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Hiroshi Shimamori - One of the best experts on this subject based on the ideXlab platform.

  • contact ion pair formation in photolyzed aniline and n n dimethylaniline in the presence of ccl4
    The Journal of Physical Chemistry, 1996
    Co-Authors: Hiroshi Shimamori, Hirofumi Musasa
    Abstract:

    Time variation of microwave Dielectric Absorption has been examined for photolyzed aniline (ANI) and N,N-dimethylaniline (DMA) in CCl4 solvent and their solutions admixed with CCl4 in benzene solvent. In CCl4 solvent, the signals for both ANI and DMA show formation of highly polar transients, which are attributed to contact ion pairs (CIP):  ANI+Cl- for ANI and possibly (DMA)2+Cl- for DMA. In benzene solvent, both ANI and DMA form the CIPs not via excited triplet states but by direct excitation of a preexisting complex, ANI·CCl4 and DMA·CCl4. In ANI the CIPs subsequently decay by back electron transfer, deprotonation with simultaneous recombination with H+, or a reaction with another CCl4 molecule, leading to HCl and other less-polar products, while in DMA the CIPs further react with a CCl4 molecule to produce even polar species. A few experiments show that the mechanism of CIP formation (and decay) for N-methylaniline is similar to that for ANI. The quantum yields for the CIP formation may be equal to or...

  • mechanism of contact ion pair formation in photolyzed mixtures of n n n n tetramethylbenzidine with halogen containing compounds in nonpolar solvent
    The Journal of Physical Chemistry, 1994
    Co-Authors: Hiroshi Shimamori, Takao Okuda
    Abstract:

    Time variation of microwave Dielectric Absorption has been examined for photolyzed solutions of N,N,N',N'- tetramethylbenzidine (TMB) admixed with a halogen-containing compound AX (AX=CCl 4 , C 2 H 5 I, C 2 H 5 Br, C 6 H 5 I, and C 6 H 5 Br) in benzene. In each solution the Dielectric Absorption signals show rapid growth after photoirradiation, indicating formation of a contact ion pair (CIP) TMB + X - (X denotes a halogen atom). The amplitudes of the signals are dependent on the AX concentration and are large for CCl - but relatively small in other molecules when compared at the same concentration

  • rates and efficiencies of contact ion pair formation in photolyzed mixtures of tmpd with halogenated compounds in nonpolar solvents
    The Journal of Physical Chemistry, 1993
    Co-Authors: Hiroshi Shimamori, Keiichi Hanamuro, Yoshitsugu Tatsumi
    Abstract:

    Time variation of microwave Dielectric Absorption has been examined for photolyzed solutions of N,N,N,N'-tetramethyl-p-phenylenediamine (TMPD) admixed with halogen-containing compounds AX (AX=CCl 4 , C 2 H 5 I, C 2 H 5 Br, C 2 H 5 Cl, C 6 H 5 I, C 6 H 5 Br, C 6 H 5 Cl, C 6 H 2 F, and C 6 F 6 ) in nonpolar solvents (mostly benzene). In solutions with CCl 4 , C 2 H 5 I, C 6 H 5 I, C 6 H 5 Br, and C 6 H 5 Cl, the Dielectric Absorption signals show first-order growths with appreciable intensities, indicating formation of a contact ion pair (CIP) TMPD + X - (X denotes a halogen atom) by reactions of these compounds with the excited triplet state of TMPD

Yoshitsugu Tatsumi - One of the best experts on this subject based on the ideXlab platform.

  • rates and efficiencies of contact ion pair formation in photolyzed mixtures of tmpd with halogenated compounds in nonpolar solvents
    The Journal of Physical Chemistry, 1993
    Co-Authors: Hiroshi Shimamori, Keiichi Hanamuro, Yoshitsugu Tatsumi
    Abstract:

    Time variation of microwave Dielectric Absorption has been examined for photolyzed solutions of N,N,N,N'-tetramethyl-p-phenylenediamine (TMPD) admixed with halogen-containing compounds AX (AX=CCl 4 , C 2 H 5 I, C 2 H 5 Br, C 2 H 5 Cl, C 6 H 5 I, C 6 H 5 Br, C 6 H 5 Cl, C 6 H 2 F, and C 6 F 6 ) in nonpolar solvents (mostly benzene). In solutions with CCl 4 , C 2 H 5 I, C 6 H 5 I, C 6 H 5 Br, and C 6 H 5 Cl, the Dielectric Absorption signals show first-order growths with appreciable intensities, indicating formation of a contact ion pair (CIP) TMPD + X - (X denotes a halogen atom) by reactions of these compounds with the excited triplet state of TMPD

Takao Okuda - One of the best experts on this subject based on the ideXlab platform.

Wulf Haase - One of the best experts on this subject based on the ideXlab platform.

  • sub hertz relaxation process in chiral smectic mixtures doped with silver nanoparticles
    Applied Physics Letters, 2012
    Co-Authors: Pradip Kr Mandal, A Lapanik, Bernd Stuehn, Robert Wipf, Wulf Haase
    Abstract:

    A thermal activated sub-hertz frequency Dielectric Absorption process in both SmC* and SmA* phases along with characteristic Goldstone mode have been observed in both pure and silver nano particle doped liquid crystal mixtures. This process is well resolved, in particular, in the composites probably due to capturing of ions/charges inside the thiol group layer around the silver particles surface, thereby increasing the resistivity of the composites. The process is interpreted as space charge accumulation of ions/charges at the interface between liquid crystals and the cell polymer layer close to the electrodes. Improved switching characteristics and reduced spontaneous polarization have been detected.

Костюков, Иван Александрович - One of the best experts on this subject based on the ideXlab platform.

  • Error of control of electrical insulation structures by Dielectric Absorption parameters according to the concept of uncertainty of measurements
    'National Technical University Kharkiv Polytechnic Institute', 2020
    Co-Authors: Беспрозванных, Анна Викторовна, Костюков, Иван Александрович
    Abstract:

    Представлена методология оценки погрешности измерений параметров диэлектрической абсорбции электроизоляционных конструкций в рамках концепции неопределенности измерений. Приведен статистический анализ результатов многократных измерений емкости и тангенса угла диэлектрических потерь витой пары не экранированного кабеля категории 5е. Получены уравнения линейной регрессии для измеренных значений параметров диэлектрической абсорбции от числа измерений. Выполнено оценивание погрешности измерений емкости и тангенса угла диэлектрических потерь не экранированного кабеля.Introduction. Measurements on alternating current of Dielectric Absorption parameters – capacitance and Dielectric loss tangent tgδ allow us to evaluate the quality of insulation of cables, electrical machines, transformers, etc., both at the technological stage of manufacture and in operation. An increase in the reliability of the measurement result of the parameters is provided by a decrease in the measurement error due to the improvement of measuring instruments and measurement methods and an increase in the number of measurements Purpose. The estimation of the error of control of electrical insulation structures by Dielectric Absorption parameters in accordance with the concept of measurement uncertainty. Methodology.The error of measurements of the capacitance and the tangent of the Dielectric loss angle is estimated using the example of a twisted unshielded pair of category 5e. A statistical analysis of the results of multiple measurements of the capacitance and the tangent of the Dielectric loss angle of an unshielded cable is carried out. The linear regression equations for the measured values of the Dielectric Absorption parameters of the number of measurements are obtained. Practical value. Ensuring unity in the methods for estimating the error of measurement results, both when using the traditional concept of «measurement result error» and when introducing the concept of «measurement result uncertainty» into practice, it will allow to unambiguously interpret and correctly compare the results of measurements of the capacitance and tangent of the Dielectric loss angle of electrical insulation structures

  • A method of wavelet analysis of time series of parameters of Dielectric Absorption of electrical insulating structures
    Національний технічний університет "Харківський політехнічний інститут", 2020
    Co-Authors: Беспрозванных, Анна Викторовна, Костюков, Иван Александрович
    Abstract:

    Установлено влияние поверхностных и трибозарядов на результаты контроля емкости и тангенса угла диэлектрических потерь экранированных и неэкранированных кабелей с полимерной изоляцией. Показана неэффективность фильтрации спектров временных рядов с помощью фильтра низких частот на основе прямого преобразования Фурье. На примере неэкранированного кабеля представлено многоуровневое вейвлет разложение временных рядов параметров и показана эффективность применения вейвлет преобразования для выявления высокочастотных и низкочастотных компонент в измеренных значениях. Обоснован оптимальный уровень разложения параметров диэлектрической абсорбции неэкранированного и экранированного кабелей с помощью вейвлета Добиши 12 порядка. Показана эффективность метода вейвлет анализа временных рядов параметров диэлектрической абсорбции, обеспечивающего повышение точности контроля и диагностики твердой полимерной изоляции электроизоляционных конструкций. Библ. 17, рис. 8.Introduction. In the objects of control there are always a number of interfaces, for example, solid insulation – electrode. On contacting surfaces, free surface charges are transferred. Surface conductivity leads to fluctuations in the measured values of the capacitance and the tangent of the Dielectric loss angle of olid insulation, the state of which is determined. The drain off of the surface charge does not lead to a decrease in the scatter of the measured Dielectric Absorption parameters. One of the main reasons for the significant time spread of the Dielectric Absorption parameters, and to a large extent (three orders of magnitude) of the Dielectric loss tangent are tribo charges caused by triboelectrification of cable structural elements. Tribo charges cause internal noise in electrical insulating structures, masking processes in the polymer insulation itself. Purpose. Substantiation of a method for analyzing the time series of Dielectric Absorption parameters, which provides increased accuracy of control and diagnostics of solid polymer insulation of electrical insulation structures based on filtering experimental data using wavelet transform. Methodology. The inefficiency of filtering the spectra of time series using a low filter based on the direct Fourier transform is shown. Multilevel wavelet decomposition of the time series of parameters is presented, and the efficiency of applying wavelet transforms to identify highfrequency and low-frequency components in the measured values. Practical value. The method of analyzing the time series of Dielectric Absorption parameters using the wavelet transform, proposed for the first time, makes it possible to increase the accuracy of monitoring and diagnostics of solid polymer insulation both at the manufacturing stage and in the operation of electrical insulating structures. This method is the basis for creating a database of control results for assessing the state of solid polymer insulation of electrical insulation structures, in particular, power and information cables. References 17, figures 8