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101.
Systems with singular-higher order Lagrangians are investigated by two methods: Dirac method and Hamilton-Jacobi method. An example is studied and it is shown that the Hamilton-Jacobi method gives the correct canonical generalized equations of motion, contrary to Dirac method, where Dirac conjecture is invalid. 相似文献
102.
A method which employs an integrating sphere and a single-wavelength (1.6 μm) pyrometer for measuring the spectral effective emissivities of superalloys in the temperature range (=650–1050°C) is described. The spectral effective emissivities for five superalloys, namely, MARM-247, MARM-509, CMSX-4, Inconel-718, N-155 and two René-N6 samples coated with YSZ thermal barrier coating were measured. Correcting the pyrometer measurements for the variations in the object emissivity would reduce the uncertainty in the temperature measurements to <±1%. 相似文献
103.
104.
The formyl carbonyl group in bis(4-methoxyphenyl)-acetaldehyde does not contribute to the formation of the carbonyl group in 4,4′-dimethoxydeoxybenzoin when the former rearranges to the latter by treatment with 50% (w/w) sulfuric acid. 相似文献
105.
Sadia Ameen Vazid Ali M. Zulfequar M. Mazharul Haq Mushahid Husain 《Central European Journal of Chemistry》2006,4(4):565-577
The temperature dependence of direct current (dc) conductivity was studied for various samples of polyaniline-polyvinylchloride
(PANI-PVC) blended films. Polyaniline was doped with different concentrations of sulfamic acid in aqueous tetrahydrofuran
(THF) and the blended films were prepared by varying the amount of doped PANI relative to a fixed amount of PVC. The dc conductivity
of PANI-PVC blended films was measured to determine the effect of sulfamic acid (dopant) in the temperature range (300–400K).
The mechanism of conduction is explained by a two-phase model. In order to evaluate the effect of the dopant, conductivity-derived
parameters such as the pre-exponential factor (σ
o) and the activation energy (ΔE) were calculated. The structural changes of polyaniline-PVC blended films were characterized
by FTIR spectroscopy that explores information about the suitability of the dopant in the chemical doping process. 相似文献
106.
Sami A. Shakir 《Physics letters. A》1983,93(9):510-512
We describe two methods for employing materials with giant Kerr nonlinearities for modulating waveguides. A beam, of relatively intense light, is used to vary the propagation constant of a waveguide with the guiding layer, or the substrate, made from a nonlinear material. 相似文献
107.
Sami F. Masri 《Experimental Mechanics》1967,7(2):49-55
An experimental study is made of the general behavior of single-particle impact dampers, using an electronic-analog computer
and a mechanical model. It is found that, under practically realizable conditions, impact damping is effective in reducing
the vibration-amplitude levels resulting from sinusoidal or random excitation.
Paper was presented at 1966 SESA Spring Meeting held in Detroit, Mich., on May 4–6. 相似文献
108.
In this paper a procedure of construction of β-expectation tolerance regions in the framework of the structural method of inference has been developed. The procedure has been applied to the generalized multivariate model and the β-expectation tolerance region for this case has been constructed assuming the normal distribution for the error variables of the model. 相似文献
109.
Statistical spectroscopy methods are used to calculate level densities for one-body Hamiltonians in the space of 440 single particle states. Comparisons are made with combinatorial counting and Fermi gas model. Possibilities to arrive at a more realistic level density formula including two-body effects are discussed. 相似文献
110.
Quantum confinement effect on the energy levels of Eu2+ doped K2Ca2(SO4)3 nanoparticles has been observed. The broad photoluminescence (PL) emission band of Eu2+ doped K2Ca2(SO4)3 microcrystalline sample observed at ~436 nm is found to split into two narrow well resolved bands, located at 422 and 445 nm in the nanostructure form of this material. This has been attributed to the reduction in the crystal field strength of the nanomaterials, which results in widening the energy band gap and splitting the broad 4f65d energy level of Eu2+. Energy band gap values of the micro and nanocrystalline K2Ca2(SO4)3 samples were also determined by measuring the UV–visible absorption spectra. These values are 3.34 and 3.44 eV for the micro and nanocrystalline samples, respectively. These remarkable results suggest that activators having wide emission bands might be subjected to weak crystal strength via nanostructure materials to modify their electronic transitions. This might prove a powerful technique for producing new-advanced materials for use in the fields of solid state lasers and optoelectronic devises. 相似文献