Using the 13.7m radio telescope at Delingha, the millimeter-wave radioobservatory of Purple Mountain Observatory, we made mapping observations in ^(12)CO J = 1 - 0 linetowards IRAS 05417+0907, located in the bright-ri...Using the 13.7m radio telescope at Delingha, the millimeter-wave radioobservatory of Purple Mountain Observatory, we made mapping observations in ^(12)CO J = 1 - 0 linetowards IRAS 05417+0907, located in the bright-rimmed cloud (BRC) BRC18. We used a 7 x 7 grid with1' spacing, a finer and larger grid than the one used by Myers et al. Our results show that there isa bipolar outflow near IRAS 05417+0907. Combining with the observations at other wave bands, wefind that the star formation process in this region is triggered by radiation-driven implosion. Thesignificant difference between the masses of BRC18 and the cores and the relatively large ratio ofassociated source bolometric luminosity to the mass show that the star formation in BRC18 may betaking place in a sequence.展开更多
The hybrid propulsion performed with paraffin waxes exhibits most attractive capabilities compared to solid or liquid engines,e.g.,throttleability and re-ignition,alongside higher regression rates compared to the conv...The hybrid propulsion performed with paraffin waxes exhibits most attractive capabilities compared to solid or liquid engines,e.g.,throttleability and re-ignition,alongside higher regression rates compared to the conventional hydroxyl terminated polybutadiene(HTPB)hybrid fuel.This is because the paraffin wax forms a thin and hydro-dynamically unstable liquid layer,and then enhances the regression rate with the entrainment of droplets from the liquid-gas interface.Nevertheless,some critical open points on the manufacturing of the paraffin fuel grains still persist,because the paraffin wax exhibits high shrinkage during the solidification phase,leading to the formation of cavities,cracks and internal rips,which may be detrimental to the mechanical properties and the structural integrity of the fuel grain.In this context,this paper deals with a wide calorimetric,thermo-mechanical and physical characterization of the paraffin wax selected to manufacture the hybrid rocket engines(HRE)fuel grain,in order to gain a thorough knowledge of the material necessary to avoid the formation of critical defects.Several manufacturing methods were investigated,and it was found that only laboratory scale processes,based on the use of a heated circular mould-piston apparatus,are able to avoid the formation of critical defects,with the application of both high temperature and pressure.展开更多
基金Supported by the National Natural Science Foundation of China. This project was supported by G1999075405 of NKBRSF, 10128306 10133020 of NSFC.
文摘Using the 13.7m radio telescope at Delingha, the millimeter-wave radioobservatory of Purple Mountain Observatory, we made mapping observations in ^(12)CO J = 1 - 0 linetowards IRAS 05417+0907, located in the bright-rimmed cloud (BRC) BRC18. We used a 7 x 7 grid with1' spacing, a finer and larger grid than the one used by Myers et al. Our results show that there isa bipolar outflow near IRAS 05417+0907. Combining with the observations at other wave bands, wefind that the star formation process in this region is triggered by radiation-driven implosion. Thesignificant difference between the masses of BRC18 and the cores and the relatively large ratio ofassociated source bolometric luminosity to the mass show that the star formation in BRC18 may betaking place in a sequence.
文摘The hybrid propulsion performed with paraffin waxes exhibits most attractive capabilities compared to solid or liquid engines,e.g.,throttleability and re-ignition,alongside higher regression rates compared to the conventional hydroxyl terminated polybutadiene(HTPB)hybrid fuel.This is because the paraffin wax forms a thin and hydro-dynamically unstable liquid layer,and then enhances the regression rate with the entrainment of droplets from the liquid-gas interface.Nevertheless,some critical open points on the manufacturing of the paraffin fuel grains still persist,because the paraffin wax exhibits high shrinkage during the solidification phase,leading to the formation of cavities,cracks and internal rips,which may be detrimental to the mechanical properties and the structural integrity of the fuel grain.In this context,this paper deals with a wide calorimetric,thermo-mechanical and physical characterization of the paraffin wax selected to manufacture the hybrid rocket engines(HRE)fuel grain,in order to gain a thorough knowledge of the material necessary to avoid the formation of critical defects.Several manufacturing methods were investigated,and it was found that only laboratory scale processes,based on the use of a heated circular mould-piston apparatus,are able to avoid the formation of critical defects,with the application of both high temperature and pressure.
