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991.
The effect of the loading conditions on the stability of rotating cylindrical shells is examined experimentally. It is established
that the critical loads of axially compressed rotating shells substantially decrease with increasing speed of rotation
__________
Translated from Prikladnaya Mekhanika, Vol. 44, No. 6, pp. 93–96, June 2008. 相似文献
992.
993.
The objective of this study was to investigate the effect of pressure and/or temperature on the polymorphic transformation of famotidine from form B to form A by using a thermal confocal Raman microspectroscopy. A compact with a wide transparent zone in the center and an opaque zone surrounding it was prepared by compressing a conical mass of famotidine form B. Two unique Raman peaks at 2897 and 2920 cm−1 for famotidine forms B and A, respectively, were used as markers. The result indicates that the opaque zone in each compact was composed of famotidine from B, and it did not undergo any polymorphic transformation by preparing with higher compression pressure and/or by heating. The Raman peak intensity ratio of the 2920 cm−1 and 2897 cm−1 bands markedly increased starting from 120 °C for the transparent zone prepared by compressing with 19.61 × 104 kPa pressure, but increased from 100 °C with 49.03 × 104 kPa pressure, indicating the occurrence of thermally induced polymorphic transformation of famotidine from form B to form A. However, the transparent zone prepared by 9.81 × 104 kPa compression pressure retained the same Raman spectrum as that of the famotidine form B, revealing that the thermally induced polymorphic transformation of famotidine was dependent on the pressure applied. There was no polymorphic transformation of famotidine in the transparent zone when it was prepared by a higher compression pressure at a lower temperature or by a lower pressure at a higher temperature. The combined effect of compression and temperature was found to accelerate the polymorphic transformation from form B to form A in the transparent zone of famotidine. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
994.
V. M. Bazovkin A. P. Kovchavtsev G. L. Kuryshev A. A. Maslov S. G. Mironov D. V. Khotyanovsky A. V. Tsarenko I. S. Tsyryulnikov 《Journal of Applied Mechanics and Technical Physics》2009,50(4):638-645
Coefficients of heat transfer to the surface in a laminar hypersonic flow (M
∞
= 21) over plane and axisymmetric models with a compression corner are presented. These coefficients are measured by an infrared
camera. The parameters varied in the experiments are the angle of the compression corner and the distance to the corner point.
Characteristics of the flow with and without separation in the corner configuration are obtained. The measured results are
compared with direct numerical simulations performed by solving the full unsteady Navier-Stokes equations. Experiments with
controlled streamwise structures inserted into the flow are described. A substantial increase in the maximum values of the
heat-transfer coefficient in the region of flow reattachment after developed laminar separation is demonstrated.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 4, pp. 112–120, July–August, 2009. 相似文献
995.
E.L. Starostin 《Journal of the mechanics and physics of solids》2009,57(6):959-969
We study the force vs. extension behaviour of a helical spring made of a thin torsionally stiff anisotropic elastic rod. Our focus is on springs of very low helical pitch. For certain parameters of the problem such a spring is found not to unwind when pulled but rather to form hockles that pop out one by one and lead to a highly non-monotonic force-extension curve. Between abrupt loop pop-outs this curve is well described by the planar elastica whose relevant solutions are classified. Our results may be relevant for tightly coiled nanosprings in future micro- and nano(electro)mechanical devices. 相似文献
996.
Microstructure and texture are known to undergo drastic modifications due to trace hypoeutectic boron addition (~0.1 wt.%) for various titanium alloys e.g. Ti–6Al–4V. The deformation behaviour of such an alloy Ti–6Al–4V–0.1B is investigated in the (α?+?β) phase field and compared against that of the base alloy Ti–6Al–4V studied under selfsame conditions. The deformation microstructures for the two alloys display bending and kinking of α lamellae in near α and softening via globularization of α lamella in near β phase regimes, respectively. The transition temperature at which pure slip based deformation changes to softening is lower for the boron added alloy. The presence of TiB particles is largely held attributable for the early softening of Ti–6Al–4V–0.1B alloy. The compression texture of both the alloys carry signature of pure α phase defamation at lower temperature and α→β→α phase transformation near the β transus temperature. Texture is influenced by a complex interplay of the deformation and transformation processes in the intermediate temperature range. The contribution from phase transformation is prominent for Ti–6Al–4V–0.1B alloy at comparatively lower temperature. 相似文献
997.
Abstract Spring wheat plants were grown in split-root containers and labelled with 15N by fertilizing one compartment of the container with 15NH4 15NO3 (95 at.-% 15N exc.). After the harvest, approx. 90% of the 15N incorporated by the plants were found in the shoots and 3% in the roots; approx. 7% had been released into the soil of the unlabelled compartment. The 15N in the soil of the unlabelled compartment was extracted with KCl and hydrolysed with HCl. Approx. 60% of the 15N was found in the hydrolysable organic N pool of the soil and 9% in the fraction of the soluble and exchangeable inorganic nitrogen. 相似文献
998.
999.
1000.
Yamamoto T Akai Y Nagata Y Suginome M 《Angewandte Chemie (International ed. in English)》2011,50(38):8844-8847