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121.
四元数体上Minkowski不等式与Bergstrom不等式 总被引:1,自引:0,他引:1
杨忠鹏 《新疆大学学报(理工版)》1999,16(1):32-39
我们对四元数体上自共轭半正定矩阵按广义Schur补给出了Bergstrom不等式的推广。然后应用自共轭半正定矩阵的Bergstrom不等式得到了Minkowski不等式,我们的结果修正了重行列不等式的一些错误。 相似文献
122.
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124.
The intersubband absorption of the four-energy-level system in strained AlGaN/GaN double quantum wells is calculated by considering the polarization effect and the strain modification on material parameters (e.g., the conduction band offset, the electron effective mass and the static dielectric constant). It is found that the electron wavefunctions mainly locate at the left well and penetrate into the left barrier. The absorption spectrum exhibits multiple peaks contributed by different transitions. The position and height of absorption peaks are not very sensitive to the structural parameters (i.e., composition and thickness) of the central barrier because of the strong built-in electric field. However, the coupling between two wells can be enhanced by strain modulation. 相似文献
125.
Inspired by the promising potential of re-configurable intelligent surface (RIS)-aided transmission in achieving the vision of 6th Generation (6G) network, we analyze the security model for a vehicular-to-infrastructure (V2I) network by considering multiple RISs (M-RIS) on buildings to act as passive relays at fixed distances from a source. In addition, multiple eavesdroppers are presented in the vicinity of the intended destination. Our aim is to enhance the secrecy capacity (SC) and to minimize secrecy outage probability (SOP) in presence of multiple eavesdroppers with the help of M-RIS in V2I communications. We propose a key-less physical layer security using beam-forming by exploiting M-RIS. The proposed approach assumes the concept of detecting eavesdroppers before the information can be transmitted via beam-forming by utilizing M-RIS. The results reveal that with consideration of M-RIS and beam-forming, the achievable SC and SOP performance is significantly improved while imposing minimum power consumption and fewer RIS reflectors. 相似文献
126.
With through space and through bond experiments in two-dimensional NMR we analyze the transformation from the thorium phosphate-hydrogen phosphate hydrate (TPHPH) to the β form of the thorium phosphate diphosphate (β-TPD) in relation with the phosphorus networks. These techniques are complementary: the through space coupling gives an insight on the dipolar phosphorus networks while the through bond coupling is particularly efficient in the detection of the P2O7 groups. With these experiments we show that in a first step, by heating the precursor TPHPH above 250 °C, it transforms into an form of TPD. This transformation is due to the complete condensation of hydrogen phosphate groups HPO4 into P2O7 entities. By heating -TPD above 950 °C it transforms into its well-known β form. The form is characterized by a hygroscopic behavior: some water molecules are present near the P2O7 groups that makes non-equivalent their phosphorus nuclei. PO4 dipolar networks are always present in the form. The main effect of these PO4 and P2O7 units is to give the system a channel structure and the water enters in them. 相似文献
127.
Yu-Long Sui 《Applied Surface Science》2006,252(12):4306-4311
In this study, silica-based organic-inorganic hybrids were prepared by the sol-gel method. Tetraethoxysilane (abbreviated as TEOS) and a kind of monomer (abbreviated as FA-APES) derived from modified 2-furancarboxylic acid (abbreviated as FA) with (3-aminopropyl)triethoxysilane (abbreviated as APES) were used as the inorganic and organic fragments, respectively. Coordination reaction between lanthanides (europium and terbium ions) and CO group of the monomer happened simultaneously. And after days of aging process the resultant materials showed characteristic luminescence of lanthanides. The enhancement of luminescence can be seen by the comparison with simply doped lanthanide hybrid systems. And it can be explained by the coordination ability of the organic counterpart. IR, NMR, UV-vis absorption, low-temperature phosphorescence spectroscopy and fluorescence spectroscopy were applied to characterize and the above spectroscopic data revealed that the triplet state energy of organic ligand matches with the emissive energy level of lanthanides (especially of Tb3+). 相似文献
128.
Anandamayee Majumdar Debashis Paul 《Journal of computational and graphical statistics》2016,25(3):727-747
We introduce new classes of stationary spatial processes with asymmetric, sub-Gaussian marginal distributions using the idea of expectiles. We derive theoretical properties of the proposed processes. Moreover, we use the proposed spatial processes to formulate a spatial regression model for point-referenced data where the spatially correlated errors have skewed marginal distribution. We introduce a Bayesian computational procedure for model fitting and inference for this class of spatial regression models. We compare the performance of the proposed method with the traditional Gaussian process-based spatial regression through simulation studies and by applying it to a dataset on air pollution in California. 相似文献
129.
研究非齐次椭圆方程divA(x,u,■u)=f(x)的双侧障碍问题,获得了解的局部有界性结果,这可以认为是经典结果的推广. 相似文献
130.
S. Capuani C. Casieri F. De Luca B. Maraviglia G.H. Raza 《Magnetic resonance imaging》1998,16(10):1289-1294
The two-dimensional FT Imaging of 13C-glucose obtained with twin spin-echo double resonance sequence is presented. The images have been obtained by a doubly tuned surface coil on samples containing water and 13C-enriched glucose in water. It is shown, both theoretically and experimentally, that the whole editing capability of the twin spin-echo double resonance imaging sequence is also preserved in the presence of the radiofrequency field inhomogeneity produced by the surface coil. As in an efficient selective irradiation method, the enhancement in the signal-to-noise ratio with respect to the direct 13C detection, depends on the number of protons J-coupled to 13C. 相似文献