Making other earths: dynamical simulations of terrestrial planet formation and water delivery

We present results from 44 simulations of late stage planetary accretion, focusing on the delivery of volatiles (primarily water) to the terrestrial planets. Our simulations include both planetary “embryos” (defined as Moon to Mars sized protoplanets) and planetesimals, assuming that the embryos formed via oligarchic growth. We investigate volatile delivery as a function of Jupiter's mass, position and eccentricity, the position of the snow line, and the density (in solids) of the solar nebula. In all simulations, we form 1-4 terrestrial planets inside 2 AU, which vary in mass and volatile content. In 44 simulations we have formed 43 planets between 0.8 and 1.5 AU, including 11 “habitable” planets between 0.9 and 1.1 AU. These planets range from dry worlds to “water worlds” with 100+oceans of water (1 ocean=1.5×10²⁴ g), and vary in mass between 0.23M_⊕ and 3.85M_⊕. There is a good deal of stochastic noise in these simulations, but the most important parameter is the planetesimal mass we choose, which reflects the surface density in solids past the snow line. A high density in this region results in the formation of a smaller number of terrestrial planets with larger masses and higher water content, as compared with planets which form in systems with lower densities. We find that an eccentric Jupiter produces drier terrestrial planets with higher eccentricities than a circular one. In cases with Jupiter at 7 AU, we form what we call “super embryos,” 1-2M_⊕ protoplanets which can serve as the accretion seeds for 2+M_⊕ planets with large water contents.     

网络安全动态防御体系研究及应用

在分析P2DR2模型的基础上,阐述了发展网络安全动态防御体系的重要性,讨论了其功能需求,提出了改进的IDS分析响应系统模型,并以其为核心构建了网络安全动态防御体系,还讨论了实现的关键技术并给出了应用实例.     

三江源地区秋季一次层积云飞机人工增雨催化试验的微物理响应

利用三江源地区一次在层积云顶部进行的飞机锯齿形催化作业及回穿探测的全球卫星定位系统(GPS)轨迹和机载云粒子测量系统(PMS)资料,在确定作业前后有效对比区间、区分云粒子相态的基础上,通过分析作业前、后液态云粒子及冰晶浓度变化、云粒子谱的演变和过冷水含量比率的变化,研究了催化的微物理响应。结果表明,作业区液态云粒子中值直径集中在3.5—18.5 μm,直径21.5—45.5 μm的云粒子基本上为冰晶,粒径大于50 μm的粒子相态为冰相;锯齿形作业后约2—23 min,在其航线下风方36 km范围内,前向散射粒子谱探头(FSSP-100)和二维灰度云粒子探头(OAP-2D-GA2,简称2DC)所测云粒子浓度、直径变化均未超出作业前云区内的自然起伏,但在过冷水含量大于0.01 g/m³的高过冷水区,液态云粒子浓度明显降低,前向散射粒子谱探头量程内的冰晶粒子浓度明显升高,冰相含水量增大,过冷水含量比率的平均值由作业前的 (68.3±23.1)% 减小至(34.2±12.4)% 。在过冷水含量越高的区域,催化效应越明显,而在低过冷水区和仅受原点催化影响的航迹交叉点处均未观测到催化响应。     

1.26米红外望远镜电控系统软件设计与实现

2011年,国家天文台兴隆基地1.26 m红外望远镜进行了全面升级改造。主要讲述望远镜电控系统软件的设计与实现,用于实现望远镜各种观测策略和运动方式的自动化操作。为了提高稳定性和可靠性,软件基于有限状态机原理设计,定义了望远镜的状态集和动作集,以及各个状态间的状态转换图;同时给出了望远镜常见异常及其处理方式,并在本地控制的基础上提供远程控制接口,使得望远镜可方便纳入兴隆基地望远镜集中控制系统。该软件及其设计思想可推广至我国其他中小口径望远镜。     

富宁渭林金矿矿化富集规律

矿体受地层和构造双重控制,褐铁矿化、硅化构造角砾岩型金矿石,微细浸染状结构。低温汽水热液与浊积岩层中的钙质交代,运移至北西西向断层次级破碎带中富集成矿。     

甘肃枣子沟金矿床地质特征及成因分析

枣子沟金矿为近年发现的大型金矿。矿床产于秦岭造山带三叠系浅变质细碎屑岩中,为一受岩脉、断裂、蚀变带控制的构造蚀变岩型金矿床,矿体严格受断裂破碎带控制。矿床地质和地球化学研究表明,成矿物质主要来源于岩浆期后中—低温热液。岩浆活动为成矿提供热动力和物质来源。     

环青藏高原盆山体系东段新构造变形特征——以川西为例

介于扬子板块与青藏高原之间的川西前陆冲断带是环青藏高原盆山体系东段的重要组成部分,它是研究喜马拉雅构造运动对青藏高原东缘沉积盆地构造作用的重要场所。本文分别选取川西南段、川西北段和川北西段米仓山前的区域构造地质剖面来研究沉积地层在喜马拉雅运动中发生的构造变形特征。通过前陆冲断构造变形带的宽度、水平缩短量,山体隆升、盆地沉降,新构造对早期古构造的叠加与改造关系的研究,揭示出在环青藏高原盆山体系内,造山带与盆地边缘的冲断构造变形从造山带向克拉通盆地内扩展的同时受欧亚大陆与印度板块碰撞及其远程效应的空间位置限制,靠近青藏高原的川西南段到远离它的川北西段,新构造变形强度、新构造变形范围、盆山耦合程度具有依次降低等特征。这种受环青藏高原盆山体系控制的前陆冲断带构造变形具有明显的资环效应,特别是对油气资源的聚集与分布有重要的影响,控制了川西南段晚期次生气藏发育,川西北段和川北西段的早期原生气藏的发育。     

Recently Ratified and Proposed Cambrian Global Standard Stratotype-section and Points

This paper briefly summarizes an officially ratified Global Standard Stratotype-section and Point (GSSP) and a proposed GSSP for global stages of the Cambrian System. The Luoyixi section near Luoyixi town, Guzhang, northwestern Hunan is ratified as the boundary stratotype for the base of the global Guzhangian Stage, which is the upmost stage of an unnamed series termed provisionally as Cambrian Series 3. The GSSP position lies 121.3 m above the base of the Huaqiao Formation in the section, coinciding with the first appearance of the cosmopolitan agnostoid trilobite Lejopyge leavigata. The Duibian B section at Duibian village, Jiangshan, western Zhejiang, is proposed as the boundary stratotype for the base of the proposed global Jiangshanian Stage that is the second stage of the Furongian Series. The proposed GSSP position lies 108.12 m above the base of the Huayansi Formation in the section, coinciding with the first appearance of the cosmopolitan agnostoid trilobite Agnostotes orientalius. This horizon is also with the first appearance of the cosmopolitan polymerid trilobite Irvingella angustilimbata.     

http://www.sciencedirect.com/science/article/pii/S1674987110000356

We have analyzed the July 15,2009,Fiordland earthquake(M_w 7.8),which occurred in the southwestern part of the South Island of New Zealand.This thrust-related earthquake in the southern Fiordland subduction zone is the largest New Zealand earthquake in the past 80 years.We have constrained a rupture model for this earthquake using coseismic offsets derived from the continuous geodetic network(Global Positioning System) of the New Zealand Institute of Geological and Nuclear Sciences (GNS Science).Our anal...     

重大滑坡灾害远程自动监测预警系统

为实现对滑坡体进行实时监测和提高滑坡应急处置能力,利用计算机技术、网络技术和无线传输技术,将数字视频实时监控技术引入重大滑坡监测预警,开发滑坡远程监测预警系统.系统对吴家岩滑坡的监测表明,该系统能及时、准确和完整地反映滑坡体的变形及危险,出现异常立即自动报警.