空间硬X射线望远镜HAPI-1及其对蟹状星云脉冲星的观测

HAPI-1是我国第一个用于空间高能天文观测的硬X射线望远镜系统,由面积145cm~2厚0.5cm的CsI(T1)主探测晶体及其下部厚5cm的NaI(T1)反符合晶体构成复合晶体探测器,采用脉冲形状甄别技术区分两种晶体的输出信号,多种物质构成的夹层式屏蔽筒和准直器使望远镜具有约4°视场角(HWHM),电子学、姿态控制和数据获取系统使望远镜具有对20—200keV能区高能光子到达时刻和能量进行空间定向观测的能力。本文介绍HAPI-1的构成和主要性能,以及1984年5月利用该望远镜在我国高空科学气球上对蟹状星云脉冲星的观测结果。     

Statistical behavior of sunspot groups on the solar disk

In the present study we have produced a diagram of the latitude distribution of sunspot groups from the year 1874 through 1999 and examined statistical characteristics of the mean latitude of sunspot groups. The reliability of the observed data set prior to solar cycle 19 is found quite low as compared with that of the data set observed after cycle 19. A correlation is found between maximum latitude at which first sunspot groups of a new cycle appear and the maximum solar activity of the cycle. It is inferred that solar magnetic activity during the early part of an extended solar cycle may contain some information about the strength of forthcoming solar cycle. A formula is given to describe latitude change of sunspot groups with time during an extended solar cycle. The latitude-migration velocity is found to be largest at the beginning of solar cycle and decreases with time as the cycle progresses with a mean migration velocity of about 1.61° per year.     

Relation between blue/ultraviolet continuum shape and the ratio of radio-to-optical emission for B3-VLA quasars

The low-frequency radio luminosity is believed to be an indicator of jet power, while the optical/ultraviolet (UV) emission is probably from accretion discs in the nuclei of steep-spectrum radio quasars. We present a correlation between the ratio of radio-to-optical luminosities and the continuum spectral index in blue/UV bands, which might indicate that the continuum shape in blue/UV bands is related to the ratio of jet to accretion power. The results may imply that the spectra and structure of accretion discs are probably affected by the interactions between jets and discs.     

Using McDaniel's model to represent non-Rayleigh reverberation

Reverberation in low-frequency active sonar systems operating in shallow water has often been observed to follow non-Rayleigh statistical distributions. McDaniel's model, generalized to allow noninteger valued parameters, has shown promise as being capable of accurately representing real data with a minimal parameterization. This paper first derives an exact analytical expression for the cumulative distribution function (CDF) of the generalized McDaniel model and then compares it with numerical inversion of the characteristic function. Both methods are seen to provide adequate and equivalent precision; however the characteristic function inversion method is significantly faster. The latter CDF evaluation technique is then applied to the analysis of simulated and real data to show that, when minimal data are available, McDaniel's model can more accurately represent a wide variety of non-Rayleigh reverberation than the K or Rayleigh mixture models. This result arises from the generality of McDaniel's model with respect to the K-distribution (i.e., the K-distribution P_fa estimate can be dominated by model mismatch error) and to its compact parameterization with respect to the Rayleigh mixture (i.e., the Rayleigh mixture model P_fa estimate is usually dominated by parameter estimation error)     

ANALYSIS AND MODELING ON CULTIVATED LAND CONVERSION —— Case Study of Hebei Province

1INTRODUCTION With the acceleration of the urbanization and industrial- ization of China, it is inevitable that cultivated land con- vertsto built-up land for industrial, commercial and resi- dential uses. During 1986- 2002 around 168.4×103ha cultivated land had converted to non-agriculture use an- nually (QU et al., 2005). Though the urbanization rate had increased from 17% in the late 1970s to 41% in 2004, China has a long way to go compared with the de- veloped countries whose urbani…     

基于X-Bridge的土地整理项日审批平台建设

本文首先介绍了国家土地开发整理项目管理信息系统的开发背景,接着对系统采用的X-Bridge平台的基本概念和工作原理进行了分析然后针对基于X-Bridge平台建设土地整理项目审批平台的实现原理、技术方法和主要功能进行了详细的阐述。该审批平台是整个国土资源部土地开发整理项目管理信息系统中的重要组成部分,是一个相对独立的系统。最后对平台成果进行了小结,证明了该系统的先进性、稳定性及待完善的工作。     

Tectonic evolution of convergent plate margins and its geological effects

Science China Earth Sciences - Oceanic lithosphere is generated at divergent plate boundaries and disappears at convergent plate boundaries. Seafloor spreading and plate subduction together...     

GPS观测到的智利及其邻区多次大地震前后地壳运动

2001年以来,智利及其邻区发生了3次7.1—7.7级和4次8级以上大地震,其震中附近至少有一个甚至多个GPS连续观测站观测到地震前后的地壳运动。从http://geodesy.unr.edu网站可获得GeoffreyBlewitt教授用GIPSY软件处理得到的南美大量GPS连续观测站南美板块（SA）区域参考框架位移时间序列,获得的这些大地震同震、震前位移积累和震后位移,特别是同震水平位移和震前水平位移积累,为探索地震预测,增添了更多有意义的震例。研究表明,这些大地震的同震水平位移也是震前水平位移积累的回跳或弹性回跳,同样也证明了震前存在前兆地壳形变;这些大地震前震中及其附近也无明显的垂直位移积累,由此证明了板块运动或地壳水平运动就是地震成因。尽管东日本和智利近海大地震的构造环境不同,日本2011年9级和智利2010年8.8级巨大地震前的地壳运动都清楚显示太平洋海底扩张。这些地震的同震水平位移回跳或弹性回跳的规律一致,地震成因都是水平挤压。智利多次大地震GPS观测到的最特殊现象是,在2015年8.3级地震震中以北,2010年8.8级地震的同震水平位移量值偏小,且方向异常一致向北,可认为是8.3级地震的前兆形变现象。临近智利的南美地区应是全球最利于地震预测探索的地区之一。      

An occurrence of tuite, γ‐Ca3(PO4)2, partly transformed from Ca‐phosphates in the Suizhou meteorite

Tuite is a high‐pressure γ‐form of Ca₃(PO₄)₂. An occurrence of tuite partly transformed from merrillite and chlorapatite was observed in the chondritic area adjacent to the shock veins in the Suizhou meteorite. Tuite grains are found in contact with both merrillite and chlorapatite, indicating two different transformation pathways. Tuite isochemically transformed from merrillite contains much higher contents of Na₂O and MgO than those transformed from chlorapatite. Tuite transformed from merrillite does not contain Cl, but tuite transformed from chlorapatite contains 1.90–3.91 wt% of Cl, hence indicating an incomplete phase transformation from chlorapatite to tuite. P‐T conditions of above 12 GPa and 1100 °C are probably required for the transformation from merrillite and chlorapatite to tuite. A temperature gradient from the hot vein at 2000 °C to the surrounding chondritic area at 1000 °C corresponds to the partial phase transitions in the Suizhou phosphates. Fast cooling of the thin shock veins plays a key role in the preservation of phosphates that suffered partial high‐pressure phase transformation.