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881.
882.
883.
Yury Yu. Rusakov Leonid B. Krivdin Valentina M. Nosova Alexander V. Kisin Valentin G. Lakhtin 《Magnetic resonance in chemistry : MRC》2012,50(10):665-671
The calculations of geminal and vicinal 29Si–1H spin–spin coupling constants across double bond in 15 alkenylmethylsilanes and alkenylchlorosilanes were carried out at the second‐order polarization propagator approach level in a good agreement with experiment. Two structural trends, namely, (i) the geometry of the coupling pathway and (ii) the effect of the electrowithdrawing substituent, have been interpreted in terms of the natural J‐coupling analysis within the framework of the natural bond orbital approach. Thus, the marked difference between cisoidal and transoidal 29Si–1H spin–spin coupling constants across double bond was accounted for the delocalization contributions including bonding and antibonding Si–C and C–H orbitals, whereas the chlorine effect was explained in terms of the steric contributions including bonding Si–Cl orbitals. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
884.
885.
Alexander Belyaev 《Pramana》2009,72(1):143-160
Large Hadron Collider (LHC) has a great chance to finally reveal supersymmetry which remains a compelling theory for over
30 years in spite of lack of its discovery. It might be around the corner the present LHC era with sensitive dark matter search
experiments and international linear collider hopefully coming up in the near future.
相似文献
886.
Alexander Efremov Youngkeun Kim Hyun-Woo Lee Kwang-Ho Kwon 《Plasma Chemistry and Plasma Processing》2011,31(2):259-271
The effects of HBr/Ar and HBr/Cl2 mixing ratios in the ranges of 0–100% Ar or Cl2 on plasma parameters, densities of active species influencing the dry etch mechanisms were analyzed at fixed total gas flow
rate of 40 sccm, total gas pressure of 6 mTorr, input power of 700 W and bias power of 300 W. The investigation combined plasma
diagnostics by Langmuir probes and the 0-dimensional plasma modeling. It was found that the dilution of HBr by Ar results
in maximum effect on the ion energy flux with expected impact on the etch rate in the ion-flux-limited etch regime, while
the addition of Cl2 influences mainly the relative fluxes of Br and Cl atoms on the etched surface with expected impact on the etch rate in the
reaction-rate-limited etch regime. 相似文献
887.
888.
Simeon Reich Alexander J. Zaslavski 《Journal of Fixed Point Theory and Applications》2010,8(2):395-403
We use the concept of porosity in order to establish a generic stable convergence theorem for infinite products of nonexpansive
mappings in Banach spaces. 相似文献
889.
Vincent Martin Thibault Le Bourdon Alexander Mattioli Pasqual 《Journal of sound and vibration》2011,330(17):4233-797
Acoustical holography can be used to identify the vibration velocity of an extended vibrating body. Such an inverse problem relies on the radiated acoustic pressure measured by a microphone array and on an a priori knowledge of the way the body radiates sound. Any perturbation on the radiation model leads to a perturbation on the velocity identified by the inversion process. Thus, to obtain the source vibration velocity with a good precision, it is useful to identify also an appropriate propagation model. Here, this identification, or adaptation, procedure rests on a geometrical interpretation of the acoustic holography in the objective space (here the radiated pressure space equipped with the L2-norm) and on a genetic algorithm.The propagator adaptation adds information to the holographic process, so it is not a regularisation method, which approximates the inverse of the model but does not affect the model. Moreover regularisations act in the variables space, here the velocities space. It is shown that an adapted model significantly decreases the quantity of regularisation needed to obtain a good reconstructed velocity, and that model adaptation improves significantly the acoustical holography results.In the presence of perturbations on the radiated pressure, some indications will be given on the interest or not to adapt the model, again thanks to the geometrical interpretation of holography in the objective space.As a numerical example, a disc whose vibration velocity on one of its sides is identified by acoustic holography is presented. On an industrial scale, this problem occurs due to the noise radiated by car wheels. The assessment of the holographic results has not yet been rigorously performed in such situations due to the complexity of the wheel environment made up of the car body, road and rolling conditions. 相似文献
890.
We discover that some unstable vacua have long memory. By that we mean that even in the theories containing only massive particles, there are correllators and expectation values which grow with time. We examine the cases of instabilities caused by the constant electric fields, expanding and contracting universes and, most importantly, the global de Sitter space. In the last case the interaction leads to a remarkable UV/IR mixing and to a large back reaction. This gives reasons to believe that the cosmological constant problem could be resolved by the infrared physics. 相似文献