网络化数据中心NetDC

IRIS等于1996年提出的网络化数据中心NetDC为用户访问各地震数据中心数据提供了一个统一的入口和界面，给用户访问数据带来极大的便利。NetDC是用C语言编写，建立在各地震数据中心的数据管理系统之上的软件系统，它很好地实现了与各数据中心现有的数据管理系统的集成，使得每个数据中心都能为用户提供更好的数据服务。本文简要介绍了网络化数据中心NetDC的概念、数据请求方法和格式，以及数据请求的处理过程等，并探讨了在我国地震系统的应用前景。     

长距离数据传输抗干扰技术研究进展

研究高温高压高湿环境下,长距离数据传输抗干扰技术,设计有效的数据传输方式,组建稳定高效的传输系统是井下甚宽频带地震仪研制项目的重要环节。长距离数据传输抗干扰技术研究进展主要包括:低功耗、小型化、高分辨率、大动态范围的数据采集核心模块,传输抗干扰技术,数据传输协议及高精度授时等。      

多极子随钻声波测井波场模拟与采集模式分析

应用三维非均匀交错网格有限差分程序模拟了多极子随钻声波测井的波场,考察了硬地层中单极子随钻声波测井响应及软地层中声源频率对多极子随钻声波测井的影响;计算了接收阵列波形的时域相干谱及频散特征,结果表明随钻测井仪器居中时,在硬地层中可以直接利用单极子声系得到地层横波速度,但地层纵波受到钻铤波的极大干扰.而在软地层中可以利用单极子声系直接测得地层纵波速度,但地层横波速度则需要使用工作在较低频率下的四极子随钻声波仪来测得,此时测井频段又会落入钻井噪声频带而受到影响.为此本文提出数值模拟手段结合物理实验的方法得到钻铤波的影响,在实际测井中通过信号处理方法而不是用在仪器本体上刻槽的方式来更完全地消除钻铤的影响.为了避免钻井噪声的影响,本文提出六极子随钻声波仪更适合软地层的横波测量.本文用数值实验结果来说明这些方法的可行性.     

Understanding acquisition and processing error in microseismic data: An example from Pouce Coupe Field,Canada

A challenge in microseismic monitoring is quantification of survey acquisition and processing errors, and how these errors jointly affect estimated locations. Quantifying acquisition and processing errors and uncertainty has multiple benefits, such as more accurate and precise estimation of locations, anisotropy, moment tensor inversion and, potentially, allowing for detection of 4D reservoir changes. Here, we quantify uncertainty due to acquisition, receiver orientation error, and hodogram analysis. Additionally, we illustrate the effects of signal to noise ratio variances upon event detection. We apply processing steps to a downhole microseismic dataset from Pouce Coupe, Alberta, Canada. We use a probabilistic location approach to identify the optimal bottom well location based upon known source locations. Probability density functions are utilized to quantify uncertainty and propagate it through processing, including in source location inversion to describe the three-dimensional event location likelihood. Event locations are calculated and an amplitude stacking approach is used to reduce the error associated with first break picking and the minimization with modelled travel times. Changes in the early processing steps have allowed for understanding of location uncertainty of the mapped microseismic events.     

MIDAS-W: a workstation-based incoherent scatter radar data acquisition system

The Millstone Hill Incoherent Scatter Data Acquisition System (MIDAS) is based on an abstract model of an incoherent scatter radar. This model is implemented in a hierarchical software system, which serves to isolate hardware and low-level software implementation details from higher levels of the system. Inherent in this is the idea that implementation details can easily be changed in response to technological advances. MIDAS is an evolutionary system, and the MIDAS hardware has, in fact, evolved while the basic software model has remained unchanged. From the earliest days of MIDAS, it was realized that some functions implemented in specialized hardware might eventually be implemented by software in a general-purpose computer. MIDAS-W is the realization of this concept. The core component of MIDAS-W is a Sun Microsystems UltraSparc 10 workstation equipped with an Ultrarad 1280 PCI bus analog to digital (A/D) converter board. In the current implementation, a 2.25 MHz intermediate frequency (IF) is bandpass sampled at 1 s intervals and these samples are multicast over a high-speed Ethernet which serves as a raw data bus. A second workstation receives the samples, converts them to filtered, decimated, complex baseband samples and computes the lag-profile matrix of the decimated samples. Overall performance is approximately ten times better than the previous MIDAS system, which utilizes a custom digital filtering module and array processor based correlator. A major advantage of MIDAS-W is its flexibility. A portable, single-workstation data acquisition system can be implemented by moving the software receiver and correlator programs to the workstation with the A/D converter. When the data samples are multicast, additional data processing systems, for example for raw data recording, can be implemented simply by adding another workstation with suitable software to the high-speed network. Testing of new data processing software is also greatly simplified, because a workstation with the new software can be added to the network without impacting the production system. MIDAS-W has been operated in parallel with the existing MIDAS-1 system to verify that incoherent scatter measurements by the two systems agree. MIDAS-W has also been used in a high-bandwidth mode to collect data on the November, 1999, Leonid meteor shower.     

怀来4井数字气汞观测及资料分析

介绍了怀来4井数字气汞观测条件及观测装置,该仪器投入观测已近6年,与模拟水汞观测相比,具有采样丰富、数字传输、保存和资料处理快捷、人为观测误差少的优点,从而使汞的信息量增加,为捕捉地震短临异常提供了有利条件。因此,对该井数字气汞观测资料进行分析和总结,为今后数字气汞在短临预报中发挥积极作用,是十分必要的。     

数字数据网在山东数字遥测地震台网中的应用

DDN是数字数据网(Digital Data Network)缩写,它是利用数字信道传输数字信号的数据传输网。采用光纤(数字微波和卫星)等数字传输通道和数字交叉复用节点组成的数字数据传输网,可以为用户提供各种速率的高质量数字专用电路和其他新业务,已满足用户多媒体通信和组建中高速计算机通信网的需要。主要作用是向用户提供永久性和半永久性连接的数字数据传输通道。DDN的主要特点为：①输速率高：在DDN网内的数字交叉连接复用设备能提供2Mbps或N*64kbps(≤2M)速率的数字传输信道;②传输质量高：数字中继大量采用光纤传输系统用户之间专有固定连接,网络时延小;③协议简单：采用交叉连接技术和时分复用技术,由智能化程度较高的用户端设备来完成协议的转换,本身不受任何规程的约束,是全透明网,面向各类数据用户;④灵活连接方式：可以支持数据、语音、图像、传输等多种业务,它不仅可以和用户终端设备进行连接,也可以和用户网络连接,为用户提供灵活的组网环境;⑤电路可靠性高：采用路由迂回和备用方式,使电路安全可靠;⑥网络运行管理简便：采用网管对网络业务进行调度监控,业务的迅速生成。     

单机地震数据采集系统NCDAS——华北地区遥测地震台网联网论文续一

设计了一套单机地震数据采集软件系统NCDAS.文中描述了该软件的总体结构、各任务块的功能、事件检测算法以及硬件环境.     

三通道无线振动数据采集系统

本文阐述了一种采用无线方式进行数据传输的振动数据采集系统。在测量端使用低频拾振器拾取振动信号,并用模数转换器实现振动参数的模数转换,精度可达19．5mV。数字振动参数以无线的方式发射出去,在接收端应用远程可视化编程系统接收采集数据。系统对振动信号的采集及时准确,无线技术使得信号传输方便;远端可视化控制系统使振动数据采集、过程监控更加直观。     

Seismic on floating ice: data acquisition versus flexural wave noise

Geophysical surveying of the Arctic will become increasingly important in future prospecting and monitoring of the terrestrial and adjacent areas in this hemisphere. Seismic data acquired on floating ice are hampered with extensive noise due to ice vibrations related to highly dispersive ice flexural waves generated by the seismic source. Several experiments have been conducted on floating ice in van Mijenfjorden in Svalbard in the Norwegian Arctic to specifically analyse the extent of flexural waves recorded with various seismic receivers and sources deployed both on top of ice and in the water below. The data show that flexural waves are severely damped at 5 m or deeper below the ice and hydrophone data suffer less from these vibrations compared with data recorded on the ice. Aliasing of single receiver hydrophone data can to some extent be suppressed using an in-line line source of detonating cord. Experiments on ice on shallow water show prominent guided wave modes often referred to as Scholte waves propagating along the seabed. In this case, both flexural and Scholte waves interfere and make a complicated pattern of coherent noise. On shallow water, the positioning and type of the seismic source must be evaluated with respect to the coherent noise generated by these waves. Geophone strings of 25 m effectively suppress both flexural and Scholte waves due to their relative short wavelengths. An airgun generates relative more low-frequency energy than a surface source of detonating cord. Accordingly, seismic mapping of deep seismic horizons seem to be best achieved using geophone strings of such length and an airgun source. For shallow targets, the use of hydrophones in combination with detonating cord is an appropriate solution. Seismic surveying in the Arctic always have to follow environmental restrictions of not disturbing or harming wildlife and not causing permanent footprints into the vulnerable tundra, which implies that the choice of seismic acquisition strategy might occur as a trade-off between optimum data quality and environmental constraints.     

多通道通用地震前兆数据采集器研制

地震前兆数据采集器专一,通用性差,给地震观测和维护带来一定的困难.采用高精度AD开发多通道通用数据采集器.该采集器具有6个采集通道,可灵活配置采样率和信号输入范围,采用网络进行数据传输和远程监控,可以连接大多数地震前兆传感器.     

An introduction to ultrahigh-pressure metamorphism

Abstract Ultrahigh-pressure (UHP) metamorphism refers to mineralogical and structural readjustment of supracrustal protoliths and associated mafic-ultramafic rocks at mantle pressures greater than ∼ 25 kbar (80-90 km). Typical products include metapelite, quartzite, marble, granulite, eclogite, paragneiss and orthogneiss; minor mafic and ultramafic rocks occur as eclogitic-ultramafic layers or blocks of various dimensions within the supracrustal rocks. For appropriate bulk compositions, metamorphism at great depths produces coesite, microdiamond and other characteristic UHP minerals with unusual compositions. Thus far, at least seven coesite-bearing eclogitic terranes and three diamond-bearing UHP regions have been documented. All lie within major continental collision belts in Eurasia, have similar supracrustal protoliths and metamorphic assemblages, occur in long, discontinuous belts that may extend several hundred kilometers or more, and typically are associated with contemporaneous high-P blueschist belts. This paper defines the P-T regimes of UHP metamorphism and describes mineralogical, petrological and tectonic characteristics for a few representative UHP terranes including the western gneiss region of Norway, the Dora Maira massif of the western Alps, the Dabie Mountains and the Su-Lu region of east-central China, and the Kokchetav massif of the former USSR. Prograde P-T paths for coesite-bearing eclogites require abnormally low geothermal gradients (approximately 7°C/km) that can be accomplished only by subduction of cold, oceanic crust-capped lithosphere ± pelagic sediments or an old, cold continent. The preservation of coesite inclusions in garnet, zircon, omphacite, kyanite and epidote, and microdiamond inclusions in garnet and zircon during exhumation of an UHP terrane requires either an extraordinarily fast rate of denudation (up to 10 cm/year) or continuous refrigeration in an extensional regime (retreating subduction zone).     

复杂山区高分辨率地震采集分析与应用—以四川盆地及周缘地区为例

震源药柱激发因素选择是影响地震资料品质的一个重要环节,在南方复杂山区高分辨率地震采集中合理选择激发岩性、井深、药量等激发因素尤为重要.本文根据复杂山区地震地质条件多样性、复杂性等特点,从理论上分析了地震激发机理、井深、药量、虚反射效应、岩性与药柱长度等对激发子波的影响,开展了基于适应近地表结构特征的动态井深设计、双微测井和综合表层结构调查（微测井和高密度电法联合）等,结合四川盆地及周缘等地区不同地震地质条件下进行了采集试验研究,获得了高品质单炮记录.

     

ADAPT区域数字地震台网数据汇集与处理软件包

已经开发了一种区域数字地震台网处理软件包，称作ADAPT(Adaptive Data Acquisition and Processing Tools）。ADAPT软件系统适用于安装在区域遥测数字地震台网中心的Windows NT计算机网络，用于汇集和处理来自台网所属台站的数字地震波形数据，其主要功能包括在线自动处理和人机交互处理两个方面。本文将介绍ADAPT系统的基本功能，分析该系统的特点，并着重说明系统中采用的地震定位方法。     

High spatial resolution data acquisition for the geosciences: kite aerial photography

This paper highlights the requirement for very high resolution (<0·25 m) elevation data for quantitative and qualitative morphometric analyses. Traditional techniques for high resolution data capture (e.g. airborne, heliborne) are prohibitively expensive for small studies and therefore a kite‐based platform was developed, in conjunction with a consumer non‐metric digital camera, for data capture. The combination of kite and digital camera is more generally termed kite aerial photography (KAP). The accuracy of data derived by digital photogrammetry and imagery acquired using a kite based non‐metric camera is assessed by three experiments: one on smooth terrain, one on tor terrain and one on a glaciofluvial esker. Ground control targets were surveyed at all three sites, with the imagery subsequently processed using the Leica Photogrammetry Suite. The results demonstrate that the method can extract a high number of sampling points at high accuracy, provided that there is suitable image texture across the site. However, final judgment concerning the suitability of derived data is dependent upon an understanding of measurement variability and user quantification of acceptable accuracy. Copyright © 2008 John Wiley & Sons, Ltd.     

地震数据采集器中以太网接口的实现

介绍INTEL公司生产的RISCCPU SA1110,提出了使用Cirrus Logic公司生产的单片IEEE802．3网络控制芯片CS8900来拓展地震数据采集器的网络功能,以实现系统的以太网接口。文中详细介绍了SA1110与CS8900的硬件接口设计。     

一种多波宽频地震数据采集设计与仪器实现关键技术

随着多波多分量技术的发展,宽频数据采集逐渐成为地震勘探的发展趋势.通过高保真获取全波场信息,并尽可能保留高频有效成分,进而利用多种波场信息相互验证和补充,是提高地震勘探精度的有效方法.受仪器带宽限制,常规设备在高频段很难同时保持高分辨率和大动态范围特征,在多波地震采集时,极容易出现分辨率不足和限幅失真等现象,极大影响多波多分量方法的实际应用效果.鉴于此,本文给出一种利用积分器、高频ADC、DAC和抽取滤波器构成的低成本宽频数据采集方法.通过构造环路滤波器（调制器）,对高频ADC输出数据中的量化噪声二次整形,并配合抽取滤波,对带外噪声进行有效压制.实际测试表明,通过精细电路结构设计,采集站有效分辨率可达24位（采样率为2 kHz）,动态范围超过140 dB,SNR达142 dB.相比传统设备,其采集数据在5~25 Hz的低频段和100 Hz以上的高频段都具有更加丰富的有效信息,非常适合多波多分量数据采集.

     

分布式多通道电法电磁法数据同步采集系统

采集系统是电磁法仪器的重要组成部分,设计出高精度、低功耗的分布式采集系统是电磁法仪器研制的重点和难点.本文设计的采集系统集成了6个采集通道,每个采集通道的A/D转换器都选用了32位的ADS1282,并通过DAC1282来提供ADS1282校准和自检所需要的外部信号.采集部分的控制中心选用了MachXO2 ZE系列这款功耗极低的CPLD.为了保证同步采集的精度,设计中采用了GPS和OCXO协同授时的方案来提供同步时钟.采集系统具备MT、CSEM、SIP等测量功能.测试结果表明,本采集系统同步精度维持在1E-11以下,待机状态下功耗为0.32 W,运行功耗2.76 W,各通道短路噪声值均在μV级,信噪比在118 dB附近,满足设计要求.