地球自由振荡弹性简正模研究进展与展望

在构建现代地球模型时,地球内部分层结构主要是根据地震波资料确定的;而地球内部密度及弹性参数,特别是地幔以下大尺度结构的密度分布,则主要是根据地球自由振荡的弹性简正模观测资料确定的.本文概述了地球自由振荡简正模本征值的求解理论和方法,介绍了球型和环型模态位移场表达式,讨论了地球自由振荡模态的衰减、分裂与耦合效应;总结了多线态分裂谱线探测和分裂参数估计的方法,综述了利用弹性简正模开展地震矩张量、地球三维非均匀性结构和内核超速旋转约束与反演研究的主要进展和存在的问题.最后作为展望,本文还讨论了地球自由振荡简正模的未来研究趋势.     

建筑三维产权体空间关系剖析

城市土地的立体化开发利用促使土地管理模式由平面管理走向更精细的空间管理,当前的建造技术支持了各种形体的建筑建设,为三维产权空间管理提供了现实案例.三维地籍的核心是对产权体的描述与管理,本文从现实的多个三维建筑形体出发,从建筑物的三维产权体与地表形态的关系、与地表的方位关系以及与地表宗地的对应关系3个角度讨论建筑产权体的...     

The effect of density-driven flow on the transport of high-concentration solutes in the hyporheic zone

In this study, both laboratory experiments and numerical simulations were conducted to investigate the effect of density-driven flow on the transport of high-concentration pollutants in the hyporheic zone. The results show that the density gradient can change the flow of pore water and the strong density-driven flow can lead to an unstable flow, which increases the effect of preferential flow and thus causes the appearance of solute fingers in the hyporheic zone. Notably, these solute fingers become more obvious with the increase of depth. The appearance of solute fingers depends on the relative strength of the pumping exchange and density gradient, which are represented by the dimensionless number M* and N* respectively. Finger flows appear near the interface when M^* is less than 0.5 N^*. This study may contribute to better understanding the transport and destination of solutes and thus may provide some insights into the assessment on pollution incidents.     

THE REMOVAL OF Zn,Cd,Pb,AND Cu IN THE CHANGJIANG ESTUARY

The waters with salinity from 10 to 23 comprise the main removal region of ion and particulateforms of heavy metals in the Changjiang estuary.The positive correlationships between Zn,Cd,Pb,Cuand the reciprocal of transparency,COD and chlorophyll-a showed that the removal of heavy metalsclosely correlate with the distribution of suspensions,the adsorption of organic materials and theassimilation by organisms.The removal of heavy metals in the Changjiang estuary water were consistentwith the sedimentation rate of the sediments in these waters,sediment types and the distributions ofheavy metals contents in the sediments.     

Spectral lags and the energy dependence of pulse width in gamma-ray bursts: contributions from the relativistic curvature effect

We compute the temporal profiles of the gamma-ray burst pulse in the four Burst and Transient Source Experiment (BATSE) Large Area Detector (LAD) discriminator energy channels, with the relativistic curvature effect of an expanding fireball being explicitly investigated. Assuming an intrinsic 'Band' shape spectrum and an intrinsic energy-independent emission profile, we show that merely the curvature effect can produce detectable spectral lags if the intrinsic pulse profile has a gradually decaying phase. We examine the spectral lag's dependences on some physical parameters, such as the Lorentz factor Γ, the low-energy spectral index, α, of the intrinsic spectrum, the duration of the intrinsic radiation   t '_d  and the fireball radius R . It is shown that approximately the lag  ∝Γ⁻¹  and  ∝ t '_d  , and a spectrum with a more extruded shape (a larger α) causes a larger lag. We find no dependence of the lag on R . Quantitatively, the lags produced from the curvature effect are marginally close to the observed ones, while larger lags require extreme physical parameter values, e.g.  Γ < 50  , or  α > −0.5  . The curvature effect causes an energy-dependent pulse width distribution but the energy dependence of the pulse width we obtained is much weaker than the observed   W ∝ E ^−0.4  one. This indicates that some intrinsic mechanism(s), other than the curvature effect, dominates the pulse narrowing of gamma-ray bursts.     

湘东某铁帽型金银矿床特征与成因探讨

湘东某铁帽型金银矿床,位于某多金属矿床中部,受一压扭性走向断裂及潜水面控制.主矿体赋存在印支期花岗班岩与下石炭统大塘阶页岩或砾岩的接触面上。矿区处于亚热带潮湿气候的低山丘陵区,氧化带比较发育,矿区中部氧化带深度较大。含金银的硫化矿体经风化剥蚀裸露地表,一些元素淋漓、迁移、流失,另一些元素残余富集,金、银极其稳定,附着在铁矿物的裂隙、空洞、晶隙中,或被吸附在粘土矿物表面,形成金银矿体。     

EVAPOTRANSPIRATION OF LOW-LYING PRAIRIE WETLAND IN MIDDLE REACHES OF HEIHE RIVER IN NORTHWEST CHINA

1 IN T R O D U C T IO NW aterbalance and interactions are foundation to utilizew aterresources rationally in arid inland river basins inC hina (W U etal.,2005).W ateravailability in those ar-eas m ay be the m ain constraint to poverty alleviation,publiche…     

甬江河床演变及航道治理

本文分析甬江动力、泥沙、边界及河床演变的基本特征,提出甬江航道整治的原则和措施。     

GRAIN PRODUCTION AND CLIMATIC VARIATION IN TAIHU LAKE BASIN

Before the end of the Ming Dynasty to the early of the Qing Dynasty, climate was warm, and heat energy was plentiful, so double-cropping of rice in Taihu Lake basin could grow without any protection. Later the global climate entered the Little Ice Age, the double-cropping of rice was extirpated nearly, grain output decreased heavily. After the Little Ice Age, although, the global climate got warm, sometimes, the thermal condition was enough for two crops no three crops one year throughout the period. So both the area and output of of double-cropping of rice was fluctuated with variation of cold/ warm. The condition of heat energy, with the movement of climatic zone, becomes a sensitive factor effecting grain production. Recently, as CO2concentra-tion in atmosphere is increasing, climate is getting warm. With the comprehensive effect of such warming and natural cooling trend, the climate in Taihu Lake basin shows the following trend: warm in winter, cooling in summer, decreasing of annual accumulated tem