RV Piscium: a marginal contact binary system     

Jiajia He  Shengbang Qian 《Astrophysics and Space Science》2009,321(3-4):209-215

The first complete charge-coupled device (CCD) light curves in B and V bands of the short-period binary system, RV Psc, are presented. It is found that the light curves of RV Psc are symmetric and belong to the EW type rather than the EA type as described in the 4th edition of the GCVS. Photometric solutions were derived by using the 2003 version of the Wilson–Devinney (W-D) method. It is shown that RV Psc is a marginal contact system (f=5.8%±6.6%) with a mass ratio of q=0.5978±0.0096. The temperature difference between both components is only 17 K. Analysis of the O-C curve suggests that the period of RV Psc shows a long-term continuous decrease at a rate of dP/dt=?5.89×10^?8 days/year. The long-time period decrease, the marginal-contact configuration, and the astrophysical parameters of the binary system, all suggest that it is a newly formed marginal contact binary from a case A mass transfer and will evolve into a normal overcontact binary.  相似文献   

The luminosity dependence of clustering properties of Luminous Red Galaxies (LRGs)     

Xin-Fa Deng  Ji-Zhou He  Jun Song  Xiao-Xia Qian  Ping Wu 《Astrophysics》2009,52(3):350-357

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Episodic crustal growth of North China as revealed by U-Pb age and Hf isotopes of detrital zircons from modern rivers   总被引：9，自引：0，他引：9  

Jie Yang  Shan Gao  Chen Chen  Honglin Yuan  Siwen Xie 《Geochimica et cosmochimica acta》2009,73(9):2660-2673

Clastic sedimentary rocks are samples of the exposed continental crust. In order to characterize the crustal growth history of North China and its possible regional variations, 479 concordant detrital zircons in three sand samples from the lower reach of the Yellow River (which drains the Tibet-Qinghai Plateau, the Western Qinling Orogen, the Qilian Orogen and the North China Craton) and two sand samples from the Luan River and the Yongding River (which run entirely within the North China Craton) were measured for U-Pb age and Lu-Hf isotopic compositions by excimer laser-ablation ICP-MS and MC-ICP-MS. Although regional variations exist, concordant detrital zircons from the Yellow River reveal three major age groups of 2.1-2.5 Ga, 1.6-2.0 Ga, and 150-500 Ma. Detrital zircons from the smaller Luan and Yongding Rivers show three broadly similar major age groups at 2.3-2.6 Ga, 1.6-2.0 Ga, and 140-350 Ma, but with narrower age ranges. Compared to the Luan and Yongding River zircons, the Yellow River zircons are characterized by a significant number of Neoproterozoic grains. Although Hf isotopic compositions show both juvenile crustal growth and crustal reworking for all age groups, much of the crustal growth of North China occurred in the Neoarchean and Mesoproterozoic. All three rivers are characterized by a common prominent group of Hf crust formation model ages at 2.4-2.9 Ga with a peak at 2.7-2.8 Ga. A less significant age group lies between 1.4 and 1.8 Ga for the Yellow River, and between 1.6 and 1.9 Ga for the Yongding River and Luan River. Crustal growth rates based on Hf continental crust formation model ages suggest 45% and 90% of the present crustal volume was formed by 2.5 Ga and 1.0 Ga, respectively, for the drainage area of the Yellow River. In comparison, 60% and 98% of the present crustal volume of the North China Craton was generated by 2.5 Ga and 1.0 Ga, respectively, for the Luan and Yongding Rivers. The 2.7-2.8 Ga age peak observed in all river samples agrees well with the coeval major peak for global crustal growth. However, the other suggested global peaks of crustal growth at 3.4 and 3.8 Ga are insignificant in North China. Taken together with our previous studies of the Yangtze Craton, which show insignificant crustal growth at 2.7-2.8 Ga, we suggest that these advocated worldwide crust formation peaks be re-examined and treated carefully. Our results also show that Phanerozoic zircons may have been derived from crustal sources separated from the mantle up to 2.0 Ga ago before the zircons crystallized, suggesting long-term preservation, reworking and recycling of the continental crust.  相似文献   

江苏省东海县片麻状碱性花岗岩的成因及年代学研究   总被引：1，自引：0，他引：1       下载免费PDF全文

夏斌  李建峰  张玉泉  刘立文  何观生  王洪  王敏  杨之青 《地质科学》2009,44(1):213-230

江苏省东海地区位于苏鲁造山带的西南缘,区内广泛出露片麻状碱性花岗岩.本文对东海地区磨山、虎山和房山片麻状碱性花岗岩的产状、岩石结构构造、碱性铁镁矿物、元素地球化学和锆石成因及SHRIMP定年等综合研究结果表明：该类岩石具有高硅、富碱、富铁贫镁和含碱性铁镁矿物等特征,说明其为碱性花岗岩;岩体还保留有沉积岩特有的层理（走向北东、倾向南东等一致的产状）,长石等造岩矿物显示在固相条件下结晶的特征,以及继承锫石大部分是不同时代的岩浆或变质锆石碎屑等,均证实其原岩是沉积岩.SHRIMP定年对变质锆石的边部获得两组₂₀₆Pb-₂₃₈U加权平均年龄,分别为224.7±9.4 Ma和209.4±2.5～212±3.5Ma,反映了东海片麻状碱性花岗岩成岩时间属于印支期,相当于晚三叠世,变质锆石的核部₂₀₆Pb-₂₃₈U年龄变化于866～248 Ma,反映原岩时代不会早于晚古生代.  相似文献   

2018年海峡M_S6.2地震社会影响调查与分析     

赖见深  陈华源  林木金  张凯  林苗禄  全建军  何丽云 《地震科学进展》2021,(3):122-129

以2018年台湾海峡M_S6.2地震造成的社会影响作为主要调查内容,选取了福建省东山县普通群众作为调查对象,从震时人的感觉、灾时应急避险情况、社会心理、防震减灾及地震预警知识普及情况等方面进行调查研究,目的是了解东山县居民地震应急避险情况及防震减灾知识普及程度等,为今后有针对性的做好防震减灾宣传,提升社会公众抵御地震灾害能力提供一定的参考。   相似文献   

基于MOS的广西北部湾沿海秋冬极大风速精细化预报     

潘静  陈峥蓉  黄燕波  于潇  张雪波  何滨 《气象研究与应用》2022,43(1):26-30

采用北部湾北部沿海6个自动站实况资料和欧洲中心细网格数值预报产品,根据模式输出统计法(MOS),对广西北部湾地区2012年—2016冬半年(9月到次年2月)日极大风速建立站点秋冬季不同预报时效的多元线性回归方程,并用2017冬半年的数据进行TS检验评分.结果表明,秋冬季日极大风速和代表引导气流的500hPa蒙古槽、代表...  相似文献   

基于转录组测序技术对调控毕加索小丑鱼(Picasso clownfish)白化体征关键基因的研究     

何丽斌  黄镇  吴水清  郑乐云 《海洋学报》2022,44(2):67-76

毕加索小丑鱼(Picasso clownfish)因其皮肤中的白色斑块分布杂乱抽象而得名,同时也由于其白色斑块的形成无规律性和稀缺性,属于名贵的小丑鱼,因此,解析毕加索小丑鱼的皮肤白斑形成机制,可以为毕加索小丑鱼的人工育种提供理论依据.在本研究中,我们对3种体色毕加索小丑鱼的背鳍和臀鳍之间的身体相同部位3种色块(黑色、...  相似文献   

瞬变电磁扩散场到虚拟波场的精细积分变换算法   总被引：1，自引：0，他引：1  

鲁凯亮  李貅  戚志鹏  樊亚楠  周建美  李文翰  李贺  张明晶  王扬州 《地球物理学报》2021,64(9):3379-3390

现有的瞬变电磁解释与反演方法主要对电阻率参数进行解释,较难给出准确的地质构造信息.为了能够较多获得地质构造信息,可将瞬变电磁扩散场信号转换为虚拟波场信号,提高瞬变电磁法的分辨率.本文采用精细积分法,实现了瞬变电磁扩散场到虚拟波场的转换.将一个高度病态的线性方程组转换成求积分的过程,大大降低了解决病态问题的难度.积分步长以2的指数增加,在保证精度的前提下,具有极高的计算效率;设置合理的终止迭代条件,进一步提高本文方法的适用性.对典型地电模型的计算,表明本文方法具有较高的精度;减小两个波峰之间的距离,证明了本文方法具有较好的分辨能力;对含有噪声信号的扩散场进行波场反变换,证明了本文方法具有较好的抗噪性.最后计算三维模型和实测数据的虚拟波场,可以很好地反映出三维地质体的界面信息,证明本文方法稳定、可靠,可以对地下地质目标体的界面进行有效识别.本文方法相比预条件正则化共轭梯度法(PRCG),在计算效率方面提升了 4倍左右;本文方法的相对误差在5％以内,而PRCG的最大相对误差可达40％～50％,精度最高可提升10倍;在分辨率与稳定性方面,也表现出较好的效果.  相似文献   

Simulation of Lake-Groundwater Interaction under Steady-State Flow     

Chuiyu Lu  Bo Zhang  Xin He  Guoliang Cao  Qingyan Sun  Lingjia Yan  Tao Qin  Tianchen Li  Zepeng Li 《Ground water》2021,59(1):90-99

MODFLOW is one of the most popular groundwater simulation tools available; however, the development of lake modules that can be coupled with MODFLOW is lacking apart from the LAK3 package. This study proposes a new approach for simulating lake - groundwater interaction under steady-state flow, referred to as the sloping lakebed method (SLM). In this new approach, discretization of the lakebed in the vertical direction is independent of the spatial discretization of the aquifer system, which can potentially solve the problem that the lake and groundwater are usually simulated at different scales. The lakebed is generalized by a slant at the bottom of each lake grid cell, which can be classified as fully submerged, dry, and partly submerged. The SLM method accounts for all lake sources and sinks, establishing a governing equation that can be solved using Newton's method. A benchmarking case study was conducted using a modified model setup in the LAK3 user manual. It was found that when there is a sufficient number of layers at the top of the groundwater model, SLM simulates an almost identical groundwater head as the LAK3-based model; when the number of layers decreases, SLM is unaffected while LAK3 may be at a risk of giving unrealistic results. Additionally, the SLM can reflect the relationship between the simulated lake surface area and lake water depth more accurately. Therefore, the SLM method is a promising alternative to the LAK3 package when simulating lake - groundwater interaction.  相似文献   

2017年11月23日重庆武隆5.0级地震前地磁谐波振幅比异常研究     

贺曼秋  李翠平  魏红梅  唐晋 《中国地震》2021,37(4):789-796

近年来,地磁谐波振幅比方法在国内得到较广泛的应用,并成为一种较为有效的地震预测方法。本文利用谐波振幅比方法,对2017年11月23日重庆武隆5.0级地震震中附近台站的地磁三分量数据进行计算,并分析了各台站10~60min周期谐波振幅比值异常特征。研究发现,异常台站几乎均位于震源机制解的拉张区(P波向下的区域),具有象限分布特征;异常台站NS向谐波振幅比值变化存在分层现象,短周期(浅部)的变化与长周期(深部)变化成相反相位,从电磁学机理看,浅部与深部之间存在EW向的面电流;近震中台站的异常低点时间存在由长周期(深部)向短周期(浅部)迁移的现象。  相似文献