Search

We analyzed the variation trend of growing season length (GSL) of different periods in provinces (regions) of China and the corresponding movement velocity of GSL isolines at 150, 200, 250, 300 and 350 days, based on daily mean temperature data of 822 meteorological stations from 1951 to 2017. In this study, the definition of GSL given by the world meteorological organization was adopted, together with Slope, Hurst and Mann-Kendall indices. The results showed that the GSL in northern China changed significantly during 1951-2017. The extension of GSL was faster in the north than the south, and faster in high-altitude areas than low-altitude ones. The trend of future GSL change in most regions of China converged with the current extension trend. The extension of GSL in northern provinces (regions) was generally 0.1-0.2 d·a基于822个气象站点1951—2017年的日均温度数据,采用世界气象组织给定的植被生长期(GSL)定义,利用Slope、Mann-Kendall和Hurst指数分析中国各省(区)不同时期的GSL变化趋势及相应时期150、200、250、300和350 d的GSL等值线移动速度。结果表明: 研究期间中国北方地区GSL变化显著。GSL增长速度表现为北方快于南方、高海拔快于低海拔。中国大部分地区未来GSL变化趋势与当前的变化趋势相同。北方绝大部分省(区)GSL增长速度在0.1~0.2 d·a

We obtain the necessary and sufficient conditions for Radford's biproduct to be a braided Hopf algebra. As an application, a nontrivial example is given.

Such reasons as the start-stop or short circuit fault of high power equipment, the operation of power supply equipment, the frequency conversion equipment and the fault of power supply network will lead to surge. Surge injected into transmission lines will produce intense transient radiated electromagnetic field, which can severely interfere in normal operation of electronic systems around and even damage them. In this paper, radiated electromagnetic field by surge injecting into transmission line is studied using FDTD method as dipole radiator and the numerical model is established. It calculated the radiated electromagnetic field at the different position in a rectangular coal tunnel. All results presented help the application and designing of surge protection for electronic device and the arrangement of electronic device and wire cable.

The energy level structures of Rydberg slates of Ru atom in 4d7(4F) ns series and 4d7(4F) nd series are measured by means of laser resonance excitation-electric field ionization method. The relative line strengths within the multiplet of an electron configuration are calculated. The theoretical results are coincident with the experiments satisfactorily. The terms of the measured spectrum lines can be identified.

35 autoionising energy levels of Ne atom in ns＇(n = l5-35) and nd＇(n = l3-30) series have been determined experimentally with pulsed electric field optogalvanic spectroscopy. The ionization limit of the ns＇ and nd＇ series was found by parametric fitting and the quantum defects of all these levels were calculated. Instead of the direct discharge, pulsed electric field was used in the experiment, to eliminate Stark effects in the optogalvanic spectroscopy.

This paper discribes the measurements of Rydberg energy levels of Ru in 4d7(4F) ns (n=28-45) and 4d7(4F) nd (n=26-48) series by means of laser resonance excitation-electric field ionization method. The first ionization potential of Ru has been determined by nonlinear fitting program. These energy levels and relevant quantum defects have been calculated by using relativistic self-consistent field method The theoretical results are coincident with the experiments very well. Besides, the first ionization potential drawn from this papes has been compared with the existing data.