Seismic structural control using semi-active tuned mass dampers

This paper focuses on how to determine the instantaneous damping of the semi-active tuned mass damper (SATMD) with continuously variable damping. An off-and-towards-equilibrium (OTE) algorithm is employed to examine the control performance of the structure/SATMD system by considering the damping as an assumptive control action. The damping modification of the SATMD is carried out according to the proposed OTE algorithm, which is formulated based on analysis of the structural movement under external excitations, and the measured responses of the structure at every time instant. As examples two numerical simulations of a five-storey and a ten-storey shear structures with a SATMD on the roof are conducted. The effectiveness on vibration reduction of MDOF systems subjected to seismic excitations is discussed. Analysis results show that the behavior of the structure with a SATMD is significantly improved and the feasibility of applying the OTE algorithm to the structural control design of SATMD is also verified.     

层序地层学研究及隐蔽油气藏预测--以南阳凹陷古近系为例

高精度层序地层学已被证明是寻找隐蔽圈闭行之有效的理论方法．运用该理论对南阳凹陷进行了研究，对地震剖面中反射界面的追踪，在古近系中识别出了各级别的层序界面，结合周缘露头、钻井、测井等资料，分析了主要目的层序内体系域的构成及高频单元变化规律，建立了层序地层模式，在此基础上预测南部陡崖式断坡带和北部缓坡式弯折带是低位域砂体和隐蔽岩性油气藏形成的有利区带．     

油田开发中的相态特征及流体组份研究--以大张坨凝析气藏为例

大张坨凝析气藏是在我国发现的高含量凝析气藏之—．开发中据相态特征及流体组份研究结果，适时调整开发方式．1994年开始试采，1995年初实施循环注气开发．该气藏的开发经历了衰竭试采循环注气2个开采过程，开发过程中定期取地层流体样品进行相态特征和流体组份研究，并注重其成果的应用，凝折油采出率29．0％，取得了较好的开发效果．证实了相态研究在凝析气藏循环注气开发全过程应用的重要性．     

岫岩-海城5.4级地震前小震震源机制解与记录特征分析

采用Pn、Pg初始波初动符号，利用乌尔夫网上半球投影，用作图方法求解了岫岩－海城震区（1999年1月－1999年11月29日）主震前辽宁数字地震台网记录（ML≥2.5)的41个小震的震源机制参数。结合前震记录的某些特征，对主震前应力方向的时空变化，震源错动性质进行分析和讨论。     

Petrogenesis of the Ulsan carbonate rocks from the south-eastern Kyongsang Basin, South Korea

Abstract The petrogenesis of the Ulsan carbonate rocks in the Mesozoic Kyongsang Basin of South Korea, which have previously been interpreted as limestone of Paleozoic age, is reconsidered in the present study. Within the Kyongsang Basin, a small volume of carbonate rocks, containing a magnetite deposit and spatially associated ultramafic rocks, is surrounded by sedimentary, volcanic and granitic rocks of the Mesozoic age. The simple cross‐cutting relationships and other outcrop features of the area indicate that the carbonate rocks are an intrusive phase and younger than the other surrounding Mesozoic rocks. The Ulsan carbonates have low concentrations of rare earth elements (REE) and trace elements with the carbon and oxygen isotope values in the range of δ¹³C_PDB = 2.4 to 4.0‰ and δ¹⁸O_SMOW = 17.0 to 19.5‰. Outcrop evidence and geochemical signatures indicate that the Ulsan carbonates were formed from crustal carbonate melts, which were generated by the melting/fluxing of crustal carbonate materials, caused by the emplacement‐related processes of alkaline A‐type granitic rocks. Compared to typical mantle‐derived carbonatites associated with silica‐undersaturated, strongly peralkaline systems, the relatively small size and geochemical characteristics of the Ulsan carbonates reflect carbonatite genesis in a silica‐saturated, weakly alkali intrusive system. Major deep‐seated tectonic fractures formed by the collapse of the cauldron or the rift system associated with the opening of the East Sea (Japan Sea) might have facilitated the ascent of the crustal carbonate melts.     

Flat mantle reflectors in Eastern China: possible evidence of lithospheric thinning

Recent 24 s deep seismic reflection records revealed five flat reflectors in the lithospheric mantle in Eastern China. With increasing depth, they are named M1 to M5 and can be seen on both field single-shot and stacked records. Reflector M1 corresponds to the Moho discontinuity, whereas M5 may be the reflection from the bottom of the current lithosphere, which is about 78 km deep according to geothermal measurements. The other three reflectors seem peculiar and might result from interactions between the lithosphere and deeper mantle. Based on lithological and geochemical data, it is suggested that the lithosphere has been thinned from about 150 km to about 60 km in the Late Mesozoic, and then has been thickened to about 78 km during the Cenozoic. The thinning process produced a granulite layer in the old lower crust caused by magmatic underplating, whereas an eclogite layer formed beneath owing to the subduction of the Paleo-Tethys and Yangtze Craton during the Permian and Early Mesozoic. Reflector M2 at about 12 s two-way traveltime (TWT) might result from the Paleozoic Moho, which represents the boundary between the previous granulite and eclogite facies. Reflector M3 at about 14 s might correspond to the bottom of the eclogite layer, beneath which the old lithospheric mantle remained. The old and the newly developed mantle may have different compositions, resulting in reflector M4. The multi-layered mantle reflectors demonstrate a mantle structure that possibly correlates with the lithospheric thinning process that occurred in Eastern China during the Late Mesozoic. The discovery of multi-layered mantle reflectors in the studied areas indicates a high heterogeneity of the upper mantle. Reflection seismology with improved technology, together with velocity and resistivity imaging and rock-physics measurements, can provide more details of the heterogeneity and related dynamic processes that occurred in the lithospheric mantle.     

前驱地震波的试验研究及波谱分析

研究了含预置裂纹的有机玻璃试样在加载实验过程中，大破裂之前出现的长周期、小振幅低频事件，并与大地震前可能出现的同类现象（即前驱地震波）进行了对比研究，根据波形记录和频谱分析得出：前驱地震波是地壳介质的长周期波动，是一种客观存在的前兆特征，具有短临前兆意义。     

兰州地区深部电性结构的初步研究

利用兰州地区现有的大地电磁资料，对该区的深部电性结构进行了初步研究。结果表明，兰州地区各地质构造单元的电性差异较明显，与区域构造有较好的对应性。     

Determination of Roughness Lengths for Heat and Momentum Over Boreal Forests

The roughness length for momentum (z_0m), zero-plane displacementheight (d), and roughness length for heat (z_0h) are importantparameters used to estimate land-atmosphere energy exchange. Although many different approaches have been developed to parameterizemomentum and heat transfer, existing parameterizations generally utilizehighly simplified representations of vegetation structure. Further, a mismatch exists between the treatments used for momentum and heat exchange and those used for radiative energy exchanges. In this paper, parameterizations are developed to estimate z_0m, d, and z_0h for forested regimes using information related to tree crown density and structure. The parameterizations provide realistic representationfor the vertical distribution of foliage within canopies, and include explicit treatment for the effects of the canopy roughness sublayer and leaf drag on momentum exchange. The proposed parameterizationsare able to realistically account for site-to-site differences in roughness lengths that arise from canopy structural properties.Comparisons between model predictions and field measurements show good agreement, suggesting that the proposed parameterizations capture the most important factors influencing turbulent exchange of momentumand heat over forests.     

规整化标定在地震遥测系统中的应用

规整化标定是模拟观测地震仪器标定的一种方法。系统介绍了规整化标定仪器的方法、参数，发现它有许多优点，是标定遥测地震仪器的一种较理想的方法。