基于光学技术的水下气泡探测实验研究   总被引：1，自引：1，他引：0  

秦华伟  陶辰超  蔡真  范相会 《海洋科学》2016,40(6):119-125

热液/冷泉溢出含有硫化氢、甲烷、二氧化碳等化学成分的气泡。实验室模拟海底热液/冷泉资源溢出气泡环境搭建了实验平台,以甲烷气体为实验气体,在黑暗环境下用高速光电探测器对气泡后向散射光进行接收,用拉曼光谱仪实现甲烷气体气泡后向散射光的拉曼检测,并与计算拉曼光谱比较。由结果可知激光拉曼光谱可以探测到气泡后向散射光,并识别气泡中含有的气体成分。通过探测气泡成分,从而判定这些气泡是否来自海底热液/冷泉等甲烷资源溢出。这样的探测方式,探测准确率高,缓解探测深度,同时避免探测设备直接与海底资源直接接触而造成的寿命缩减,为将来的海洋探测与实际应用打下了良好的基础。  相似文献   

Monitoring the recovery of a previously exploited surf-zone fish community in the St Lucia Marine Reserve,South Africa,using a no-take sanctuary area as a benchmark     

BQ Mann  H Winker  JQ Maggs  SN Porter 《African Journal of Marine Science》2016,38(3):423-441

Limiting accessibility to a fishing area can reduce fishing effort effectively and may therefore promote local recovery of depleted stocks. In January 2002, beach driving was banned in South Africa, thereby reducing angler access to large areas of the coastline, particularly in less-developed areas. In November 2001 a project had been established in the St Lucia Marine Reserve, on the east coast of South Africa, to compare surf-zone fish populations inside a no-take sanctuary zone with those in an adjacent exploited area. Subsequent to the ban, the aim of the project was adapted such that surf-zone fish populations were monitored for potential recovery in what had been the exploited area, located to the north of Cape Vidal, which anglers could no longer access easily, because of the prohibition on beach driving. Standardised research fishing was conducted at two sites in the previously exploited area and two sites in the no-take sanctuary. Conventional stock-status indicators showed evidence of recovery in the four most common species caught in the previously exploited area, in terms of both abundance and biomass. Generalised additive mixed models were used to account for the influence of targeting specific species; however, subtle differences in habitat between the sampling sites, improved angling skill over time, variability in recruitment, and differential species-specific responses complicated interpretation of results. The implications of the findings are discussed in terms of the future monitoring and management of marine protected areas both within the St Lucia Marine Reserve and farther afield.  相似文献   

How to allocate limited healthcare resources: Lessons from the introduction of antiretroviral therapy in rural Mozambique     

《Applied geography (Sevenoaks, England)》2017

Proper allocation of limited healthcare resources is a challenging task for policymakers in developing countries. Allocation of and access to these resources typically varies based on how need is defined, thus determining how individuals access and acquire healthcare. Using the introduction of antiretroviral therapy in southern Mozambique as an example, we examine alternative definitions of need for rural populations and how they might impact the allocation of this vital health service. Our results show that how need is defined matters when allocating limited healthcare resources and the use of need-based metrics can help ensure more optimal distribution of services.  相似文献   

对海上高分辨率二维地震作业的认识     

赵庆献  罗文造  李龙振 《海洋技术学报》2002,21(1):37-41

1994－1996年，广州海洋地质调查局承担了南海西部石油公司在北部湾的部分高分辨率二维地震调查工程，调查船使用设备为1993年从美国引进的OYO地震仪（型号为DAS－1），施工过程前期进行了参数选择试验。本文介绍了高分辨地震调查参数选择依据、高分辨率二维采集中的一些注意事项、高分辨率二维采集中的一些注意事项、高分辨率地震资料的采集方法以及一些参数设定的原因。  相似文献   

Hurricanes Cause Population Expansion of the Branching Coral Acropora palmata (Scleractinia): Wound Healing and Growth Patterns of Asexual Recruits     

P. Fong  D. Lirman 《Marine Ecology》1995,16(4):317-335

Abstract. Three mechanisms aiding recovery and expansion of a population of Acropora palmata on a patch reef that was directly in the path of Hurricane Andrew were documented: rapid wound healing, high rates of asexual recruitment, and rapid growth rate of the new recruits. In addition, the growth pattern of new recruits was assessed in order to quantify the initial sequence of Structural changes during the transition from recruit to adult morphology. Wound healing was initially rapid (1.59 cm of linear growth per month). but slowed with time. Nine months after the storm, 72% of 218 hurricane-generated fragments of A. palmata had cemented to the bottom, becoming new asexual recruits. Within 18 months of the storm, the number of fragments in the same area had increased to 271, average fragment size was larger, and 94% had become recruits. Recruits showed complex patterns of branch formation, including rapid growth of solitary proto-branches, differential growth of proto-branches dependent on recruit orientation, and dominance within aggregates of proto-branches. We present a conceptual model that suggests A. palmata is adapted to disturbances of both low intensity and high frequency (conditions typical of reef flat zones) and episodic high intensity and low frequency events (hurricanes and tropical storms).  相似文献   

Application of in situ target-strength estimations in lakes: examples from rainbow-smelt surveys in Lakes Erie and Champlain   总被引：1，自引：0，他引：1  

Rudstam  L.G; Parker  S.L; Einhouse  D.W; Witzel  L.D; Warner  D.M; Stritzel  J.L; Parrish  D.L; Sullivan  P.J 《ICES Journal of Marine Science》2003,60(3):500-507

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Seal sizes and habitat conditions assessed from aerial photography and video analysis     

Estep  Kenneth W.; MacIntyre  Ferren; Noji  Thomad T.; Stensholt  Boonchai; Oritsland  Torger 《ICES Journal of Marine Science》1994,51(3):253-261

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Water-level fluctuations, emersion regimes, and variations of echinoid populations on a Caribbean reef flat     

John D. Cubit  Donald M. Windsor  Ricardo C. Thompson  Jeff M. Burgett 《Estuarine, Coastal and Shelf Science》1986,22(6)

This paper examines fluctuations in water level over a Caribbean reef flat at Punta Galeta, Panamá. In an analysis of approximately ten years of records, the mean diurnal range of the tides was 24·5 cm and varied <2 cm from year to year. Daily mean water levels varied erratically over a range of approximately 30 cm. Monthly mean water levels fluctuated seasonally over a range of about 10 cm and were consistently higher than those at the regional tidal reference station at Cristóbal. On days with more wave action, water levels at Galeta increased relative to those at Cristóbal, suggesting that waves were ‘pumping’ water onto the reef flat. The monthly mean water levels at the two sites were not correlated, indicating that tidal data from conventional stations in deeper water cannot be extrapolated to reef flats, except as estimates of minimum potential water levels.Most of the reef flat was within 6 cm vertical span just below mean lower low water. The highest elevations within this range were exposed above water level for an average of 918 hours per year, as compared with 144 hours per year at the lowest elevation. Most exposures lasted less than 10 hours, with a modal duration of 3–5 hours; however, exposures longer than 12 hours occurred at nearly all elevations in all years. Exposures of the reef flat were most frequent between February and June and between August and November, a pattern apparently caused by a combination of seasonal oscillations of regional sea levels, the annual pattern of the solstitial tides, and waves generated by seasonal trade winds.The fluctuations in water levels apparently affected the abundances of some species of sea urchins on the reef flat. Populations of Lytechinus variegatus and Diadema antillarum declined or disappeared from the reef flat during seasons of repeated subaerial exposures, but recolonized the habitat in periods of higher water levels. Although they are reported to suffer heavy mortality during emersion, Echinometra lucunter and E. viridis did not exhibit reductions in abundance that were synchronous with the seasonal exposures of the reef flat.  相似文献   

Discharge Control on Boundary of Tidal Models and Measuring Techniques of Low Current Velocity     

Li Guochen Xu Jinhuan Associate Prof.  Dept. of Navigation  Ocean Eng.  Hohai University  Nanjing Lecturer  Dept. of Navigation  Ocean Eng.  Hohai University  Nanjing 《中国海洋工程》1992,(3)

This paper describes the discharge control technique on boundary used in two models, one is the model of hot water drainning in Dayawan Nyclear Power Plant, Guangdong, and the other is the model for trainhing the sand bar at the Guanhe Estuary, Jiangsu. Many years of application shows that this technique has the advantages of good reliability, repeatability and validity. The speedometer of hydrogen bubble is also introduced in this paper. The device can display and store tracing lines in a computer, and help operators to obtain the value and direction of transient velocity of a nonsteady current, thus, the problem of measurment of low current velocity in tidal model tests is solved and the automation of the measurement of current velocity is realized.  相似文献   

A stabilized assumed deformation gradient finite element formulation for strongly coupled poromechanical simulations at finite strain     

WaiChing Sun  Jakob T. Ostien  Andrew G. Salinger 《国际地质力学数值与分析法杂志》2013,37(16):2755-2788

An adaptively stabilized finite element scheme is proposed for a strongly coupled hydro‐mechanical problem in fluid‐infiltrating porous solids at finite strain. We first present the derivation of the poromechanics model via mixture theory in large deformation. By exploiting assumed deformation gradient techniques, we develop a numerical procedure capable of simultaneously curing the multiple‐locking phenomena related to shear failure, incompressibility imposed by pore fluid, and/or incompressible solid skeleton and produce solutions that satisfy the inf‐sup condition. The template‐based generic programming and automatic differentiation (AD) techniques used to implement the stabilized model are also highlighted. Finally, numerical examples are given to show the versatility and efficiency of this model. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献