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21.
Chloride doped polyaniline conducting polymer films have been prepared in a protic acid medium (HCl) by potentiodynamic method
in an electrochemical cell and studied by cyclic voltammetry and FTIR techniques. The FTIR spectra confirmed Cl- ion doping in the polymers. The polymerization rate was found to increase with increasing concentration of aniline monomer.
But the films obtained at high monomer concentration were rough having a nonuniform flaky polyaniline distribution. Results
showed that the polymerization rate did not increase beyond a critical HCl concentration. Cyclic voltammetry suggested that,
the oxidation-reduction current increased with an increase in scan rate and that the undoped polyaniline films were not hygroscopic
whereas chloride doped polyaniline films were found to be highly hygroscopic. 相似文献
22.
The phenomenon of persistent tunneling photoconductivity was studied using the tunneling spectroscopy technique at liquid-helium temperature: the separation between the unoccupied levels in a δ-doped layer at the GaAs surface decreased after illumination. This decrease was due to an increase in the width of the quantum well of the δ-doped layer. For photon energies hv exceeding the GaAs band gap E g , this increase in the width of the quantum well was related to the accumulation of positive charge in the depth of GaAs induced by the generation of the electron-hole pairs and photoionization of deep centers. For hv < E g (including the case of CO2 laser), only photoionization is important. The experimental data agree with the self-consistent calculations. The critical temperature for the effect has been determined (T c = 45 K); at higher temperatures, the effect disappears. 相似文献
23.
N. P. Yeliseyeva 《Journal of Communications Technology and Electronics》2006,51(4):380-384
Rigorous analytic expressions for radiation resistance R Σ of an electric dipole are obtained for three mutually orthogonal orientations of the dipole’s axis with respect to a plane metal screen or right-angle corner of infinite dimensions. Radiation resistance R Σ of the dipole oriented arbitrarily in space is calculated and analyzed as a function of the distance from the screen. 相似文献
24.
V. N. Durcheva S. M. Puchkova 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2006,40(2):71-78
Operation of the dam in a transitional mode is described.
__________
Translated from Gidrotekhnicheskoe Stroitel’stvo, No. 1, January 2006, pp. 8–15. 相似文献
25.
This work considers the problem of increasing the performance of the ciphers based on Data-Dependent (DD) operations (DDO)
for VLSI implementations. New minimum size primitives are proposed to design DDOs. Using advanced DDOs instead of DD permutations
(DDP) in the DDP-based iterative ciphers Cobra-H64 and Cobra-H128 the number of rounds has been significantly reduced yielding
enhancement of the “performance per cost” value and retaining security at the level of indistinguishability from a random
transformation. To obtain further enhancement of this parameter a new crypto-scheme based on the advanced DDOs is proposed.
The FPGA implementation of the proposed crypto-scheme achieves higher throughput value and minimizes the allocated resources
than the conventional designs. Design of the DDO boxes of different orders is considered and their ASIC implementation is
estimated. 相似文献
26.
Electromechanical transducers for sensing and actuating disturbances or vibrations have been used in many fields of applications. There have been transducers of different configuration developed for the unidirectional transduction. This paper demonstrates a single element transducer for tri-axial components made of a piezoelectric cylindrical shell. The separation of the tri-axial transductions is achieved by devising a proper electrode arrangement. The structure and the fundamental idea are first presented, and then the numerical analysis by means of the finite element modeling follows, and their characteristics and behaviors are then experimentally verified. 相似文献
27.
Diphenylzinc, alone or in combination with water and butanone as coinitiators, was used as a polymerization initiator system for a variety of lactones at varying temperatures. The resulting data indicate that the course of the polymerization is greatly influenced by the lactone structure, as well as by the molar ratio of coinitiator to diphenylzinc. When used alone, diphenylzinc exhibited high activity as an initiator in δ‐valerolactone polymerizations, although it was less efficient when used in the β‐butyrolactone and the β‐propiolactone polymerizations. Activity in the polymerization of β‐lactones was increased by adding small amounts of butanone or water. It was also observed that the diphenylzinc–butanone combination was more effective than the diphenylzinc–water mixture in the polymerizations of β‐butyrolactone and β‐propiolactone. Copyright © 2003 Society of Chemical Industry 相似文献
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30.
V. N. Tsygankov V. V. Safonov A. I. Kozlov V. P. Gavrilov 《Inorganic Materials》2003,39(10):1076-1078
The GeO2–NiO system is studied in the stability range of Ni2GeO4 by temperature-dependent resistivity measurements, in combination with x-ray diffraction, differential thermal analysis, and thermogravimetry. The resistivity of the starting mixtures and heat-treated samples is measured in the composition range 55–90 mol % NiO. The effect of air humidity on the resistivity of the samples is examined. 相似文献