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121.
Two infinite families of two–character sets in PG(5,q) arising from the Veronese surface of PG(5,q) are constructed. 相似文献
122.
Correlation equations for friction factors and convective coefficients in tubes containing bundles of internal, longitudinal fins 总被引:2,自引:0,他引:2
Finned tubes are commonly employed in tubular heat exchangers to augment the heat transfer rates between two dissimilar fluid
streams. The goal of this study is two-fold: a) to determine the laminar, fully developed velocity and temperature fields
for long, internal, longitudinal finned tubes; and b) to construct empirical correlation equations applicable for the asymptotic
friction factor and the asymptotic Nusselt numbers as a function of the number of fins and the relative fin height in the
bundle. Neither the fluid dynamics nor the heat transfer literature provides information for the second goal, which can be
extremely useful to thermal engineers for the implementation of Computer-Aided Design (CAD) of internal, longitudinal finned
tubes in heat exchange devices. Moreover, for the validity of the correlation equations, a seldom adopted criterion for the
critical Reynolds number has also been introduced as an indispensable guideline to warrant laminar regimes.
Received on 24 January 1997 相似文献
123.
S. Cafieri M. D’Apuzzo M. Marino A. Mucherino G. Toraldo 《Journal of Optimization Theory and Applications》2006,129(1):55-75
In this paper, we present an interior-point algorithm for large and sparse convex quadratic programming problems with bound
constraints. The algorithm is based on the potential reduction method and the use of iterative techniques to solve the linear
system arising at each iteration. The global convergence properties of the potential reduction method are reassessed in order
to take into account the inexact solution of the inner system. We describe the iterative solver, based on the conjugate gradient
method with a limited-memory incomplete Cholesky factorization as preconditioner. Furthermore, we discuss some adaptive strategies
for the fill-in and accuracy requirements that we use in solving the linear systems in order to avoid unnecessary inner iterations
when the iterates are far from the solution. Finally, we present the results of numerical experiments carried out to verify
the effectiveness of the proposed strategies. We consider randomly generated sparse problems without a special structure.
Also, we compare the proposed algorithm with the MOSEK solver.
Research partially supported by the MIUR FIRB Project RBNE01WBBB “Large-Scale Nonlinear Optimization.” 相似文献
124.
125.
Fusicoccin incubated for 17 h in 6 M HCl at 37°C gives rise to a chromophoric system having an absorption maximum at 555 nm. A colorimetric method for the determination of pure fusicoccin and of fusicoccin in fermentation liquors and infected plant tissues is described. The method is useful for 50–800 μg of fusicoccin. 相似文献
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128.
Salvatore Plescia Giuseppe Daidone Vincenzo Sprio Maria Luisa Marino 《Journal of heterocyclic chemistry》1976,13(3):629-631
The reactivity of pyrrole derivatives towards the semicarbazone of ω-bromoacetophenone has been reported. Substituents at position 1 of the pyrrole ring greatly affect the course of the reaction. 1,4,4a,4b,5,8,8a,8b-Octahydro-9H-pyrrolo[2,3-c:4,5-c′]dipyridazine derivative or α- and α,α-pyrrolyl derivatives were obtained depending on the substituents. The structures reported were assigned on the basis of satisfactory analytical and spectroscopic data. 相似文献
129.
130.