Numerical Prediction of Regular Wave Breaking on Very Gentle Slopes     

LI  Yucheng 《中国海洋工程》2002,16(1):79-87

Regular wave deformation and breaking on very gende slopes is calculated by Mixed-Eulerian-Lagrangian procedure. The velocity potentials and their normal derivatives on the boundary are calculated through the mixed 0-1 boundary element method. The wave elevation and the potentials of time-stepping integration are detertnined by the 2nd-order Taylor expansion at the nodes of free surface boundary elements. During calculation the x-coordinates of the free surface element nodes are supposed to remain unchanged, i.e. the partial derivatives of wave elevation and potentials with respect to x are considered as zero. The numerical results of asymmetric parameters of breaking waves are verified by experimental study. It is shown that when the wave asymmetry is weak, the maximum horizontal velocity of water particales occurs at the wave peak and, the average ratio of this maximum velocity to wave celerity is 0.96. However, when the wave asymmetry is strong, the maximum horizontal velocity of water particles occu  相似文献   

Vibration Characteristics of An Offshore Platform and Its Vibration Control   总被引：1，自引：0，他引：1  

LI  Hua-jun 《中国海洋工程》2002,16(4):469-482

A template offshore platform, located in the Bohai Bay of China, has exhibited excessive, unexpected vibration un-der mildly hostile sea conditions, which has affected the normal operation of the platform. Since the structure was de-signed to sustain more severe wave climate, the cause of the excessive vibration has been suspected to originate from other sources. The main objectives of this study are to investigate the causes of the excessive vibration, and to explore possible remedies to solve the problem, In this paper, the vibration behavior of the offshore platform is analyzed by means of finite element (FE) modeling, field measurements and laboratory test. Results of analysis suggest that relative movement and impact between the piles and the jacket legs exist, i. e. the piles and the jacket are not perfectly connected. The discon-nection of the piles and jacket weakens the overall stiffness of the platform, and therefore produces unexpected excessive vibration. In this study, measures for reducing  相似文献   

故乡的海     

胡欣怡 《海洋世界》2021,(3):52-55

我曾和很多人提起过,暑风下那片闪烁着波光的浩渺瀚海。记忆朦胧久远得就好像是无垠星空下的一个梦,却还是能拿来述说,忍不住一遍遍回忆,直到听与讲的人俱陶醉在耳边的海涛声中,灵魂安歇在形红的日出之下。  相似文献   

激光测量采集车在城市部件调查中的应用     

徐建新  张光伟  羌鑫林  蒋莹  高磊 《测绘与空间地理信息》2013,(Z1):237-239

车载移动测量技术在国内已经发展了几年的时间,三维点云数据结合多相机曝光的RGB信息可以直接生成真实三维场景,通过该技术手段可以大大提高城市部件数据采集能力。激光点云数据经过处理后,将基于点云采集的城市部件信息导入SuperMap二三维一体化GIS平台,实现了城市部件数据的管理与三维场景展示。  相似文献   

新疆及其毗邻地区荒漠昆虫区系的形成与演变   总被引：1，自引：0，他引：1  

黄人鑫  HU Hong-ying  吴卫  范兆田  索菲娅 《干旱区地理》2005,28(1):38-44

荒漠昆虫区系的形成与演变是昆虫学研究的中心议题之一,在对新疆现代荒漠昆虫区系研究的基础上,结合自侏罗-白垩纪以来新疆及其毗邻地区出现的地质事件、气候变迁、植被演替等研究资料分析表明,荒漠昆虫的祖先主要是中生型昆虫。我国塔里木盆地、东疆诸盆地、贺兰山以西及蒙古等地,被称为中央亚细亚的地区,荒漠昆虫的起源是在侏罗纪和白垩纪的交替时期,其区系形成是在白垩纪末至早第三纪的古新世;而准噶尔盆地、中亚细亚东部地区等的被称为中亚细亚的地区,荒漠昆虫的起源较中央亚细亚为晚,是在白垩纪,区系形成是在早第三纪的始新世。土著种的特化是区系形成的基本途径,物种的迁移也具有重要作用,但主要为由东到西的迁移。早第三纪末期开始的喜马拉雅造山运动使环境走向极度干旱荒漠化,带来了古荒漠昆虫区系的解体和现代荒漠昆虫区系的形成;随着喜马拉雅山的隆起和古地中海的干涸,物种的迁移逐渐变为由西向东。第四纪大冰川活动促使中亚细亚成为强大的物种形成中心,从而给新疆荒漠昆虫区系带来重大影响,致使中亚细亚成分常常占到40％以上。  相似文献   

Changes in the Chemical Components of Light Crude Oil During Simulated Short Term Weathering     

MA Qimin )  LUO Xia)  and YU Zhigang) ) College of Environmental Science  Engineering  Ocean University of China  Qingdao  P. R. China ) College of Chemistry  Chemical Engineering  Ocean University of China  Qingdao  P. R. China 《中国海洋大学学报(英文版)》2007,6(3):231-236

To unambiguously identify spilled oils and to link them to the known sources are extremely important in settling ques-tions of environmental impact and legal liability. The fate and behavior of spilled oils in the environment depend on a number of physicochemical and biological factors. This paper presents the results regarding changes in chemical composition of light crude oil during simulated short-term weathering based on natural environmental conditions. The results show that the saturated hydrocarbons of the light crude oil mainly distribute between n-C8 and n-C23 and the most abundant n-alkanes are found in the n-C10 to n-C16. The main chemical components of the light crude oil are n-alkanes and isoprenoids. The aromatic compounds are subordinate chemical components. Under the conditions of the weathering simulation experiment,n-alkanes less than n-C12,toluene and 1,3-dimethyl ben-zene are lost after 1 d weathering,the n-C13,n-C14,naphthalene and 2-methyl-naphthalene are lost on the fifth day of weathering,and n-C15 alkane components show certain weatherproof capability. The ratios n-C17/pristane and n-C18/phytane are unaltered and can be used to identify the source of the light crude oil during the first 8 d of weathering. After 21 d,the ratio pristine/phytane can not pro-vide much information on the source of the spilled light crude oil. Triterpanes(m/z 191) as biomarker compounds of light crude oil are more valuable.  相似文献   

德国测量杂志(ZfV)1998年(第123卷)学术论文题录     

［编者注］  德国《测量》杂志 《测绘学报》1999,28(7)

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Genetic Analysis of Four Populations of Redlip Mullet(Chelon haematocheilus) Collected in China Seas     

MENG Wei)  GAO Tianxiang)  *  and ZHENG Bing) ) Key Laboratory of Mariculture  Ministry of Education  Ocean University of China  Qingdao  P. R. China ) Shandong Ocean Exploration Center  Qingdao  P.R.China 《中国海洋大学学报(英文版)》2007,6(1):72-79

1 Introduction The redlip mullet, (Chelon haematocheilus) (Tem-minck et Schlegel, 1845), belongs to the family Mugili-dae. It is mainly distributed in the coastal areas of Korea, Japan and China (Wang et al., 2000). Because of the good adaptation to envir…  相似文献   

Characteristics of Drought and Flood in Zhejiang Province, East China： Past and Future     

FENG Lihua  HONG Weihu 《中国地理科学(英文版)》2007,17(3):257-264

On the basis of large amount of historical and measured data,this paper analyzed the regional,periodic,frequency,continuing,and response characteristics of droughts and floods in Zhejiang and proposed the conception of ratio of peak runoff.Main characteristics of droughts and floods in Zhejiang are as follows:1)The western Zhejiang region is plum rain major control area,and the eastern coastal region of Zhejiang is typhoon major control area.2)Within a long period in the future,Zhejiang will be in the long period that features droughts.3)In Zhejiang the 17th century was frequent drought and flood period,the 16th,19th,and 20th centuries were normal periods,while the 18th century was spasmodic drought and flood period.4)The severe and medium floods in Zhejiang were all centered around the M-or m-year of the 11-year sunspot activity period.5)There are biggish years of annual runoff occurred in El Ni?o year(E)or the following year(E 1)in Zhejiang.The near future evolution trend of droughts and floods in Zhejiang is as follows:1)Within a relatively long period in the future,Zhejiang Province will be in the long period of mostly drought years.2)Between 1999 and 2009 this area will feature drought years mainly,while the period of 2010-2020 will feature flood years mostly.3)Zhejiang has a good response to the sunspot activities,and the years around 2009,2015,and 2020 must be given due attention,especially around 2020 there might be an extremely severe flood year in Zhejiang.4)Floods in Zhejiang have good response to El Ni?o events,in El Ni?o year or the following year much attention must be paid to.And 5)In the future,the first,second,and third severe typhoon years in Zhejiang will be 2009,2012,and 2015,respectively.  相似文献   

在第三届全国地层会议上的讲话     

温家宝 《地质通报》2000

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