干耦合超声波检测及波初至的自动拾取

目前岩石力学参数测定，受限于探头及数据采集设备，多在实验室环境完成，同时，传统超声收发探头对接触面平整度要求较高，需要对岩石表面打磨处理，且需要涂抹导声糊。这些都极大限制了超声测量系统的应用范围。为实现对岩石钻孔内的长效监测，对声波发射、接收机制及岩石内超声信号的频域特性进行分析，通过AIC算法拾取波前初至，利用小波去噪和改进AIC法（NAIC）求波初至到达精确时间，研究了基于干耦合岩石内部参数测量系统，在岩石内部实现了超声信号的发射接收、信号瞬态触发、高速采集，并将最终结果通过无线方式传输至数据记录仪。分别对Φ50 mm×100 mm花岗岩及砂岩岩样进行了超声波传输参数测量，Φ114 mm×280 mm花岗岩岩样测量距离分别为150、200 mm，利用NAIC、STA/LTA、MER、ETA 4种算法对该数据进行处理，并与第三方仪器测定结果进行比较。结果表明：基于干耦合声波测速采集系统，对不同工作接触面适应性较好，数据误差在规范允许范围内。小波降噪适用于背景干扰少、频率范围集中的超声接收信号，在到时拾取方面，除STA/LTA外其余3种算法在去噪后的到时拾取精度均得到有效提高，其中尤以NAIC法最为明显，到时平均误差由1.21 ?s锐减至0.19 ?s。     

Smaller source earthquakes and improved measuring techniques allow the largest earthquakes in Iceland to be stress forecast (with hindsight)

A group of three earthquakes in 2000 June in SW Iceland included the two largest earthquakes in Iceland in the past 30 yr. Previously, temporal changes in shear-wave splitting had not been recognized before these earthquakes as there were too few small earthquakes to provide adequate shear-wave data, and they were not stress forecast, even with hindsight. These large earthquakes were subject to a special investigation by the European Community funded PREPARED Project during which the seismic catalogue was extended to include smaller magnitude earthquakes. This more detailed data set, together with a semi-automatic programme for measuring the parameters of shear-wave splitting greatly increased the number of time-delay measurements.
The new measurements displayed the typical temporal variations before larger earthquakes as seen elsewhere: a long-term increase in time delays, interpreted as stress accumulation before the earthquake; and a decrease, interpreted as crack coalescence, immediately prior to the earthquake. The logarithms of the durations of both the implied accumulation of stress and the crack coalescence have the same self-similar relationships to earthquake magnitude as found elsewhere in Iceland. This means that, in principle, the time and magnitude of the larger earthquakes could have been stress forecast in real time had the smaller source earthquakes of the extended catalogue and the improved measuring procedures been available at the time.     

改进型焦利氏秤与传统实验对比研究

针对高校教材《普通物理实验》中液体表面张力系数的测定实验存在的一些问题,进行了认真分析,指出传统实验前后所测量的一些物理量不是等精度测量,因而有必要对实验原理和公式进行修正。改进型焦利氏秤,在载物台下装有测量机构,实验测量方法有所改变,实验思路更加明确,并经实验比对,使用改进型焦利氏秤做此实验,不仅操作和计算简便,而且所得结果更接近公论值,取得了良好的效果。     

用改进的佐迪反演方法进行二维电阻率图像重建

针对佐迪反演方法在二维拟断面应用中的缺陷进行了三个方面的改进：固定佐迪反演方法中用于转换电极距和深度关系的深度转换因子,可使绝大多数数字模型的反演过程稳定收敛;在调整视电阻率的公式中加入一个迭代系数,可使计算值快速趋向于观测值,减少了迭代次数;对于含有噪声的数据,加入滤波因子可以在一定程度上抑制噪声。通过数字模拟和野外实测数据对改进后的佐迪反演方法在二维电阻率反演应用中的可行性进行了验证。模拟研究包含了简单模型,也包含一些复合模型,二者均取得较理想的应用效果。     

Formation Mechanism and Stability Assessment of the Colluvial Deposit Slope in Zuoyituo

The basic features of the colluvial deposit slope in Zuoyituo such as geological conditions, dimensions, slip surfaces and groundwater conditions are described concisely in this paper. The formation mechanism of the slope is discussed. It is considered that the formation of the colluvial deposit slope in Zuoyituo has undergone accumulation, slip, load, deformation and failure. The effects of rainfall on slope stability are categorized systematically based on existing methodology, and ways to determine the effects quantitatively are presented. The remained slip force method is improved by the addition of quantitative relations to the existing formulae and programs. The parameters of the colluvial deposit slope are determined through experimentation and the method of back-analysis. The safety factors of the slope are calculated with the improved remained slip force method and the Sarma method. The results show that rainfall and water level in the Yangtze River have a significant effect on the stability of the colluvial deposit slope in Zuoyituo. The hazards caused by the instability of the slope are assessed, and prevention methods are put forward.     

异常评序方法的改进及其应用效果

从元素组合及其含义出发,来确定异常的分类和异常评序中各元素参与计算的方法。其优点是综合考虑到矿化遭剥蚀的程度,使得异常排序更合理。     

轨道交通中线测设统一数学模型的建立

根据对常用的两种中线测设数学模型的分析，从线路中线曲率半径的特点出发，提出了中线整体积分数学模型，并导出其计算公式。为了实现整体积分模型的计算，对龙贝格积分算法进行了改进，并用于武汉市轨道交通一号线一期工程的中线测设。比较和分析表明，从实用性和精度等方面来说，整体积分模型是目前轨道交通最优的中线测设模型。     

一种改进的InSAR城市地面沉降监测精度评价方法

针对InSAR沉降监测精度评定方法的单一性,综合考虑建筑物自身沉降和时空基准难以统一的问题,构建了改进的反距离权重插值模型。以宁波东部新城某沉降区域的PS-InSAR监测结果为试验数据,在统一时空基准的前提下,利用改进IDW插值模型对监测结果进行精度评定,并以交叉验证的方式验证了该插值方法的准确性。试验证明：通过对比两个实测水准点,使用改进的IDW插值获取的InSAR监测结果误差为0.3和0.8,相比于普通IDW和Kriging方法提高了大约1.1 mm。     

改进的自适应遗传算法支持下点云与BIM模型配准

在钢结构数字化检测中,点云与设计模型的配准是进行数字化检测的关键步骤,配准的精确度决定了检测分析的准确度。传统配准方法一般先进行粗配准再进行精确配准,计算量大且收敛速度缓慢。针对精确配准存在的问题,本文提出了基于改进的自适应遗传算法用于点云与设计模型的配准方法,自适应地调整交叉概率与变异概率的执行顺序及概率值的大小,提高了种群的多样性及收敛速度。试验证明,改进后的自适应遗传算法极大地提高了点云与模型配准精度和收敛速度。     

基于改进内梅罗指数的东海中鹿岛生态养殖区水质评价

为明确东海中鹿岛生态养殖区水质现状,于2017年6月对该海区开展了水质调查,结果表明,中鹿岛海区NH_4~+-N含量、NO_2~--N和NO_3~--N含量的总和、PO_4~(3-)-P含量、pH、盐度和温度的最大值分别为0. 395±0. 011、0. 016±0. 001、0. 029±0. 000 mg/dm~3、8. 21±0. 00、32. 53±0. 05、25. 07±0. 16℃。选取改进内梅罗指数对中鹿岛海区水质进行评价,结果表明,该海区整体水质较为清洁,海区内侧水质水平分布差异显著(p 0. 05),存在明显的分块,其原因可能是由水产养殖活动分布格局引起;对改进内梅罗指数进行水层间方差分析的置换检验表明,改进内梅罗指数在水层间差异不显著(p 0. 05),间接说明海区水体垂向交换能力较强,有利于底部营养物质的交换,对于天然饵料的生长较为有利。