Models for the X‐ray spectra and variability of luminous accreting black holes

The X‐ray spectra of luminous Seyfert 1 galaxies often appear to be reflection dominated. In a number of Narrow Line Seyfert 1 (NLS1) galaxies and galactic black holes in the very high state, the variability of the continuum and of the iron line are decoupled, the reflected component being often much less variable than the continuum. These properties have been interpreted as effects of gravitational light bending. In this framework, we present detailed Monte‐Carlo simulations of the reflection continuum in the Kerr metric. These calculations confirm that the spectra and variability behaviour of these sources can be reproduced by the light bending model. As an alternative to the light bending model, we show that similar observational properties are expected from radiation pressure dominated discs subject to violent clumping instabilities and, as a result, have a highly inhomogeneous two‐phase structure. In this model, most of the observed spectral and variability features originate from the complex geometrical structure of the inner regions of near‐Eddington accretion flows and are therefore a signature of accretion physics rather than general relativity. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Power spectra from ‘spotted’ accretion discs

We are carrying out a project to calculate power spectra of variability, assuming a model of a ‘spotted’ accretion disc near a black hole. We consider relativistic effects that change photon energy and produce light‐bending and time‐delays acting on the X‐ray signal received by an observer. We assume that the life‐time and the intrinsic emissivity of individual.aring events are described in terms of a simple stochastic process. This allows us to give approximate analytical formulae and compare them with numerical computations. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

金坝金矿床地质特征

金坝超微粒型金矿床有30多个矿体,划分6个矿带.矿带NE向展布,带长350~2000m.矿体呈透镜状、似层状、串珠状产出.者桑复背斜控制矿化带的分布,断裂构造为含矿热液提供运移通道,次级构造控制矿体具体储存部位及矿体的形态产状.赋矿层位以上二叠统为主(含5个矿带),还有下中三叠统.容矿岩石有泥质粉砂岩、粉砂岩、粉砂质凝灰岩、凝灰岩、泥质白云岩、细碧岩、辉绿岩脉等.矿化类型:地层岩石破碎带蚀变岩型、脉岩破碎蚀变岩型以及石英脉型.围岩蚀变有黄铁矿化、毒砂化、硅化、碳酸盐化等.矿石类型按自然分类为氧化矿石和原生矿石;按岩石类型划分为凝灰岩类矿石,粉砂岩、粉砂质泥岩类矿石,泥质白云岩矿石,辉绿岩矿石以及细碧岩矿石.矿石含金品位0.5×10^-6~15.9×10^-6.原生矿石金属矿物有黄铁矿、毒砂、黄铜矿;氧化矿石金属矿物有褐铁矿、臭葱石等;而脉石矿物主要取决于各自的容矿岩石.矿石的化学组成:SiO₂比原岩低,(Fe₂O₃+FeO)高于原岩,富K贫Na.微量元素Au、Ag、As、Sb、Cu高于原岩.矿石为泥质结构、细碎屑结构、凝灰结构、辉绿结构、粒状结晶结构、环边环带结构;碎裂构造、角砾构造、浸染状构造、结核状蜂窝状构造等.金以微包体金的形式赋存于褐铁矿、毒砂、黄铜矿中.     

区域气候模式对东亚气候时空演变特征的模拟研究

利用区域环境集成模式系统对东亚地区进行了1987年1月到1996年12月的长期积分试验,重点采用经验正交函数分析方法分析和比较模式模拟及观测气候主分量时空特征,从而考察区域气候模式对东亚地区的区域气候模拟能力.结果表明:(1) RIEMS能够较好地抓住地面气温年平均状况及其年变化和年际变率的主要特征;(2)尽管模式对降水的模拟能力没有对地面气温模拟的强,但RIEMS模式基本上能够模拟出降水的空间分布以及降水的季节变化特征,同时能够抓住降水的年际变率.       

城市居民距离认知研究——以校园大学生群体为对象的调查分析

以广州市大学生的行为活动和距离认知调查为基础,应用行为地理学理论和统计方法,总结了校园大学生群体距离认知的一般特征以及影响距离认知的因素,分析提出了校园大学生群体认知的3圈层空间结构模式,并进一步分析了大学生个人属性及其日常活动空间与距离认知的相互关系.     

Influence of Gas Hydrate on the Acoustic Properties of Sediment: A Comprehensive Review with a Focus on Experimental Measurements

In recent years, natural gas hydrate has attracted increasing attention worldwide as a potential alternative energy source due to its attributes of wide distribution, large reserves, and low carbon. Since the acoustic characteristics of hydrate-bearing reservoirs clearly differ from those of adjacent formations, an acoustic approach, using seismic and acoustic logging, is one of the most direct, effective and widely used methods among the identification and characterization techniques for hydrate reservoir exploration. This review of research on the influence of hydrate (content and distribution) on the acoustic properties (velocity and attenuation) of sediments in the past two decades includes experimental studies based on different hydrate formation methods and measurements, as well as rock physics models. The main problems in current research are also pointed out and future prospects discussed.     

QPOs in microquasars and Sgr A.: measuring the black hole spin

In all four microquasars which show double peak kHz QPOs, the ratio of the two frequencies is 3:2. This strongly supports the suggestion that twin peak kHz QPOs are due to a resonance between some modes of accretion disk oscillations. Here, we stress that fits to observations of the hypothetical resonances between vertical and radial epicyclic frequencies (particularly of the parametric resonance) give an accurate estimate of the spin for the three microquasars with known mass. Measurement of double peak QPOs frequencies in the Galaxy centre seems also to be consistent with the 3:2 ratio established by previous observations in microquasars, however the SgrA* data are rather difficult for the same exact analysis. If confirmed, the 3:2 ratio of double peak QPOs in SgrA* would be of a fundamental importance for the black hole accretion theory and the precise measurement could help to solve the question of QPOs nature. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Advances in cloud physics and weather modification in China

The capabilities of cloud-resolving numerical models, observational instruments and cloud seeding have improved greatly over recent years in China. The subject of this review focuses on the main progresses made in China in the areas of cloud modeling, field observations, aerosol–cloud interactions, the effects of urbanization on cloud and precipitation, and weather modification.Well-equipped aircraft and ground-based advanced Doppler and polarized radars have been rapidly applied in cloudseeding operations. The combined use of modern techniques such as the Global Positioning System, remote sensing, and Geographical Information Systems has greatly decreased the blindness and uncertainties in weather-modification activities.Weather-modification models based on state-of-the-art cloud-resolving models are operationally run at the National Weather Modification Centre in China for guiding weather-modification programs.Despite important progress having been made, many critical issues or challenges remain to be solved, or require stronger scientific evidence and support, such as the chain of physical events involved in the effects induced by cloud seeding. Current important progresses in measurements and seeding techniques provide the opportunity and possibility to reduce these deficiencies. Long-term scientific projects aimed at reducing these key uncertainties are extremely urgent and important for weather-modification activities in China.     

2011年湖南一次强暴雨过程中尺度分析

以LAPS局地分析资料为主,综合利用卫星云图、地面自动站资料和NCEP提供的全球分析资料,对2011年6月9—10日湖南一次特大暴雨过程进行了分析,结果表明:降水主要发生在对流云团中亮温TBB-70℃的区域的偏西一侧,在TBB-80℃的区域内降水最强;锋前暖区中的对流云团,在中低层是以条件不稳定机制为主的垂直上升运动,而在中高层,是以条件对称不稳定机制为主的垂直上升运动。中尺度对流系统在不断东移南压的过程中,受高层的辐散性流场的抽吸作用和低层的对流不稳定而发展加强。强气旋性切变和正涡度平流触发中尺度气旋发生、发展,β中尺度涡旋是此次特大暴雨过程的直接影响系统。对整层的高度场和流场进行滤波分析发现,此次暴雨过程中的中尺度气旋活跃,强降水雨团与中尺度低层辐合、高层辐散中心基本重合。利用高(低)层中尺度辐散(合)中心位置确定暴雨中心有一定的预报指导作用。     

南麂列岛岩相潮间带多毛类生态初步研究

为了解南麂列岛国家海洋自然保护区岩礁相潮间带多毛类的生态现状和功能,于2012年5月(春季)、8月(夏季)、11月(秋季)和2013年2月(冬季)在保护区内进行了4次底栖生物调查,对采集的多毛类样品进行鉴定,并依此计算丰度、生物量和相关生物多样性指数。四季共采集到多毛类85种,春季多毛类平均丰度和平均生物量分别为492个/m2和39.50 g/m2,夏季为895个/m2和20.95 g/m2,秋季为639个/m2和16.51 g/m2,冬季为511个/m2和9.04 g/m2。各断面的物种多样性指数为2.950~4.864,均匀度指数为0.922~0.990,种类丰富度指数为2.486~7.087。最后通过分析发现,潮汐、季节变化和人类活动等因素不同程度地影响了多毛类在岩相潮间带的空间分布及群落特征。