A new set of low-resolution spectral and UBVJHKL-photometric observations of the symbi- otic nova PU Vul is presented. The binary has been evolving after its symbiotic nova outburst in 1977 and now it is in the nebula...A new set of low-resolution spectral and UBVJHKL-photometric observations of the symbi- otic nova PU Vul is presented. The binary has been evolving after its symbiotic nova outburst in 1977 and now it is in the nebular stage. It is found that the third orbital cycle （after 1977） was characterized by great changes in associated light curves. Now, PU Vul exhibits a sine-wave shape in all the light curves （with an amplitude in the U band of about 0.7 mag）, which is typical for symbiotic stars in the quiescent state. Brightness variability due to pulsations of the cool component is now clearly visible in the VRI light curves. The amplitude of the pulsations increases from 0.5 mag in the V band to 0.8 mag in the I band. These two types of variability, as well as a very slow change in the physical parameters of the hot component due to evolution after the outburst of 1977, influence the spectral energy distribution （SED） of the system. The variability of emission lines is highly complex. Only hydrogen line fluxes vary with orbital phase. An important feature of the third orbital cycle is the first emergence of the OVI, 6828A Raman scattering line. We determine the temperature of the hot component by means of the Zanstra method applied to the He II, 4686A line. Our estimate is about 150000 K for the spectrum obtained near orbital maximum in 2014. The VO spectral index derived near pulsation minimum corresponds to M6 spectral class for the cool component of PU Vul.展开更多
New photometry for two Algol-type binaries, 0.8065 d）, was carried out using the 60-cm telescope EU Hya （P = 0.7782 d） and AW Vul （P = at Xinglong station of National Astronomical Observatories, Chinese Academy of...New photometry for two Algol-type binaries, 0.8065 d）, was carried out using the 60-cm telescope EU Hya （P = 0.7782 d） and AW Vul （P = at Xinglong station of National Astronomical Observatories, Chinese Academy of Sciences. With the updated Wilson-Devinney code, photometric el- ements were derived from the multi-color light curves. The modeled results indicate that the two systems are near-contact binaries, whose secondary components fill their Roche lobes. The fill-out factors of the primaries are fp = 81.2 （±0.2）% for EU Hya and fp --- 82.4 （±0.3）% for AW Vul. Period analysis implies that there exists a downward parabola with a light-time orbit from the （O - C） curve. This kind of periodic oscillation may be attributed to the light-time orbit effect of a third companion. The long-term period de- crease may be caused by mass and angular momentum loss. When the orbital period decreases, the fill-out factor of fp will increase. Our results indicate that the primaries will also eventually fill their Roche lobes. EU Hya and AW Vul may possibly evolve from semi-detached binaries into contact ones.展开更多
Groundwater plays a critical role in maintaining ecological balance and ensuring social operations,especially in arid and semiarid regions(Hu et al.,2023;Han et al.,2022;Ma et al.,2014).The over-exploitation of ground...Groundwater plays a critical role in maintaining ecological balance and ensuring social operations,especially in arid and semiarid regions(Hu et al.,2023;Han et al.,2022;Ma et al.,2014).The over-exploitation of groundwater,coupled with the influx of pollutants from human activities into the soil,significantly degrades the environment in certain regions(Jia et al.,2019;Famiglietti,2014;Giordano,2009;Konikow and Kendy,2005;Bohlke,2002;Shah et al.,2000).展开更多
From their ambiguous start,made even more ambiguous by the androgynous and illusive vocals of lead singer Mike Milosh,Rhye captivated listeners with their subdued R&B-influenced pop.Though Milosh admits this initi...From their ambiguous start,made even more ambiguous by the androgynous and illusive vocals of lead singer Mike Milosh,Rhye captivated listeners with their subdued R&B-influenced pop.Though Milosh admits this initial cloud of mystery was never intentional.展开更多
From their ambiguous start,made even more ambiguous by the androgynous and illusive vocals of lead singer Mike Milosh,Rhye captivated listeners with their subdued R&B-influenced pop.Though Milosh admits this initi...From their ambiguous start,made even more ambiguous by the androgynous and illusive vocals of lead singer Mike Milosh,Rhye captivated listeners with their subdued R&B-influenced pop.Though Milosh admits this initial cloud of mystery was never intentional.展开更多
输电线路在自然灾害或人为破坏等外力干扰下,易受损坏或发生故障,致使电力系统全部或部分功能丧失。将输电线路物理脆弱性定位于"功能失效",从人与环境对输电线路造成的压力、输电线路自身状态及功能失效后的响应等方面进行分...输电线路在自然灾害或人为破坏等外力干扰下,易受损坏或发生故障,致使电力系统全部或部分功能丧失。将输电线路物理脆弱性定位于"功能失效",从人与环境对输电线路造成的压力、输电线路自身状态及功能失效后的响应等方面进行分析,构建输电线路物理脆弱性评估指标体系;借鉴已有评估方法,提出基于压力指数、状态指数和响应指数的评估模型;应用三角图法对输电线路进行物理脆弱性评估和分类,分析影响输电线路物理脆弱性的主要因素。以某500 k V输电线路为例进行实例分析,结果表明影响该输电线路脆弱性关键因素为压力和响应。展开更多
基金supported by RNF grant 17-12-01241(problem formulation and analysis)support from grants VEGA 2/0008/17 and APPV15-0458support from grant RFBR 15-07-04512-A
文摘A new set of low-resolution spectral and UBVJHKL-photometric observations of the symbi- otic nova PU Vul is presented. The binary has been evolving after its symbiotic nova outburst in 1977 and now it is in the nebular stage. It is found that the third orbital cycle （after 1977） was characterized by great changes in associated light curves. Now, PU Vul exhibits a sine-wave shape in all the light curves （with an amplitude in the U band of about 0.7 mag）, which is typical for symbiotic stars in the quiescent state. Brightness variability due to pulsations of the cool component is now clearly visible in the VRI light curves. The amplitude of the pulsations increases from 0.5 mag in the V band to 0.8 mag in the I band. These two types of variability, as well as a very slow change in the physical parameters of the hot component due to evolution after the outburst of 1977, influence the spectral energy distribution （SED） of the system. The variability of emission lines is highly complex. Only hydrogen line fluxes vary with orbital phase. An important feature of the third orbital cycle is the first emergence of the OVI, 6828A Raman scattering line. We determine the temperature of the hot component by means of the Zanstra method applied to the He II, 4686A line. Our estimate is about 150000 K for the spectrum obtained near orbital maximum in 2014. The VO spectral index derived near pulsation minimum corresponds to M6 spectral class for the cool component of PU Vul.
基金support from the National Natural Science Foundation of China under grant Nos.11473009 and U1131102the Open Research Program Foundation(No.OP 201110)
文摘New photometry for two Algol-type binaries, 0.8065 d）, was carried out using the 60-cm telescope EU Hya （P = 0.7782 d） and AW Vul （P = at Xinglong station of National Astronomical Observatories, Chinese Academy of Sciences. With the updated Wilson-Devinney code, photometric el- ements were derived from the multi-color light curves. The modeled results indicate that the two systems are near-contact binaries, whose secondary components fill their Roche lobes. The fill-out factors of the primaries are fp = 81.2 （±0.2）% for EU Hya and fp --- 82.4 （±0.3）% for AW Vul. Period analysis implies that there exists a downward parabola with a light-time orbit from the （O - C） curve. This kind of periodic oscillation may be attributed to the light-time orbit effect of a third companion. The long-term period de- crease may be caused by mass and angular momentum loss. When the orbital period decreases, the fill-out factor of fp will increase. Our results indicate that the primaries will also eventually fill their Roche lobes. EU Hya and AW Vul may possibly evolve from semi-detached binaries into contact ones.
基金supported by the Center for Hydrogeology and Environmental Geology Survey,1:50000 Hydrogeological Survey of Yimeng Mountains(No.12120114010902)。
文摘Groundwater plays a critical role in maintaining ecological balance and ensuring social operations,especially in arid and semiarid regions(Hu et al.,2023;Han et al.,2022;Ma et al.,2014).The over-exploitation of groundwater,coupled with the influx of pollutants from human activities into the soil,significantly degrades the environment in certain regions(Jia et al.,2019;Famiglietti,2014;Giordano,2009;Konikow and Kendy,2005;Bohlke,2002;Shah et al.,2000).
文摘From their ambiguous start,made even more ambiguous by the androgynous and illusive vocals of lead singer Mike Milosh,Rhye captivated listeners with their subdued R&B-influenced pop.Though Milosh admits this initial cloud of mystery was never intentional.
文摘From their ambiguous start,made even more ambiguous by the androgynous and illusive vocals of lead singer Mike Milosh,Rhye captivated listeners with their subdued R&B-influenced pop.Though Milosh admits this initial cloud of mystery was never intentional.
文摘输电线路在自然灾害或人为破坏等外力干扰下,易受损坏或发生故障,致使电力系统全部或部分功能丧失。将输电线路物理脆弱性定位于"功能失效",从人与环境对输电线路造成的压力、输电线路自身状态及功能失效后的响应等方面进行分析,构建输电线路物理脆弱性评估指标体系;借鉴已有评估方法,提出基于压力指数、状态指数和响应指数的评估模型;应用三角图法对输电线路进行物理脆弱性评估和分类,分析影响输电线路物理脆弱性的主要因素。以某500 k V输电线路为例进行实例分析,结果表明影响该输电线路脆弱性关键因素为压力和响应。
