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91.
An approximate method of determining the free vibration characteristics of ring and/or stringer-stiffened cylindrical shells with cutouts is presented in this paper. The method is based on the Rayleigh-Ritz technique in which beam characteristic functions (axially) and trigonometric functions (circumferentially) are used in the displacement series for the shell reference surface. It was found that the cutouts generally tend to decrease the frequencies. This effect is the largest on the fundamental frequency. Physically this means that a cutout reduces the effective shell stiffness to a greater extent than it does the effective mass. The mode shapes display strong coupling of the distinct wave forms of an otherwise uniform shell. They also reveal the possibility of peak amplitudes in the normal displacements both near and away from the edges of the cutouts. The reductions in the lower frequencies (caused by cutouts) for the stiffened shell were found to be less than those for the unstiffened shell. 相似文献
92.
An algorithm for generating cutting planes for mixed-integer knapsack polyhedra is described. The algorithm represents an exact separation procedure and is based on a general methodology proposed by one of the authors in an earlier paper. Computational results are presented. © 1998 The Mathematical Programming Society, Inc. Published by Elsevier Science B.V. 相似文献
93.
94.
G. E. Boyd 《Journal of solution chemistry》1977,6(2):95-109
Osmotic coefficients for aqueous mixtures of sodium chloride with sodiumpara-ethylbenzenesulfonate NapEBS and lithiumpara-ethylbenzenesulfonate LipEBS with NapEBS obtained by the gravimetric isopiestic vapor pressure comparison method are interpreted with the Scatchard neutral-component and with the Pitzer ion-component equations. Ionic and mean ionic activity coefficients for Na+ and Cl– ions and for NaCl, respectively, were also determined with an electrochemical cell. The ±(NaCl) values at constant unit ionic strength,I=1.00, were compared with those computed from osmotic-coefficient measurements. Strong anion-anion interactions were observed in the NaCl-NapEBS mixtures. 相似文献
95.
Susan M. Boyd Martin Beverley Leif Norskov Roderick E. Hubbard 《Journal of computer-aided molecular design》1995,9(5):417-424
Summary We have developed a program, HookSpace, which provides a simplistic approach to assessing the diversity of molecular databases. The spatial relationship between pairs of intramolecular functional groups can be analysed in a variety of ways to provide both qualitative and quantitative measures of diversity. Results are described and contrasted for two commercially available databases and a combinatorial library of benzodiazepam derivatives. HookSpace highlights the main differences in molecular content of these data sets. 相似文献
96.
97.
Kenneth D. Paull Robert H. Shoemaker Michael R. Boyd Jack L. Parsons Prabhakar A. Risbood William A. Barbera Mahenda N. Sharma David C. Baker Elli Hand Dominic A. Scudiero Anne Monks Michael C. Alley Manfred Grote 《Journal of heterocyclic chemistry》1988,25(3):911-914
A new tetrazolium salt, XTT, has been synthesized. XTT is reduced by a considerable variety of cell lines to a water-soluble formazan. XTT appears to merit further investigation as a reagent for broader application to cell culture assay systems. 相似文献
98.
99.
The vector analyzing power iT11 for deuterons elastically scattered by 4He has been measured for c.m. angles between 51.8° and 158.9° and deuteron energies in the range 11.5 to 17 MeV. The results show that d-α scattering is a convenient analyzer for deuteron vector polarization in the energy range investigated, since the angular dependence of iT11 is fairly insensitive to energy and the magnitude of iT11 is quite large at some angles. 相似文献
100.
This paper explores stability in a three differential equation model of ungulates, their forage and their predators. Stability most depends on the feeding efficiency of exploiters relative to the growth potential of those exploited. Stable, natural systems probably require relatively inefficient exploitation, refuges for the exploited population or prey switching by generalist exploiters. Increased exploitation of ungulates enhances ungulate-forage stability but, lacking prey refugia, eventually overexploits the ungulates. Multiple, stable equilibria representing sustained ungulate yield and ungulate extinction probably characterize big game. Under traditional management, game populations will approach the zone of attraction of the second of these equilibria. 相似文献