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1.
《Marine Policy》2005,29(1):69-73
Large sums are spent annually collecting and, increasingly, electronically encoding field data, making them widely accessible. Earlier data were recorded on paper, and archived at a few institutions, which eventually discard them. Data recovery and distribution is a valuable contribution to science, as it counters the ‘shifting baseline’ syndrome and ensures long-term returns on funds society invested in data gathering. Data recovery need not be expensive. We present the data recovery from the Guinean Trawling Survey, conducted in the early 1960s off West Africa, which cost 0.2% of initial survey costs. Research and graduate training institutions, as well as funding agencies should make digital data globally available as part of their deliverables. 相似文献
2.
Thin fluid-filled spherical shells have been used as passive sonar targets for many years. They possess a large target strength which is highly dependent on the sound-speed mismatch between the fluid contained within the shell and the exterior fluid surrounding the shell. In the past, to obtain the appropriate mismatch, the interior fluid mixture contained chlorofluorocarbons (CFCs). Due to a recent production ban on CFCs, it is necessary to choose alternative fluids. The present research analyzes the backscattering target strength of a fluid-filled spherical shell as a function of several material parameters as a guide to choosing alternative fluids and shell materials. Calculations over a broad range of material values display the target strength dependence on the interior fluid parameters as well as the parameters defining the metallic shell. The range of material values presented here is far larger than any previous study addressing the focusing effects of fluid-filled spherical shells. The results should aid in determining liquid fillers and shell materials which yield the maximum possible backscattered returns. Also, several experiments were conducted with stainless steel shells containing a hydrochlorofluorocarbon (HCFC), dichlorofluoroethane. The results are compared with results found from calculations as well as from other experiments involving shells containing a previously used CFC mixture 相似文献
3.
《Marine Policy》2017
While neoliberalism is often framed as a withdrawal of the state, many scholars have noted that what is occurring is not so much a withdrawal, as a repositioning. Although many social services and regulatory functions once provided by government agencies have indeed been eroded, there has been a simultaneous channeling of new resources into other arenas, in an effort to create conditions in which private corporations can operate more profitably. This, however, often places the state in a contradictory position, simultaneously serving as regulator, investor, and development advocate for the private sector. This can become especially problematic in moments of ecological crisis when decisive and unbiased responses are needed. This paper explores these dynamics through an examination of the cycles of growth and crisis that have characterized the aquaculture industry on the south coast of Newfoundland since the late 1970s as well as the ongoing attempts by aquaculture advocates to characterize industrial-scale fish farming as a sustainable industry, despite evidence to the contrary. 相似文献
4.
黄河流域在我国经济社会发展和生态安全方面具有十分重要的地位,其下游的黄河三角洲分布有世界上暖温带保存最广阔、最完善、最年轻的滨海湿地生态系统,该区域特殊的地质地貌决定了其生态多样性,需要进行重点研究和保护。文章立足于我国现有湿地保护政策和湿地面积缩小的现状,提出黄河三角洲湿地保护可着重围绕其岸线变化、冲淤速率、地形地貌等开展研究,并采用减压分洪扩充法等治理修复方法扩大湿地面积,为推动黄河流域及黄河三角洲湿地的生态保护和高质量发展提供有效参考。 相似文献
5.
海底沉积物纵波波速与物理-力学性质的理论关系和比较 总被引：2，自引：1，他引：2
本文提出以密度变化比和等效弹性模量变化比为参数描述海底沉积物纵波波速,得到密度变化比是由孔隙率、海水密度和海底沉积物固相密度构成的复合参数,建立了以复合参数和等效弹性模量变化比为变量的泰勒多项式海底沉积物纵波波速公式。基于单因素分析法得出纵波波速可表示为参考声速与调制函数的乘积,沉积物的参考声速由海底底质物理性质确定,建立了复合参数-声速的近似理论模型。对该理论模型与现有的主要纵波波速经验公式的分析结果表明,孔隙率-纵波波速经验公式只是参考声速不同,但调制函数是互相等效的,验证了本文海底沉积物纵波波速理论关系的有效性。 相似文献
6.
Various offshore structures, especially large structures such as Tension Leg Platforms (TLP), are usually supported by concrete piles as the foundation elements. The stress distribution within such a large structure is a dominant factor in the design procedure of an offshore pile. To provide a more accurate and effective design for offshore foundation systems under axial and lateral wave loads, a finite element model is employed herein to determine the stresses and displacements in a concrete pile under similar loading conditions. A parametric study is also performed to examine the effects of the stress distribution due to the changing loading conditions. 相似文献
7.
The distribution of dissolved (soluble and total) and particulate (leachable and total) aluminum was examined in the Columbia River and estuary, in near-field and far-field river plumes, and in adjacent coastal waters of Washington and Oregon during the River Influence on Shelf Ecosystems (RISE) cruise of May/June 2006. Dissolved and particulate aluminum (Al) concentrations were significantly greater in the river than in the coastal waters that mixed to form the plume. Dissolved Al concentrations in the Columbia River (∼80 nM) were low relative to other major rivers. Leachable and total particulate Al concentrations within the river reached concentrations greater than 1000 nM and 18,000 nM, respectively. Dissolved Al within the Columbia River estuary showed a significant removal (∼60%) at salinities between 0 and 10 with salt-induced flocculation of colloidal Al complexes and enhanced particle scavenging being probable explanations for aluminum removal. Dissolved and particulate Al concentrations were significantly greater in near-field plumes relative to surrounding coastal waters. As the plume advected from near-field to far-field away from the river mouth, dilution of the plume with lower dissolved Al surface waters as well as particle scavenging along the flow path appeared to be controlling dissolved Al distributions. Particle settling as well as dilution with lower particle-load waters led to observed decreases in particulate Al as the plume moved from near-field to far-field. However, the percent-leachable particulate aluminum in both near-field and far-field plumes was remarkably constant at ∼7%. Dissolved and particulate Al in a far-field plume over 100 km southwest of the Columbia River mouth were over an order-of-magnitude greater than surrounding waters, illustrating the importance of the Columbia River plume as a mechanism for transporting Al offshore. Aluminum could be used to trace the input of biologically-required elements such as iron into waters off the shelf. 相似文献
8.
《Marine Policy》2013
Recent advocacy of human rights approaches (HRA) for the governance of small-scale fisheries (SSF) in developing countries overlooks evidence that HRA facilitates a neo-liberal agenda. Further, this advocacy is seemingly uninformed by serious consideration of the extensive human rights literature. As a result, the essential relationship of human rights to neo-liberal philosophy and processes, as well as nation/state icons and institutional practices, remains hidden. Neither is it demonstrated that “development” was redefined within the neo-liberal context of the property-holding individual functioning efficiently within a market-imposed discipline, nor that this has been protected since the 1980s by having co-opted HRA. Paradoxically, the likely result of an HRA as promoted is a disruption of the very collective community cultural, economic and social values that provide the realistic ethical, moral and practical basis for implementing an effective and meaningful HRA. This essay examines and demonstrates how the HRA advances the cause of neo-liberal penetration into communities within the context of Western development practice and philosophy, its basis in neo-classical economics, and its congruence with neo-liberalism. The role of collective communal values is examined as an alternative for securing human rights. 相似文献
9.
Variations are found in the shape and the steepness of wind-generated surface gravity waves between very young waves, such
as seen in a laboratory tank, and larger waves of various wave ages encountered at sea as the result of wind stress over larger
fetches. These differences in the characteristic shape of wind waves are presented as a function of the wave age. The wave
steepness is also expressed as a function of wave age, the measurement of which is consistent with the 3/2-power law connecting
wave height and characteristic period, normalized by the air friction velocity. 相似文献
10.
An understanding of the paleoenvironment and the main sedimentary processes behind preserved deposits is crucial to correctly interpret and represent lithofacies and facies associations in geomodels that are used in the hydrocarbon industry, particularly when a limited dataset of cores is available. In this paper a fairly common facies association is discussed containing massive sands - here defined as thick (>0.5 m) structureless sand beds devoid of primary sedimentary structures, or with some faint lamination - deposited by mass failures of channel banks in deep fluvial and estuarine channels. Amongst geologists it is generally accepted that liquefaction is the main trigger of large bank failures in sandy subaqueous slopes. However, evidence is mounting that for sand deposits a slow, retrogressive failure mechanism of a steep subaqueous slope, known as breaching, is the dominant process. A model of breaching-induced turbidity current erosion and sedimentation is presented that explains the presence of sheet-like massive sands and channel-like massive sands and the sedimentary structures of the related deposits. Sheet-like packages of spaced planar lamination that are found together with massive sand bodies in deposits of these environments are identified as proximal depositional elements of breach failure events. The model, acquired from sedimentary structures in deposits in the Eocene estuarine Vlierzele Sands, Belgium, is applied to outcrops of the Dinantian fluvial Fell Sandstone, England, and cores of the Tilje and Nansen fms (Lower Jurassic, Norwegian Continental Shelf). The possible breach failure origin of some other massive sands described in literature from various ancient shallow water environments is discussed. Breach failure generated massive sands possibly also form in deep marine settings. The potentially thick and homogeneous, well-sorted sand deposits bear good properties for hydrocarbon flow when found in such an environment. However, in case of deposition in an estuarine or fluvial channel, these sand bodies are spatially constricted and careful facies interpretation is key to identifying this. When constructing a static reservoir model, this needs to be considered both for in-place volume calculations as well as drainage strategies. 相似文献
11.
Offshore waters are in a process of transition, revealing diverse and heterogenic interests in marine resources. This increasing complexity leads to limits in developing and managing the different and often spatially overlapping maritime activities independently of one another. On a showcase basis we discuss ways and manners as well as the preconditions of an offshore co-management approach for the fledgling actor groups offshore wind farmers and mariculturists. Both groups may benefit through the integration of operation and maintenance (O&M) activities. Their resources in terms of offers, needs and constraints characteristics and thereof deduced potentialities for interaction is a prerequisite for initiating a co-management process. This process is more likely to develop and succeed if an interface management that acts as a moderator, disclosing the interests of the actor groups and offering possibilities for concerted action, guides it. It is concluded that such an institutional arrangement may in the long term contribute to a sound methodological tool for a co-management approach between different offshore maritime sectors. 相似文献
12.
Almroth BC Sturve J Stephensen E Holth TF Förlin L 《Marine environmental research》2008,66(2):271-277
The use of fish in environmental monitoring has become increasingly important in recent years as anthropogenic substances, many of which function as prooxidants, are accumulating in aquatic environments. We have measured a battery of antioxidant defenses as a measure of oxidative status, as well as protein carbonylation as a measure of oxidative damage, in corkwing wrasse (Symphodus melops) captured near a disused copper mine, where water and sediment are contaminated with heavy metals, and an aluminum smelter, a site contaminated with PAHs. Results were compared to two different reference sites. Fish at the heavy metal site had lower glucose-6-phosphate dehydrogenase activity and elevated protein carbonyls (1.8 times) compared to fish from the reference site. At the PAH site, EROD was increased 2-fold, while total glutathione and methemoglobin reductase concentration, were decreased. No differences were seen in protein carbonyl levels at the PAH site. Measures of both antioxidant defenses and oxidative damage should be used when assessing effects of xenobiotics on oxidative stress in fish species. 相似文献
13.
Nonlinear Dynamics and Bifurcations of a Supercavitating Vehicle 总被引：1，自引：0，他引：1
In this effort, a numerical study of the bifurcation behavior of a supercavitating vehicle is conducted. The vehicle model is nonsmooth; this is a result of the planing force acting on the vehicle. With a focus on dive-plane dynamics, bifurcations with respect to a quasi-static variation of the cavitation number are studied. The system is found to exhibit rich and complex nonlinear dynamics including nonsmooth bifurcations such as the grazing bifurcation; smooth bifurcations such as Hopf bifurcations, cyclic fold bifurcations, and period-doubling bifurcations; and aperiodic behaviors such as transient chaotic motions and chaotic crises. The tailslap phenomenon of the supercavitating vehicle is identified as the consequence of a Hopf bifurcation followed by a grazing event. It is shown that the occurrences of these bifurcations can be delayed or triggered earlier by using dynamic linear feedback control laws employing washout filters. 相似文献
14.
《Marine Policy》2017
Hong Kong (HK) has enacted laws providing: (1) Regimes that address pollution prevention responsibilities for parties involved in shipping activities to ensure that ships used in HK waters comply with applicable rules and standards; (2) civil damages remedy for wrongful death, personal injury or property damage caused by an environmental incident; and (3) a system of penalties to address the rare cases where the behavior of the polluter is considered intolerable and must be punished as a criminal offence. Being acquainted with this legal and policy framework is of beneficial interest for the maritime industry in HK. This article first summarizes the existing general legal framework, and later presents the results of an empirical study to determine what repercussions there could be within the HK maritime industry as a result of these laws and policies being applied in cases that result in civil liability compensation and criminal charges. The empirical research demonstrates that the laws and policies are in general sufficient and effective, but that flaws still remain in the limitation of liability scheme, as well as uncertainties as to which particular kinds of environmental violations should result in either civil or criminal enforcement. To address these concerns, it is first suggested that HK should impose greater liability in areas where prior law provided insufficient liability, as this will act as a more potent deterrent; and second, that HK should clearly delineate an appropriate role for criminal enforcement in the environmental regulatory scheme, so as to lessen concerns about over-criminalization. 相似文献
15.
Hamizan Yusof Muhammad Saad Shahbudin Naim Mohd Azrul Khodzori Mohd Fikri Akmal Hanapiah Muhammad Faiz Mohd 《Ocean Science Journal》2021,56(3):317-325
Ocean Science Journal - Previous studies indicated that artificial live rock (ALR) has the potential to be used as a substrate for coral juveniles. The present study reported a potential of ALR as... 相似文献
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《Marine Policy》2005,29(3):223-234
In a previous paper on Canal management we examined the treaties and regulations underpinning firstly American and later Panamanian administration of the Canal. We also looked at the transfer of the Canal into Panamanian hands, including the management models used, ending with a review of toll structures and results. The subject of this paper is the operation of the Canal and the heated debate surrounding its modernisation, with a view to determining the adequacy of projected plans, as well as any future requirements, for maintaining its capacity in the 21 century. This paper seeks to analyse the Canal's operation, modernisation programmes and traffic systems as well as its key element: human resources. 相似文献
19.
《Marine Policy》2013
Many coastal communities have strong links to fishing that span generations where fishing is a way of life that goes beyond the means to earning a living. Fishing's influence is not confined to those activities that take place at sea, but spills over onto land to create a particular identity and sense of place in coastal towns inherently linked to fishing. Using Hastings in south-east England, with Britain's largest beach-launched fleet, as a case study, this paper considers how marine fishing contributes to place-making. Through an examination of the physical environment and semi-structured interviews, the study found that fishers have deep attachments to the fishing beach, called the Stade, which also defines their identity as individuals and as a fishing community. Non-fishers also value the contribution that fishing makes to the character of the town and its importance for related industries such as tourism. A deeper understanding of the attachments that fishers and non-fishers form with fishing places is needed to inform both local planning and regeneration strategies and, more broadly, fisheries and marine policy. 相似文献
20.
文章以环渤海地区17个沿海城市和27个内陆城市为研究对象,系统构建旅游产业发展指数评价体系,采用综合指数评价模型、改进的引力模型和Arcgis10.0地理空间分析等方法,测度环渤海地区沿海与腹地旅游空间联系强度,揭示海陆旅游产业的相互作用关系和时空演化态势。研究表明,环渤海地区沿海城市旅游产业发展水平普遍高于内陆城市,时序上海陆系统的联系逐渐增强,空间上呈现局部聚集和整体分异态势;区域经济发展水平、旅游资源禀赋基础和交通运输体系建设是影响沿海与腹地旅游空间联系强度的主要因素。进而提出促进跨区域产业融合和资源配置、优化旅游开发空间格局、建立整体营销机制等对策建议,以期推动环渤海地区沿海与腹地旅游产业的协同发展。 相似文献