基于LMS的自适应数字波束形成的FPGA实现

介绍了一种针对DBF(自适应数字波束形成)的最小均方(LMS)自适应处理方法,并在工程上用 FPGA(现场可编程门阵列)实现算法的验证和调试.该算法比较简单,易于在工程上用硬件来实现.     

Application of Gaussian beam pre-stack depth migration in rugged seabed

Strong fluctuation of seabed, abrupt variation in depth and dip of seabed bring seismic imaging problems, such as irregular reflection waves, obvious multiple waves, serious lateral wave development, poor imaging on base surface and depression structure, low signal-to-noise ratio of middle and deep layers. In this paper, Gaussian beam migration imaging method is used to analyze the imaging effect of rugged seabed in deep water area, and the ray tracing method of wavefront construction method is used to analyze the kinematic characteristics of seismic waves. By improving the design of seismic data acquisition and observation system, imaging quality of fine structures is improved.     

GGR Biennial Critical Review: Analytical Developments Since 2012

Advances in the chemical, crystallographic and isotopic characterisation of geological and environmental materials can often be ascribed to technological improvements in analytical hardware or to innovative approaches to data acquisition and/or its interpretation. This biennial review addresses key laboratory methods that form much of the foundation for analytical geochemistry; again, this contribution is presented as a compendium of laboratory techniques. We highlight advances that have appeared since January 2012 and that are of particular significance for the chemical and isotopic characterisation of geomaterials. Prominent scientists from the selected analytical fields present publications they judge to be particular noteworthy, providing background information about the method and assessing where further opportunities might be anticipated. In addition to the well‐established technologies such as thermal ionisation mass spectrometry and plasma emission spectroscopy, this publication also presents new or rapidly growing methods such as electron backscattered diffraction analysis and atom probe tomography – a very sensitive method providing atomic scale information.     

马钢集团南山矿业公司凹山采场西北帮高危边坡治理施工实例

以马钢集团南山矿业公司凹山采场西北帮高危边坡治理工程为例,介绍了其治理工程的措施,包括锚索、排水孔、挂网喷锚、挡土墙、框架混凝土梁等防护措施及施工技术,并对提高边坡的整体稳定性进行了总结。     

边坡框架梁文克尔简化计算方法及工程应用

为了改进边坡框架梁的计算方法,基于文克尔地基梁假定,考虑框架梁与土体的互相作用,通过关键点拟合的方法,把指数函数和三角函数简化为一元二次函数,推导出边坡框架梁的简化计算公式。该方法被应用于福建一处边坡支护工程,采用锚索框架梁支护,施工过程中对边坡进行位移监测。研究结果表明,传统的文克尔地基梁计算需要求解微分方程,计算过程比较复杂,不适合设计中使用,而简化后的计算方法容易掌握,可以方便计算出框架梁的端部弯矩和跨中弯矩。边坡位移监测结果表明该简化计算方法安全可行。研究结果对边坡框架梁的工程设计有一定的参考作用。      

Cation ordering in NiAl2O4 spinel by a 111 systematic row CBED technique

A focussed probe wide angle systematic row CBED technique has been used to determine the degree of cation inversion, i.e. the magnitude of the cation ordering parameter x, in (Ni_{1− x} Al _x ) [Ni _{x /2}Al_{1− x /2}]₂O₄ spinel to an estimated accuracy of ±0.1. For comparison purposes, the same technique has also been applied to an MgCr₂O₄ spinel (where very little cation inversion is expected). The simplicity of this CBED technique in conjunction with the fact that the experimental data can be obtained from small illuminated areas several tens to 100 nm in diameter, suggests that it may be a very useful technique for estimating the extent of cation inversion in multi-phase mineralogical specimens containing spinels. Received: 19 October 1998 / Revised, accepted: 14 June 1999     

提高深基坑喷锚网支护效果的技术措施

结合工程设计和施工经验及有关资料,讨论了应用超前锚管、边坡补强、加强劲梁等措施来保证喷锚网支护的开挖深度和提高支护效果的技术方法     

地震勘探中相控阵震源的方向特性研究

电磁驱动式可控震源在城市浅层地震勘探中所面临的最突出的困难是微弱的反射信号常常淹没在很强的背景噪声之中.为了提高地震记录的信噪比,可以利用多台可控震源阵列实施相位控制形成定向地震波束以增强地震波的能量.本文讨论这种相控阵震源的波束形成机制.引入了地震波场的边际能量密度的概念,利用地震波场的时间切片技术,对模型空间各个方向上的能量强度进行了定量分析.用有限差分法对相控阵震源Chirp信号扫描的地震响应进行了数值模拟.当定向地震波束的汇聚带与观测排列的空间范围相一致时,相控阵震源合成地震记录的能量强度要显著高于单个可控震源情形的能量强度,波形振幅的均匀性要明显优于常规组合激发震源情形波形振幅的均匀性.     

防撞梁在超高车辆撞击铁路桥梁中的防撞性能研究

作为交通运输工程中不可或缺的一部分,铁路桥梁在生命线及基础设施系统中发挥着重要的作用,一旦被超高车辆撞击,将会造成难以估计的生命及财产损失。提出4个不同配置（横梁、支撑）防撞梁,作为一种缓冲机制安装于桥梁可能发生撞击的主梁底部区域,并通过1:5缩尺模型对防撞梁的防撞性能及工作原理进行研究,并提出基于数值模拟的简化分析方法,实验结果表明:4个防撞梁对于降低桥梁在冲击荷载下的动力响应均有很好效果,能够有效降低桥梁结构在冲击荷载下的动力响应,塑性变形折减至50%,变形能力较好的防撞梁防撞性能更好,此外,基于数值模拟的简化分析方法是有效的。     

基于粘滞阻尼器的元江大桥减震设计方案

为了提高大跨度桥梁的抗震性能水平,基于粘滞阻尼器的结构减震控制技术成为专家学者研究的重点和工程设计人员首先考虑的抗震设防措施。现有成果主要集中在大跨度公路斜拉桥的研究和应用,在山区的非规则高墩钢桁连续梁桥研究的较少。以云南省元江大桥为例,采用Midas/civil建立弹性分析的有限元模型,对元江大桥进行了动力特性分析。采用快速非线性时程分析方法对粘滞阻尼器参数进行了优化分析,并且总结了粘滞阻尼器参数对高墩连续梁桥的减震作用规律。最后,通过有控和无控结构的地震动响应对比分析,评价了安装阻尼器后的结构主控部位的减震效果。结果表明:减震控制提高了结构的安全性。