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通过工程实例，介绍了应用潜水电磁铁处理桩孔施工中掉铁件事故的方法及操作要领，它具有实用价值。 相似文献
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黄幼才 《武汉大学学报(信息科学版)》1993,(1)
本文从充分利用可能得到的信息的观点出发,讨论了测量平差的抗差性和优效性及其他们之间的关系。阐述了抗差估计理论和经典估计理论的本质区别。提出了测量平差抗差化的基本原则,并对几种估计的抗差能力和效率作了比较。 相似文献
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To achieve accurate positioning of autonomous underwater vehicles, an appropriate underwater terrain database storage format for underwater terrain-matching positioning is established using multi-beam data as underwater terrain-matching data. An underwater terrain interpolation error compensation method based on fractional Brownian motion is proposed for defects of normal terrain interpolation, and an underwater terrain-matching positioning method based on least squares estimation (LSE) is proposed for correlation analysis of topographic features. The Fisher method is introduced as a secondary criterion for pseudo localization appearing in a topographic features flat area, effectively reducing the impact of pseudo positioning points on matching accuracy and improving the positioning accuracy of terrain flat areas. Simulation experiments based on electronic chart and multi-beam sea trial data show that drift errors of an inertial navigation system can be corrected effectively using the proposed method. The positioning accuracy and practicality are high, satisfying the requirement of underwater accurate positioning. 相似文献
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《Marine Policy》2014
Given their potential for social and ecosystem disruption along with job creation and economic stimulus, the proliferation of extremely large-scale investment projects worldwide has created a dilemma for policymakers and public authorities. Although one method of balancing the varied interests of stakeholders is to require that development projects be sustainable, the definition of this concept has become muddled and few practical frameworks for its implementation have emerged. One strategy that does exist, however, is the just sustainability framework. The present study sought to assess the just sustainability of the Açu industrial seaport megaproject in Rio de Janeiro State, Brazil through the application of a questionnaire among 60 active marine artisan fishers of a nearby community. The results indicate that the megaproject was not sustainable. Furthermore, the results of the just sustainability indicators triangulated both with the study's primary fisher ethnographic data and with peer-reviewed scientific assessments of similar projects, thus confirming the potential value of the just sustainability framework for assessment and policy formulation. 相似文献
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根据聊城市1949-2007年的耕地数据,以耕地变化率来描述耕地数量变化的速率,借助Fisher最优分割法将耕地变化率状态分为5个等级,利用规范化后的各阶自相关系数为权重,运用加权马尔可夫链模型对聊城市耕地需求量进行预测。结果表明,预测值与实际值的相对误差为0.01%,预测结果非常理想,同时也验证了加权后的马尔可夫预测法更具科学性和实用性。 相似文献