平稳过滤白噪声激励下海洋桩基平台响应分析   总被引：1，自引：0，他引：1  

吴智平  罗传信 《海洋工程》1995,(4)

本文研究了平稳过滤白噪声激励下海洋桩基平台响应分析方法，该方法将强地面运动视为三向平稳过滤白噪声随机过程，应用留数定理推导出积分平台响应的表达式。对一水深为１１４．３ｍ的海洋桩基平台进行了平稳过滤白噪声激励下响应的计算，其成果与平稳白噪声激励下的响应和响应谱法计算结果进行了对比，并得出了相应的结论。  相似文献   

The oil spill behaviour model of the canadian atmospheric environment service. Part II: Evaluation of model guidance for emergency response     

S. Venkatesh  V.R. Neralla  W. Hume  N. Parker  B. Thomson 《大气与海洋》2013,51(1):109-117

Abstract

In a companion paper the theoretical basis for the Canadian Atmospheric Environment Service oil spill behaviour model was discussed along with its evaluation, in non‐real time, using data collected from field experiments and a real spill. This paper deals with the use of the model in real time to provide guidance in support of the emergency created by an oil spill in the Canadian Beaufort Sea. The spill of about 2440 barrels of diesel oil occurred in September 1985, the result of storm damage to an artificial island used for hydrocarbon exploration.

Model simulations were carried out for two time periods while the spill was being tracked. These simulations identified the marked shifts in the direction of movement of the spill. While the predictive skills for the two time periods varied, with re‐initialization the final observed slick location was predicted to within 2 km. This model prediction was used by the regulatory authorities as guidance information in locating the slick when it could not be easily spotted from the air. The prediction of the size of the slick 27 h after initial time was in very good agreement with observations. A qualitative evaluation of the model‐simulated weathering of the oil was also carried out.  相似文献   

Test of three methods to detect the overbank flow from water level time‐series analysis     

O. Navratil  M. B. Albert  P. Breil 《水文研究》2010,24(17):2452-2464

In this study, we propose to identify morphological and hydraulic characteristics related to overbank flows in the water level time‐series available at many gauged stations. The results obtained at 13 river stations (the catchment sizes vary from 10 to 1700 km² with contrasted geology, land use and rainfalls regime) show that overflow mechanisms at the river‐reach scale can be systematically identified in the water level frequency distribution estimated with the peaks‐over‐threshold (POT) method. A first level (Lts1) was in the range of the incipient flooding onto the floodplain. Even if the definition of this level is variable in terms of flooded area at the reach scale, this method can be useful in providing a first estimation of the bankfull level for many gauged stations, without complex and costly field surveys. A second level (Lts2) was systematically detected on average 38 cm above the topographic flat floodplain elevation. The Lts2 inflection in the water‐level frequency distribution is assumed to reflect a composite effect of catchment hydrology and local hydraulics and channel geometry, without possibility to make a clear distinction between both processes at the moment. The local or reach scale effect would probably play an essential role in the frequency distribution as flood attenuation at catchment scale may explain the inflection Lts2 at only three sites. In light of the knowledge acquired in laboratory flumes with compound channels, most of the time Lts2 level would correspond to the level of resumption of flow both in the main channel and the floodplain. Once this method is validated in various physiographic contexts, it should apply to many hydrometric stations for both synchronic (e.g. regional analysis) and diachronic analysis (e.g. evolution over time of the bankfull discharge) to evaluate anthropic impacts on river morphology. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

山东枣庄熊耳山崮形地貌成因及地质景观保护     

安仰生  张旭  陈希武  甘延景  赵艳杰  王言雨 《山东国土资源》2007,(Z1)

山东枣庄熊耳山国家地质公园内,具双龙大裂谷、抱犊崮国家级森林公园、崮形地貌、崩塌地质遗迹、龙床水库等自然地质景观;地质地貌景观具重要的地学研究与观赏价值,挖掘地质景观资源,应遵循在保护中开发、在开发中保护的原则,此是公园管理部门一项长期的任务。  相似文献   

Diversity, Distribution and Prioritization of Fodder Species for Conservation in Kullu District, Northwestern Himalaya, India     

S. S. Samant Man Singh Manohar Lal Shreekar Pant 《山地科学学报》2007,4(3):259-274

In the Indian Himalayan Region predominantly rural in character, livestock is one of the main sources of livelihood and integral part of the economy. Livestock mostly rely on fodder from wild. The diversity, distribution, utilization pattern, nativity, endemism, rarity, seasonality of availability, nutritive values, perceived economic values and pressure use index of livestock have not been studied. The present study attempts to enumerate 150 species of fodder representing trees (51 spp.), shrubs (54 spp.) and herbs (45 spp.). Poaceae (19 spp.) and Fabaceae (13 spp.) amongst families and Salix (6 spp.), Ficus, Clematis, and Desmodium (5 spp., each) amongst genera are rich in species. Maximum species were found in the 1801 ~ 2600 m zone, and the remaining two zones showed relatively low diversity. Out of the 150 species, 109 are used in summer, 5 winter and 36 throughout year. During rainy season, mostly grasses are used as fodder. Only 83 species are native to the Himalayan region, one species, Strobilanthus atropuroureus is endemic and 35 species are near endemic. The nutritive values of the fodder species were reviewed, and economic values and status of the species were also assessed. The pressure use index of the species was calculated on the basis of cumulative values of the utilization pattern, altitudinal distribution, availability, status, nativity and endemism. Amongst the species, Grewia oppositifoilia, Morus serrata, Indigofera heterantha, Quercus leucotrichphora, Ulmus villosa, U. wallichiana and Aesculus indica showed highest PUI indicating high preference and pressure. Season wise prioritization of the species for different altitudinal zones has been done. Appropriate strategy and action plan have been suggested for the conservation and management of fodder species.  相似文献   

SCISSORS DIFFERENCE AND ITS IMPACTS ON ECONOMIC VALUE OF CULTIVATED LAND IN CHINA     

WANG Xiu-fen CHEN Bai-ming BI Ji-ye 《中国地理科学(英文版)》2005,15(3):193-199

1IN T R O D U C T IO NAs we allknow,China isa countrywith vastpopulationand scarcelandpercapita(Y ANG and LI,2000)."T rea-suringlandverymuch,utilizinlgandrationallaynd pro-tectingthe cultivatedland conscientiously"is funda-mental statepolicyofChina.At the…  相似文献   

模型驱动数据空间分辨率对模拟生态水文过程的影响     

顾慧  唐国平  江涛 《地理研究》2020,39(6):1255-1268

设定两种独立的调参方案,检验将高/低分辨率下的调参值应用到低/高分辨率中驱动模型模拟的可行性;同时分析驱动数据分辨率的差异对模型模拟生态水文过程的影响;此外,设置9种集水面积阈值,分析驱动数据分辨率与集水面积阈值对模拟结果的影响。结果表明两种调参方案下模拟的水文与生态数据相关性强、差异小,说明调参方案受驱动数据分辨率的影响不明显;分辨率对土地覆被和土壤类型面积影响小,而对高程和坡度影响大;驱动数据分辨率降低,模拟径流的均值减小、峰值增大、生态变量值增大;驱动数据分辨与集水面积阈值之间不存在交互作用;集水面积阈值增大,模拟径流的均值、峰值均减小,生态变量值也减小,但阈值变化对峰现时间无影响。  相似文献   

Thresholds for run‐off generation in a drained closed depression     

Mark R. Williams  Stanley J. Livingston  Gary C. Heathman  Scott J. McAfee 《水文研究》2019,33(18):2408-2421

Hydrological threshold behaviour has been observed across hillslopes and catchments with varying characteristics. Few studies, however, have evaluated rainfall–run‐off response in areas dominated by agricultural land use and artificial subsurface drainage. Hydrograph analysis was used to identify distinct hydrological events over a 9‐year period and examine rainfall characteristics, dynamic water storage, and surface and subsurface run‐off generation in a drained and farmed closed depression in north‐eastern Indiana, USA. Results showed that both surface flow and subsurface tile flow displayed a threshold relationship with the sum of rainfall amount and soil moisture deficit (SMD). Neither surface flow nor subsurface tile flow was observed unless rainfall amount exceeded the SMD. Timing of subsurface tile flow relative to soil moisture response on the shoulder slope of the depression indicated that the formation and drainage of perched water tables on depression hillslopes were likely the main mechanism that produced subsurface connectivity. Surface flow generation was delayed compared with subsurface tile flow during rainfall events due to differences in soil water storage along depression hillslopes and run‐off generation mechanisms. These findings highlight the substantial impact of subsurface tile drainage on the hydrology of closed depressions; the bottom of the depression, the wettest area prior to drainage installation, becomes the driest part of the depression after installation of subsurface drainage. Rapid connectivity of localized subsurface saturation zones during rainfall events is also greatly enhanced because of subsurface drainage. Thus, less fill is required to generate substantial spill. Understanding hydrologic processes in drained and farmed closed depressions is a critical first step in developing improved water and nutrient management strategies in this landscape.  相似文献   

陕西古人类化石资源及其科学价值     

李兴文  郭岐明  唐永忠 《江苏地质》2022,46(3):251-259

自20世纪60年代发现蓝田直立人化石以来,陕西已经发现了8处更新世古人类化石地点,成为中国人类化石资源分布密集区之一。陕西古人类化石涵盖了直立人、早期智人至晚期智人的人类演化阶段,基本形成了一个较为连续的人类演化序列。在蓝田公王岭、蓝田陈家窝子、洛南龙牙洞发现的古人类化石属于直立人,在大荔甜水沟发现的古人类化石属于早期智人,在志丹、黄龙、长武、南郑发现的古人类化石属于晚期智人。陕西丰富的古人类化石对于研究直立人在欧亚大陆早期人类扩散和迁徙过程、早期现代人多地区起源、中国古人类演化的关键阶段等一系列关键学术问题具有非常重要的科学价值。  相似文献   

悦洋银多金属矿床黄铁矿化学成分标型特征及其矿床学意义          下载免费PDF全文

贾伟晨  王翠芝  陈鹏 《地质找矿论丛》2023,38(2):146-154

悦洋银多金属矿目前的保有储量已不能满足矿山持续生产的需求,需要进行深-边部找矿工作。本文基于成因矿物学理论,通过矿物地球化学方法对矿区内的黄铁矿化学成分标型特征进行了研究。结果表明：(1)黄铁矿中w(Co)/w(Ni)值、As-Co-Ni三角图解、w(Au)/w(Ag)值、w(S)/w(Se)值等特征,联合显示该黄铁矿的成因为岩浆热液(火山热液成因)型;(2)悦洋银多金属矿中稀散元素Se、Ga、Ge可以作为伴生资源开发利用;(3)由黄铁矿微量元素中简化的前缘晕元素组合(As-Sb-Ag)、近矿晕元素组合(Au-Cu-Pb-Zn)、尾晕元素组合(Co-Ni)的三元相图显示,采区矿脉主要处于矿体的中下部,说明在深-边部还有一定的找矿前景;(4)基于该矿床硫化物的研究,结合区域地质、矿区地质特征,岩相学特征等,认为蚀变分带是悦洋银多金属硫化物矿体的找矿标志,即浅部碳酸盐化带、中部硅化+冰长石化带、深部绢英岩化带、硅化+冰长石化带是寻找矿体的直接标志。  相似文献