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101.
This paper concerns the optimum thickness distribution of unconstrained viscoelastic damping layer treatments for plates. The system loss factor is expressed in terms of the mechanical properties of the plate and damping layer and the layer/plate thickness ratio. Optimum distributions of the thickness ratio that maximize the system loss factor are obtained through sequential unconstrained minimization techniques. Results are presented for both simply-supported and edge-fixed rectangular plates with aspect ratios of 1·0 to 4·0. These results indicate that the system loss factor can be increased by as much as 100%, or more, by optimizing the thickness distribution of the damping treatment. Also revealed are the regions of the plate where added damping treatments are most effective.  相似文献   
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103.
The azoalkenes (1) have been prepared from the corresponding hydrazones of dichloroacetalhyde; they react with 1,3-dicarbonyl compounds to give first the addition-elimination products (4) and then pyrroles (6).  相似文献   
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Thiohydroxylamine has been identified as one of the reaction products from the discharge reaction of N2 + H2S. Both cis and trans conformers have been observed. The rotational spectra have been studied from 56 to 170 GHz for the normal species and several deuterated isotopic species of each conformer. The electric dipole moments of both conformers have been determined. A number of the transitions of the cis conformer exhibit splittings due to the nuclear quadrupole moment of the 14N nucleus. A least squares fit of the frequency splittings have led to an analysis of the eQq values. Ab initio calculations using a 4-31G basis set both with and without polarization functions have been carried out to aid in the analysis and to provide a final structural comparison with the microwave results.  相似文献   
107.
We present the results of an energy-independent partial-wave analysis of the reaction π+p→ππN at nine c.m. energies between 1400 and 1700 MeV. New bubble chamber data from the Cambridge-Imperial College-Westfield College Collaboration were fitted, together with earlier data from Oxford, using the isobar model in a maximum likehood fitting program. The isobars used were Δ(1236), N1(1470) and ?(770) and allowance was made for an incoherent contribution from an I=2 s-wave phase shift produced by one-pion exchange in the t-channel. The results of this analysis are compared with the predictions of symmetry schemes. The ?1N amplitudes of the S31 and D33 members of the {70, 1?} multiplet are clearly observed and their signs unambiguously determined for the first time. Structure in the P31 wave is discussed in relation to recent claims of a low mass resonance. Possible explanations of the complicated behaviour of the P33 wave are discussed; its N1(1470)π decay is observed for the first time.  相似文献   
108.
Water can exist within solids in many forms : adsorbed on the surface or within micropores, occluded in voids, trapped within a molecular cage as in clathrates, or chemically bonded to species within the crystal lattice. Only in the latter case does it markedly alter the microscopical properties of a crystal. The water molecule possesses an unusually low molecular refraction coefficient. When bound to a crystal, it strongly depresses the principal refractive indices from those of the parent (anhydrous) compound. Examination of optical-crystallographic data from several hundred compounds shows a linear relationship between the per cent water and the mean refractive index for a given series of crystal hydrates. Moisture evolved on heating may be identified by its characteristictemperature and rate of evolution and by other physical and microchemical tests. Hot stage and micro DTA methods are discussed, along with special techniques for the examination of hydrated crystals in the scanning and transmission electron microscopes.  相似文献   
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