海底视像图像的灰度不均匀校正方法的研究     

金淑英  包更生  马洪超  申屠海港 《武汉大学学报(信息科学版)》2000,25(6):531-536

点光源照射的亮度不均匀使获得的海底视像图像的灰度分布极不均匀 ,给海底多金属结核矿物的颗粒自动识别、粒径测量、储量的计算带来误差。本文针对点光源照射的多金属结核海底视像图像 ,提出了 3种方法进行灰度不均匀校正 ,并作了比较。实验结果表明 ,统计原图灰度值的二维分布特性 ,用二阶三次多项式函数拟合此灰度分布 ,再逐像元进行灰度位伸的方法能更有效地消除点光源对海底视像图像灰度的影响。  相似文献   

The 1997 Umbria-Marche (Italy) earthquake sequence: Tomographic images obtained from data of the GNDT-SSN temporary network     

A. Michelini  D. Spallarossa  M. Cattaneo  A. Govoni  A. Montanari 《Journal of Seismology》2000,4(4):415-433

We present some preliminary images of the 3-D P-wavevelocity model and of the relocated seismicityobtained from the data collected by the GNDT-SSNtemporary network installed in the epicentral area ofthe earthquake sequence that followed the 26September, 1997, Central Italy main shock(M_w = 6.0). This network consisted of a total of 15stations, was deployed in the southern part of thearea affected by the earthquake sequence and operatedfor a total of 17 days starting on 10/18/97.Our results indicate that 1) the P-velocity structuredisplays a pattern of lateral variations consistentwith the general NW-SE trend of the Apennines in thearea; 2) the aftershock foci distribute, in thesouthern part of the sequence, on distinct and welldefined SW dipping planes which surface intersectionsmatch previously recognized active normal faults; 3)a distinct zone of aftershock quiescence is observedin correspondence of the 10/12 (M_L = 5.3) and10/14/97 (M_L = 5.7) hypocenters near Sellano; 4)the seismicity at the southern end is very shallow andit is unclear the relationship between the 1997 andthe 1979 Norcia sequences.  相似文献   

局限性胸腔积液的X线与CT分析研究     

顾业强  袁令锦 《CT理论与应用研究》2000,9(4):23-25

笔者总结了３２例局限性胸腔积液的Ｘ线与ＣＴ影像学表现,发现其影像学有特异性表现,对于鉴别胸腔积液与良、恶性肿瘤亦起到重要作用。  相似文献   

商人流迁与市场系统的时空组织模式     

石忆邵 《世界地理研究》2000,9(4):52-57

本文分别讨论了流动商在地方性交换系统、区域间贸易系统及流动性零售系统中的作用及其市场系统的时空分布特征,并分析了网上空间市场的崛起对商人流迁影响。  相似文献   

The airflow field and dynamic processes of pyramid dunes   总被引：3，自引：0，他引：3  

Weimin Zhang  Jianjun Qu  Zhibao Dong  Xiaoze Li  Wanfu Wang 《Journal of Arid Environments》2000,45(4):357

Dune sedimentary structure and wind tunnel experimental results show that the pyramid dunes on the cliff top surface of Dunhuang Mogao Grottoes are formed under three wind directions (NE, SW and NW); the deformation and separation variety of chain dune. The local air circulation (SW) is key to the development of the pyramid dunes. Analysing the morphological dynamic processes indicates that inherent relations exist between trihedral pyramid dunes and other complex sand dune types (linear, reticulate and polyhedral pyramid dunes). The wind regime of multidirection, in conjunction with the connected main and subsidiary sand ridges, resulted in the geomorphological forms adapted to the near-surface air streams. It is concluded that integrated studies, including sedimentary structures and wind tunnel experiments, can make more efficient contributions to an overall, systematic and thorough understanding of the developmental processes of the pyramid dunes than previously used single-study methods.  相似文献   

利用上行波进行VSP数据旅行时反演     

朱键  王永昌 《地球科学与环境学报》1999,21(3)

利用双层剥层法同时对层速度和界面形态参数进行反演,并采用最小二乘法迭代求解。为了消除局部极值的影响,减少病态方程的产生,利用了 Ｍｏｎｔｅ Ｃａｒｌｏ 方法调整参数初始值。通过改变参数单位以均衡微分系数矩阵元素等措施,使这种反演方法具有较快的速度和较好的稳定性。对井底以上地层和井底以下地层均适用。  相似文献   

GPS测量技术在假设坐标系中的应用探讨     

胡捍东  臧峰 《测绘与空间地理信息》2009,32(1)

目前,GPS全球定位系统已广泛应用于大地测量、工程测量、航空摄影测量、地形测量及变形观测等各个方面.小范围内的工程测量常采用假设坐标系,本文将以两个勘测项目为例,叙述GPS测量系统在假设坐标系中的应用.  相似文献   

Development of Precise Geoid Model for the Establishment of Consistent Height System in Geoga Grand Bridge Construction Area     

Dong-Ha LEE  Hong-Sic YUN  He HUANG 《中国海洋工程》2009,23(4):679-694

  相似文献   

局地海啸波传播数学模型的研究     

李大鸣  付庆军  林毅 《海洋技术学报》2009,28(1)

推导了地震海啸波传播的理论方程,并时局地地震海啸情况下的理论方程进行了求解.基于Boussinesq方程出发,建立了二维局地海啸渡传播数学模型;对局地海啸进行了数值计算,计算方法采用有限差分方法.差分格式采用交替方向隐格式,即ADI方法.利用该模型对发生在台湾海峡的一次地震海啸进行了模拟计算.将计算结果与理论方程的计算结果以及实际情况进行了对比.计算结果较好.为局地海啸波传播提供了一种模拟方法.  相似文献   

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邓标  洪绍明  宋雷 《大地测量与地球动力学》2009,29(3):125-127

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