The excitation and evolution of magnetohydrodynamic density waves are considered in a differentially rotating thin gaseous disk embedded with both an azimuthal magnetic field and a vertical magnetic field perpendicula...The excitation and evolution of magnetohydrodynamic density waves are considered in a differentially rotating thin gaseous disk embedded with both an azimuthal magnetic field and a vertical magnetic field perpendicular to the disk. Our results shows that the effect of isopedic vertical magnetic fields tend to stabilize the fast MHD density waves while slow MHD density waves are not affected by such vertical magnetic fields for either rigid or differential rotation.展开更多
The magnetic fluid is used as working medium in pilot stage of electro-hydraulic servoamplifier. Utilizing the magnetization viscous character of the fluid, a new type of electro-hydraulicservo amplifier without any m...The magnetic fluid is used as working medium in pilot stage of electro-hydraulic servoamplifier. Utilizing the magnetization viscous character of the fluid, a new type of electro-hydraulicservo amplifier without any moving parts in its pilot stage has been developed. This research provides a way for improving the frequency property and reliability of electro-hydraulic servoelements.展开更多
The magamp (magnetic amplifier) is widely used in power supplies due to its low cost, simplicity and other advan-tages. This paper discusses a novel application of the magamp in switching power supplies, where the mag...The magamp (magnetic amplifier) is widely used in power supplies due to its low cost, simplicity and other advan-tages. This paper discusses a novel application of the magamp in switching power supplies, where the magamp is used to regulate pulse width modulation (PWM) instead of power signal in the main circuit. This method extends the application of the magamp in power supplies, and makes it possible to further regulate control signal when PWMs have been generated. Based on this applica-tion, a new current-sharing (CS) scheme using the magamp is proposed, which uses a modified inner loop CS structure. In this scheme PWMs are generated by one main controller, and CS is achieved by regulating PWMs using a magamp in each module. Compared with traditional application of the magamp, the new CS scheme can be used in most topologies and only requires magamps of low power capacity. Then a test circuit of parallel power supply is developed, in which CS is achieved by a PWM regulator with the magamp. The proposed scheme is also used to upgrade an electroplate power to make it capable of paralleling supplies. Experimental results show that the proposed scheme has good CS performance.展开更多
A mixed hydrogen and helium（H ＋ He） spectrum with a clear steepening at ~700 TeV has been detected by the ARGO-YBJ experiments. In this paper, we demonstrate that the observed H ＋ He spectrum can be reproduced wel...A mixed hydrogen and helium（H ＋ He） spectrum with a clear steepening at ~700 TeV has been detected by the ARGO-YBJ experiments. In this paper, we demonstrate that the observed H ＋ He spectrum can be reproduced well with a model of cosmic rays escaping from the supernova remnants（SNRs） in our Galaxy. In this model, particles are accelerated in a SNR through a non-linear diffusive shock acceleration mechanism. Three components of high energy light nuclei escaped from the SNR are considered. It should be noted that the proton spectrum observed by KASCADE can be also explained by this model given a higher acceleration efficiency.展开更多
文摘The excitation and evolution of magnetohydrodynamic density waves are considered in a differentially rotating thin gaseous disk embedded with both an azimuthal magnetic field and a vertical magnetic field perpendicular to the disk. Our results shows that the effect of isopedic vertical magnetic fields tend to stabilize the fast MHD density waves while slow MHD density waves are not affected by such vertical magnetic fields for either rigid or differential rotation.
文摘The magnetic fluid is used as working medium in pilot stage of electro-hydraulic servoamplifier. Utilizing the magnetization viscous character of the fluid, a new type of electro-hydraulicservo amplifier without any moving parts in its pilot stage has been developed. This research provides a way for improving the frequency property and reliability of electro-hydraulic servoelements.
基金Project (No. 50677063) supported by the National Natural Science Foundation of China
文摘The magamp (magnetic amplifier) is widely used in power supplies due to its low cost, simplicity and other advan-tages. This paper discusses a novel application of the magamp in switching power supplies, where the magamp is used to regulate pulse width modulation (PWM) instead of power signal in the main circuit. This method extends the application of the magamp in power supplies, and makes it possible to further regulate control signal when PWMs have been generated. Based on this applica-tion, a new current-sharing (CS) scheme using the magamp is proposed, which uses a modified inner loop CS structure. In this scheme PWMs are generated by one main controller, and CS is achieved by regulating PWMs using a magamp in each module. Compared with traditional application of the magamp, the new CS scheme can be used in most topologies and only requires magamps of low power capacity. Then a test circuit of parallel power supply is developed, in which CS is achieved by a PWM regulator with the magamp. The proposed scheme is also used to upgrade an electroplate power to make it capable of paralleling supplies. Experimental results show that the proposed scheme has good CS performance.
基金Supported by the National Natural Science Foundation of China(11433004,11363006,11103016,11173020)Top Talents Program of Yunnan Province(2015HA030)the Natural Science Foundation of Yunnan Province(2015FB103)
文摘A mixed hydrogen and helium（H ＋ He） spectrum with a clear steepening at ~700 TeV has been detected by the ARGO-YBJ experiments. In this paper, we demonstrate that the observed H ＋ He spectrum can be reproduced well with a model of cosmic rays escaping from the supernova remnants（SNRs） in our Galaxy. In this model, particles are accelerated in a SNR through a non-linear diffusive shock acceleration mechanism. Three components of high energy light nuclei escaped from the SNR are considered. It should be noted that the proton spectrum observed by KASCADE can be also explained by this model given a higher acceleration efficiency.
