The present work has been undertaken to tailor Pt/Al 2 O 3 catalysts active for NO oxidation even after severe heat treatments in air. For this purpose, the addition of Pd has been attempted, which is less active for this reaction but can effectively suppress thermal sintering of the active metal Pt. Various Pd-modified Pt/Al 2 O 3 catalysts were prepared, subjected to heat treatments in air at 800°C and 830°C, and then applied for NO oxidation at 300°C. The total NO oxidation activity was shown to be significantly enhanced by the addition of Pd,
A novel interferometric fiber-optic gyroscope with amplified optical feedback by an Er-doped fiber amplifier (EDFA) is proposed and theoretically investigated (the proposed gyroscope is named the feedback EDFA-FOG, FE-FOG in what follows). The FE-FOG functions like a resonant fiber-optic gyro (R-FOG) because of its multiple utilization of the Sagnac loop; however, it is completely different because a low-coherence light source is used. In addition, the gyro output signal is pulsed because the modulation frequency of the phase modulator placed in the Sagnac loop is selected to match the total round-trip time delay of the light, which includes the Sagnac-loop delay plus that of the feedback loop of the fiber amplifier. The sharpness of the output pulse can be adjusted by both the gain of an EDFA and the modulation depth of the phase modulator. When rotation occurs the peak position of the output pulse is shifted as a result of the Sagnac effect. The resolution of the rotation measurement depends on the sharpness of the output pulse. The techniques of both the open-loop and closed-loop methods are described in detail, which shows the great advantage of the proposed gyroscope over the to the conventional interferometric fiber-optical gyroscope (I-FOG).
For the purpose of heightening hydrocarbon desorption temperature for hydrocarbon adsorption-combustion catalyst, we researched about some kinds of zeolites and of hydrocarbon adsorption elements. The hydrocarbon desorption temperature for 5 type of zeolites were measured by temperature programmed desorption (TPD) with model gas which simulated engine start exhaust one. The TPD measurement showed that the beta zeolite had that the highest hydrocarbon desorption temperature and its amounts was largest among all zeolites evaluated in this study. Ag, Mg, Ni, Co, Cu, Ce and Sr addition to beta zeolite increased the toluene desorption temperature as much as 170-320℃. On the other hand, among these added elements, only Ag increased the pentane desorption temperature by 90℃. The chemical states of Ag was measured with an ultra violet visible spectrophotometer (UV-vis). UV-vis suggested that Ag + and Ag 0 (metal) increased the desorption temperature of paraffin and aromatics, respectively. After the endurance test by being exposed to an air excessive gas and a fuel excessive gas alternately at 800℃ or 850℃ for the catalysts, the desorption temperature of the hydrocarbon, especially of paraffin lowered. These phenomena were thought to be caused by the change of chemical state for Ag + which existed besides the ion exchange site to Agx n+ (cluster) or Ag 0 and by the sintering of Ag. The hydrocarbon desorption temperature obtained in the vehicle test was the same as the temperature predicted from the chemical state of Ag and the composition of the exhaust gas.
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