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81.
该文介绍了公路沥青路面结构设计的方法。路面厚度设计是在结构组合设计的基础上,通过力学和性能分析确定各结构层所需的厚度;同时,利用结构分析也可了解路面结构的应力和位移状况,从而判断结构层组合的合理性,并进行相应的调整。 相似文献
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Two major environmental problems currently affecting the Louisiana coastal zone are a high rate of wetland loss and high levels of surface water pollution. The application of secondarily treated wastewater to wetlands can be a means of dealing with both of these problems. The benefits of wetland wastewater treatment include improved surface water quality, increased accretion rates to balance a high relative water level rise due mainly to subsidence, improved plant productivity and habitat quality, and decreased capital outlays for conventional engineering treatment systems. Wetland treatment systems can, therefore, be designed and operated to restore deteriorating wetlands. Hydrologically altered wetlands, which are common in the Louisiana coastal zone, are appropriate for receiving municipal and some types of industrial effluent. While the U.S. Environmental Protection Agency has determined wetland wastewater treatment is effective in treating municipal effluent, it has discouraged the use of natural wetlands for this purpose. At the same time, funds are being used for the construction of artificial wetlands to treat municipal effluent. In the Louisiana coastal zone, however, wetlands are deteriorating and disappearing due to hydrological alteration and a high rate of relative sea level rise. If no action is taken, these trends will continue. Effluent discharge to existing wetlands should be incorporated into a comprehensive management plan designed to increase sediment and nutrient input into subsiding wetlands in the Louisiana coastal zone, improve water quality, and result in more economical waste‐water treatment. The authors believe that the Louisiana example serves as a model for other coastal areas especially in light of projections of accelerated sea level rise. 相似文献
85.
This papers examines the different choices of High Speed Craft (HSC) hull design available and briefly looks at the advantages and disadvantages of each hull form. The trends in various design aspects of HSC such as speed, capacity and size are studied. An investigation on the HSC development is conducted and the future of HSC in the UK is studied. A study onboard an HSC with the aim of trying to determine what passengers think of HSC and why they travel by them is also conducted. Finally, an analysis of the possible market for HSC is carried out. 相似文献
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Standardized and free-format questionnaires on the state of coastal management were fielded to coastal management practitioners during three workshops and a national feedback and recommendation workshop. The most commonly cited responses were identified for each of 13 political regions and overall trends were identified. Management frameworks frequently included research, community organizing, education, livelihood, resource enhancement, resource protection, regulation, and networking components. Gender issues, documentation, and infrastructure investment were rare. The most commonly perceived environmental problem was illegal/ destructive fishing and its associated overfishing and low fish catch. The most commonly cited socioeconomic problem was the inadequacy of law enforcement. The best monitored variables were usually those related to environmental management: status and change of habitats, resources, and degree of enforcement/patrolling activities. The most common nonregulatory enhancement, aside from environmental education (which is the most popular), was mangrove reforestation. In terms of regulations, the majority of the respondents have reportedly formulated an integrated coastal management plan. In practice, regulating destructive and illegal fishing practices and then the establishment of fish sanctuaries are the next most implemented. The most popular quality-of-life enhancement strategies focused on the improvement of sustainable fishing as a livelihood and on a variety of supplementary livelihoods. The most usual institutional intervention being implemented was the setting up of local community people's organizations. Major factors which may influence success or failure of coastal management and recommendations on research, community organizing and livelihood, legislation and policies, implementation and coordination, and networking are also summarized. 相似文献
88.
Craig J. Forsyth 《Maritime Policy and Management》2013,40(4):249-255
This paper analyses the occupational future of the American merchant seaman. Reasons for the decline, foreign competition, technological change, effective manning and the feast or famine cycle are analysed. Strategies for the resurgence of the occupation are discussed. 相似文献
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V. J. Chapman 《Coastal management》2013,41(3):333-345
Abstract Although New Zealand has a population of 3 million and a coastline of about 10,000 miles there are already heavy pressures on some parts of it. Historically, subdivisions of less than 10 acres require the setting aside of a one‐chain esplanade reserve as part of a general reserve contribution. Some national and regional parks also include significant areas of coast. Recently the Lands and Survey Department has commenced a detailed study of the coastline. Another very recent development is the requirement of an Environmental Impact Report for all major government works. The Waitemata Harbour has been the subject of a detailed study and the reports are now beginning to appear. There has been a heavy demand for shallow bays and estuaries for sanitary land fill, as well as for dredge fill. The main pressure on the coast at present is for holiday cottage sites and some legislative changes may be necessary. In the future new marinas will probably be considered particularly in relation to the extent they provide for the general public rather than a selected few. Industry is only just beginning to make an impact upon the coast. New power stations, natural gas or thermonuclear, are likely to be located on the coastline and this would bring some environmental problems. Recently, it has been argued that to ensure wise use of the coastline there should be national, rather than local or regional, control by a specially appointed Coastal Commission. 相似文献
90.
On the 20th of December,2012,Det Norske Veritas (DNV) and Germanischer Lloyd (GL) respectively published the news on their home pages that a merger agreement had been signed by both parties.With the advent of the Christmas holiday,the media has enteredinto a quiet period.However,the merger between DNV and GL has undoubtedly had a significant and profound influence on the international maritime industry,and the birth of the super classification society might be just a new beginning. 相似文献