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Search Results: 1 - 10 of 71344 matches for " 郑小慎 "
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基于频繁特征项集的文档聚类研究

计算机应用 , 2006,
Abstract: ?提出了基于频繁特征项集的文档聚类方法。对预处理后的文档,通过apriori算法找出文档频繁特征项集,依据其子集中频繁特征词语对相关文档进行聚类,该方法能够有效降低特征项的维数,并能够通过频繁特征词语集合对聚类后的类别进行适当的描述。
1984~2013年间曹妃甸海岸线变迁分析
Analysis of Coastline Changes in Caofeidian from 1984 to 2013
 [PDF]

张贺,
Open Journal of Nature Science (OJNS) , 2016, DOI: 10.12677/OJNS.2016.43033
Abstract:
针对海岸带作为海洋与陆地过渡地带,是全球变化非常敏感的地带。研究海岸线变化及其驱动因素对于了解海岸带生态环境变化具有重要意义。本文以多时相Landsat MSS/TM/ETM影像为主要数据源,在ENVI和GIS中利用Sobel算法人机交互提取海岸线,对1984年~2013年间的海岸线演变进行时空分析并生成岸线动态变化图。结果表明:曹妃甸区域海岸线不断向海内扩张,其变化主要是人为的填海造陆的结果。在人类活动的作用下,海岸特征也发生了变化,自然海岸逐渐转化为人工海岸。
The coastal zone is the transition zone of marine and land, and it is very sensitive to global change. Researching the coastline change and its driving factors is of great significance for us to understand the change of coastal zone ecological environment. This article interactively extracted coastlines by Sobel algorithm in ENVI and GIS, took a spatio-temporal analysis of the coastline from 1984 to 2013 and generated dynamic changes of coastline maps. The results show that the shoreline of Caofeidian is keeping the domestic expansion, and the change is largely the results of man-made land reclamation. Under the influence of human activity, coastal features have also changed, and nature coast is gradually converted into artificial coast.
渤海湾春季水体光谱特征分析
Analysis of Water Spectral Characteristics of Bohai Bay in Spring
 [PDF]

刘春琳, , 刘文岭, 刘燕钦
Adances in Marine Sciences (AMS) , 2015, DOI: 10.12677/AMS.2015.23006
Abstract:
基于2011年5月渤海湾典型站点的CTD观测数据和实测光谱数据分析了渤海湾的水体光谱特性。通过对比实测站位水体光谱和温度、盐度、密度、光合有效辐射和叶绿素浓度在水体中的分布状况,分析了海洋环境要素对水体光谱特性的影响。结果表明在510~620 nm光谱范围内,水体光谱辐射峰的高度由叶绿素浓度和光合有效辐射共同作用决定;在380~440 nm和705~800 nm波长范围水体光谱辐射峰的高度不仅受叶绿素浓度和光合有效辐射影响,还受其他环境要素影响。
Based on the CTD data and the measured spectral data of Bohai Bay in May, 2011, the water spec-tral characteristics of typical survey stations are analyzed. In this paper, the effects of marine en-vironmental elements on the spectral properties of the water body are analyzed by comparing water spectra and the distribution of temperature, salinity, density, photosynthetic active radiation and chlorophyll concentration of Bohai Bay. The results showed that the water body spectral radiation peak height is determined by the chlorophyll concentration and photosynthetic active radiation interaction in the 510 - 620 nm spectral range, but it is determined not only by the chlo-rophyll concentration and photosynthetic active radiation interaction, but also by other environ-mental factors in the 380 - 440 nm and 705 - 800 nm spectral range.
基于MODIS数据反演的渤海叶绿素浓度时空变化
钱莉,刘文岭,
海洋通报 , 2011, DOI: 10.11840/j.issn.1001-6392.2011.6.015
Abstract: 采用离散时间功率谱、距平、滑动平均等统计学方法分析了MODIS反演得到的渤海海域2002-2009年叶绿素浓度的时空变化特征。结果表明,叶绿素浓度多年月平均值的波峰出现在2-3月份,波谷在7月份。叶绿素多年平均值近海明显高于外海,由近海往外递降,最低值出现在渤海海峡和北黄海口附近。通过对叶绿素浓度多年月距平值进行离散时间功率谱的分析并进行F检验,能通过95%显著性检验有7.5年和2.5年两个显著性变化周期。2003-2009年间叶绿素浓度差值图像的空间分布表明,2006年整个渤海海域叶绿素浓度高于7年均值。
Documents clustering based on frequent term sets
基于频繁特征项集的文档聚类研究

ZHENG Xiao-shen,

计算机应用 , 2006,
Abstract: 提出了基于频繁特征项集的文档聚类方法。对预处理后的文档,通过Apriori算法找出文档频繁特征项集,依据其子集中频繁特征词语对相关文档进行聚类,该方法能够有效降低特征项的维数,并能够通过频繁特征词语集合对聚类后的类别进行适当的描述。
基于水色遥感的黄、东海叶绿素a浓度季节和年际变化特征分析
,魏皓,王玉衡
海洋与湖沼 , 2012, DOI: 10.11693/hyhz201203036036
Abstract: 海洋叶绿素a浓度是衡量海洋浮游植物的生物量和富营养化程度的最基本指标之一。黄、东海叶绿素a浓度年际变化显著, 其影响因素需深入分析。本文依据黄、东海的地理位置、水深和生态特征将其分为5个区域进行研究。由5个区域叶绿素a浓度的季节变化可以看出, 水华发生早晚依次是黄海西岸—北黄海中部—南黄海中部—东海陆架区—东海近岸海区。从年际变化可以看出, 除东海陆架外, 其它4个区域的变化幅度均较大。在冬季和夏季, 5 个区域的基础生物量在2008年均达到最低; 在春季和秋季, 黄、东海近岸和北黄海中部的年际变化较大, 5 个区域在2006年春季均达到最高; 2009年秋季较其它年份均低。5个区域基础生物量由高到低为: 黄、东海近岸较高, 然后是北黄海中部和南黄海中部, 东海陆架最低。从与水温、风速和有效光合辐射的相关分析来看, 浮游植物生长的年际变化受海面风速的影响较大。近岸区域水体混合均匀, 营养盐丰富, 风速较小时水体稳定有利于浮游植物生长, 而水深较深区域, 风速较大时, 营养盐易补充到表层, 有利于浮游植物生长。
SEASONAL AND INTER-ANNUAL VARIATIONS OF CHLOROPHYLL-a CONCENTRATION BASED ON THE REMOTE SENSING DATA IN THE YELLOW SEA AND EAST CHINA SEA
基于水色遥感的黄、东海叶绿素a浓度季节和年际变化特征分析

ZHENG Xiao-Shen,WEI Hao,WANG Yu-Heng,
,魏 皓,王玉衡

海洋与湖沼 , 2012,
Abstract: Inter-annual variability of chlorophyll-a concentration was significant in the Yellow Sea (YS) and the East China Sea (ECS). According to the geographical location, water depth and ecological characteristics, the YS and ECS were divided into five sub-regions. Seasonal variations of chlorophyll-a concentration indicated the phytoplankton bloom in these sub-regions occurred first in YS-coast, then subsequently in NYS-center, SYS-center, ECS-shelf, and finally in ECS-coast. Inter-annual variations of chlorophyll-aconcentration in four of the sub-regions were large, except in ECS-shelf. In winter and summer, the average chlorophyll-a concentration of the five sub-regions all reached the minimum values in 2008. In spring, the average chlorophyll-a concentration of the five sub-regions reached the maximum in 2006. In autumn, the values in 2009 were lower than in other years. The biomass in YS-coast was the highest, followed by in ECS-coast, in NYS-center, in SYS-center, and in ECS-shelf. The main factor affecting the inter-annual variation of phytoplankton was wind. In shallow coastal waters where nutrients were rich, low wind speed and increased stability of water column were favorable for the growth of phytoplankton. In deep open ocean waters, high speed wind brought nutrients to the surface and thus helped the growth of phytoplankton.
神光ⅲ原型受激拉曼与受激布里渊散射份额测量
李志超,,杨冬,,,丁永坤,李三伟,蒋小华,王哲斌,章欢
强激光与粒子束 , 2010,
Abstract: ?激光注入率测量是黑腔耦合效率测量至关重要的一个环节,主要通过散射光测量来实现。在神光ⅲ原型激光装置上进行的黑腔物理实验中,利用pin探头阵列进行了散射光角分布测量。通过拟合分析,发现原型装置上激光等离子体非线性相互作用较神光ⅱ装置要强,其中受激拉曼份额在10%量级,受激布里渊散射在20%量级。将由此评估的激光靶耦合效率代入辐射温度定标率公式中,得出的辐射温度值与实验中dante测量值符合较好,说明对参量过程份额的评估具有一定可靠性。
有机溶剂、表面活性剂及NaCl对对二氯苯在水中活度系数的影响
,,王连生
环境化学 , 2015,
Abstract: 本文利用气相色谱法测定了对二氯苯在不同组成的水溶液体系中的活度系数,其中包括二组份与三组份共溶剂体系、表面活性剂-水体系与NaCl-水体系。实验结果表明对二氯苯在二组份和三组份共溶剂体系中的活度系数的对数值与各组份的体积分数之间有线性加和关系;表面活性剂在达到临界胶束浓度以上时,可显著降低对二氯苯在水中的活度系数;对二氯苯在NaCl水溶液中的活度系数与NaCI的含量之间成正比关系。作者还利用UNIFAC法估算了对二氯苯在各种共溶剂体系中的活度系数,所得估算值与测定值相接近。
混沌时间序列的LSSVM预测方法
,李钟
华侨大学学报(自然科学版) , 2014, DOI: 10.11830/ISSN.1000-5013.2014.04.0373
Abstract: 结合相空间重构理论,提出运用最小二乘支持向量机(LSSVM)建立混沌时间序列的预测模型,并用粒子群优化(PSO)解决LSSVM参数寻优的问题.通过与RBF神经网络构建的预测模型相比较,计算预测模型的均方根误差来评价模型的性能.结果表明:采用PSO优化的LSSVM预测模型的预测精度更高.
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