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61.
62.
Claire Cates Haulk John Drew Charles R. Johnson J. Hunter Tart 《Linear and Multilinear Algebra》1997,43(1):35-51
For a given n-by-n matrix A, we consider the set of matrices which commute with A and all of whose principal submatrices commute with the corresponding principal submatrices of A. The properties of this set are examined, with particular attention to its dimension. 相似文献
63.
Here we prove that every compact differential manifold has a smooth algebraic model defined over Q. In dimension 2 we find an algebraic model (may be singular) defined over Q and birational over Q to the projective plane. 相似文献
64.
Scott McCullough 《Integral Equations and Operator Theory》1992,15(1):43-71
Kernels over the unit disk for which a version of Carathéodory interpolation is true are characterized in a simple computationally verifiable manner. 相似文献
65.
Robert J. Daverman 《Topology and its Applications》2007,155(2):105-111
This paper sets forth three mismatch properties, strictly ordered in strength, about sewings of crumpled n-cubes. The strongest is a sufficient but not a necessary condition for a sewing to yield Sn, and the weakest, a necessary but not sufficient one. We show that when both crumpled cubes satisfies the Disjoint Disks Property, then the weakest property implies the sewing yields Sn, and we also show that the intermediate property leads to the same conclusion when just one of the crumpled cubes possesses the Disjoint Disks Property. In addition, we develop examples that confirm sharpness of the relevant Disjoint Disks conditions. 相似文献
66.
Nicolae Tomozeiu 《Applied Surface Science》2006,253(1):376-380
Thin films of a-SiOx (0 < x < 2) were prepared by reactive r.f. magnetron sputtering from a polycrystalline-silicon target in an Ar/O2 gas mixture. The oxygen partial pressure in the deposition chamber was varied so as to obtain films with different values of x. The plasma was monitored, during depositions, by optical emission spectroscopy (OES) system. Energy dispersive X-ray (EDX) measurements and infra-red (IR) spectroscopy were used to study the compositional and structural properties of the deposited layers.Structural modifications of SiOx thin films have been induced by UV photons’ bombardment (wavelength of 248 nm) using a pulsed laser. IR spectroscopy and X-ray photoemission spectroscopy (XPS) were used to investigate the structural changes as a function of x value and incident energy. SiOx phase separation by spinodal decomposition was revealed. The IR peak position shifted towards high wavenumber values when the laser energy is increased. Values corresponding to the SiO2 material (only Si4+) have been found for laser irradiated samples, independently on the original x value. The phase separation process has a threshold energy that is in agreement with theoretical values calculated for the dissociation energy of the investigated material.For high values of the laser energy, crystalline silicon embedded in oxygen-rich silicon oxide was revealed by Raman spectroscopy. 相似文献
67.
We report the temperature dependence of electrical resistance (R) and thermopower (S) of clathrate Cs8Sn44 under high pressure up to 1.2 GPa. We observe a reversible gap widening, prominent relaxation effect of R, irreversible increase of |S| under high pressure. We also find that the power factor S2σ (σ: electrical conductivity) reaches a maximum at pressure of 0.3 GPa. Comparison of the experimental results with band structure calculations suggests that the intrinsic vacancy in the clathrate structure of Cs8Sn44 plays an important role in transport properties under high pressure. Measurements on Cs8Zn4Sn42, a clathrate which has defects other than vacancies, are compared with Cs8Sn44. The results indicate that replacing Sn by Zn has similar effect as the intrinsic vacancy on S. 相似文献
68.
Bruno Zimmermann 《Monatshefte für Mathematik》2002,135(3):253-258
We give a list including all finite groups G which admit smooth orientation preserving actions on homology 3-spheres (arbitrary actions, i.e. possibly with fixed points;
if the action is free then the group G has periodic cohomology and the classification of such groups is well known). The main work in this direction is due to M.
Reni. In the present paper, we complete and extend his results for the case of nonsolvable groups G.
Received 19 March 2001; in revised form 15 September 2001 相似文献
69.
Yuval Z. Flicker 《Mathematische Annalen》1993,297(1):199-219
70.
Dilek Yildiz JeronimusP.A.J. vanBeeck MichelL. Riethmuller 《Particle & Particle Systems Characterization》2004,21(5):390-402
Two‐phase flows hold an interest in many areas of science and engineering. In the safety field, one such topic is the accidental release of flammable and toxic pressure‐liquefied gases. In case of such a release, a flashing vapor explosion takes place resulting in a very dense two‐phase cloud. If the released substance is flammable, this cloud can be combustible and can lead to deflagration or detonation. For understanding the source processes of flashing and risk assessment, data related to cloud characteristics (i.e. droplet size, velocity etc.) is needed especially in the near region of the release. Due to the non‐equilibrium nature of the near field regions accurate data measurement is not possible with intrusive techniques. Therefore, laser‐based optical techniques (like Particle Image Velocimetry (PIV), Particle Tracking Velocimetry and Sizing (PTVS), Phase Doppler Anemometry (PDA) etc.) present the only possibility to obtain information for particle diameter and velocity evolution in this harsh environment. 相似文献