Seismic events with non-shear component: II. Rock bursts with implosive source component

The rock burst mechanism of an implosive character is introduced and discussed; it is based on the idea that the compressional component of the stress field around the loaded stress concentrator can participate in the rock burst event. For easier classification of the rock burst from this viewpoint, a set of P-wave radiation patterns of the rock burst with a varying portion of the implosive component and varying propagation velocity of the displacements is presented and discussed. To support the credibility of the rock burst mechanism of an implosive character the seismic signals of the rock bursts from the mid-Bohemian coal district with negative signs of the P-wave first onsets are presented.     

锾法找铀矿的初步试验结果

本文从化探角度出发,讨论了鑀在岩、矿石和土壤中的分市特征及其与铀成矿作用之间的关系。以鑀和铀、镭之间,其衰变成因联系和不同的地球化学性质为基础,对锾法在寻找铀矿中的应用进行了初步探讨。通过在湘西,湘南四种不同类型的20个铀矿床(点)上的大量综合对比,证明了它不仅对铀、镭放射性平衡破坏研究有其独特之处,并且可以推测出成矿过程中的地球化学变化,从而解释铀矿床的成因,评价异常点、带,因此是铀矿普查勘探攻深找盲的一种有效手段。它具有野外工作方法简便、显示直观、影响因素少和便于综合对比等优点。由于氧化还原反应广泛参加了铀矿床的形成和破坏,所以在其它方法(如伽玛、铀量、氡及其子体测量)反映不明显的情况下,鑀法仍有较好的显示。     

地下探杯中氡的积累规律

根据氡的迁移机制(如扩散、对流、大气抽吸等),采用理论计算的方法,得出埋入地下的探杯中的氡浓度与杯口邻近土壤空气中的氡浓度达到自然状态平衡约需0.7—10小时,而杯中氡浓度与其短寿衰变子体达到放射性平衡需4小时。因此,一般认为两者共需4.5—12小时左右。钍射气与其短寿命子体达到放射性平衡的时间需3—4天。当钍含量高出背景值时,探杯的照射时间则需3—4天。用ZnS探杯埋入地下做了野外试验,与上述理论计算结果基本相符。对这种平衡过程的了解,不仅为选取最佳的埋杯时间提供了理论依据,而且也有助于各种测氡方法的异常解释。     

Field measurement of the velocity of overland flow using dye tracing

A new method of computing the mean velocity of overland flow using dye tracing is proposed in which a specified cross-section is divided into zones of relatively uniform flow characteristics, termed partial sections. The mean surface velocity for each partial section is determined by timing the passage of injected dye, and this figure is multiplied by 0.67, 0.70, or 0.80, depending on whether the flow is laminar, transitional, or turbulent, to give mean velocity. The mean velocity for the entire cross-section is calculated by multiplying the mean velocity of each partial section by its cross-sectional area, summing the products for all the partial sections, and dividing by the total area of the cross-section. A field test shows that mean velocity derived in this manner differs from mean velocity derived by the discharge method (i.e. by dividing discharge measured volumetrically by cross-sectional area) by an average of only 7.07 per cent. Thus the partial-section technique appears to provide a reliable method of estimating mean velocity of overland flow.     

Laboratory measurements of the fall velocity of fine sediment in an estuarine environment

The study of the fall velocity variation of fine sediment in estuarine areas plays an important role in determining how various factors affect the flocculation process.Previous experimental studies have focused solely on the relation between the median fall velocity and influencing factors,while in the current study,the variation of the fall velocity in quiescent water also was examined.The experimental results showed that the vertical distribution of sediment concentration was more uneven,and larger variations occurred earlier during the settling process under higher salinity and/or sediment concentration conditions.The fall velocity initially increased then decreased over time,peaking at～20 min after settling began,and stabilizing at a value similar to that in freshwater,regardless of the initial sediment concentration and salinity combinations.Along the water depth,the fall velocity increased monotonically with a gradually decreasing gradient.The median fall velocity increased then decreased with increased salinity.The salinity at which the peak fall velocity occurred depended on the initial sediment concentration.The relation between the median fall velocity and initial sediment concentration displayed an obvious two-stage pattern(i.e.,accelerated flocculation and decelerated,hindered settling) at higher salinities;whereas the maximum median fall velocity was observed at two consecutive sediment concentration values under lower salinity conditions.Finally,an empirical equation estimating the median fall velocity of cohesive fine sediment was formulated,incorporating the effects of both salinity and sediment concentration.     

陕西潼关县桐峪金矿区水文地质特征

简要叙述了小秦岭金矿田桐峪矿区水文地质特征、地下水的主要赋存形式、富集规律，以及补给、迳流、排泄条件等。     

关联时滞大系统分散镇定的算法

利用提出的关联结构分解方法，对具有关联时滞的大型线性定常连续时间系统的稳定与分散镇定问题进行了探讨；给出了相应的理论结果和计算机算法。所做的数值实验验证了算法的有效性和结论的正确性。     

利用第七代IGRF计算1995.0年中国及邻区地磁场

本文介绍了第七代国际地磁参考场，利用ＩＧＲＦ１９９５计划并绘制１９９５．０年中国及邻区地磁图，考虑了地球扁率对计算结果的影响。     

THE SIMULATION OF INTRASEASONAL ANOMALOUSLY ADVANCING AND RETREATING OF WESTERN PACIFICSUBTROPICAL HIGH

Using IAP-AGCM, a model developed by the institute of atmospheric research, Academia Sinica,controlled numerital expertrients on SST and east Asian circulation have been performed and some conclusions have been reached as follows. The abnomality of subtropical high has a two-month remote lagging response to SSTA of the western tropical Pacific, the South China Sea and the Bay of Bengal. Theabnormality always appears in pair for the western Pacific subtrphal high and the eastern Pacific subtropical high, with the latter beginning earlier than the former. When the SST of the western trophal Pacific, South China Sea and Bay of Bengal anomalously decreases(increases), the subtropical high iskept anomalously more to the south(north),consistently so is the location at which two zonal geopotential waves meet in the subtropical western Pacific. Under the action of the SSTA above and when ablocking pattern over east Asia continent appears, the assembling location of the joinin8 waves for thewestern Pacific is closely related to that of the blocking high, which is especially important to consistentabnormality of the subtropical high.