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951.
952.
高速网上3维海量地形数据的实时交互浏览的实现   总被引:13,自引:2,他引:13  
针对高速网上3维海量地形数据传输和显示特点,提出了一套海量地形数据处理、存储方法,包括数据的预处理和数据的存储结构,数据存储有利于高速网络访问;并根据人的视觉生理特征,提出了一种多分辨率地形表示模板形成,较好地处理了实时交互游览地形的真实感和巨大数据需求之间的冲突。设计了一种适合网络实时传输海量地形数据的传输协议,使系统充分利用网络带宽同时又不浪费带宽。通过在中国高速互联试验网络NFSCNet上的大量演示,表明所提出的技术方案是切实可行的,证明了高速网对3维海量地形实时交互浏览的必要性和可行性。  相似文献   
953.
通过对比分析2003年以来6种气象无人机起飞和5种降落方式的飞行测试,得出30Kg以下无人机的起飞和降落方式对场地的要求,以及优点和不足;试验证明,弹射起飞和伞降与滑降相结合的回收方式在民用领域中适应性最好,可广泛用于我国的山地、丘陵和平原地形环境,是经济性、安全性俱佳的小型无人机起降方式。  相似文献   
954.
955.
Using the Celtic Sea and the North Sea as case studies, the fleet-based approach is shown to be the pathway to implement an effective ecosystem approach to fisheries management (EAFM) in European seas. First, a diagnostic on the health of each ecosystem is proposed based on the reconstruction of long time-series of catch, the analysis of mean indicators or stocks trajectories derived from ICES stock assessment results, and the analysis of ecosystem indicators. Then, a fleet-based synthesis is presented using indicators of both the ecological impact and the economic performances of the major fleets operating within each ecosystem. In particular, assessment diagrams show whether each fleet segment, on average, sustainably exploits the stocks. Although results are preliminary due to the poor quality of available data, the analysis shows that simple indicators can be estimated and clearly highlight contrasts between fleet segments. Such an approach contributes to the evolution from a stock-based to a fleet-based management, which reflects the ecological, economical and social pillars of the sustainable development of fisheries.  相似文献   
956.
Tropical coastal and marine social–ecological systems (CM-SESs) differ from other social–ecological systems through the higher degree of risk and uncertainty associated with coastal and marine resource extraction, the dynamic nature of aquatic and human resources, and often unclear tenure. CM-SES resource management and poverty-alleviation strategies must be adaptive and holistic. The Sustainable Livelihoods Approach (SLA) provides a framework for understanding and guiding policy-making in CM-SES. Case studies from the past 10 years analyze tropical coastal and marine-resource dependent livelihoods and/or to evaluate current CM-SES management using the SLA. These studies have shown that, despite the rounded and inclusive approach of projects such as the Sustainable Fisheries Livelihoods Programme, key challenges for researchers and practitioners remain including rights and access allocation, corruption, lack of local financial, intellectual and innovative capacity and centralized governance. Whilst the SLA may increase understanding of local-level dynamics within CM-SES, more consultation at interdisciplinary frontiers is needed in order to formulate practical solutions to the core problems of tropical CM-SES management.  相似文献   
957.
Management of fish populations is often focused on the exploitation of adult fish. Maintaining the habitat requirements of all life stages may also be an important consideration. We investigated the value of structured habitat to juvenile fishes within a northeastern New Zealand harbour using artificial seagrass units (ASUs). Specifically, we deployed ASUs across treatments with high vs. low habitat manipulations. We hypothesised that if the abundance of recruiting juvenile fishes was greater on the high habitat availability treatments this would suggest that the availability of habitat was limiting juvenile fish abundance. Our analyses were focused on the four most abundant fishes that settled on our ASUs: snapper (Pagrus auratus); spotty (Notolabrus celidotus); trevally (Pseudocaranx dentex); and an assemblage of pipefish species. For snapper, spotty and pipefish, abundance was greater on the high habitat availability treatments. This result would be unlikely to occur if the availability of juvenile fishes was limiting, suggesting that juvenile fish abundance is more likely to be limited by habitat. In terms of spatial gradients, spotty abundance and size increased with distance into the harbour. The spatial gradient present for spotty indicates the importance of placing the habitat dependency of juvenile fish into a landscape context. Overall, these results demonstrate that maintaining structured habitats may be an important consideration for some valuable inshore fish populations in northeastern New Zealand.  相似文献   
958.
提出了一种基于分层思想的自适应数据滤波方法。该方法采用迭代选权方法的基本思想,在实现中加入了自适应与分层的思想,使其也可用于处理城区点云数据。提出了滤波方法评价体系,并对该滤波方法进行了评价。  相似文献   
959.
The introduction of the Single Aliquot Regenerative Dose (SAR) protocol established luminescence dating as an indispensable tool in Quaternary research. A major impediment of this technique is the time required for measurements, since the protocol is repeated for various aliquots of each sample to establish a sound statistical basis. To reduce the demand on machine time, Standardised Growth Curve (SGC) approaches have been developed and successfully applied for samples from some regions. However, differences in luminescence properties require careful testing of this techniques when applied to samples with other geological background.In this study, the application of the SGC approach of Li et al. (2016) is successfully verified for multi-grain aliquots of coarse-grained quartz and feldspar samples from three sites in northern Switzerland. In-depth quality control measures ensure the reproducibility of equivalent dose (De) values obtained by the common SAR protocol and sample-specific SGCs. For both minerals little sensitivity was found to the re-normalisation dose and the sample-specific SGCs performed well. In contrast to other studies, no different types of dose response curve shape were observed for quartz. A minimum number of full SAR measurements of eight and six aliquots per sample has been found appropriate for quartz and feldspar, respectively. For the fading corrected feldspar signals, site-specific SGC worked well and De values of up to 800 Gy were consistently replicated.In summary, sample-specific SGCs for samples from northern Switzerland perform well and their application reduces measurement times by up to 70%. The construction of a regional SGC may well be beneficial, however, caution regarding the choice of given doses and curve fitting is recommended and a thorough verification of SGC results is needed before the technique is widely applied.  相似文献   
960.
詹美旭  刘倩倩  黄旭  李琬  王建军 《地理科学》2021,41(10):1718-1728
首先探索了城市体检治理的新模式,明确了涵盖“市?区?镇街?社区”不同尺度行政主体纵向传导、横向联动的规范化城市体检组织模式。其次,基于“指标设计?征求意见?指标筛选?指标确认”4个步骤完善城市体检指标体系,提出了数据收集的标准化、模块化工作思路。再次,城市体检的指标评价应坚持多维度、差异性、定量定性相结合等原则,以六维分析法为基础对城市问题进行识别与诊断。另外,城市体检的公众参与过程需要充分体现市民的知情权、参与权和监督权。城市政府需要搭建市民深度参与的常态化、共治型治理平台,各部门需要以问题为导向,开展协同式、全周期系统治理,最终推动建立全社会共建共治共享的常态化工作机制。  相似文献   
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