A numerical model for Type II supernovae — The collapse stage

We use the following numerical model for the collapse stage of a Type II supernova of 15 M_⊙. Our electron capture rate includes the effects of the inverse reaction and the neutron-proton mass difference. This decreases the electron density at the collapse stage and led to rather large values of the maximum inward velocity and of the corresponding mass (Umax = 3.06 × 10⁹cm/s, Mmax=0.76 M_⊙). These larger values are more favourable for the propagation of shock after the rebounce and the triggering-off of a Type-II supernova explosion. For neutrino transport, we use a leakage model and an equilibrium diffusion model, respectively, for the thin and thick stages and a grey atmosphere model to assess the effect of neutrino precipitation on the collapse. We found this effect to be small, the energy precipitation to be not more than 10^?5 the neutrino energy loss and the momentum precipitation not more than 10^?6 the gravitational acceleration.     

On some problems of seismic crustal phase

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Annual amphidromes: a common feature in the ocean?

The scientific term "amphidrome" is usually associated with tides in oceanography. The dozen tidal amphidromes observed in the ocean are critical points that determine the fundamental pattern of the global tidal system. Exploration of recently available satellite data with an unprecedented 1-2 decades duration suggests that an amphidrome is not a tide-only phenomenon in the ocean. Analysis of altimeter-derived sea level anomaly (SLA) data and radiometer-derived sea surface temperature (SST) data allows ten amphidromic points to be clearly identified in annual SLA and SST variations. These amphidromes are located in the tropical areas of the Pacific, Atlantic, and Indian oceans. Their existence implies that the annual cycle (in time) of the atmosphere-ocean system is translated into a rotary variation (in space) for many of the geophysical parameters. It can be concluded that annual amphidromes are common, the knowledge of which is of particular interest, given their annually "constant" nature, for the monitoring and understanding of oceanic, climatic, as well as biological variabilities at seasonal to decadal scales, which strongly affect many aspects of the natural and societal activities on the globe.     

黄海及其沿岸历史地震初步研究

黄海及其边缘，经历史地震资料整理，地震参数估定与编目，截至1949年8月，共有M≥3级地震2187次，其中M≥43/4级地震259次，资料显示大致有三个相对集中活跃区，16世纪曾有过历史地震活动高潮。     

Seismic response predictions of multi‐span steel bridges through pushover analysis

In the new trend of seismic design methodology, the static pushover analysis is recommended for simple or regular structures whilst the time‐history analysis is recommended for complex structures. To this end, the applicable range of the pushover analysis has to be clarified. This study aims at investigating the applicability of pushover analysis to multi‐span continuous bridge systems with thin‐walled steel piers. The focus is concentrated on the response demand predictions in longitudinal or transverse directions. The pushover analysis procedure for such structures is firstly summarized and then parametric studies are carried out on bridges with different types of superstructure‐pier bearing connections. The considered parameters, such as piers' stiffness distribution and pier–0.5ptdeck stiffness ratio, are varied to cover both regular and irregular structures. Finally, the relation of the applicability of pushover analysis to different structural formats is demonstrated and a criterion based on the higher modal contribution is proposed to quantitatively specify the applicable range. Copyright © 2003 John Wiley & Sons, Ltd.     

极化分析研究及其在波场分离中的应用

不同的波在空间的质点运动轨迹和极化方向是不同的，利用三分量或二分量记录，在特定的以ｔ０为中心，长为Ｎ△ｔ的滑动时窗中计算出描述波的质点运动轨迹和极化方向的特征参数。利用这些参数可以设计出合适的极化滤波函数，保留那些满足特定要求的质点运动，而衰减那些不满足设计要求的质点运动，利用某些算子可以把弹性波分解成Ｐ波和ＳＶ波，而且衰减面波；利用另外一些算子可以把Ｐ波和ＳＶ波衰减而使面波增强。这些算子甚至可以在嗓音和信号具有相同频率的情况下，成功地提高信嗓比。     

地质雷达快速检测运营公路隧道隐患

为了评价运行多年隧道的衬砌质量，查找隐患，开展了拱顶的地质雷达无损快速检测。在雷达波形剖面图上分析空洞、不密实异常，推断出大量隐患。物探成果经过开凿验证，证明其隐患定位成功率在85％以上。地质雷达快速检测方法为隧道病害治理提供了可靠的基础资料。     

1961-2005年中国霾日气候特征及变化分析

利用1961-2005 年中国霾日统计资料, 对中国霾的时空气候分布特征、变化趋势进行了详细分析, 并探讨了霾变化的可能原因及其与太阳总辐射、日照时数变化的关系。结果表明: 近45 年来, 中国年和四季霾日的空间分布特征均呈现东多西少的空间分布态势, 东部地区集中在三个多发区, 分别为长江中下游、华北和华南; 季节变化, 除东北地区、青藏高原、西北西部四季霾日均很少且变化不明显外, 其余大部分地区均呈现为冬季多, 夏季少, 春秋 季居中的特点。近45 年, 全国平均年霾日数呈现明显的增加趋势, 2004 年为最高值。我国东部大部地区主要呈现增加趋势, 尤其霾多发地区, 如长江中下游、珠江流域及河南西部等 地, 霾日增加幅度大, 趋势显著, 人类活动造成的大气污染物增加及天气气候变化是这些地区霾日呈现增加趋势的可能原因, 我国西部地区和东北大部地区则以减少趋势为主。华北、长江中下游地区、华南地区霾日变化趋势与日照时数变化趋势相反, 霾的增加是造成太阳总 辐射减少的主要原因之一。东北地区、西北地区、西南地区、青藏高原霾日变化和日照时数变化均呈现不明显的减少趋势, 但由于这些地区霾日发生少, 其变化不会对日照时数和太阳总辐射变化造成很大的影响。     

新疆乌鲁木齐地区震源深度分布与断层关系研究

采用新疆维吾尔自治区地震局精度较高的常规地震目录和双差定位目录,对乌鲁木齐地区震源深度的分布特征及与断层的关系进行了研究。结果表明,乌鲁木齐地区的平均震源深度随震级的增加而加深,并形成3个分布层。震源绝大多数分布在上地壳1～35km深度范围内,优势集中在上地壳16～25km深度范围内。平均震源深度的空间分布特征与断层的展布密切相关,乌鲁木齐市附近的3组断裂所夹持的地块震源深度最浅,深度处于17～21km之间,而在周边一些深大断裂上震源深度较深。不同构造部位的震源深度剖面显示,清水河子断裂、齐古断裂、依连哈比尔尕等断裂的断裂面处于无震蠕滑或闭锁状态,地震主要发生在其下的滑脱层中;而在霍尔果斯、西山、二道沟等断裂上,震源深度从滑脱层延伸到断裂面上,反映出断裂未完全闭锁时的弱运动状态,显示这些断裂为新的活动断裂。震源深度的分布还与乌鲁木齐地区复杂的地壳结构有关,地震多分布在低速体之上或低速体和高速体之间的夹层中