We present the observational results from a detailed timing analysis of the black hole candidate EXO 1846-031 during its outburst in 2019 with the observations of Insight-HXMT,NICER and MAXI.This outburst can be class...We present the observational results from a detailed timing analysis of the black hole candidate EXO 1846-031 during its outburst in 2019 with the observations of Insight-HXMT,NICER and MAXI.This outburst can be classified roughly into four different states.Type-C quasi-periodic oscillations(QPOs)observed by NICER(about 0.1-6 Hz)and Insight-HXMT(about 0.7-8 Hz)are also reported in this work.Meanwhile,we study various physical quantities related to QPO frequency.The QPO rms-frequency relationship in the energy band 1-10 keV indicates that there is a turning pointing in frequency around2 Hz,which is similar to that of GRS 1915+105.A possible hypothesis for the relationship above may be related to the inclination of the source,which may require a high inclination to explain it.The relationships between QPO frequency and QPO rms,hardness,total fractional rms and count rate have also been found in other transient sources,which can indicate that the origin of type-C QPOs is non-thermal.展开更多
卫星电源分系统是卫星的能源心脏,对其体积、重量与性能的要求越来越严格。为提高卫星性能,增加有效载荷,电源分系统的性能比和性能价格比等指标亟待提升,但现有的变换器还不能应对更高性能的要求。为探究适用于卫星PCU(Power Control U...卫星电源分系统是卫星的能源心脏,对其体积、重量与性能的要求越来越严格。为提高卫星性能,增加有效载荷,电源分系统的性能比和性能价格比等指标亟待提升,但现有的变换器还不能应对更高性能的要求。为探究适用于卫星PCU(Power Control Unit)系统的DC-DC变换器,该文针对Y型拓扑开关电源,提出了一种新型斜率补偿峰值电流控制方法,该电路继承了连续电流模式的优点,控制方式简单且转换效率高。该拓扑变压器还克服了普通推挽类拓扑结构的磁通不平衡问题,适应航天领域的发展需要。为验证该电路的电性能与控制方式的合理性,后期进行了模型仿真与原理样机搭建,实验结果表明所提出的新型控制Y型电路转换效率很高,该控制策略适用于对转换效率及集成度要求较高的系统级场合。展开更多
PSR B0540-69 has a braking index measurement in its persistent state： n = 2.129± 0.012. Recently, it has been reported to have changes in its spin-down state： a sudden 36% increase in the spin- down rate. Combi...PSR B0540-69 has a braking index measurement in its persistent state： n = 2.129± 0.012. Recently, it has been reported to have changes in its spin-down state： a sudden 36% increase in the spin- down rate. Combining the persistent state braking index measurement with different spin-down states, PSR B0540-69 is more powerful than intermittent pulsars in constraining pulsar spin-down models. The pulsar wind model is applied to explain the variable timing behavior of PSR B0540-69. The braking index of PSR B0540-69 in its persistent state results from the combined effect of magnetic dipole radiation and particle wind. The particle density reflects the magnetospheric activity in real-time and may be responsible for the changing spin-down behavior. Corresponding to the 36% increase in the spin-down rate of PSR B0540-69, the relative increase in the particle density is 88% in the vacuum gap model. The braking index calculated with the model in the new state is n = 1.79. Future observations that measure the braking index of PSR B0540-69 in the new spin-down state will be very powerful in distinguishing between different pulsar spin-down models and different particle acceleration models in the wind braking scenario. The variable timing behavior of PSR J 1846-0258 is also understandable in the pulsar wind model.展开更多
基金the HXMT mission,a project funded by China National Space Administration(CNSA)and the Chinese Academy of Sciences(CAS)supported by the National Key R&D Program of China(2016YFA0400800)the National Natural Science Foundation of China(Grant Nos.11673023,U1838201,U1838115,U1838111,U1838202,11733009 and U1838108)。
文摘We present the observational results from a detailed timing analysis of the black hole candidate EXO 1846-031 during its outburst in 2019 with the observations of Insight-HXMT,NICER and MAXI.This outburst can be classified roughly into four different states.Type-C quasi-periodic oscillations(QPOs)observed by NICER(about 0.1-6 Hz)and Insight-HXMT(about 0.7-8 Hz)are also reported in this work.Meanwhile,we study various physical quantities related to QPO frequency.The QPO rms-frequency relationship in the energy band 1-10 keV indicates that there is a turning pointing in frequency around2 Hz,which is similar to that of GRS 1915+105.A possible hypothesis for the relationship above may be related to the inclination of the source,which may require a high inclination to explain it.The relationships between QPO frequency and QPO rms,hardness,total fractional rms and count rate have also been found in other transient sources,which can indicate that the origin of type-C QPOs is non-thermal.
文摘卫星电源分系统是卫星的能源心脏,对其体积、重量与性能的要求越来越严格。为提高卫星性能,增加有效载荷,电源分系统的性能比和性能价格比等指标亟待提升,但现有的变换器还不能应对更高性能的要求。为探究适用于卫星PCU(Power Control Unit)系统的DC-DC变换器,该文针对Y型拓扑开关电源,提出了一种新型斜率补偿峰值电流控制方法,该电路继承了连续电流模式的优点,控制方式简单且转换效率高。该拓扑变压器还克服了普通推挽类拓扑结构的磁通不平衡问题,适应航天领域的发展需要。为验证该电路的电性能与控制方式的合理性,后期进行了模型仿真与原理样机搭建,实验结果表明所提出的新型控制Y型电路转换效率很高,该控制策略适用于对转换效率及集成度要求较高的系统级场合。
基金supported by the West Light Foundation of CAS(LHXZ 201201)the 973 Program(2015CB857100)Qing Cu Hui of CAS
文摘PSR B0540-69 has a braking index measurement in its persistent state： n = 2.129± 0.012. Recently, it has been reported to have changes in its spin-down state： a sudden 36% increase in the spin- down rate. Combining the persistent state braking index measurement with different spin-down states, PSR B0540-69 is more powerful than intermittent pulsars in constraining pulsar spin-down models. The pulsar wind model is applied to explain the variable timing behavior of PSR B0540-69. The braking index of PSR B0540-69 in its persistent state results from the combined effect of magnetic dipole radiation and particle wind. The particle density reflects the magnetospheric activity in real-time and may be responsible for the changing spin-down behavior. Corresponding to the 36% increase in the spin-down rate of PSR B0540-69, the relative increase in the particle density is 88% in the vacuum gap model. The braking index calculated with the model in the new state is n = 1.79. Future observations that measure the braking index of PSR B0540-69 in the new spin-down state will be very powerful in distinguishing between different pulsar spin-down models and different particle acceleration models in the wind braking scenario. The variable timing behavior of PSR J 1846-0258 is also understandable in the pulsar wind model.
