深层岩体松动爆破中不耦合装药效应的探讨

基于冲击波在交界面两侧压力和速度必须各自相等的连续性条件,求解爆轰产物中适用的反射波方程和介质中适用的冲击波方程,得到药包周围介质中冲击波的初始参数.通过波的传播机理,把集中药包应力波随距离的衰减公式扩展到延长药包,并计算耦合与不耦合装药爆破时距爆心相同距离处岩石中冲击波的参数.由计算结果可知:(1)耦合装药爆破时形成的冲击波压力超过岩石抗压强度极限几十倍以上,药包周围岩石形成粉碎区;(2)与耦合装药爆破相比,不耦合装药爆破可以降低孔壁处岩石中冲击波初始压力,但可以增加孔壁后岩石中的冲击波压力.合理的不耦合系数,可使岩石不形成粉碎区,大幅度减少能量耗散;(3)水一般认为是非线性弹性介质,因此水介质成为炸药爆轰产物与岩石间的弹性缓冲层,增加了能量传递,延长了冲击波作用时间,加大了爆炸的作用范围.     

A kinematic hardening constitutive model for sands: the multiaxial formulation

This paper explores the possibility of using well-accepted concepts—Mohr-Coulomb-like strength criterion, critical state, existence of a small strain elastic region, hyperbolic relationship for representing global plastic stress–strain behaviour, dependence of strength on state parameter and flow rules derived from the Cam-Clay Model—to represent the general multiaxial stress–strain behaviour of granular materials over the full range of void ratios and stress level (neglecting grain crushing). The result is a simple model based on bounding surface and kinematic hardening plasticity, which is based on a single set of constitutive parameters, namely two for the elastic behaviour plus eight for the plastic behaviour, which all have a clear and easily understandable physical meaning. In order to assist the convenience of the numerical implementation, the model is defined in a ‘normalized’ stress space in which the stress–strain behaviour does not undergo any strain softening and so certain potential numerical difficulties are avoided. In the first part the multiaxial formulation of the model is described in detail, using appropriate mixed invariants, which rationally combine stress history and stress. The model simulations are compared with some experimental results for tests on granular soils along stress paths lying outside the triaxial plane over a wide range of densities and mean stresses, using constitutive parameters calibrated using triaxial tests. Furthermore, the study is extended to the analysis of the effects induced by the different shapes of the yield and bounding surfaces, revealing the different role played by the size and the curvature of the bounding surface on the simulated behaviour of completely stress- and partly strain-driven tests. Copyright © 1999 John Wiley & Sons, Ltd.     

关于喜马拉雅地带深反射地震剖面数据采集参数的讨论

本文介绍了中美联合在喜马拉雅地区进行深反射地震测量中采用的数据采集参数，并分析其合理性及采集系统的局限性。结果表明，采用的参数大多是合理的，试验是成功的。激发条件是影响记录质量的关键，单井５０ｍ深５０ｋｇ炸药的炮或者单井２５ｍ深双井组合，５０ｋｇ炸药的炮能够获得来自７０—７５ｋｍ深的Ｍｏｈｏ及Ｍｏｈｏ之下的反射震相。５０ｓ长的记录长度对于水平层的勘探深度可达１５０—１８０ｋｍ。观测系统对低频干扰波不能进行有效的压制，但在数据处理时可用滤波的方法消除低频干扰波的影响。     

粒子群优化算法在遥感影像增强中的应用

遥感影像的复杂性给影像增强处理带来了困难。非完全Beta函数增强方法具有理想的增强效果,但是,其参数的合理选取是算法的关键与难点。粒子群优化算法(PSO)是基于鸟群群体智能的新型进化计算技术,具有自适应、自组织等智能特性,具有强大的寻找最优解的能力。这里将PSO用于Beta函数参数的自适应选取,实现了基于PSO的非完全Beta函数增强方法,并通过航空和卫星遥感影像的增强实验,验证了该方法的有效性。     

连续曲率张力样条方法参数选取

连续曲率张力样条方法在最小曲率格网化方程中引入张力参数,可以消除最小曲率拟合曲面在已知数据点之间的区域存在的较大波动和无关变形点,张力参数的取值在区间[0,1)。针对海面高数据,研究了张力参数取不同值的结果,得到了张力参数的最佳取值范围。     

参数约束平差法

将附有参数先验精度信息的平差问题扩展为参数约束平差,给出了参数约束平差法在数值计算上可以统一自由网平差的新概念,不再考虑自由网平差中较为繁琐的基准条件,并用算例加以说明。     

准噶尔和塔里木盆地不同岩性岩电参数研究

准噶尔盆地和塔里木盆地存在着各种不同岩性的岩石,大量的岩电实验证明,不同的岩性岩电参数不同,砂岩以及砂岩中的低阻油藏、砾岩、碳酸岩盐、火山岩其岩电参数有很大的差别;对同一岩性,高温高压下的岩电参数和常温常压下的岩电参数有很大的差异;不同矿化度下的岩电参数不同,岩石的润湿性对岩电参数也有较大的影响.本文给出不同岩性岩电参数实验结果并分析造成这种差异的原因.     

120°E磁赤道上空电离层电子浓度总含量的混沌特性分析及非线性预测初探

本文利用120°E磁赤道上空电离层TEC1996～2004年的观测数据讨论电离层TEC参量的混沌特性,并探讨利用混沌理论对电离层参量进行预报的可能性. 实际计算表明,在指定经纬度的TEC时序数据中存在混沌特性,其关联维数为36092,李雅普诺夫指数为03369. 采用混沌“加权一阶局域法”进行预测较为成功. 对预测误差分析表明,预测点在1～144之间误差相对较小,标准差约为76438 TECU,相关系数约为09172.     

Nearby galaxies. IV. The global Hubble parameter and the dispersion of the Hubble relation

Using a spherically symmetric model of the Virgo flow the global Hubble parameter has been estimated from the observed radial velocities and the photometrically measured distances of nearby galaxies. Adopting the observed recession velocity of the Virgo Cluster to about 1000 km s⁻¹ and the infall velocity of the Local Group to 350 km s⁻¹ the global Hubble constant results to 73 ± 10 km s⁻¹ Mpc⁻¹. This value corresponds with the distance of the Virgo Cluster of 18 ± 2 Mpc. The cosmic dispersion of the galaxies around the Hubble relation is of order of 35 km s⁻¹.     

3D Motion parameters determination based on binocular sequence images

Introduction Amongexistingvisionmoniteringandtheesti mationof3Dmotion,nearlyallinvestigations aremoniteringandtracingthemotionobject basedonsinglesequenceimages.Themotionin formationbyanalyzingthesinglesequenceima gesisrelative,whichincludesascaleoffactor…