GPS共视法时间比对在陕西天文台的建立

利用国产GPS定时型接收机,按照国际共视规程,陕西天文台建立了GPS共视法时间比对.研究了影响比对精度的因素,实现了微机控制的数据自动采集和处理,实现了国际间的全面共视比对.1991年3月起,BIPM已正式用于国际原子时TAI的计算中。     

A study on element-stratigraphy of Okinawa Trough

Regular distribution patterns of elements Ca, Sr, K, Na, Mg, Fe, Mn, Ti, Cu, Co, Ni, Zn, Pb, Cr, Rb, Ba, Cd, and U in Late Quaternary strata have been studied in detail. The regional variation patterns of elements in these strata are similar to those in recent surface sediments, showing that the sedimentary environment has been relatively stable since Late Quaternary. Element distribution changes with the variations of lithological characters. Contents of Ca and Sr increase in coarse sediments, while those of other elements decrease. Na content increases in the pumice layer. Mn, content tends to increase sharply towards the surface layer. Ca content decreases sharply in strata where water depth is more than 2,000 m. The strata can be divided based on the distribution curves of element assemblages. The variations in contents of most elements in Holocene Series are smaller than those in Late Pleistocene Series, which might be related to the factors of glacial and interglacial changes, sea level fluctuations and material source differences. Contribution No. 1488 from Institute of Oceanology, Academia Sinica     

A landscape pattern analysis method based on boundaries and nodes: A case study in upper Minjiang River, China

Traditionally,patch-based analysis at the landscape scale fragmentation has been used in the study of landscape ecology while the study of boundary and node has not been considered as much detail until recently.This study investigated the possibility of applying boundary-and node-based methods in landscape pattern analysis to the upper reaches of the Minjiang River in the southwestern China.Boundary-based and node-based landscape indices were selected to be used in analyzing changes in landscape patterns,and the results were compared with analysis using traditional pattern indices.We compared the responses of patch-area-based,boundary-length-based and node-number-based indices,and concluded that boundary-based and node-based indices are more sensitive to disturbance than patch-based indices with various patterns,and node-based indices are even more sensitive than boundary-based ones.Thus,the results suggest that boundary-based and node-based pattern analysis methods provide helpful supplementary information to traditional patch-based pattern analysis methods.The results about pattern dynamics of landscapes in the upper reaches of the Minjiang River based on boundaries and nodes showed that with human disturbance,the dominance of forest landscape was weakened by other landscape types; thus the landscape pattern of the study area became more homogeneous and the boundary network became more complex.These changes further augmented disturbance interfaces in the landscape and increased the possibilities of further landscape fragmentation.     

二氧化氯控制欧洲鳗细菌性疾病

以二氧化氯作为一种新型的消毒剂和杀菌剂 ,以传统含氯制剂 (如漂白粉、二氯异氰尿酸钠、三氯异氰尿酸 )作为对照 ,比较其在治疗欧洲鳗细菌性疾病及改善养殖水质方面的显著特性 ,其作用活性与环境 (如 p H、温度、氨及有机物 )因子的关系。结果表明 ,二氧化氯 (Cl O2 )对爱德华氏菌、嗜水气单胞菌和柱状屈挠杆菌有很好的杀灭效果 ,能迅速治愈欧洲鳗的赤鳍病和肝肾病 ,且能有效改善养殖水体 ,水中生化需氧量比对照组下降 10 %～ 30 % ,化学耗氧量下降 5% ,溶氧量提高 8%～ 10 %。当二氧化氯体积分数为 8m L/m3时 ,其杀菌率均高达 90 %以上 ,为氯制剂的 1.8倍 ,且活性不受环境因子的影响     

Walking Access Distance of Metro Passengers and Relationship with Demographic Characteristics: A Case Study of Nanjing Metro

In the metropolises of China, the metro plays an increasingly important role in commuting because of its efficiency, affordability, and cleanliness. This paper attempts to explore the relationship between walking access distance to metro stations and the demographic characteristics of passengers, such as age, monthly income, travel frequency, gender, and travel purpose, as well as the influence of the urban context. Nanjing Metro Line 2 is selected as the case study. By using different methods such as a questionnaire survey, spatial decay function, analysis of covariance (ANOVA), network analysis of routes, and K-means cluster analysis, it is suggested that demographic characteristics have a significant impact on the pedestrian walking distance, with the exception of gender. Furthermore, the paper finds a spatial decay effect in walking access distance, the decay rate of which, however, varies across stations. Terminal stations have a larger pedestrian catchment area than in regular and exchange stations. Moreover, the passengers of Nanjing Metro Line 2 can be classified into six groups according to their demographic characteristics, among which education and occupation are vital indicators in determining their willingness to walk to the stations. Middle-class passengers have a higher dependence on the metro and tend to walk longer than other groups do. This study provides an important reference for planners and transport sectors to optimize land-use and transport infrastructures.     

New photometric investigation of the low-mass-ratio contact binary star V1853 Orionis

Four-color charge-coupled device(CCD) light curves in the B, V, Rc and I c bands of the totaleclipsing binary system V1853 Orionis(V1853 Ori) are presented. By comparing our light curves with those published by previous investigators, it is determined that the O'Connell effect on the light curves has disappeared. By analyzing those multi-color light curves with the Wilson-Devinney code(W-D code),it is discovered that V1853 Ori is an A-type intermediate-contact binary with a degree of contact factor of f = 33.3%(3.7%) and a mass ratio of q = 0.1896(0.0013). Combining our 10 newly determined times of light minima together with others published in the literature, the period changes of the system are investigated. We found that the general trend of the observed minus calculated(O-C) curve shows a downward parabolic variation that corresponds to a long-term decrease in the orbital period with a rate of d P/dt =-1.96(0.46)×10^-7 d yr^-1. The long-term period decrease could be explained by mass transfer from the more-massive component to the less-massive one. By combining our photometric solutions with data from Gaia DR_2, absolute parameters were derived as M_1 = 1.20 M⊙, M_2 = 0.23 M⊙, R_1 = 1.36 R⊙and R_2 = 0.66 R⊙. The long-term period decrease and intermediate-contact configuration suggest that V1853 Ori will evolve into a high fill-out overcontact binary.     

水（金）星凌日的程序化预报方法

本文介绍了预报水(金)星凌日的计算方法和凌日图的绘制方法,建立了一套完整的预报程序。作为该程序的一个简单应用,我们结合DE200历表及美国海军天文台提供的岁差章动程序,给出了1999年水星凌日的预报结果。     

Data processing and initial results from the CE-3 Extreme Ultraviolet Camera

The Extreme Ultraviolet Camera(EUVC) onboard the Chang'e-3(CE-3)lander is used to observe the structure and dynamics of Earth's plasmasphere from the Moon. By detecting the resonance line emission of helium ions(He+) at 30.4 nm, the EUVC images the entire plasmasphere with a time resolution of 10 min and a spatial resolution of about 0.1 Earth radius(RE) in a single frame. We first present details about the data processing from EUVC and the data acquisition in the commissioning phase, and then report some initial results, which reflect the basic features of the plasmasphere well. The photon count and emission intensity of EUVC are consistent with previous observations and models, which indicate that the EUVC works normally and can provide high quality data for future studies.     

RV Piscium: a marginal contact binary system

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.     

丽江天文观测站全天相机介绍

全天相机作为一个对天文观测台站全天云量信息进行监视的工具,对天文观测的正常进行发挥着重要的作用,目前世界上主要天文台均配备有全天相机,为了满足对全天云量信息进行实时监视的需求,丽江天文观测站正式安装架设了一套全天相机系统。从硬件安装架设、软件调试到实际测试等方面,详细介绍了全天相机系统的设计方案以及遇到的问题,讨论了对问题的解决措施,重点介绍了根据天光亮度数值调整相机曝光时间的方法,这也是主要创新与特色之处。