基于CompactRIO的多通道强震动数据采集器FPGA的实现

提出以Compact RIO作为硬件平台,用Lab VIEW FPGA技术实现48通道强震动数据采集器底层数据采集功能。详细阐述了设计要点及从技术上实现了时钟同步、数据采集、标定信号输出、量程设置、状态显示、外触发信号接入等功能。结果表明,数据采集器的噪声、动态范围、幅频响应等主要技术指标满足国内地震行业标准DB/T 10-2001的要求,数据采集器的线性度误差满足DB/T 22-2007的要求。实现的阶段成果能为人们利用NI产品进行强震动数据采集器开发提供重要参考。     

OBC与拖缆数据的子波域匹配滤波方法研究

海底电缆（OBC）采集方式的出现,导致OBC采集与拖缆采集数据进行拼接成为三维连片地震资料处理中的一个重要环节.由于采集方式不同,数据在振幅、频率、相位等方面均存在较大差异.为了消除和减小这些差异,为后续的地质解释和油气预测提供便利,本文提出了一种在子波域的1范数匹配滤波方法来计算匹配滤波因子,以用来提高OBC数据和拖缆数据的匹配精度,改善连片处理的数据品质,为后续的地质解释和油气预测提供便利.通过实际资料检验,子波域匹配滤波方法在OBC与拖缆数据拼接应用中取得了较好的效果.     

Spectral decomposition and de‐noising via time‐frequency and space‐wavenumber reassignment

The reassignment method remaps the energy of each point in a time‐frequency spectrum to a new coordinate that is closer to the actual time‐frequency location. Two applications of the reassignment method are developed in this paper. We first describe time‐frequency reassignment as a tool for spectral decomposition. The reassignment method helps to generate more clear frequency slices of layers and therefore, it facilitates the interpretation of thin layers. The second application is to seismic data de‐noising. Through thresholding in the reassigned domain rather than in the Gabor domain, random noise is more easily attenuated since seismic events are more compactly represented with a relatively larger energy than the noise. A reconstruction process that permits the recovery of seismic data from a reassigned time‐frequency spectrum is developed. Two approaches of the reassignment method are used in this paper, one of which is referred to as the trace by trace time reassignment that is mainly used for seismic spectral decomposition and another that is the spatial reassignment that is mainly used for seismic de‐noising. Synthetic examples and two field data examples are used to test the proposed method. For comparison, the Gabor transform method, inversion‐based method and common deconvolution method are also used in the examples.     

Model‐based attenuation for scattered dispersive waves

Coherent noise in land seismic data primarily consists in source‐generated surface‐wave modes. The component that is traditionally considered most relevant is the so‐called ground roll, consisting in surface‐wave modes propagating directly from sources to receivers. In many geological situations, near?surface heterogeneities and discontinuities, as well as topography irregularities, diffract the surface waves and generate secondary events, which can heavily contaminate records. The diffracted and converted surface waves are often called scattered noise and can be a severe problem particularly in areas with shallow or outcropping hard lithological formations. Conventional noise attenuation techniques are not effective with scattering: they can usually address the tails but not the apices of the scattered events. Large source and receiver arrays can attenuate scattering but only in exchange for a compromise to signal fidelity and resolution. We present a model?based technique for the scattering attenuation, based on the estimation of surface‐wave properties and on the prediction of surface waves with a complex path involving diffractions. The properties are estimated first, to produce surface?consistent volumes of the propagation properties. Then, for all gathers to filter, we integrate the contributions of all possible diffractors, building a scattering model. The estimated scattered wavefield is then subtracted from the data. The method can work in different domains and copes with aliased surface waves. The benefits of the method are demonstrated with synthetic and real data.     

Reconstructing the gravity gradient anomaly field from surveys with wide line spacing using equivalent source processing: an error analysis

When anomalous gravity gradient signals provide a large signal‐to‐noise ratio, airborne and marine surveys can be considered with wide line spacing. In these cases, spatial resolution and sampling requirements become the limiting factors for specifying the line spacing, rather than anomaly detectability. This situation is analysed by generating known signals from a geological model and then sub‐sampling them using a simulated airborne gravity gradient survey with a line spacing much wider than the characteristic anomaly size. The data are processed using an equivalent source inversion, which is used subsequently to predict and grid the field in‐between the survey lines by means of forward calculations. Spatial and spectral error analysis is used to quantify the accuracy and resolution of the processed data and the advantages of acquiring multiple gravity gradient components are demonstrated. With measurements of the full tensor along survey lines spaced at 4 × 4 km, it is shown that the vertical gravity gradient can be reconstructed accurately over a bandwidth of 2 km with spatial root‐mean square errors less than 30%. A real airborne full‐tensor gravity gradient survey is presented to confirm the synthetic analysis in a practical situation.     

文化地理学概念、理论的逻辑关系之分析——以“学科树”分析近年中国大陆文化地理学进展

梳理近年中国大陆文化地理学进展,需要说明近年代表性的研究课题或著述与文化地理学学科体系之间的关系。1990-2005年中国大陆文化地理学主要从五个文化地理学主题开展研究。然而这五个主题之间的逻辑关系不十分清晰,也没有说清主要概念和理论之间的关系。因此本文首先搭建文化地理学的“学科树”。地理学的主要研究对象是“地方和区域”,文化地理学的目标是从文化的角度分析“地方”的形成机制。本文将这个研究目标作为文化地理学“学科树”的主干,此外建立了“层间关系”和“尺度转换”两个分支,它们是探究地方性的两类方法。本文其次将文化地理学涉及的主要概念和理论分别挂在主干和两个分支上,并努力呈现出主要概念和理论出现的先后顺序,揭示文化地理学的发展进程。本文最后用“学科树”,分析了中国大陆主要文化地理学研究者自己提出的代表性著述。分析的结果是：第一,关于地方形成机制的案例类型多样,多是基于结构主义认识论的分析。第二,关于层间关系的研究已经突破了自然与文化两层关系的分析,延展到文化各层之间的关系。第三,在不同尺度文化区转换的领域研究较薄弱。     

Selecting candidate V-type asteroids from the analysis of the Sloan Digital Sky Survey colors

We present a systematic method to identify possible basaltic (V-type) asteroids using the Moving Objects Catalog (MOC) of the SDSS. The method is based on the Principal Components Analysis of the MOC colors combined with some refined criteria of segregation of the taxonomic classes. We found several V-type candidates outside the Vesta family, most of them in the inner asteroid belt. We also identified a few candidates in the middle/outer belt. Notwithstanding, their basaltic nature still needs to be conformed by spectroscopy, and these candidates are potential targets for observation using large telescopes.     

昆明市连续运行GPS参考站系统的研究及建设

本文详细论述现代昆明和数字昆明对GPS参考站系统的需求,介绍了昆明市连续运行GPS参考站系统的设计、选址,叙述了系统的组成和功能、LEICA主副站技术的特点,以及本系统的创新点,最后介绍系统测试及运行的状况,系统为全社会提供信息服务的前景。     

CASS 7.0数据与MapGIS数据之间的格式转换

针对软件各自的数据特点及MapGIS强大的功能,编写CASS与MapGIS对照表进行数据转换是最常用、也是最有效的方法,本文通过编写对照表实现两种数据的转换,从而实现两者的资源共享。     

两种坐标系之间的转化探讨

全国第二次土地调查成果资料要求采用1980西安坐标系,各地原有成果坐标系多为1954年北京坐标系,为使两个坐标系下成果相互转换简便充分,转换参数求解方便,将转换模型推理归纳得出新的参数,为坐标转换程序编写提供便利,同时提高转化精度。