利用灰色理论进行图像边缘检测   总被引：8，自引：1，他引：8  

胡鹏  傅仲良  陈楠 《武汉大学学报(信息科学版)》2006,31(5):411-414

提出了一种基于灰色系统理论的边缘检测算法。该算法根据边缘点在像素邻域数列上表现出的与非边缘点的不同特征，分别选择典型非边缘像素的邻域数列和待检测图像所有像素的邻域数列作为参考数列和比较数列，利用斜率关联度计算两者之间的灰关联度，据此区分是否为边缘像素。实验表明，该算法对于椒盐噪声和随机噪声有较好的抗噪能力，提取边缘效果较好。  相似文献   

一次春季罕见的降水天气过程分析     

王晓明  张智勇 《气象》2006,32(5):94-98

对吉林省2005年春季（4月19--22日）罕见的降水天气过程在大尺度环流形势、物理条件分析的基础上，重点对其逐时自动站风场资料进行分析，结果表明利用逐时自动站风场分析的中尺度切变对强降水落区、降水强度和强降水发生的时间都具有很好的指示意义；中尺度切变的形成也与地形条件有关。  相似文献   

Interannual Thermocline Signals and El Nio-La Nia Turnabout in the Tropical Pacific Ocean     

钱维宏  胡豪然 《大气科学进展》2006,(6)

One of the fundamental questions concerning the nature and prediction of the oceanic states in the equatorial eastern Pacific is how the turnabout from a cold water state (La Nina) to a warm water state (El Nino) takes place, and vice versa. Recent studies show that this turnabout is directly linked to the interannual thermocline variations in the tropical Pacific Ocean basin. An index, as an indicator and precursor to describe interannual thermocline variations and the turnabout of oceanic states in our previous paper (Qian and Hu, 2005), is also used in this study. The index, which shows the maximum subsurface temperature anomaly (MSTA), is derived from the monthly 21-year (1980-2000) expendable XBT dataset in the present study. Results show that the MSTA can be used as a precursor for the occurrences of El Nino (or La Nina) events. The subsequent analyses of the MSTA propagations in the tropical Pacific suggest a one-year potential predictability for El Nino and La Nina events by identifying ocean temperature anomalies in the thermocline of the western Pacific Ocean. It also suggests that a closed route cycle with the strongest signal propagation is identified only in the tropical North Pacific Ocean. A positive (or negative) MSTA signal may travel from the western equatorial Pacific to the eastern equatorial Pacific with the strongest signal along the equator. This signal turns northward along the tropical eastern boundary of the basin and then moves westward along the north side of off-equator around 16°N. Finally, the signal returns toward the equator along the western boundary of the basin. The turnabout time from an El Nino event to a La Nina event in the eastern equatorial Pacific depends critically on the speed of the signal traveling along the closed route, and it usually needs about 4 years. This finding may help to predict the occurrence of the El Nino or La Nina event at least one year in advance.  相似文献   

巴楚-伽师6.8级地震地质灾害及未来地震地质灾害     

罗福忠  胡伟华  赵纯青  姜慧  尹力亚尔·阿不力孜 《内陆地震》2006,20(1):33-39

2003年2月24日新疆巴楚—伽师交界地区发生了MS6.8地震。地震的发生除了对建筑物及构筑物与水利、交通、电力、电信设施造成了不同程度的破坏外,在地震烈度Ⅶ度以上(包括Ⅶ度)地区产生了不同程度的地震地质灾害。地震地质灾害主要为场地砂土液化、地裂缝与河流陡岸滑塌等类型。随后在新疆巴楚—伽师6.8级地震灾区开展了地震小区划工作,对Ⅶ、Ⅷ、Ⅸ度区进行了场地工程地质条件勘测与综合评价,判定该地区未来可能产生的主要地震地质灾害为场地砂土液化、河流陡岸滑塌。  相似文献   

温度、湿度对地磁Z基线值的影响及分析     

叶富华  林建  胡俊明  陈运能 《四川地震》2006,(1):14-18

仪器墩体受潮湿影响所产生的局部形变而引起的ZB磁变仪倾斜,是引起成都台CB3ZB变化幅度大,形成N字型年变化及其它类似形态变化的主要原因。实践证明,水泥墩湿引起的形变大,防潮效果差。而质地单纯均匀的石头墩受潮湿后引起的形变小,防潮效果好。  相似文献   

2003年内蒙巴林左旗-阿鲁科尔沁旗5.9级地震及其前兆异常分析     

陈立强  张跃刚  胡新亮  袁国旭  李明威 《华北地震科学》2006,24(1):43-46

2003年8月16日内蒙古巴林左旗—阿鲁科尔沁旗之间发生了Ms5.9级地震,震前该区测震学指标和河北省北部距该地区较近台站的前兆测项中都出现了一些异常。本文对这些异常的特征进行了分析,同时讨论了这些异常和这次地震的关系。这次地震打破了华北、东北地区的5级地震平静,可能预示新一轮地震活跃的开始。  相似文献   

内蒙古地区中强地震序列特征研究     

胡博  徐建德  于红梅 《华北地震科学》2006,24(4):6-11

根据内蒙古地震台网记录报告,对内蒙古地区中强地震(Ms≥5.0)的序列类型进行分析判断,对研究区地震序列类型的地区分布作了总结,并对不同类型序列与地质构造环境的关系作了简单分析,结果对本区今后的中强地震趋势判定有一定帮助。  相似文献   

Fine upper crustal structure of Jiashi strong earthquake swarm region in Xinjiang inferred from high resolution seismic refraction profile data     

徐朝繁张先康  段永红杨卓欣酆少英  胡修奇 《地震学报(英文版)》2006,19(1):62-71

Introduction Jiashi-Artux area in southwest Xinjiang is one of the most active earthquake provinces at pre-sent in Chinese mainland. In the last century, about 3/4 strong earthquakes in Chinese mainland hit this area, and especially from January 21 to April 16 in 1997, 7 earthquakes with the magnituderanging from 6.0 to 6.9 occurred in a very small area of 9 km×18 km near Jiashi (ZHU et al, 1998). It has never taken place before in Chinese mainland that a series of strong earthquakes shoo…  相似文献   

Temporal-spatial variations of euphotic depth of typical lake regions in Lake Taihu and its ecological environmental significance   总被引：5，自引：0，他引：5  

ZHANG Yunlin  QIN Boqiang  HU Weiping  WANG Sumin  CHEN Yuwei  CHEN Weimin 《中国科学D辑(英文版)》2006,49(4):431-442

Euphotic depth can be defined as the portion of wa- ter column that supports the net primary productivity. Its lower end is the critical depth, namely, the depth measured when the daily net primary productivity is zero[1]. In the ecosystems of oceans, lakes and rivers, phytoplankton live in the euphotic depth and euphotic depth is usually taken as the lower boundary, when studying the primary productivity and biomass of phytoplankton; therefore the corresponding depth is sometimes called the t…  相似文献   

Wavelet filter analysis of splitting and coupling of seismic normal modes below 1.5 mHz with superconducting gravimeter records after the December 26, 2004 Sumatra earthquake     

Jacques Hinderer 《中国科学D辑(英文版)》2006,49(12):1259-1269

New generation superconducting gravimeters (SGs), which have been demonstrated to be better than the best seismometers STS-1 at frequencies below 1 mHz, can be accepted as the quietest vertical seismometers for observation of long-period earth free oscillations. Wavelet filtering with narrow band-pass frequency response as shown in this paper is very helpful in removing at- mospheric pressure effects from on gravity records in long-period seismic mode frequency bands. The processing of high quality SG records after the great Sumatra earthquake (Dec. 26, 2004) with wavelet filtering leads to clear observations of all coupled toroidal modes below 1.5 mHz except these for 0T5, 0T7 and 1T1; moreover 1T2 and 1T3 are, for the first time, unambiguously revealed in the vertical components of the free oscillations. The three well-resolved splitting singlets of overtones 2S1 are observed from a single SG record for the first time.  相似文献