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11.
南方(湖南、贵州、四川、云南、重庆等)煤田在绳索取心钻进时,遇到的问题及解决办法有一定的普遍性。针对该区的地层特点,提出了合理的钻进方法及钻具配套方案;根据施工区的条件及孔深要求,进行了设备配套的研究;从研究区内事故发生的普遍性入手,摸索出一套较为合理的事故处理方案和工艺配套措施。通过多方面的研究,形成了一套比较合理的配套方案,据此方案在云贵川湘等地施工,均取得了较好的经济效益与社会效益方面。 相似文献
12.
Mark A. Gammon 《Ocean Engineering》2011,38(10):1054-1064
A fishing boat hull is used as an example of how hull form optimization can be accomplished using a Multi-Objective Genetic Algorithm (MOGA). The particular MOGA developed during this study allows automatic selection of a few Pareto Optimal results for examination by the designers while searching the complete Pareto Front. The optimization uses three performance indices for resistance, seakeeping and stability to modify the hull shape to obtain optimal hull offsets as well as optimal values for the principal parameters of length, beam and draft. The modification of the 148/1-B fishing boat hull, the parent hull form of the ?stanbul Technical University (?TÜ) series of fishing boats, is presented by first fixing the principal parameters and allowing the hull offsets to change, and secondly by simultaneously allowing variation of both the principal parameters and the hull offsets. Improvements in all three objectives were found. For further research the methodology can be modified to allow for the addition of other performance objectives, such as cost or specific mission objectives, as well as the use of enhanced performance prediction solvers. In addition, one or more hulls could be evaluated by experiment to validate the results of using this particular optimization approach. 相似文献
13.
The East Sea, with an average depth of 1700 m, has long been subject to heavy fishing pressure, resulting in derelict fishing gear. Most derelict fishing gears, such as fishing nets, fishing ropes, and crab pots, sink to the seabed and do not degrade. This gear results in “ghost fishing,” which has adverse impacts on deep benthic habitats. Recently, the Korean government has started to remove derelict fishing gears from the deep seabed of the East Sea by bottom trawling with heavy hooks (50–80 kg) and ropes. A total of 207.8 and 252.2 tons of marine debris in 2009 and 2010, respectively, were removed from the seabed, most of which were derelict fishing gears. Contrary to monitoring surveys and clean-up in shallow waters, removal of marine debris from remote deep habitats is much more difficult and dangerous for removal crews. 相似文献
14.
Application of a vessel monitoring system to advance sustainable fisheries management—Benefits received in Taiwan 总被引:1,自引:0,他引:1
Vessel monitoring systems (VMS) are considered important instruments for fisheries monitoring, control and surveillance (MCS) to reverse the current depressed state of the world’s fisheries, and have been mandated worldwide by fishery management agencies. The essential function of the system is to provide near-real time vessel position; the potential applications could, however, be more than that. This study explores the additional benefits, with practical examples, that Taiwan has received from implementing the system: in improving the quantity and quality of logbooks recovered, obtaining access to fishery-independent fishing effort estimates and prompt catch/effort reporting, enabling the possibility of regional management and understanding of both fleet dynamics and vessel behavior, and increasing efficiency of vessel safety protection. For other distant-water fishing nations, Taiwan’s experiences serve to demonstrate how the application of VMS technology can advance sustainable fisheries management. 相似文献
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在对深部煤田地质钻孔钻进工艺研究的基础上,有针对性选择使用聚合物泥浆,解决了基浆配制用水及泥浆抗地表水水质污染问题。通过改变双管钻具长度和改换取心钻头的切削具,满足软硬互层对钻头钻进效率的影响。在煤系地层钻进中,除采用常规的单管钻具钻进外,在见煤预告下过后,采用加长双管取心钻具,既可保证了回次进尺,又可保证岩心的采取。多项措施落实,不仅解决了生产中的一些难题,收到了较好的效果,而且创造了河北省煤田地质局煤田地质单孔钻探深度2 009.12m的新纪录,为今后深部钻孔的施工积累了经验。 相似文献
17.
为了满足选冶试验矿样质量的需要,刚果(金)Sicomines铜钴矿区选用了大口径取心(≥Φ325 mm)钻探工艺。实际应用表明,针对完整或破碎地层条件选用不同的筒状钻具及取心工艺是大口径取心工程成功的关键。 相似文献
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19.
大量的研究和钻探取样证明,不仅海洋深处存在着天然气水合物,陆地永久冻土带也存在天然气水合物。从目前的地质探测技术发展现状看,确定冻土层水合物的储藏深度、含量等物理化学特性还必须靠取样钻探技术。论述了全球陆地永久冻土带天然气水合物的钻探现状,介绍了陆地永久冻土带天然气水合物取心钻具的结构设计、试制过程和在海拔4200m的青海祁连山地区进行永久冻土带天然气水合物钻探技术研究过程中取得的成果。 相似文献
20.
《Marine Policy》2015
Commercial fishing data were used to reconstruct historical spatio-temporal patterns of fishing effort and landings in the bottom longline fishery of the Azores. Key events during an important 15-year period were charted, through fisher interviews together with GIS analysis. While effort distribution varied over time, the prevailing pattern was a shift in focus from eastern to western areas and from shelf/slope to offshore banks and seamounts in response to policy measures (e.g. banning bottom longline inside 3 NM, public aids for modernization of the fleet) and reduced fishing yields. Areas 12–50 NM from shore represented the most vital fishing grounds in terms of fishing effort and production. Declining landings of the major demersal species, in recent years, indicate that present catch levels are not sustainable and further measures need to be taken in order to sustain fisheries resources. Knowledge of fleet behavior and the distribution of fishing effort, particularly in patchy environments, provide valuable insights into the impacts of past management decisions and help predict the outcome of new policies both in this region and elsewhere. 相似文献