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971.
Vasanthakumar N. Bhat 《The Journal of the Operational Research Society》1994,45(3):345-353
The switched Poisson process (SPP), also known as the doubly stochastic Poisson process, has been widely used in the modelling of point processes whose rates vary subject to some random mechanism. The class of SPP includes a wide range of both renewal and non-renewal processes with squared coefficients of variation being larger than one. In this paper, we survey various approaches to approximate a non-renewal process by a renewal process. We derive the expressions for the first two moments of the inter-renewal time of a renewal process that approximates the SPP. We illustrate the quality of these approximations with numerical results in queueing applications. We believe that our approximations have potential applications in areas such as reliability, inventory control, telecommunications and maintenance. 相似文献
972.
A. F. Blinokhvatov O. V. Markovtseva M. N. Nikolaeva 《Chemistry of Heterocyclic Compounds》1992,28(3):266-268
Substituted 4H-pyrans were obtained in high preparative yields by the reaction of 1,5-diketones with acetic anhydride and boron trifluoride etherate in diethyl ether. It is assumed that the heterocyclization of 1,5-diketones includes a step involving the formation and transformations of an acyloxy carbonium ion.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 320–322, March, 1992. 相似文献
973.
B. M. Forster J. M. Bailey G. A. Beer J. L. Beveridge J. H. Brewer W. N. Hardy T. M. Huber K. R. Kendall A. R. Kunselman J. A. Macdonald G. M. Marshall G. R. Mason A. Olin M. Senba J. B. Warren 《Hyperfine Interactions》1991,65(1-4):1007-1013
Muonic hydrogen isotopes (μ− p, μ− d, and μ−t) are simple quantum mechanical systems ideally suited for studies of numerous fundamental phenomena in electroweak and strong
interactions as well as in applied areas such as muon chemistry or muon catalyzed fusion.
Emission of muonic hydrogen isotopes into vacuum helps to overcome the limitations which are normally imposed on conventional
investigations with gaseous and liquid targets. A proof of principle experiment for this new technique was performed at TRIUMF
last year. Negative muons with 30 MeV/c momentum were stopped in a thin film of solid hydrogen and produced very low energy μ−d in vacuum. The distribution center of the normal velocity components of emitted μ−d atoms was measured to be ∼1 cm/μs. The yield of μ−d in vacuum is an increasing function of H2 film thickness δ up to a value of δ≥1 mm. 相似文献
974.
975.
976.
V. L. Rusinov A. Yu. Petrov O. N. Chupakhin 《Chemistry of Heterocyclic Compounds》1992,28(11):1335-1339
Two variants of a synthesis for nitropyrazolopyridines from aminopyrazoles and two- or three-carbon nitrosynthons are examined.For Communication 19 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1560–1564, November, 1992. 相似文献
977.
Optical methods are described for determining the parameters of semiconducting quantum dots synthesized in a glassy borosilicate
matrix. The limitations of these methods and the magnitudes of their errors are analyzed. The parameters of CdSxSe1−x
nanocrystals in the commercial glasses KS-10, OS-12, Corning 2–61, and other experimental samples are determined.
Fiz. Tverd. Tela (St. Petersburg) 39, 1865–1870 (October 1997) 相似文献
978.
The photoconductivity and electrical conductivity, the thermally stimulated polarization and depolarization currents, the
permittivity, and the dielectric losses of noncentrosymmetric Ca3Ga2Ge4O14 crystals of a structural type of trigonal calcium gallogermanate (CGG) have been studied for the first time in the temperature
interval 100–700 K in air and in vacuum. The features of the temperature behavior of CGG are associated, in particular, with
the effect of electrically active defects and partial disordering of the cation sublattice of the crystal structure, which
generates polar formations (dipoles) of several kinds. Certain parameters of the electromigration and of the electrically
active defects that cause charge-relaxation and polarization effects are determined. It is concluded that dipole relaxation
in CGG makes it a new representative of a class of materials in which reorientation of the dipoles as a system of mobile local
distortions of the structure has a substantial effect on the physical properties.
Fiz. Tverd. Tela (St. Petersburg) 39, 871–876 (May 1997) 相似文献
979.
The stable quasistationary mixing of ternary gas mixtures in a system of two chambers connected by a capillary is described
by a theoretical model which predicts the density distribution of the mixture along the length of the diffusion channel. It
is demonstrated that inversion of the density gradient can occur due to a nonlinear concentration distribution of the heavy
component in a diffusion “gate” effect. The results obtained using this model are compared with the experimental data.
Zh. Tekh. Fiz. 68, 14–17 (May 1998) 相似文献
980.
Semicontinuity and Quasiconvex Functions 总被引:11,自引:0,他引:11
Criteria are derived for quasiconvex functions under lower semicontinuity and upper semicontinuity conditions. The results thus obtained generalize earlier results for convex functions. We also give new conditions under which a given function is r-convex in the sense given by Avriel. 相似文献