A new mechanism of radiation emission in the polar gap of a pulsar is proposed. It is the curvature radiation emitted by positrons moving towards the surface of the neutron star along inclined magnetic field and refle...A new mechanism of radiation emission in the polar gap of a pulsar is proposed. It is the curvature radiation emitted by positrons moving towards the surface of the neutron star along inclined magnetic field and reflected from the surface. Such radiation interferes with transition radiation emitted from the neutron star when positrons hit the surface. Proposed mechanism explains the mystery of the interpulse shift in the Crab pulsar at high frequencies discovered by Moffett and Hankins twenty years ago. We have found also reflected energy flux and spectrum, discussed coherence and disappearance of interpulse shift with increase of frequency.展开更多
Thermodynamics analysis was carried out for solar thermal receivers with different selective coatings.The relation between the energy conversion efficiency of a medium-high temperature solar thermal system,the spectra...Thermodynamics analysis was carried out for solar thermal receivers with different selective coatings.The relation between the energy conversion efficiency of a medium-high temperature solar thermal system,the spectral properties of selective coating and the operating temperature of the receiver were discussed.Furthermore,the relation between the optimum operating temperatures,the exergy efficiencies and the incident solar flux were analyzed for the traditional concentrating system and concentrating beam splitting system,respectively.According to the analysis results for the thermal receiver with blackbody surface and selective coatings,the optimum cutoff wavelength was obtained for the ideal selective coating.An analysis method for the optimum operating temperature calculation was developed for thermal receivers with selective coating.The optimum operating temperature for an actual selective coating was analyzed on the basis of the proposed theory.展开更多
文摘A new mechanism of radiation emission in the polar gap of a pulsar is proposed. It is the curvature radiation emitted by positrons moving towards the surface of the neutron star along inclined magnetic field and reflected from the surface. Such radiation interferes with transition radiation emitted from the neutron star when positrons hit the surface. Proposed mechanism explains the mystery of the interpulse shift in the Crab pulsar at high frequencies discovered by Moffett and Hankins twenty years ago. We have found also reflected energy flux and spectrum, discussed coherence and disappearance of interpulse shift with increase of frequency.
基金supported by the National Basic Research Program of China("973" Project)(Grant No.2010CB227305)
文摘Thermodynamics analysis was carried out for solar thermal receivers with different selective coatings.The relation between the energy conversion efficiency of a medium-high temperature solar thermal system,the spectral properties of selective coating and the operating temperature of the receiver were discussed.Furthermore,the relation between the optimum operating temperatures,the exergy efficiencies and the incident solar flux were analyzed for the traditional concentrating system and concentrating beam splitting system,respectively.According to the analysis results for the thermal receiver with blackbody surface and selective coatings,the optimum cutoff wavelength was obtained for the ideal selective coating.An analysis method for the optimum operating temperature calculation was developed for thermal receivers with selective coating.The optimum operating temperature for an actual selective coating was analyzed on the basis of the proposed theory.
