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211.
Madegowda Mahendra Beeranahally H Doreswamy Hirihally C Devarajegowda Venkatesh B Devaru Sridhar M Anandalwar Javaregowda S Prasad 《Analytical sciences》2003,19(10):1463-1464
The title compound was extracted from the natural product of plant origin. It crystallizes in tetragonal space group P4(1) or P4(3), with cell parameters a = 15.795(2)A, c = 11.970(5)A and Z = 4. The structure exhibits intermolecular hydrogen bonds of the type C-H...O. 相似文献
212.
In this paper we consider a queueing model that results from at least two apparently unrelated areas. One motivation to study a system of this type results from a test case of a computer simulation factor screening technique calledfrequency domain methodology. A second motivation comes from manufacturing, where due to cyclic scheduling of upstream machines, the arrival process to downstream machines is periodic. The model is a single server queue with FIFO service discipline and exponential interarrival and service times where the arrival and/or service rates are deterministic cyclic functions of the customer sequence number. We provide steady state results for the mean number in the system for the model with cyclic arrival and fixed service rates and for the model with fixed arrival and cyclic service rates. For the model with both cyclic arrival and service rates, upper and lower bounds are developed for the steady state mean waiting time in the system. Throughout the paper various implications and/or insights derived from the results of this study are discussed for frequency domain methodology.The authors acknowledge the financial support of the CBA/GSB Faculty Research Committee of the College of Business Administration, The University of Texas at Austin. 相似文献
213.
Ares J. Rosakis Sridhar Krishnaswamy Hareesh V. Tippur 《Optics and Lasers in Engineering》1990,13(3-4):183-210
Several possible sources of inaccuracy that occur in the classical interpretation of caustics patterns generated during transient crack growth in elastic materials are examined using a ‘Bifocal Caustics’ set-up and a new full field optical technique called ‘Coherent Gradient Sensing’. During unsteady dynamic crack growth, strict KdI-dominance is generally absent, especially at times close to crack initiation and arrest, even in regions outside the crack-tip 3-D zone where plane stress conditions persist. In such cases a truly transient higher order expansion is found to be essential for correctly describing stress fields outside the 3-D zone. 相似文献
214.
215.
216.
R. Sridhar 《Mathematical Programming》1995,71(2):195-206
Superfluous matrices were introduced by Howe (1983) in linear complementarity. In general, producing examples of this class is tedious (a few examples can be found in Chapter 6 of Cottle, Pang and Stone (1992)). To overcome this problem, we define a new class of matrices
and establish that in
superfluous matrices of any ordern 4 can easily be constructed. For every integerk, an example of a superfluous matrix of degreek is exhibited in the end. 相似文献
217.
218.
Sridhar Komarneni 《Journal of Sol-Gel Science and Technology》1996,6(2):127-138
This review deals with the solution-sol-gel processing of some structural ceramics such as alumina, zirconia, mullite and cordierite and brings out the most significant advances in the preparation of dense ceramics. In the Al2O3 system, seeding of gels with -Al2O3 and other isostructural seeds led not only to lower crystallization temperature but also enhanced densification with refined microstructure through solid-state epitaxy. This breakthrough of seeding has led to improved abrasive grains with large commercial market. Although highly dense, partially stabilized zirconia ceramics were prepared using monodisperse and spherical or nanophase zirconia sol-gel powders, no commercial applications seem to have been realized thus far. In the Al2O3–SiO2 system, compositionally different sol-gel nanocomposites (diphasic gels) led to enhanced densification of mullite at lower temperatures because of the occurrence of densification and crystallization processes almost simultaneously. Mullite powders derived from the diphasic gel route are a breakthrough and are now commercially marketed by Chichibu Cement Company. Highly dense cordierite was prepared by using three sols, i.e., the compositionally different sol-gel nanocomposites in an analogous manner to that of mullite. Although this process appears to be highly cost-effective, especially for the fabrication of substrates, it has not yet been utilized for commercial applications. The use of sol-gel nanocomposites in the processing of various ceramics is expected to be fully exploited in the future. 相似文献
219.
Kodama T Ueda M Nakamuro Y Shimizu K Komarneni S 《Langmuir : the ACS journal of surfaces and colloids》2004,20(12):4920-4925
The cation exchange properties of alkali and alkaline earth metal cations at room temperature were investigated on an ultrafine, highly charged Na-4-mica (with the ideal mica composition Na4Mg6Al4Si4O20F4.xH2O). Ultrafine mica crystallites of 200 nm in size led to faster Sr2+ uptake kinetics in comparison to larger mica crystallites. The alkali metal ion (K+, Cs+, and Li+) exchange uptake was rapid, and complete exchange occurred within 30 min. For the alkaline earth metal ions Ba2+, Ca2+, and Mg2+, however, the exchange uptake required lengthy periods from 3 days to 4 weeks to be completed, similar to its Sr uptake, as previously reported. Kinetic models of the modified Freundlich and parabolic diffusion were examined for the experimental data on the Ba2+, Ca2+, and Mg2+ uptakes. The modified Freundlich model described well the Ba2+ ion uptake kinetics as well as that for the Sr2+ ion, while for the Ca2+ and Mg2+ ions the parabolic diffusion model showed better fitting. The alkali and alkaline earth ion exchange isotherms were also determined in comparison to the Sr2+ exchange isotherm. The thermodynamic equilibria for these cations were compared by using Kielland plots evaluated from the isotherms. 相似文献
220.
M. Lakshmi Kantam G.T. Venkanna Ch. Sridhar K.B. Shiva Kumar 《Tetrahedron letters》2006,47(23):3897-3899
Copper exchanged fluorapatite (CuFAP) is an effective heterogeneous catalyst for N-arylation of heterocycles with bromo- or iodoarenes using K2CO3 as base. N-Arylated products were isolated in good to excellent yields, demonstrating the versatility of the reaction. 相似文献