On June 25, 2016, the Long March 7(LM-7) launch vehicle completed its maiden flight successfully. LM-7, as a new generation of medium and basic launch vehicle based on the design concepts of non-toxic and nonpolluting...On June 25, 2016, the Long March 7(LM-7) launch vehicle completed its maiden flight successfully. LM-7, as a new generation of medium and basic launch vehicle based on the design concepts of non-toxic and nonpolluting, was developed for the purpose of launching a cargo spacecraft to the Chinese space station. Based on the experience on launching cargo spacecraft and satellites, LM-7 can be adapted for mainstream satellite launch missions in the future with its characteristics of serialization and continuous optimization. LM-7 is expected to be used to launch manned spacecraft in the future. This paper presents a general review of LM-7 with regard to the general scheme and provides references for the development prospects of a medium launch vehicle series in China.展开更多
Two additional solutions of new shear-horizontal surface acoustic waves (SH-SAWs) are found in this theoretical report. The SH-SAW propagation is managed by the free surface of a solid when it has a direct contact wit...Two additional solutions of new shear-horizontal surface acoustic waves (SH-SAWs) are found in this theoretical report. The SH-SAW propagation is managed by the free surface of a solid when it has a direct contact with a vacuum. The studied smart solid represents the transversely isotropic piezoelectromagnetic (magnetoelectroelastic or MEE) medium that pertains to crystal symmetry class 6 mm. In the developed theoretical treatment, the solid surface must be mechanically free. Also, the magnetic and electrical boundary conditions at the common interface between a vacuum and the solid surface read: the magnetic and electrical displacements must continue and the same for the magnetic and electrical potentials. To obtain these two new SH-SAW solutions, the natural coupling mechanisms such as eμ-hα and εμ-α2 present in the coefficient of the magnetoelectromechanical coupling (CMEMC) can be exploited. Based on the obtained theoretical results, it is possible that a set of technical devices (filters, sensors, delay lines, lab-on-a-chip, etc.) based on smart MEE media can be developed. It is also blatant that the obtained theoretical results can be helpful for the further theoretical and experimental studies on the propagation of the plate SH-waves and the interfacial SH-waves in the MEE (composite) media. The most important issue can be the influence of the magnetoelectric effect on the SH-wave propagation. One must also be familiar with the fact that the surface, interfacial, and plate SH-waves can frequently represent a common tool for nondestructive testing and evaluation of surfaces, interfaces, and plates, respectively.展开更多
In the recent years,with rapid development of mobile internet,new media platform has been developing at full speed,such as twitter,WeC hat and APP. It has wide information dissemination channels,fast release frequency...In the recent years,with rapid development of mobile internet,new media platform has been developing at full speed,such as twitter,WeC hat and APP. It has wide information dissemination channels,fast release frequency and efficient interactive mode. According to the characteristics of new media,we set forth the current situation of public weather service. Through the questionnaire survey,we have analyzed the actual demand of public from three aspects,including the public reading habits,characteristics of sharing and transmission and defect of information distribution. Finally,we have discussed the future trend of meteorological new media,which will promote public service effectiveness of meteorological new media by considering requirement,applying new technology and reasonably using platform.展开更多
文摘On June 25, 2016, the Long March 7(LM-7) launch vehicle completed its maiden flight successfully. LM-7, as a new generation of medium and basic launch vehicle based on the design concepts of non-toxic and nonpolluting, was developed for the purpose of launching a cargo spacecraft to the Chinese space station. Based on the experience on launching cargo spacecraft and satellites, LM-7 can be adapted for mainstream satellite launch missions in the future with its characteristics of serialization and continuous optimization. LM-7 is expected to be used to launch manned spacecraft in the future. This paper presents a general review of LM-7 with regard to the general scheme and provides references for the development prospects of a medium launch vehicle series in China.
文摘Two additional solutions of new shear-horizontal surface acoustic waves (SH-SAWs) are found in this theoretical report. The SH-SAW propagation is managed by the free surface of a solid when it has a direct contact with a vacuum. The studied smart solid represents the transversely isotropic piezoelectromagnetic (magnetoelectroelastic or MEE) medium that pertains to crystal symmetry class 6 mm. In the developed theoretical treatment, the solid surface must be mechanically free. Also, the magnetic and electrical boundary conditions at the common interface between a vacuum and the solid surface read: the magnetic and electrical displacements must continue and the same for the magnetic and electrical potentials. To obtain these two new SH-SAW solutions, the natural coupling mechanisms such as eμ-hα and εμ-α2 present in the coefficient of the magnetoelectromechanical coupling (CMEMC) can be exploited. Based on the obtained theoretical results, it is possible that a set of technical devices (filters, sensors, delay lines, lab-on-a-chip, etc.) based on smart MEE media can be developed. It is also blatant that the obtained theoretical results can be helpful for the further theoretical and experimental studies on the propagation of the plate SH-waves and the interfacial SH-waves in the MEE (composite) media. The most important issue can be the influence of the magnetoelectric effect on the SH-wave propagation. One must also be familiar with the fact that the surface, interfacial, and plate SH-waves can frequently represent a common tool for nondestructive testing and evaluation of surfaces, interfaces, and plates, respectively.
基金Supported by Soft Science Project of Beijing Meteorological Bureau[2017Y05]
文摘In the recent years,with rapid development of mobile internet,new media platform has been developing at full speed,such as twitter,WeC hat and APP. It has wide information dissemination channels,fast release frequency and efficient interactive mode. According to the characteristics of new media,we set forth the current situation of public weather service. Through the questionnaire survey,we have analyzed the actual demand of public from three aspects,including the public reading habits,characteristics of sharing and transmission and defect of information distribution. Finally,we have discussed the future trend of meteorological new media,which will promote public service effectiveness of meteorological new media by considering requirement,applying new technology and reasonably using platform.
