华北板块北缘中段含铁变质岩系的时代和构造环境初探

内蒙北部苏尼特右旗以北二道井、哈拉干和红格尔地区的含铁变质岩系中变质基性火山岩Ｓｍ－Ｎｄ全岩等时线年龄为１５１１±７６Ｍａ，这表明该岩系属中元古代而不是以往推测的早古生代，等时线的εＮｄ（ｔ）值为＋６．３±１．７，属亏损型地幔源区岩相学分析表明它形成于规模不大，具中等水深和较弱水动力条件的较封闭海域。据上述特征推测，华北板块北缘中曾存在中元古代初动型火山陆缘。     

微波等离子体炬原子发射光谱法测定铁和铝的研究

研究了低功率微波等离子体炬原子发射光谱法（ＭＰＴ－ＡＥＳ）对Ｆｅ，Ａｌ的测定。样品经气动雾化后，分别以流动注射与连续式两种方式引入ＭＰＴ。考察了用这两种进样方式时ＭＰＴ－ＡＥＳ的分析性能，证明低功率ＭＰＴ－ＡＥＳ具有良好的分析特性。     

大 陆 岩 石 圈 研 究

大陆岩石圈和大洋岩石圈有着深刻的差别，运用板块构造理论和模式研究大陆岩石圈会遇到许多特殊的问题。本文从陆缘演化和多个板块构造旋回叠加两方面做了初步探讨，提出岩浆型被动陆缘是独立的一类古陆缘；在辨认后续板块构造旋回叠加中，新构造成分和格局的确定有重要意义。本文还讨论了汲取大陆地质研究经验，在新的学科水平上重新解释传统大地构造学中一些有用概念的意义。     

被动椭圆形标志物应变分析的计算机模拟

本文采用计算机数学模拟的方法更深入地探讨了椭圆形标志物应变分析技术(R_f/Φ去应变法、Shimamoto等提出的代数法、调和平均值法和算术平均值法)的适用条件。一共形成了十一组有代表性的应变前数组,四种变形路径:纯剪、单剪、纯剪加单剪和体变。当应变前数组在(-90°,90°)内均匀分布或随机分布时,无论变形路径是哪一种(共轴的还是非共轴的),上述的所有方法都是适用有,且以代数法最佳。当应变前数组具有优选方位(单峰分布)且变形路径为共轴递进变形时,在一定条件下,R_f/Φ法能用来估计应变。经分析发现当应变足够大时,调和平均值法是一种简单快速的应变计算法。     

Recent advances in solar radio physics

We review high spatial resolution microwave observations of solar active regions, coronal loops and flares. Observations of preflare active regions are presented; in particular we discuss the interpretations of reversal of polarization at the flare site and the role of newly emerging flux in triggering the onset of flares. We discuss the spatial locations of microwave burst emitting regions; loops or arcades of loops appear to be the sites of flare energy release in microwave bursts. We provide direct observational evidence of magnetic reconnection as the primary cause of acceleration of electrons in microwave bursts.     

土-结构动力相互作用对结构控制的影响

本文研究了土-结构动力相互作用对采取不同控制措施的结构控制效果的影响。文中首先建立了主动调谐质量阻尼器(ATMD)、半主动磁流变阻尼器(MR)和被动多重调谐质量阻尼器(MTMD)等三种结构控制措施在时域中的控制算法和控制律，然后基于子结构法，采用间接边界元方法，通过傅里叶变换，推导了分别安装三种结构控制措施的受控结构在频域中的运动方程，数值仿真分析了某36层高层建筑的地震反应及其控制效果。结果表明，当采用ATMD或MTMD控制时，考虑土-结构动力相互作用后结构地震反应有所减小；当采用MR控制时，考虑土-结构动力相互作用后结构地震反应有很大程度的减小。由此看来，在设计软土地基上高层结构的结构控制措施时，不考虑土-结构动力相互作用对结构控制效果的影响是偏于安全的。     

植被覆盖地表主动微波遥感反演土壤水分算法研究

主动微波遥感监测土壤水分具有全天时、全天候并对地物有一定的穿透能力等特点,突破了传统测量方法和光学遥感获取土壤水分的局限。文中在分析植被对微波信号影响的基础上,总结了当前国内外基于主动微波遥感监测植被覆盖地表土壤水分的原理和方法,指出利用，宋朝景“水-云模型”从总的极化雷达后向散射中去除植被影响后,能够改进后向散射系数和土壤含水量之间的关系。最后利用ENVISAT ASAR数据,结合实地采样获得的土壤含水量数据拟合两者之间的关系,结果表明农作物覆盖地表土壤水分变化的估算算法还需要进一步发展和改进以提高反演精度。     

Exfoliation of kaolinite by urea-intercalation precursor and microwave irradiation assistance process

A type of exfoliated kaolinite was produced by urea-intercalation and original microwave irradiation assisted method. The product was investigated by Fourier transformation infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electronic microscopy (SEM), Brunauer-Emmett-Teller (BET) and laser particle analysis techniques. FT-IR spectra show that NHCO molecule exists in the intercalated kaolinite. XRD analyses indicate that the kaolinite sheet-like structure was disordered after microwave irradiation. The urea decomposition process and explosion effect between the sheet-like structures of kaolinite under microwave irradiation were discussed. The SEM and BET analyses reveal that the end product is exfoliated kaolinite with thin particles and increased surface area. Size and zeta potential analyses show that the particle size distribution is between 250 nm and 550 nm with normal distribution and the particle is negatively charged. In comparison with the conventional grind method, the process adopted appears to be economic and the exfoliated kaolinite end product may display a significantly enhanced performance in industrial applications.     

Long‐term landscape evolution: linking tectonics and surface processes

Research in landscape evolution over millions to tens of millions of years slowed considerably in the mid‐20th century, when Davisian and other approaches to geomorphology were replaced by functional, morphometric and ultimately process‐based approaches. Hack's scheme of dynamic equilibrium in landscape evolution was perhaps the major theoretical contribution to long‐term landscape evolution between the 1950s and about 1990, but it essentially ‘looked back’ to Davis for its springboard to a viewpoint contrary to that of Davis, as did less widely known schemes, such as Crickmay's hypothesis of unequal activity. Since about 1990, the field of long‐term landscape evolution has blossomed again, stimulated by the plate tectonics revolution and its re‐forging of the link between tectonics and topography, and by the development of numerical models that explore the links between tectonic processes and surface processes. This numerical modelling of landscape evolution has been built around formulation of bedrock river processes and slope processes, and has mostly focused on high‐elevation passive continental margins and convergent zones; these models now routinely include flexural and denudational isostasy. Major breakthroughs in analytical and geochronological techniques have been of profound relevance to all of the above. Low‐temperature thermochronology, and in particular apatite fission track analysis and (U–Th)/He analysis in apatite, have enabled rates of rock uplift and denudational exhumation from relatively shallow crustal depths (up to about 4 km) to be determined directly from, in effect, rock hand specimens. In a few situations, (U–Th)/He analysis has been used to determine the antiquity of major, long‐wavelength topography. Cosmogenic isotope analysis has enabled the determination of the ‘ages’ of bedrock and sedimentary surfaces, and/or the rates of denudation of these surfaces. These latter advances represent in some ways a ‘holy grail’ in geomorphology in that they enable determination of ‘dates and rates’ of geomorphological processes directly from rock surfaces. The increasing availability of analytical techniques such as cosmogenic isotope analysis should mean that much larger data sets become possible and lead to more sophisticated analyses, such as probability density functions (PDFs) of cosmogenic ages and even of cosmogenic isotope concentrations (CICs). PDFs of isotope concentrations must be a function of catchment area geomorphology (including tectonics) and it is at least theoretically possible to infer aspects of source area geomorphology and geomorphological processes from PDFs of CICs in sediments (‘detrital CICs’). Thus it may be possible to use PDFs of detrital CICs in basin sediments as a tool to infer aspects of the sediments' source area geomorphology and tectonics, complementing the standard sedimentological textural and compositional approaches to such issues. One of the most stimulating of recent conceptual advances has followed the considerations of the relationships between tectonics, climate and surface processes and especially the recognition of the importance of denudational isostasy in driving rock uplift (i.e. in driving tectonics and crustal processes). Attention has been focused very directly on surface processes and on the ways in which they may ‘drive’ rock uplift and thus even influence sub‐surface crustal conditions, such as pressure and temperature. Consequently, the broader geoscience communities are looking to geomorphologists to provide more detailed information on rates and processes of bedrock channel incision, as well as on catchment responses to such bedrock channel processes. More sophisticated numerical models of processes in bedrock channels and on their flanking hillslopes are required. In current numerical models of long‐term evolution of hillslopes and interfluves, for example, the simple dependency on slope of both the fluvial and hillslope components of these models means that a Davisian‐type of landscape evolution characterized by slope lowering is inevitably ‘confirmed’ by the models. In numerical modelling, the next advances will require better parameterized algorithms for hillslope processes, and more sophisticated formulations of bedrock channel incision processes, incorporating, for example, the effects of sediment shielding of the bed. Such increasing sophistication must be matched by careful assessment and testing of model outputs using pre‐established criteria and tests. Confirmation by these more sophisticated Davisian‐type numerical models of slope lowering under conditions of tectonic stability (no active rock uplift), and of constant slope angle and steady‐state landscape under conditions of ongoing rock uplift, will indicate that the Davis and Hack models are not mutually exclusive. A Hack‐type model (or a variant of it, incorporating slope adjustment to rock strength rather than to regolith strength) will apply to active settings where there is sufficient stream power and/or sediment flux for channels to incise at the rate of rock uplift. Post‐orogenic settings of decreased (or zero) active rock uplift would be characterized by a Davisian scheme of declining slope angles and non‐steady‐state (or transient) landscapes. Such post‐orogenic landscapes deserve much more attention than they have received of late, not least because the intriguing questions they pose about the preservation of ancient landscapes were hinted at in passing in the 1960s and have recently re‐surfaced. As we begin to ask again some of the grand questions that lay at the heart of geomorphology in its earliest days, large‐scale geomorphology is on the threshold of another ‘golden’ era to match that of the first half of the 20th century, when cyclical approaches underpinned virtually all geomorphological work. Copyright © 2007 John Wiley & Sons, Ltd.     

Shaking‐table tests on reinforced concrete frames with different isolation systems

The effectiveness of seismic isolation in protecting structural and non‐structural elements from damage has been assessed in an extensive programme of shaking‐table tests, carried out on four identical 1/3.3‐scale, two‐dimensional, reinforced concrete (R/C) frames. Four different isolation systems were considered, namely: (i) rubber‐based, (ii) steel‐based, (iii) shape memory alloy (SMA)‐based and (iv) hybrid, i.e. based on both SMA and steel components, isolation systems. This paper presents a comprehensive overview of the main results of the experimental tests on base‐isolated models, whose structural response is described through: (i) maximum base displacements; (ii) maximum interstorey drifts; (iii) maximum storey accelerations and (iv) maximum storey shear forces. The evolution of the fundamental frequency of vibration of the R/C frame during the tests is also described. The beneficial effects of using base isolation resulted in no or slight damage, under strong earthquakes, to both structural and non‐structural members, as well as to the internal content of the building. The comparison with the experimental results obtained in shaking‐table tests on similar fixed‐base models emphasizes these positive aspects. Finally, advantages and drawbacks related to the use of each isolation system are discussed in the paper. Copyright © 2006 John Wiley & Sons, Ltd.