减震缓冲器的设计构想

应用隔震原理可以起到减轻地震作用力的效果。在实际应用中将隔震原理转化为隔震技术,需要解决好相应的技术问题。为此,本文在这方面做了一些探索,设计了一种专用装置——减震缓冲器。该装置是通过设置核心部件——弹力钢球,使其与隔震支座配合作用,既较好地起到了化解、缓冲部分地震波的作用,同时也解决了在单独使用隔震支座时可能遇到的问题。     

Research on Energy Radiation Characteristics of an Airgun Source Excited in Land Reservoir

The energy radiation process of an airgun seismic source in land reservoir is studied based on the underwater wavelet data collected in the airgun excitation experiments in Binchuan, Yunnan, China. The empirical formula for calculating the bubble pulsation period and the maximum radius of the underwater airgun seismic source is obtained. The results show that: ① The energy radiation efficiency is higher vertically than horizontally. ② The vertical bubble energy radiation efficiency increases with the increase of the air supply pressure. ③ The vertical energy radiation efficiency of the airgun seismic source is 9.4% when the air supply pressure is 15 MPa. ④ The higher the air supply pressure, the further the propagating distance of the superposition-enhanced pressure wave of an airgun source.     

Condensation Induced by Rarefaction Waves and Reflected Rarefaction Waves

ＣｏｎｄｅｎｓａｔｉｏｎＩｎｄｕｃｅｄｂｙＲａｒｅｆａｃｔｉｏｎＷａｖｅｓａｎｄＲｅｆｌｅｃｔｅｄＲａｒｅｆａｃｔｉｏｎＷａｖｅｓ￥ＦｕＹｕｎｆｅｉ（傅云飞）ＨａｎＺｈａｏｙｕａｎ（韩肇元）ａｎｄＧｏｎｇＭｉｎｗｅｉ（龚闽卫）（Ｄｅｐａｒｔｍｅｎｔｏ...     

等离子体湍动对准垂直激波中粒子加速的影响

本文利用试验粒子方法研究了在考虑等离子体湍动的情况下带电粒子在准垂直激波中的加速, 在计算中, 我们采用组合模型来拟合等离子体湍动. 计算结果表明, 在存在等离子体湍动的情况下, 粒子可横越背景磁场运动, 从而被激波反射的上游粒子在到达下游后可被等离子体湍动散射回到上游, 并再次被激波反射并加速, 这样的过程可重复很多次, 因而粒子可被加速到很高的能量. 我们还研究了激波角, 粒子的初始能量和等离子体湍动的强度, 以及相干长度和两种湍动组分强度比与加速粒子的能谱之间的关系.     

碳中和愿景下煤炭行业发展的危机与应对

含预制裂隙的煤岩,在外载荷作用下具有与完整煤岩不同的力学特性及破坏特征。采用金刚石线切割法对完整煤岩试样进行不同倾角(30°、45°、60°)的三维宏观裂隙预制,通过单轴与三轴压缩试验,结合声发射监测手段,进行裂隙煤岩在不同加载条件下的强度、变形、破坏模式、裂隙扩展规律和声发射特征的研究,探究具有冲击倾向性裂隙煤岩失稳破坏的规律。结果表明：完整煤岩强度、弹性模量与围压具有良好的线性关系,围压从0~16 MPa,强度提升了400%,其破坏模式为剪切破坏,剪切角度呈增大趋势。预制裂隙的存在降低煤岩强度,30°、45°、60°裂隙煤岩强度分别降低了13%、24%、37%,破坏时由裂隙尖端扩展翼型新裂隙,新裂隙沿最大主应力方向扩展与预制裂隙汇合贯通,煤岩发生失稳破坏。裂隙煤岩在围压增大到一定水平时发生“逆围压效应”,即围压越大,强度劣化越明显,当围压达到8 MPa,3种裂隙煤岩强度均降低了200%。完整煤岩在破坏阶段声发射强度达到极值,裂隙煤岩因裂隙扩展发育在各阶段会产生声发射信号激增点,可根据此判断裂隙煤岩的破坏程度及所处应力状态。     

A universal vertical stellar density distribution law for the Galaxy

This article applies nonstandard analysis to derive jump conditions for one-dimensional, diverging, magnetogasdynamic shock waves emerging on the surface of a star. It is assumed that the shock thickness occurs on an infinitesimal interval and the jump functions for the flow parameters occur smoothly across this interval. Predistributions of the Heaviside function and the Dirac delta measure are used to model the flow variables across a shock wave. The equations of motion expressed in nonconservative form are then applied to derive unambiguous relationships between the jump functions for the flow parameters. It is shown here that the equations modeling a family of magnetogasdynamic shock waves yield products of generalized functions that may be analyzed consistently using nonstandard predistributions.     

A self-similar flow behind a shock wave in a gravitating or non-gravitating gas with heat conduction and radiation heat-flux

The propagation of a spherical shock wave in an ideal gas with heat conduction and radiation heat-flux, and with or without self-gravitational effects, is investigated. The initial density of the gas is assumed to obey a power law. The heat conduction is expressed in terms of Fourier’s law and the radiation is considered to be of the diffusion type for an optically thick grey gas model. The thermal conductivity and the absorption coefficient are assumed to vary with temperature and density, and the total energy of the wave to vary with time. Similarity solutions are obtained and the effects of variation of the heat transfer parameters, the variation of initial density and the presence of self-gravitational field are investigated.     

Analytical and graphical determination of the trajectory of a fireball using seismic data

In this paper we discuss two methods, one analytical and the other graphical, to determine the trajectory of a fireball using the arrival times of atmospheric shock waves recorded by a seismic network. In the analytical method the trajectory and the raypaths are assumed to be straight and we solve for the fireball velocity, the azimuth (?) and elevation angle (δ) of the trajectory, the coordinates of the intersection of the trajectory with the earth's surface, and the corresponding intersection time (t₀). Because the problem is nonlinear, we solve it iteratively. The fireball velocity cannot be determined uniquely, and trades off with t₀. The graphical method is based on the drawing of contours of arrival times, which should be elliptical for fireball shock waves. If the distribution of seismic stations is appropriate, the horizontal projection of the fireball is given by the axis of symmetry of the contours, which allows the estimation of ?, while δ can be estimated from the spacing between contours along the symmetry axis. Application of the two methods to data from four fireballs shows that the graphically derived parameters can be within a few degrees of the analytical parameters. In addition, a fireball recorded in the Czech Republic has reliable trajectory parameters derived from video recordings, which allows an independent assessment of the quality of the parameters determined analytically. In particular, ? and δ have errors of and , respectively, which are not particularly large considering that the station distribution was not favorable.     

东南极格罗夫山陨石(GRV 052382):一块强烈冲击变质的橄辉无球粒陨石

GRV052382陨石是在南极格罗夫山地区发现的强烈冲击变质的橄辉无球粒陨石。它主要由橄榄石(75%)、易变辉石(5%)、富碳填隙物(20%)和少量金属组成。橄榄石呈半自形等粒细晶结构,颗粒大小约10~20μm,细晶颗粒间有少量辉石质的熔融填隙物。根据富碳填隙物分布和颗粒间的裂隙,可以区分出原粗粒橄榄石结构的轮廓,原颗粒大小约0.5~1.5mm。这些原粗粒橄榄石具有还原边结构,即边缘的橄榄石细晶富MgO,而核部橄榄石细晶富FeO。因强烈的还原作用,这些原粗粒橄榄石的核部成分变化大(Fa12.2-21.8),因此,原橄榄石核部成分Fa应为21.8%或略高。易变辉石呈浑圆粒状,大小约0.4~0.9mm,在颗粒之间其成分基本相当(En76.4-82.6Wo4.6-9.8Fs10.9-13.8),但在颗粒内部因冲击作用,产生波浪状韵律成分变化。富碳质填隙物充填在原粗粒橄榄石颗粒之间,主要由碳质和富MgO的硅酸盐组成。碳质多型主要为石墨,呈不规则蠕虫状或网脉状,大小约0.2~0.4mm,其中包含有少量金刚石颗粒(约1~3μm)。因此,这些特征表明GRV052382具有橄辉无球粒陨石结构,为单矿岩质橄辉无球粒陨石。根据橄榄石成分,GRV 052382陨石被进一步划分为富FeO亚型(I型)。此外,强烈冲击变质特征,即:(1)橄榄石冲击细晶结构;(2)橄榄石细晶颗粒具有圆化特征,其间存在熔融填隙物;(3)易变辉石晶体具有波浪状韵律成分变化;(4)易变辉石中存在大量不规则气孔;(5)金属Fe沿裂隙或气孔充填;(6)石墨发生金刚石相变等,表明GRV052382陨石的冲击变质程度为S6。因此,GRV052382陨石可能是经受最强烈冲击变质的橄辉无球粒陨石,这不仅为橄辉无球粒陨石的冲击历史提供直接证据,而且有可能获得其母体早期经历的冲击作用信息。     

Non linear shallow water modelling of bore-driven swash: Description of the bottom boundary layer

The paper presents a simple approach to estimate the bottom shear stress in the swash zone by coupling the Non Linear Shallow Water Equations with the momentum integral equation for the bottom boundary layer. The approach allows not only the computation of the frictional dissipation term in the equations but also to have an insight into the flow structure in the water column during a swash event. The numerical results have been compared with a new set of experiments involving a single dam-break generated swash event. Three different grain sizes, ranging from coarse sand to gravel, have been tested in the laboratory.