Non-destructive porosity determinations of antarctic marine sediments derived from resistivity measurements with an inductive method

The fractional porosity of marine sediments is one of the fundamental index properties of rocks. For the determination of porosity a nondestructive, inductive method was used on unsplit sediment cores. The results were compared with galvanically measured resistivities using a miniature Wenner array on split cores. The measurements agree well except for cores with high clay content where measurement frequency related effects cause a resistivity difference of about 10%. Porosities were derived from resistivities using a published resistivity-porosity relationship by Boyce (1968) and compared with sample porosities. A comparison of both data sets shows good agreement.     

拖拉机驾驶机器人设计及人机协作方法研究

针对农用拖拉机智能化程度低,以及现有的人工智能水平尚无法完全实现自主驾驶控制拖拉机等问题,本文设计一种基于人机协作的拖拉机驾驶机器人.拖拉机驾驶机器人可以对拖拉机进行快速、无损、智能化升级,其结构由转向控制机械手、换挡机械手、旋耕机升降控制机械手和踏板控制机械腿等组成.通过研究人机协作的控制方法,提出了人机协作介入准则和基于转向电机电流反馈扭矩检测的人机协作模式切换方法,研制了原理样机验证拖拉机驾驶机器人的可行性和人机协作控制策略的有效性,对促进精准农业,提高现代农业智能化装备水平具有重要的现实意义.     

薛家岗遗址出土古玉器的材质特征

通过肉眼和显微镜观察，采用比重法、硬度法、X射线衍射法、红外光谱法、激光拉曼光谱法等无损仪器检测法对122件薛家岗出土玉器进行了玉种鉴定，探讨了玉器的物理性质和结构特征，并提出了出土古玉器的保护问题。分析结果表明，肉眼鉴别风化严重的古玉器，误判几率较大；彻底排除玉器内空气的影响，比重法分析可准确判定严重受沁古玉器的物相组成；古玉器内部与表层在颜色、致密度等存在差异，但主要物相组成相同。     

DYNAMIC RESPONSE OF INTACT PILES TO IMPULSE LOADS

The objective of this work was to evaluate the theoretical capabilities of the non-destructive impact–response method in estimating the length and cross-sectional area of intact piles. Three-dimensional (3-D) axisymmetric finite element models were developed to simulate the testing. The results obtained were compared to one-dimensional solutions to evaluate the importance of 3-D effects. Extensive parametric studies were then performed on piles without defects. In each parametric study, the results from the direct use of time histories of displacements or velocities, the mobility function and the Fourier transform of the recorded displacements (impact-echo method) were compared in order to assess their relative advantages and disadvantages. The effects of the relative stiffness of the surrounding soil to that of the pile and of the embedment depth were also investigated for all three methods. In a companion paper the use of these procedures to detect defects such as bulbs (increases in the cross-sectional area of the pile) or necks (decreases in area) is studied. © 1997 by John Wiley & Sons, Ltd. Int. J. Numer. Anal. Meth. Geomech., vol. 21, 255–275 (1997)     

隧道中的地质雷达技术应用效果

地质雷达勘探技术以其独有高分辨率、高效率、无损检测的特点可满足超前地质预报施工要求，在隧道施工，能够准确预报掌子面前方岩体构造情况和不良地质体，对隧道混凝土衬砌常见的问题如：衬砌和围岩的结合部的缺陷、局部裂缝、衬砌厚度不足、土衬砌与围岩出现的脱空、回填欠实、富水区等进行有效的检测。     

高频雷达在混凝土无损检测中的应用及关键技术

本文阐述了混凝土体无损检测的基本方法技术。将地质雷达方法引入该领域中,结合工程实例研究地质雷达在混凝土非破损检测中的应用效果。并针对实际问题,利用分形技术对雷达资料进行处理,以提取雷达高分辨率信息。     

高密度电阻率法在城市地下目的物探测中的应用

城市地下目的物的无损探测一直是城市建设中的重要课题.从地下管渠、防空洞、地下构筑物等方面的探测实例出发,全面阐述高密度电阻率法在城市地下目的物探测中的应用效果,说明采用高密度电阻率法对城市地下目的物的探测是有明显效果的,其图像特征与实际目的物的形态相近,成果直观且有效.     

地质雷达在湖南邵阳金江水库坝体隐患探测中的应用研究

在金江水库坝体隐患探测中,使用地质雷达发现坝体的主要隐患来自坝体基岩的溶洞和因断裂、裂隙等渗漏通道在残坡积土层中所成的土洞。水库水位浸润线标高和残坡积土与基岩接触界面标高较接近,而使此高程的防渗能力更加薄弱,这也是此坝体的隐患之一。同时,根据地质雷达影像特征可探测灌浆工程的灌浆深度和水泥浆扩散半径,提出它可作为水利部门堤坝灌浆工程质量无损检测的一种新的技术手段。     

非破坏性开放式激光剥蚀电感耦合等离子体质谱法原位测定大尺寸陶瓷样品主微量元素组成

激光剥蚀电感耦合等离子体质谱法(LA-ICP-MS)通常采用体积固定的封闭剥蚀池,大尺寸样品要经过切割或破碎,能够放入剥蚀池后才可以再进行LA-ICP-MS分析,因此,这种常规密闭式LA-ICP-MS难以应用于无法破碎的珍稀大尺寸样品分析.为实现大尺寸样品的非破坏性微区原位主微量元素分析,本文基于自行设计的开放式样品采...     

Spatio-temporal variation in the structure of a deep water Posidonia oceanica meadow assessed using non-destructive techniques

The Malta‐Comino Channel (Maltese islands, central Mediterranean), supports extensive meadows of the seagrass Posidonia oceanica that in some places extend to a depth of around 43 m, which is rare for this seagrass. To assess spatial and temporal variation in the state of the deeper parts of the P. oceanica meadow with time, data on the structural characteristics of the seagrass meadow at its lower bathymetric limit were collected during the summers of 2001, 2003 and 2004 from four stations (two stations within each of two sites) located at a similar depth, over a spatial extent of 500 m. Shoot density was estimated in situ, while data on plant architecture (number of leaves, mean leaf length, and epiphyte load) were successfully obtained using an underwater photographic technique that was specifically designed to avoid destructive sampling of the seagrass. Results indicated that P. oceanica shoot density was lower than that recorded from the same meadow during a study undertaken in 1995; the observed decrease was attributed to the activities of an offshore aquaculture farm that operated during the period 1995–2000 in the vicinity of the meadow. ANOVA indicated significant spatial and temporal variations in meadow structural attributes at both sites during the 3‐year study; for example, shoot density values increased overall with time at site A; a indication of potential recovery of the meadow following cessation of the aquaculture operations. Lower shoot density values recorded from site B (compared with site A) were attributed to higher epiphyte loads on the seagrass, relative to those at site A. The findings, which include new data on the structural characteristics of P. oceanica occurring at depths >40 m, are discussed with reference to the use of the non‐destructive photographic technique to monitor the state of health of deep water seagrass meadows.