine-B chromate ion-associate complex as an electroactive material in a poly(vinyl chloride) membrane plasticized with o-nitrophenyloctyl ether as a solvent mediator. In a phosphate buffer solution of pH 6 - 7, the sensor displays a stable, reproducible and linear potential response over the concentration range of 1 x 10(-1) - 5 x 10(-6) mol l(-1) with an anionic Nernstian slope of 30.8 +/- 0.5 mV decade(-1) and a detection limit of 1 x 10(-6) mol l(-1) Cr(VI). High selectivity for Cr(VI) is offered over many common anions (e.g., I-, Br-, Cl-, IO4-, CN-, acetate, oxalate, citrate, sulfate, phosphate, thiosulfate, selenite, nitrate) and cations (e.g., Ag+, Ca2+, Sr2+, Co2+, Ni2+, Cu2+, Mn2+, Fe2+, Zn2+, Cd2+, Al3+, Cr3+). The sensor is used for determining Cr(VI) and/or Cr(III) ions in separate or mixed solutions after the oxidation of Cr(III) into Cr(VI) with H2O2. As low as 0.2 microg ml(-1) of chromium is determined with a precision of +/-1.2%. The chromium contents of some wastewater samples were accurately assessed, and the results agreed fairly well with data obtained by atomic absorption spectrometry. 相似文献
95.
A. V. Mudryi A. V. Ivanyukovich M. V. Yakushev R. Martin A. Saad 《Journal of Applied Spectroscopy》2007,74(3):415-420
The effect of a strong magnetic field (induction up to 10 T) on free and bound excitons in CuInS2 single crystals is studied. A diamagnetic shift to higher energies is observed in the luminescence and reflectance spectra
for free-exciton lines ALPB ≈ 1.5348 eV, AUPB ≈ 1.5361 eV, and BC ≈ 1.557 eV. The diamagnetic shifts of free-exciton lines ALPB, AUPB, and BC provide a basis for estimating the exciton reduced masses
= 0.131m0,
= 0.13 4m0, and μBC = 0.111m0, respectively. Bound-exciton lines in luminescence spectra are split under the influence of the magnetic field. The magnitude
of the Zeeman effect (g-factor of the magnetic splitting) is estimated.
__________
Translated from Zhurnal Prikladnoi Spektroskopii Vol. 74, No. 3, pp. 373–377, May–June, 2007. 相似文献
96.
Synthesis of Nanoporous Ni‐Co Mixed Oxides by Thermal Decomposition of Metal‐Cyanide Coordination Polymers 下载免费PDF全文
Mohamed B. Zakaria Dr. Ming Hu Dr. Malay Pramanik Dr. Cuiling Li Dr. Jing Tang Prof. Ali Aldalbahi Prof. Saad M. Alshehri Dr. Victor Malgras Prof. Yusuke Yamauchi 《化学:亚洲杂志》2015,10(7):1541-1545
A straightforward strategy to prepare nanoporous metal oxides with well‐defined shapes is highly desirable. Through thermal treatment and a proper selection of metal‐cyanide coordination polymers, nanoporous nickel‐cobalt mixed oxides with different shapes (i.e., flakes and cubes) can be easily prepared. Our nanoporous materials demonstrate high electrocatalytic activity for oxygen evolution reaction. 相似文献
97.
Alkylation of N,N-dialkylcarboxamides with 1,3-dehydroadamantane has been accomplished for the first time. The reaction involves the C–H bond in the α-position with respect to the carbonyl group and provides a convenient one-step preparation of substituted carboxylic acid amides containing an 1-adamantyl substituent and a pharmacophoric group in the amide moiety. 相似文献
98.
Danjie Zhang Ming-Hui Chen Joseph G. Ibrahim Mark E. Boye Wei Shen 《Journal of computational and graphical statistics》2017,26(1):121-133
Joint models for longitudinal and survival data are routinely used in clinical trials or other studies to assess a treatment effect while accounting for longitudinal measures such as patient-reported outcomes. In the Bayesian framework, the deviance information criterion (DIC) and the logarithm of the pseudo-marginal likelihood (LPML) are two well-known Bayesian criteria for comparing joint models. However, these criteria do not provide separate assessments of each component of the joint model. In this article, we develop a novel decomposition of DIC and LPML to assess the fit of the longitudinal and survival components of the joint model, separately. Based on this decomposition, we then propose new Bayesian model assessment criteria, namely, ΔDIC and ΔLPML, to determine the importance and contribution of the longitudinal (survival) data to the model fit of the survival (longitudinal) data. Moreover, we develop an efficient Monte Carlo method for computing the conditional predictive ordinate statistics in the joint modeling setting. A simulation study is conducted to examine the empirical performance of the proposed criteria and the proposed methodology is further applied to a case study in mesothelioma. Supplementary materials for this article are available online. 相似文献
99.
100.
On drag, Strouhal number and vortex-street structure 总被引:5,自引:0,他引:5
A phenomenological model for the vortex-shedding process behind bluff cylindrical bodies is proposed. Relationships between Strouhal frequency St, drag coefficient cD, Reynolds number Re and geometric wake parameters are obtained from mass conservation, momentum conservation in the transverse direction and energy considerations. For the first time, Roshko's (Technical Report TN 3169, NACA, US Government Printing Office, Washington DC, 1954) experimental discovery of vortex-street similarity behind different cylinders is analytically derived. In addition, the empirically obtained Strouhal-frequency laws of Roshko (Technical Report TN1191, NACA, US Government Printing Office, Washington DC, 1954) and Fey (Phys. fluids A 10 (1998) 1547) are also reproduced. Measurements of St and cD including their Re dependency for flows around cylinders with circular, square, triangular, semi-circular and other cross sections agree favorably with the proposed model. 相似文献