基于分数阶时间导数的黏弹性衰减VTI介质中平面波传播

目前在地震勘探频带范围内通常假设品质因子Q与频率无关,且呈衰减各向同性.事实上,相比较速度各向异性,介质的衰减各向异性同样不可忽视.本文将衰减各向异性和速度各向异性二者与常Q模型相结合,建立了黏弹性衰减VTI介质模型,并基于分数阶时间导数理论,给出了对应的本构关系和波动方程.利用均匀平面波分析和Poynting定理,推导出准压缩波qP、准剪切波qSV和纯剪切波SH的复速度、相速度、能量速度以及品质因子的解析表达式.对模型的正确性进行了数值验证,并分析了qP,qSV和SH波在介质中的传播特性.数值试验结果表明：本模型能够实现理想的恒定Q行为,表现了品质因子和速度的各向异性特征,显示出黏弹性增强将导致能量速度和相速度的频散曲线变化剧烈;速度和衰减各向异性参数与传播角度之间的耦合效应对qP,qSV和SH波的速度和能量影响明显;qP,qSV和SH波的频散曲线和波前面随着衰减各向异性强度的改变发生显著变化,其中耦合在一起的qP和qSV波变化趋势相同,而SH波与它们呈现相反的变化规律.本研究为从常Q模型角度分析地震波在衰减各向异性黏弹性介质中的传播特征奠定了理论基础.

     

一种用于海底类型聚类的新方法

By using sonar imaging, this paper presents a new algorithm for the clustering of seabed types based on the self-organizing feature maps （SOFM） neural network. The theory as well as data processing is studied in detail. Some valuable conclusions and suggestions are given     

A Directed-Line-Segment-Based Photogrammetry Method to Survey the Tunneling Working Surface of Mine Roadway

Absolute orientation is a basic technical work in digital image geologic logging of underground coal mine. Traditional control-point-based absolute orientation method requires setting object space control points of the known three-dimensional coordinates, which may lead to low efficiency. Therefore, this paper proposed a point-free close-range photogrammetry absolute orientation algorithm, which utilized direction line segments including plumb line segments and line segments with known directions and lengths to identify the dimensional orientation of a stereoscopic model. Experiment results show that the precision of the orientation results is favorable. σ _X and σ _Y are as high as 0.5 mm, and σ _Z is 0.3 mm. Finally, this paper introduced the application of the proposed algorithm in rapid geological logging of coal mine roadway, which was fast and reliable, convenient and feasible.     

Real-time envelope cross-correlation detector: application to induced seismicity in the Insheim and Landau deep geothermal reservoirs

We develop and test a real-time envelope cross-correlation detector for use in seismic response plans to mitigate hazard of induced seismicity. The incoming seismological data are cross-correlated in real-time with a set of previously recorded master events. For robustness against small changes in the earthquake source locations or in the focal mechanisms we cross-correlate the envelopes of the seismograms rather than the seismograms themselves. Two sequenced detection conditions are implemented: After passing a single trace cross-correlation condition, a network cross-correlation is calculated taking amplitude ratios between stations into account. Besides detecting the earthquake and assigning it to the respective reservoir, real-time magnitudes are important for seismic response plans. We estimate the magnitudes of induced microseismicity using the relative amplitudes between master event and detected event. The real-time detector is implemented as a SeisComP3 module. We carry out offline and online performance tests using seismic monitoring data of the Insheim and Landau geothermal power plants (Upper Rhine Graben, Germany), also including blasts from a nearby quarry. The comparison of the automatic real-time catalogue with a manually processed catalogue shows, that with the implemented parameters events are always correctly assigned to the respective reservoir (4 km distance between reservoirs) or the quarry (8 km and 10 km distance, respectively, from the reservoirs). The real-time catalogue achieves a magnitude of completeness around 0.0. Four per cent of the events assigned to the Insheim reservoir and zero per cent of the Landau events are misdetections. All wrong detections are local tectonic events, whereas none are caused by seismic noise.     

安宁河及邛海周边地区地脉动特征分析

根据地脉动测试获得的安宁河和邛海周边地区45个场点的地脉动数据,采用谱分析方法对所测得的数据进行处理。结合场地条件对地脉动谱曲线进行分析总结,得到了该区地脉动频谱特性,给出了不同场地条件下的场地地脉动卓越周期建议值,所得结果可以为西昌市防震减灾规划提供场地背景资料和分析依据,也可为西昌市以后的工程场地选址、场地类别划分和结构抗震设计等提供参考。     

黄土高原典型小流域道路特征及影响因素

通过GPS野外实测黄土高原纸坊沟小流域的道路特征,在GIS空间分析等方法支持下研究了流域内各级道路的分布规律。研究表明:黄土高原道路可分为4级,2级以下的土路是小流域的代表路型。各级别道路总长度都随级别增大而增加且累计总长度与道路级别线性相关,道路平均长度和密度则随级别增大而减小。道路网系和流域水系在结构规律上具有一定的相似性。不同级别道路分布范围受地形特征影响不同。爬坡道路坡度与地表坡度之间存在线性回归关系,且次级道路分布受主路控制;典型爬坡路在大于25°坡度范围内多呈"之"字形弯曲,随坡度的减小道路弯曲跨度和与等高线夹角增大。研究结果有助于定量模拟黄土高原地区道路分布特征,并为土壤侵蚀模型中道路影响因子的确定提供参考。     

Allowed Quantity of Explosive Charge Depending on the Distance from the Blast

This paper analyses results of trial, construction and quarry blasting, carried out in sediment rock deposits, mainly limestone and dolomite. Based on results of seismic measurements and engineering geological observations in sedimentary formation, an empirical relationship was established between ground vibration and geological strength index (GSI). The charge weight of explosive that may be detonated per delay for any given distance of nearby structures from the blast is approximately determined by using the concept of the scaled distance (SD) along with the DIN 4150 standard.     

New insights into rare earth element (REE) particulate generated by cigarette lighters: an electron microscopy and materials science investigation of a poorly understood indoor air pollutant and constraints for urban geochemistry

Cigarette smoking is a well-recognized cause of lung cancer and other diseases and is a major contributor to indoor air pollution in numerous settings worldwide. Most cigarette lighters use rare earth element (REE) mischmetal in their flints in order to aid ignition, and these lighters thus have pyrophoric properties. REE particulate emitted from these lighters presents a complexity in the role of health of smokers that has yet to be explored fully. Furthermore, these particles are likely present in numerous urban settings and contribute to the complexities of urban geochemistry. Details of the material properties of rare earth element (REE) particulate derived from smoking lighters are determined first the first time. Particulate was investigated using back-scatter detection scanning electron microscopy techniques and transmission electron microscopy techniques. Several particle types were observed and demonstrate a diverse range of size and textures, many of which are previously not documented and are much smaller than previous basic scanning electron microscopy investigations. These include irregularly shaped fragments of mischmetal, micrometer-scale spherules, aggregates of nanospherules, and platy sponge-like nanoparticles. All of these particles have significant REE content, and most are of a particle size that can be deposited deep in the lung. The available literature regarding toxicity of REEs and the material science data presented here argues very strongly for cause for concern.     

GPS/BDS/GLONASS/Galileo多系统融合在中国区域的仿真分析

通过STK软件对GPS、BDS、GLONASS、Galileo四个系统的星座结构进行仿真,并选择单系统与多系统组合定位的方式对中国区域内的可见卫星数、GDOP值和定位精度进行覆盖分析。结果表明,GPS/BDS/GLONASS/Galileo四系统组合定位在我国的GDOP值可达0.7~0.8,定位精度可达3~4m,优于其他方式的组合定位;同时四系统组合定位下的GDOP值降低,定位精度更好,GDOP值与定位精度的波动异常得到了抑制,导航定位的性能与稳定性也得到了相应的提升。