A realistic model for point-sources imaged on array detectors: The model and initial results     

W. J. Merline  Steve B. Howell 《Experimental Astronomy》1995,6(1-2):163-210

We have constructed a computer model for simulation of point-sources imaged on two-dimensional detectors. An attempt has been made to ensure that the model produces data that mimic real data taken with 2-D detectors. To be realistic, such simulations must include randomly generated noise of the appropriate type from all sources (e.g. source, background, and detector). The model is generic and accepts input values for parameters such as pixel size, read noise, source magnitude, and sky brightness. Point-source profiles are then generated with noise and detector characteristics added via our model. The synthetic data are output as simple integrations (onedimensional), as radial slices (two-dimensional), and as intensity-contour plots (three-dimensional). Each noise source can be turned on or off so that they can be studied separately as well as in combination to yield a realistic view of an image. This paper presents the basic properties of the model and some examples of how it can be used to simulate the effects of changing image position, image scale, signal strength, noise characteristics, and data reduction procedures.Use of the model has allowed us to confirm and quantify three points: 1) The use of traditionalsize apertures for photometry of faint point-sources adds substantial noise to the measurement which can significantly degrade the quality of the observation; 2) The number of pixels used to estimate the background is important and must be considered when estimating errors; and 3) The CCD equation normally used by the astronomical community consistently overestimates the signal-to-noise obtainable by a measurement while a revised equation, discussed here, provides a better estimator.  相似文献   

Aftershocks series monitoring of the September 18, 2004 M = 4.6 earthquake at the western Pyrenees: A case of reservoir-triggered seismicity?     

M. Ruiz  O. Gasp  J. Gallart  J. Díaz  J.A. Pulgar  J. García-Sansegundo  C. Lpez-Fernndez  J.M. Gonzlez-Cortina 《Tectonophysics》2006,424(3-4):223

On September 18, 2004, a 4.6 mbLg earthquake was widely felt in the region around Pamplona, at the western Pyrenees. Preliminary locations reported an epicenter less than 20 km ESE of Pamplona and close to the Itoiz reservoir, which started impounding in January 2004. The area apparently lacks of significant seismic activity in recent times. After the main shock, which was preceded by series of foreshocks reaching magnitudes of 3.3 mbLg, a dense temporal network of 13 seismic stations was deployed there to monitor the aftershocks series and to constrain the hypocentral pattern. Aftershock determinations obtained with a double-difference algorithm define a narrow epicentral zone of less than 10 km², ESE–WNW oriented. The events are mainly concentrated between 3 and 9 km depth. Focal solutions were computed for the main event and 12 aftershocks including the highest secondary one of 3.8 mbLg. They show mainly normal faulting with some strike-slip component and one of the nodal planes oriented NW–SE and dipping to the NE. Cross-correlation techniques applied to detect and associate events with similar waveforms, provided up to 33 families relating the 67% of the 326 relocated aftershocks. Families show event clusters grouped by periods and migrating from NW to SE. Interestingly, the narrow epicentral zone inferred here is located less than 4 km away from the 111-m high Itoiz dam. These hypocentral results, and the correlation observed between fluctuations of the reservoir water level and the seismic activity, favour the explanation of this foreshock–aftershock series as a rapid response case of reservoir-triggered seismicity, burst by the first impoundment of the Itoiz reservoir. The region is folded and affected by shallow dipping thrusts, and the Itoiz reservoir is located on the hangingwall of a low angle southward verging thrust, which might be a case sensible to water level fluctuations. However, continued seismic monitoring in the coming years is mandatory in this area to infer more reliable seismotectonic and hazard assessments.  相似文献   

S-wave velocity structure, mantle xenoliths and the upper mantle beneath the Kaapvaal craton   总被引：1，自引：0，他引：1  

Angela Marie Larson  J. Arthur Snoke  David E. James 《Geophysical Journal International》2006,167(1):171-186

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H/V ratio: a tool for site effects evaluation. Results from 1-D noise simulations   总被引：9，自引：1，他引：9  

Sylvette Bonnefoy-Claudet  Cécile Cornou  Pierre-Yves Bard  Fabrice Cotton  Peter Moczo  Jozef Kristek  Donat Fäh 《Geophysical Journal International》2006,167(2):827-837

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Verification of the motion fields over Southeast Asia by the Florida State University (FSU) superensemble forecast     

Mastura Mahmud  Robert S. Ross 《Singapore journal of tropical geography》2006,27(2):176-190

The Florida State University (FSU) multimodel superensemble forecast is evaluated against several other operational weather models for the Southeast Asia region. The superensemble technique has demonstrated its exceptional skills in forecasting precipitation, motion and mass fields compared to either individual global operational or ensemble mean forecasts. The motion field investigation for the season of 2001 reveals that the superensemble forecasts are closer to the observed data compared to the other global member operational models through its low systematic errors at the 850 hPa level. The FSU multimodel superensemble forecasts exhibit the lowest root mean square errors (RSMEs), the highest correlation against the best observed data and the lowest systematic errors compared to the other operational model members. These forecasts have the potential to provide better daily weather predictions over the Southeast Asia region, particularly during the early northeast monsoon that often causes heavy rainfall in the equatorial part of the Southeast Asia region.  相似文献   

The Dahuiyeh (Zarand) earthquake of 2005 February 22 in central Iran: reactivation of an intramountain reverse fault   总被引：3，自引：0，他引：3  

M. Talebian  J. Biggs  M. Bolourchi  A. Copley  A. Ghassemi  M. Ghorashi  J. Hollingsworth  J. Jackson  E. Nissen  B. Oveisi  B. Parsons  K. Priestley  A. Saiidi 《Geophysical Journal International》2006,164(1):137-148

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The detection of low magnitude seismic events using array-based waveform correlation   总被引：12，自引：0，他引：12  

Steven J. Gibbons  Frode Ringdal 《Geophysical Journal International》2006,165(1):149-166

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探地雷达数据可视化方法     

张志勇  刘艳阳  陈越  刘庆成 《华东地质学院学报》2006,29(4):353-356

采用文件映射降低大数据量探地雷达(GPR)数据显示对计算机内存的需求,同时使GPR数据可以当作一维数组进行数据处理,方便对数据的随机、实时访问;应用直接写位图、视区分割的成图方案,实现对GPR数据的实时显示;通过位图调色板实现GPR数据调色板,灵活应用该技术可使本来需要对原始数据进行大量运算的算法通过调整调色板实现,提高了GPR数据处理的速度。  相似文献   

斯通利波和渗透率的关系分析     

LI Hai-peng KOU Long-jiang QIN Shu-hong College of GeoExploration of Science  Technology  Jilin University  Changchun  China 《吉林大学学报(地球科学版)》2006,(Z2)

理论和实际资料证明,在渗透性地层,低频斯通利波出现的频散和能量衰减与地层渗透率有关,因此可利用斯通利波的传播速度和能量衰减等特性来估算地层渗透率。斯通利波的能量和渗透率负相关。因为斯通利波能量代表了斯通利波的有关信息,因此可以认定斯通利波和渗透率负相关。  相似文献   

中国深空测控网建立方案的研究     

魏二虎  刘经南  黄劲松 《武汉大学学报(信息科学版)》2005,30(7):592-596

概述了深空测控网的基本技术要求,总结了我国卫星测控网和国内现有射电观测设施的技术、组成和分布,分析和论述了将我国现有的测控设施建设成深空测控网的具体方案。  相似文献