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941.
We study regiorously the solvability of the direct and inverse problems associated with Ψx–JΨy = QΨ,(x,y) ∈ ?2, where (i) Ψ is an N × N-matrix-valued function on ?2 (N ≦ 2), (ii) J is a constant, real, diagonal N × N matrix with entries, J1 > J2 > …? > JN and (iii) Q is off-diagonal with rapidly decreasing (Schwartz) component functions. In particular we show that the direct problem is always solvable and give a small norm condition for the solvability of the inverse problem. In the particular case that Q is skew Hermitian the inverse problem is solvable without the small norm assumption. Furthermore we show how these results can be used to solve certain Cauchy problems for the associated nonlinear evolution equations. For concreteness we consider the N-wave interactions and show that if a certain norm of Q(x, y, 0) is smallor if Q(x, y, 0) is skew Hermitian the N-wave interations equation has a unique global solution. 相似文献
942.
H.H. Sung 《Solid State Communications》2005,135(6):377-381
We report the results of our investigation in CeNi2−xCuxSn2 (x=0, 0.4, 1.0, 1.6 and 2.0), a new pseudoternary series with CaBe2Ge2-type tetragonal structure. Substitution of Cu for Ni leads to a linear increase in the constants a, c and the unit cell volume v. As probed by the low temperature dependence of ac susceptibility χac(T), the Tf temperature, which corresponds to the freezing temperature of the spin-glass clusters, is annihilated above 2.0 K significantly for the samples with x≥1.6. This observation proves conclusively that the Ni-rich samples in the series CeNi2−xCuxSn2 have the advantage of forming the spin-glass-like state. 相似文献
943.
The spin-lattice relaxation rates for 1H and 39K nuclei in K3H(SO4)2 and KHSO4 single crystals, which are potential candidate materials for use in fuel cells, were determined as a function of temperature. The spin-lattice relaxation recovery of 1H can be represented for both crystals with a single exponential function, but cannot be represented by the Bloembergen-Purcell-Pound (BPP) function, so is not related to HSO4 motion. The recovery traces of 39K, which predominantly undergoes quadrupole relaxation, can be represented by a linear combination of two exponential functions. The temperature dependences of the relaxation rates for 39K can be described with a simple power law T1−1=αT2. The spin-lattice relaxation rates for the 39K nucleus in K3H(SO4)2 and KHSO4 crystals are in accordance with a Raman process dominated by a phonon mechanism. 相似文献
944.
S.F. Hu W.Z. WongS.S. Liu Y.C. WuC.L. Sung T.Y. Huang 《Solid State Communications》2003,125(6):351-354
Quantum effects in silicon nanowires due to one-dimensional carrier confinement were observed at room temperature. Electrical transport properties were measured on narrow thin-silicon-on-insulator wires that were defined by e-beam lithography and further narrowed and thinned down by oxidation to a final thickness of around 3 nm, and a width of 29 nm. The room temperature current-voltage characteristics of the resulting silicon nanowires are shown to exhibit a zero current state may be due to the occurrence of Coulomb blockade. 相似文献
945.
The effect of elastic anisotropy on the strain fields and confinement potentials in InAs/GaAs quantum dot (QD) nanostructures was investigated for an isolated dot and a stacked multi-layer dots using finite element analysis and model solid theory. The assumption of isotropy tends to underestimate especially hydrostatic strain that is known to modify confinement potentials in conduction band. Consideration of anisotropy results in a wider band gap and shallower potential well as compared with the isotropic model. Since the band gap and potential well depth would be related to opto-electronic properties of quantum dot systems via quantum mechanical effects, it is suggested that consideration of elastic anisotropy in the calculation of strains and band structures is necessary for the design of QD-based opto-electronic devices. 相似文献
946.
A new optically active ONNO-type tetradentate ligand, ethylenediamine-N,N′- di-S-isobutylacetate (SS-eniba), has been synthesized. During the preparation of diaqua cobalt(III) complexes of SS-eniba, [Co(SS-eniba)(H2O)2]+, the title ligand has coordinated stereospecifically to the cobalt(III) ion to give three isomers, Δ-s-cis, Δ-uns-cis and Λ-uns-cis, which have been isolated and characterized via electronic absorption, circular dichroism (CD), and 1H NMR spectroscopy, along with elemental analysis data. The preparation of Δ-s-cis-[Co(SS-eniba)Cl2]+ and Δ-s-cis-[Co(SS-eniba)CO3]+ are also reported. 相似文献
947.
Time-resolved light-scattering measurements have been conducted to investigate the influence of a diblock copolymer additive on the phase boundaries and the kinetics of the phase separation of a polymer blend. The blend studied was a polystyrene-d8/polybutadiene (PSD/PB) mixture with a diblock copolymer composed of the same homopolymers. It was observed that the critical temperature of the blend, which has an upper critical solution temperature (UCST), decreased with increasing copolymer content and the kinetics of the phase separation via a spinodal decomposition mechanism slowed down in the presence of the copolymer. The features of the spinodal peak position and intensity as a function of time with and without copolymer additive were analyzed for near and off-critical compositions in various temperature jumps. The intermediate and late-stage growth rates do not follow a universal scaling function with the addition of diblock copolymers. © 1995 John Wiley & Sons, Inc. 相似文献
948.
Hoon Young Cho Eun Kyu Kim Suk-Ki Min Sung Ho Choh 《Applied Physics A: Materials Science & Processing》1989,48(4):359-363
We studied the midgap levels by using isothermal capacitance transient spectroscopy (ICTS) in Hb-GaAs which had been processed by rapid thermal annealing (RTA). As the annealing time at 850 °C increased, the EL2 trap (E
c–0.81 eV) was transformed to the EX2 trap (E
c–0.73 eV) and eventually to the EX1 trap (E
c–0.87 eV). The diffusivity of the EL2 trap obtained from the experimental result of the heat treatment was about 1.02·10–8cm2/s at 850 °C. This result indicate that the EL2 trap contains an interstitial arsenic atom. The result of the transformation to the EX1 and EX2 traps suggests that, when the EL2 trap is VAsASiVGaAsGa, the EX2 trap may be VAsVGaAsGa, which Asi is diffused out during a thermal annealing. 相似文献
949.
Ki Hwan Hong Ming Ye Young Mo Kim Kevin F. Kevorkian Gerald S. Berke 《Journal of voice》1997,11(1):23-32
In spite of the presumed importance of the strap muscles on laryngealvalving and speech production, there is little research concerning the physiological role and the functional differences among the strap muscles. Generally, the strap muscles have been shown to cause a decrease in the fundamental frequency (F0) of phonation during contraction. In this study, an in vivo canine laryngeal model was used to show the effects of strap muscles on the laryngeal function by measuring the F0, subglottic pressure, vocal intensity, vocal fold length, cricothyroid distance, and vertical laryngeal movement. Results demonstrated that the contraction of sternohyoid and sternothyroid muscles corresponded to a rise in subglottic pressure, shortened cricothyroid distance, lengthened vocal fold, and raised F0 and vocal intensity. The thyrohyoid muscle corresponded to lowered subglottic pressure, widened cricothyroid distance, shortened vocal fold, and lowered F0 and vocal intensity. We postulate that the mechanism of altering F0 and other variables after stimulation of the strap muscles is due to the effects of laryngotracheal pulling, upward or downward, and laryngotracheal forward bending, by the external forces during strap muscle contraction. 相似文献
950.
We calculate the decay constant ratios ? ηc/? J/ψ and ? ηb/? ψ. In the calculation we take into account the mock meson structures of the mesons, as well as the difference of the wave functions at origin of the vector and pseudoscalar mesons studied by Ahmady and Mendel. We find that the different spin structures of the mesons much affect the ratios. We incorporate our results in the prediction of the branching ratios of B → K η c. 相似文献