数字滤波在地裂缝和地形变研究中的应用     

任伟中 《岩土力学》1997,18(4):41-47

运用数字滤波理论来区分西安地裂缝、地面垂直地形变活动量中构造活动变形量和释水固结压密变形量。结果表明，地裂缝活动时序中低频长周期成份占绝大部分，而地面垂直地形变活动时序中高频短周期成份占绝对优势。释水固结压密变形量约占总变形量的60％～90％。  相似文献   

一次大型客机起降时积冰的分析     

孙伟中 《干旱气象》1997,(3)

对一次客机积冰用不同方法计算分析，得出如下结论：假霜点温度判别法比－８Ｄ判别法预报飞机积冰更为优越，同一气象条件下降落时大速度客机比小速度客机积冰严重，同一机型降落时比起飞时积冰严重，锋面逆温层底部积冰强度最大。  相似文献   

Water Quality Improvements in Liverpool Docks: The Role of Filter Feeders in Algal and Nutrient Dynamics     

Stephen B.  Wilkinson  Weizhong  Zheng  Janette R.  Allen  Nicola J.  Fielding  Vanessa C.  Wanstall  George  Russell Stephen J.  Hawkins 《Marine Ecology》1996,17(1-3):197-211

Abstract. The redevelopment of disused docks around Liverpool into areas suitable for shops, offices, housing and recreational watersports has necessitated the maintenance of good water quality in these areas. The main source of water to the docks is the River Mersey, which contains high concentrations of nutrients, encouraging algal blooms - including potentially nuisance species - in the enclosed dock basins. Since 1988 an extensive monitoring programme has been run sampling the hydrography, plankton and benthos of the docks. During this period there has been an improvement in water quality, including a reduction in summer phytoplankton biomass and anoxic bottom water. There are strong indications that phytoplankton biomass has been severely reduced by the filter feeding of Mytifus edulis . Changes in the composition of the benthic community since 1988 suggest that the large population of M. edulis is now suffering from limited recruitment. The long-term development and stability of the system is discussed with reference to community succession and its link to ecosystem functioning.  相似文献   

The decomposition rates of dead plant materials of two species of Spartina and the changes in their nutritive components     

Jiang Fuxing  Wang Weizhong  Zhao Ming  Zhong Chongxin 《海洋学报(英文版)》1988,7(1):119-125

-The detritus from the decomposition of dead plant materials of Spartina with great biomass provides abundant food for the heterotrophs in estuarine and nearshore coastal waters. It is for this reason that the decomposition rates of S. anglica and S. alterniflora near the estuary of obsolete Huanghe River were studied. The changes in nutritive components during decomposition are also studied.Results showed that the decomposition rate of dead leaves of S. anglica on ultra-low marsh was about 90% for the first year. In the eighth month, it was 80% and 76 % respectively for S. anglica and S. alterniflora on low marsh. Protein content of the two species of Spartina increased in the course of decomposition, with a maximum increment of 100% or more. The energy value also increased, whereas cellulose content decreased markedly. The percentage content of ash and lipid varied significantly with zonal differences.  相似文献   

毫米波雷达在北仑港区海雾监测中的应用     

胡利军  冯凯  杨豪  傅伟忠 《气象科技》2020,48(2):171-177

2016年底,毫米波雷达在国内首次作为一种海雾监测的技术手段被引入到宁波北仑港区。本文利用2015—2018年北仑港周边多个区域自动站的能见度监测资料,分析区域内海雾分布特点,并对比了2018年两次低能见度天气个例。结果表明:①不同区域海雾差别较大,沿海区域雾日比陆地多,高海拔的较低海拔多;②港区海雾主要出现在3—6月并有逐月增多趋势;③毫米波雷达监测到的海雾个例,回波强度在-20dBz左右,可完整记录雾的空间分布及其生消过程,毫米波雷达能清晰监测到云、雾的分层分布。毫米波雷达在港区海雾监测中具有明显优势。  相似文献   

Scale-free Structure of Town Road Network in Southern Jiangsu Province of China     

SU Weizhong YANG Guishan YAO Shimou YANG Yingbao 《中国地理科学(英文版)》2007,17(4):311-316

From the viewpoint of Graph Theory this paper builds a town road network graph of regional scale, and proposes numerical vertex degree (Di), rank vertex degree (Dr) and population size vertex degree (Dp) on the base of vertex degree (D). Then the indicators of Di, Dr, Dp and mathematical statistics methods are applied to investigating scale-free structure of town road networks in the southern Jiangsu Province. The results show that the distribution of Di does not exhibit scale-free properties, but Dr and Dp do. Additionally the correlation coefficient between Dp and Di is only 0.569, but the spatial correlation between Dp and Dr is very evident on the base of correlation analysis and spatial analysis of GIS. The mutual mechanism between Dp and Dr spatially represents a "Core-Belt" model of town development of regional scale. The town development model is open and clustered, and beneficial to both economic development and ecological protection. And then we suggest that Suzhou City, Wuxi City, Changzhou City and Wujin City control towns' high-density pattern by conducting centralization and consolidation policies, and properly controlling and planning higher rank roads; whereas Nanjing City, Zhenjiang City, Jintan City and Liyang City must strengthen the development of towns along higher rank roads.  相似文献   

回线源TEM山地勘探中的地形影响和校正方法     

邱卫忠 《煤田地质与勘探》2012,40(5):78-81

陕西黄陵、山西王家岭的大回线和山西中条山小发射回线瞬变电磁探测,表现出了不同的地形影响特点。在典型地形影响规律的基础上,通过测道图判断影响的性质;根据电流线聚集与发散机理,对地形影响的不同表现性状给出了解释。研究表明:对于典型的地形影响,可采用通常的比值、滤波等校正方法;非典型的大回线地形影响,将视电阻率-深度剖面上原被空气置换部分挖除是合理的;小回线装置较少受地形影响,可以仅作各测点的高程校正。   相似文献   

Deformities in silver pomfret Pampus argenteus caught from Kuwait waters     

陈卫忠 《中国海洋湖沼学报》2010,28(6):1227-1229

During sampling for spawning stock of the silver pomfret, Pampus argenteus in Kuwait waters, a few seriously deformed individuals were captured. These individuals had been attacked and wounded, but had healed and survived. The fish body deformities are believed to be caused by predation attempts on silver pomfret by predators such as sharks, groupers, and croakers.  相似文献   

长江三峡及邻区构造应力场和震源错动类型的研究   总被引：2，自引：2，他引：0  

高锡铭  王少江  殷志山  王威中  曾新平 《大地测量与地球动力学》1994,(2)

在文献［３］提出的用计算机确定震源断层面解的基础上，进一步给出了解的置信度。置信度由两个因子组成（Ｃ_１，Ｃ_２）。其中Ｃ_１为初动符号的符合比，Ｃ_２为解的不可变动空间与全部空间的比。使用长江三峡及邻区（北纬２８°－３４°，东经１０８°－１１４°）１９７４年以来的初动观测资料，确定了Ｍｓ≥２．１的４０次地震的断层面解、该区的区域应力场和分区应力场及平均错动性质。此外还给出了黄陵背斜地区的应力场特征。结果表明，黄陵背斜的地震构造活动具有整体性，构造过程发生在１５～２０ｋｍ的深度，张应力轴的方向分布显示以背斜为中心的幅射状态。  相似文献   

基于暴雨衰减特性的上海市长历时综合暴雨公式          下载免费PDF全文

贾卫红  徐卫忠  李琼芳  周正模 《水科学进展》2021,32(2):211-217

编制适用于不同历时的综合暴雨公式是协调城市管网排水与区域防洪治涝的重要基础。选用上海市代表雨量站徐家汇站65 a实测雨量资料,建立不同重现期暴雨强度与历时关系,解析暴雨衰减规律,编制单一重现期暴雨公式,结合雨力公式推求适用不同重现期的长历时综合暴雨公式,并推导出暴雨重现期公式。结果表明:不同重现期1~24 h历时暴雨强度均以0.74的衰减指数衰减,据此推求的长历时综合暴雨公式可计算1~24 h任意历时、2~100 a任意重现期的设计暴雨,且平均相对和平均绝对均方根误差分别为1.9%和0.009 mm/min,符合规范要求;暴雨重现期公式可估算1~24 h历时内任意场次暴雨的重现期,高效地服务于城市洪涝防治决策。成果已纳入上海市治涝地方标准,对其他城市具有参考价值。  相似文献