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1.
The finite-data performance of a minimum-variance distortionless response (MVDR) beamformer is analyzed with and without spatial smoothing, using first-order perturbation theory. In particular, expressions are developed for the mean values of the power gain in any direction of interest, the output power, and the norm of the weight-error vector, as a function of the number of snapshots and the number of smoothing steps. It is shown that, in general, the smoothing, in addition to decorrelating the sources, can alleviate the effects of finite-data perturbations. The above expressions are reduced to the case in which no spatial smoothing is used. These expressions are valid for an arbitrary array and for arbitrarily correlated signals. For this case, an expression for the variance of the power gain is also developed. For a single interference case it is shown explicitly how the SNR, spacing of the interference from the desired signal and the correlation between them influence the beamformer performance. Simulations verify the usefulness of the theoretical expressions 相似文献
2.
[reaction: see text] A novel Cu(I)-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides with acrylates has been developed. Up to 98/2 exo/endo selectivity and up to 98% enantiomeric excess have been achieved. 相似文献
3.
Malati Raghunath 《Tetrahedron letters》2005,46(47):8213-8216
Among the bisphosphine ligands, we have previously developed Cn-TunePhos (n = 1-6) as a family of ligands with tunable bite angles. The increase in spacer -CH2- groups in this family of ligands causes changes in ligand dihedral angle, which in turn causes P-Pd-P bite angle variation. Pd-catalyzed asymmetric alkylations and cycloadditions have been tested with Cn-TunePhos ligands. This study aims at a possible correlation between ligand bite angles with enantioselectivity of the Pd-catalyzed asymmetric products. 相似文献
4.
Satish N. Dighe Ravindra V. Bhattad Raghunath R. Kulkarni Kishor S. Jain 《合成通讯》2013,43(23):3522-3527
The synergy of the combined use of DMSO and an ionic liquid viz. (bbim)+Br? has brought about a rapid and efficient esterification of sodium carboxylates with acyl and alkyl halides under ambient conditions in excellent isolated yields (90–95%) in short reaction times (12–40 min). 相似文献
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Madhukar N. Jachak Maruti G. Ghagare Dilip R. Birari Ramhari V. Rote Muddassar A. Kazi Sanjay M. Jachak Raghunath B. Toche 《Monatshefte für Chemie / Chemical Monthly》2010,46(3):569-576
Abstract
A novel synthesis of pyrazole-4-carboxamides is reported. The reaction of N-(3-(dimethylamino)-2-formylacryloyl)formamide, an intermediate obtained by Vilsmeier–Haack formylation of acetonitrile, with hydrazine hydrate or monosubstituted hydrazines provides such compounds in good yields. This method has advantages over other methods for construction of such ring systems previously described in the literature. 相似文献8.
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Toche RB Janrao RA Bagul SM Patil SP Pagar BP Nikam PS 《Journal of fluorescence》2011,21(4):1617-1624
Suzuki-Miyaura cross coupling was successfully used for C5-arylation in 4-amino-2-chloroquinoline-3-carbaldehyde using arylbornic acid and tetrakistriphenylphosphine palladium catalyst in water. Friedländer condensation reaction on 4-amino-2-chloro/2-arylquinoline-3-carbaldehyde and aromatic ketones gave novel aryl and diarylbenzo[h] [1, 6]naphthyridines in good yields. Fluorescence quantum yields were increased by introducing C2 and C5 π donor aryl benzo[h][1, 6]naphthyridines derivatives. 相似文献
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