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841.
842.
A new and accurate relationship for the shear modulus in the fiber direction of unidirectional fiber composites is derived, based on the Kerner model concepts but not using its approximate relationships. Furthermore, this model is extended by taking into account the mesophase between the fiber and the matrix accomodating smoothly the mechanical properties between neighbouring phases. The introduction of the mesophase results in an improvement of the theoretical predictions, which now approach close to experimental values for the moduli of different fibrous composites. 相似文献
843.
P. Lichard 《Zeitschrift fur Physik C Particles and Fields》1987,37(1):125-137
We propose a method of evaluating the soft dilepton production rate in hadron-nucleus and nucleus-nucleus collisions at high energies based on summing the contributions from quark-antiquark systems (chains) created in individual hadron-nucleon interactions. The individual contributions are determined by using the square dependence of the soft dilepton production rate on hadron multiplicity predicted for hadron-hadron collisions by the soft-quarkannihilation model and observed recently inpp collisions at the CERN ISR. The possibility of additional contributions originating from the annihilation of quarks and antiquarks that belong to different chains is taken into account in a phenomenological way, which nevertheless enables to correlate different phenomena in soft dilepton production. More detailed predictions are given for proton-nucleus collisions at 200 GeV/c. 相似文献
844.
A self-consistent system of gravitational field with a binary mixture of perfect fluid and dark energy given by a cosmological
constant has been considered in Bianchi Type-V universe. The perfect fluid is chosen to be obeying either the equation of
state p=γρ with γ ε |0,1| or a van der Waals equation of state. The role of A-term in the evolution of the Bianchi Type-V universe has been
studied. 相似文献
845.
Summary Certain characteristics of a two-fiber sensor device, of the type proposed by Papaet al. for sea water turbidity monitorship, are examined. The extension of medium from which most of the received backscattered
power originates is investigated, together with possible effects of multiple scattering on the received power. Laboratory
measurements testing the results of the analysis are reported.
Riassunto Sono esaminate alcune caratteristiche di un sensore a due fibre, del tipo di quello proposto da Papaet al. per il monitoraggio della torbidità dell'acqua di mare. è stata studiata l'estensione della zona del mezzo da cui proviene la maggior parte della radiazione retrodiffusa ricevuta. Sono stati considerati effetti di diffusione multipla. I risultati dell'analisi sono stati controllati con misure in laboratorio.
Резюме Исследуются некоторые характеристики дву-qh-нитевого датчика, предложенного Папа и др. для мониторирования мутности морской воды. Исследуется расширение зоны в среде, из которой формируется основная часть рассеянного назад излучения. Также рассматриваются эффекты многократного рассеяния. На основе лабораторных измерений проводится проверка результатов анализа.相似文献
846.
J. A. Ratto Paul T. Inglefield R. A. Rutowski K.-L. Li Alan Anthony Jones Ajoy K. Roy 《Journal of Polymer Science.Polymer Physics》1987,25(7):1419-1430
Carbon-13 and proton spin-lattice relaxation times were measured at two field strengths on solutions 10% by weight of two polycarbonates in C2D2Cl4 from ?20 to +120°C. The first polycarbonate is an asymmetrically substituted form with one chlorine on one of the two phenylene aromatic rings of the bisphenol unit, whereas the second polycarbonate is symmetrically substituted with two chlorines on each of the two rings. The nuclear spin relaxation data are interpreted in terms of several local motions likely in these polymers. Segmental motion was described by the Hall–Helfand correlation function. Segmental motion in the monosubstituted polycarbonate is somewhat slower than in unsubstituted polycarbonate, whereas segmental motion in the tetrasubstituted polycarbonate is considerably slower. Phenylene ring rotation is observed in unsubstituted polycarbonate and in the monosubstituted polycarbonate above 40°C. Below 40°C in the monosubstituted species, and at all temperatures in the tetrasubstituted species, ring rotation is replaced by ring libration as the predominant motion contributing to spin lattice relaxation. In addition, the rotational motion of the two types of rings in the asymmetric monosubstituted form are very similar although not identical. The substituted ring is slightly less mobile than the rings of unsubstituted polycarbonate. This indicates a strong coupling of ring motion, although the coupling leads to less than synchronous motion. Methyl group rotation is present in both polymers and is little affected by the various structural modifications. 相似文献
847.
George R. T. Hendry 《Journal of Graph Theory》1989,13(2):245-248
The Ramsey numbers r(F1, F2) are tabulated for essentially all but six pairs of graphs F1 and F2 with five vertices. 相似文献
848.
The first twelve members of the n-alkyl 2,5-bis-(4'-cyanobiphenyloxybutyloxy)-benozates have been prepared. The compounds are nematogenic; in addition the first three members exhibit a smectic A phase. The nematic-isotropic transition temperatures decrease with little or no alternation on increasing the number of methylene groups in the lateral chain; this is analogous to the behaviour found in monomeric and polymeric mesogens possessing lateral alkyl chains. 相似文献
849.
850.
Using the Ward-Takahashi identity, on-shell condition, bound Dirac equation and off-shell expansion, a reduced version of half off-shell virtual photon nucleon vertex has been suggested. The vertex are decomposed into several different order terms: the on-shell terms, first and second off-shell terms. The off-shell behaviour of the form factors is discussed in the one meson loop model. Using the reduced vertex and parametrized off-shell form factors the quasielastic response functions are calculated for several nuclei at ¦q¦–kf and for56Fe at large ¦q¦ up to 1.14 GeV/c and at ?q2=0.9 (GeV/c)2. The Coulomb sums are evaluated and a comparison of the theoretical prediction with data is given. The off-shell electron nucleon cross section is calculated and compared with the “cc1” off-shell extrapolation. 相似文献