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931.
Yiqian Jiang Chi Zhang Zhenjiang Ye Binduo Xu Yongjun Tian Yoshiro Watanabe 《中国海洋大学学报(英文版)》2020,19(2):446-452
The Japanese Spanish mackerel Scomberomorus niphonius(Cuvier,1832)is widely distributed in the subtropical and temperate waters of the northwestern Pacific Ocean,supporting one of the most important commercial fisheries in China.However,ignoring the potential population structure changes induced by fishing pressure and climate change may undermine the population stability under the current management strategy.In this study,the population structure of the Japanese Spanish mackerel was investigated based on a morphometric truss network system.A total of 534 individuals were randomly collected from commercial gill nets spanning eight major spawning grounds in the Bohai,Yellow,and East China Seas during the peak spawning seasons respectively.A total of 17 measurements(including eye diameter)were conducted in each specimen and subjected to principal component analysis(PCA)and discriminant function analysis(DFA).The results of PCA indicated that the first two factors cumulatively caused 78.38%of the total morphometric variation and observable differences,primarily fin the caudal and trunk areas.The results of DFA revealed that the eight spawning groups can be divided into three stocks,i.e.,southern,middle,and northern stocks,with 68.7%of total accuracy.In contrast to previous studies,the spawning groups of the Japanese Spanish mackerel demonstrated a tendency to disperse to northern regions.In conclusion,this study found that to maintain the stability of the population structure and the total production of Japanese Spanish mackerel S.niphonius(Cuvier,1832),a newly revised management method should be developed and implemented. 相似文献
932.
By sampling in the field and analyzing the soil samples in the laboratory in 1982 and 2005 the soil fertility data were obtained.
Through application of geo-statistics combined with GIS, the temporal–spatial variability of the pH, organic matter, total
nitrogen, total phosphorus and total potassium in soil of Xiaojiang watershed from 1982 to 2005 were analyzed. Results showed
that: (1) the pH value and total potassium in soil showed an increasing trend, but the organic matter, total nitrogen and
the total phosphorus in soil declined in the past 20 years in Xiaojiang watershed, (2) the parameters fitted by semivariogram
models for fertility indices changed significantly in the past 20 years and (3) the result estimated by ordinary Kriging indicated
the spatial pattern of the soil fertility indices changed significantly in the past 20 years. The soil pH increased in the
east and southeast, but decreased in the middle of the watershed. The organic content of the soil matter decreased in the
east, southeast and southwest, but increased in the northeast and middle of the watershed. The total nitrogen content of the
soil decreased in the east, but increased in the middle of watershed. The total phosphorus content of the soil decreased in
the whole watershed. The total potassium content of the soil increased in the southwest and southeast, but decreased in the
middle of the watershed and (4) the change of land use and soil management measures was the main driving force of variability
of soil properties. 相似文献
933.
地下小尺度散射体的检测和识别对于提高地震勘探的分辨率具有重要意义,目前业界普遍采用绕射波分离及成像方法检测地下散射体,而绕射波成像的质量主要取决于绕射波和反射波波场分离的程度.本文将被动源震源定位问题中常用的时间反转原理引入到地下散射体检测中,首先通过分析被动源和主动源模型反传波场的聚焦状态,验证了时间反转原理应用于地下散射体检测中的可行性;并引入机器学习中的朴素贝叶斯分类算法,给出适用于时间反转散射体检测的分类算法框架,计算模型中每个点成为散射体的概率,最终检测出地下散射体最有可能存在的位置.散射体模型和Sigsbee2a模型的试算结果证实了本文方法在不需对反射波和绕射波分离的情况下,即可实现对地下散射体的检测和定位,同时由于考虑了多次散射的影响,检测结果能准确反映地下散射体的位置. 相似文献
934.
935.
SRTM高程数据辅助的国产卫星长条带影像匹配 总被引:1,自引:0,他引:1
针对国产卫星数据特点及长条带影像匹配困难问题,提出了一种基于全球SRTM数据的影像匹配方法。本文探讨了长条带影像物理分块机制,并引入LBP/C算子实现了兴趣点的筛选。在全球SRTM数据的辅助下,采用投影轨迹法,建立了近似核线方程。沿核线方向,进行局部畸变改正,进而消除匹配窗口的几何变形与辐射差异,利用金字塔匹配策略,逐层进行相关匹配。最后,在原始层引入MPGC(Multi-photo Geometrically Constrained Matching)算法与RANSAC(Random Sample Consensus)算法,进行精化匹配,并剔除误匹配点。文中综合运用了小面元几何纠正法与基于控制网的匹配生长算法,从而提高了匹配点的精度与均匀性。本文方法可在并行环境下全自动实现不同分辨率、不同视角、不同时相的多轨道长条带影像匹配,获得高精度的同名点观测值。以天绘一号与资源三号卫星影像作为试验数据,与现有匹配算法进行对比结果表明该算法具有较好的鲁棒性,能够达到较高的匹配精度。 相似文献
936.
This paper presents a component object model (COM) based framework for managing, analyzing and visualizing massive multi-scale digital elevation models (DEMs). The framework consists of a data management component (DMC), which is based on RDBMS/ORDBMS, a data analysis component (DAC) and a data render component (DRC). DMC can manage massive multi-scale data expressed at various reference frames within a pyramid database and can support fast access to data at variable resolution. DAC integrates many use-ful applied analytic functions whose results can be overlaid with the 3D scene rendered by DRC, DRC provides view-dependent data paging with the support of the underlying DMC and organizes the potential visible data at different levels into rendering. 相似文献
937.
938.
邸艳 《测绘与空间地理信息》2013,(1):180-182
结合辽宁省低丘缓坡调查工程,简单论述了ArcMap软件在构建TIN、合TIN、裁TIN方面的应用和如何保证数据的质量。 相似文献
939.
基于日降雨量的年均降雨侵蚀力估算模型及其应用——以四川省凉山州为例 总被引:2,自引:0,他引:2
为提高连续性降雨强度、降雨量、雨滴动能等数据缺乏地区修正通用土壤侵蚀方程(RUSLE)的计算精度,提出了针对我国西南地区基于日降雨的年均降雨侵蚀力估算模型。进而RUSLE与GIS技术结合,剖析了四川省凉山州的土壤侵蚀空间分布特征。研究表明,四川省凉山州西北部土壤侵蚀较轻,东部和南部侵蚀较高,特别是金沙江干流沿岸、雅砻江下游、黑水河和美姑河等流域侵蚀最为严重。结合土地利用和坡度分析,凉山州>6°的旱地土壤侵蚀最严重,而林地和草地土壤侵蚀的强弱主要取决于植被覆盖程度。 相似文献
940.
1 INTRODUCTION Nitric oxide (NO), a highly free radical gas, is recently discovered as messenger molecule involved in different cellular and developmental events including cell proliferation, differentiation and apoptosis as well as neural pathfinding and synapse formation. NO is synthesized from amino acid L-arginine by catalytic action of a family of isoen-zymes called nitric oxide synthases (NOS) (Palmer, 1988). NOS require nicotinamide adenine dinucleo-tide phosphate (NADPH) as a… 相似文献