双天线干涉实验中的数据处理

主要根据我们实现的相关函数的获取方式，讨论对数据后处理的理解。     

Mapping of Regional Soil Salinities in Xinjiang and Strategies for Amelioration and Management

Information on the spatial distribution of soil salinity can be used as guidance in avoiding the continued degradation of land and water resources by better informing policy makers. However, most regional soil-salinity maps are produced through a conventional direct-linking method derived from historic observations. Such maps lack spatial details and are limited in describing the evolution of soil salinization in particular instances. To overcome these limitations, we employed a method that included an integrative hierarchical-sampling strategy(IHSS) and the Soil Land Inference Model(So LIM) to map soil salinity over a regional area. A fuzzy c-means(FCM) classifier is performed to generate three measures, comprising representative grade, representative area, and representative level(membership). IHSS employs these three measures to ascertain how many representative samples are appropriate. Through this synergetic assessment, representative samples are obtained and their soil-salinity values are measured. These samples are input to So LIM, which is constructed based on fuzzy logic, to calculate the soil-forming environmental similarities between representative samples and other locations. Finally, a detailed soil-salinity map is produced through an averaging function that is linearly weighted, which is used to integrate the soil salinity value and soil similarity. This case study, in the Uyghur Autonomous Region of Xinjiang of China, demonstrates that the employed method can produce soil salinity map at a higher level of spatial detail and accuracy. Twenty-three representative points are determined. The results show that 1) the prediction is appropriate in Kuqa Oasis(R2 = 0.70, RPD = 1.55, RMSE = 12.86) and Keriya Oasis(R2 = 0.75, RPD = 1.66, RMSE = 10.92), that in Fubei Oasis(R2 = 0.77, RPD = 2.01, RMSE = 6.32) perform little better than in those two oases, according to the evaluation criterion. 2) Based on all validation samples from three oases, accuracy estimation show the employed method(R2 = 0.74, RPD = 1.67, RMSE = 11.18) performed better than the multiple linear regression model(R2 = 0.60, RPD = 1.47, RMSE = 14.45). 3) The statistical result show that approximately half(48.07%) of the study area has changed to salt-affected soil, mainly distributed in downstream of oases, around lakes, on both sides of rivers and more serious in the southern than the northern Xinjiang. To deal with this issue, a couple of strategies involving soil-salinity monitoring, water management, and plant diversification are proposed, to reduce soil salinization. Finally, this study concludes that the employed method can serve as an alternative model for soil-salinity mapping on a large scale.     

一致性哈希算法在数据库集群上的拓展应用

在数据库集群的研究中,可扩展性是一个重要的性能指标。为实现在数据高速增长或部分集群服务器故障情况下,数据依然能够快速、可靠、安全的分布到新的集群服务器节点上的目的,就必须合理设置数据划分的策略。将Key-Value存储技术中使用的一致性哈希算法思想借鉴运用到并行分析型数据库集群中,提出针对大规模结构化类特殊数据的一致性哈希划分方法,并在MapReduce框架下设计具体的数据划分方案。最后,以TPC-DS作为测试基准,与同类系统进行性能对比测试,实验结果表明方案不仅有良好的划分性能,且扩展性也较好。     

一致性哈希算法在数据库集群上的拓展应用

在数据库集群的研究中,可扩展性是一个重要的性能指标.为实现在数据高速增长或部分集群服务器故障情况下,数据依然能够快速、可靠、安全的分布到新的集群服务器节点上的目的,就必须合理设置数据划分的策略.将Key-Value存储技术中使用的一致性哈希算法思想借鉴运用到并行分析型数据库集群中,提出针对大规模结构化类特殊数据的一致性哈希划分方法,并在MapReduce框架下设计具体的数据划分方案.最后,以TPC-DS作为测试基准,与同类系统进行性能对比测试,实验结果表明方案不仅有良好的划分性能,且扩展性也较好.     

南渡江河口洪、枯季节水文泥沙变化特征及台风“海鸥”对入海水沙的影响

基于2014年最新的洪、枯季节实测资料,分析了南渡江河口海域水文泥沙的季节性变化特征,借助台风"海鸥"过境期间的河道监测数据,研究了台风天气造成的洪水事件对河流入海水沙通量的影响。研究结果表明:(1)洪、枯季节河口海域的水体层化作用不强,洪季的水温高于枯季,但盐度低于枯季。水温呈现向海递减的趋势,而盐度整体分布较为均匀;(2)河口水体含沙量近岸大于远岸,枯季河口三角洲泥沙向西输运。洪季含沙量明显高于枯季,大量泥沙在台风季节被冲刷入海,而后向海或向西输运扩散;(3)河口海域为不规则全日潮,呈现东西向往复流特征。温度、盐度和浊度均呈现较强的潮汐性变化特征;(4)枯季河道内存在明显的盐水楔,锋面处的垂向梯度很大,在口门向陆大约12—15 km以远的河道水体不再受潮汐影响;(5)台风"海鸥"影响下,南渡江洪峰期间的径流量和含沙量均远远超过多年平均值,反映了南渡江河口地区"台风季节"的特点。     

海洋初始状态对预报2002/03年中太平洋型厄尔尼诺事件的作用

2002/03年厄尔尼诺事件,是暖海温中心出现在赤道中太平洋区域的一种新型厄尔尼诺,即中太平洋型厄尔尼诺。本文基于一个厄尔尼诺预测系统,利用三组回报试验来详细区分海洋表层和次表层初始状态对预报2002/03年中太平洋型厄尔尼诺事件的作用,并由此来探寻对预报厄尔尼诺演变过程最有利的初始条件。回报试验分为三组:(1)仅同化海表温度观测(sea surface temperature;简称SST)来优化海洋表层初始状态(Assim_SST);(2)仅同化海表高度观测(sea level;简称SL)来更新海洋次表层初始状态(Assim_SL);(3)同时同化SST和SL观测来一起更新海洋表层和次表层初始状态(Assim_SST+SL)。回报试验结果表明,三种不同的初始条件都可以使模式提前一年成功地预报2002/03年厄尔尼诺事件,并且"Assim_SST+SL"回报试验的效果最好。三组回报试验结果间的对比表明:海洋表层和次表层初始状态均对成功地预报该事件有重要作用,但其作用分别集中在事件发展的不同阶段。精确的海洋表层初始状态更容易激发模式预报出一次厄尔尼诺事件,而更合理的海洋次表层初始状态则能有效地提高厄尔尼诺事件预报的强度。     

极地深海冰盖条件下声传播数值试验

研究极地深海声传播特征具有重要的经济、军事价值,战略意义重大。基于KRAKENC分层弹性介质简振波模型对极地深海冰盖条件下的声传播特征进行数值模拟,得出极地海域向上折射环境和较小深度声源,是形成声道现象必要条件;冰盖的散射作用导致声传播衰减强烈,且深度越大的水层受冰盖影响越小,受海底边界影响越大;声源深度越小,受冰盖影响越大。     

调和分析方法在海洋磁力测量日变改正中的应用

针对海洋磁力测量数据处理中面临的磁扰期间的日变改正问题,基于傅立叶级数建立了日变数据处理谐波分析模型;通过应用于大批量实测日变数据处理,确定了谐波截断次数,实现了日变基值、平静日变改正和磁扰改正的合理分离。     

Impacts of the two types of El Niño on Pacific tropical cyclone activity

It is well known that Tropical cyclone(TC) activities over the Pacific are affected by El Nino events. In most studies El Nino phenomena have been separated into east Pacific warming(EPW) and central Pacific warming(CPW) based on the location of maximum SST anomaly. Since these two kinds of El Nino have different impacts on Pacific tropical cyclone activities, this study investigates different features of TC activities and the genesis potential index(GPI) during EPW years and CPW years. Four contrib- uting factors, i.e., the low-level absolute vorticity, the relative humidity, the potential intensity and the vertical wind shear, are exam- ined to determine which factors are most important in causing the anomalous TC activities. Our results show that during EPW years in July–August(JA0), TC activities are more frequent with stronger intensity over the Western North Pacific(WNP) and Eastern North Pacific(ENP). The maximum anomaly center of TC activities then drifts eastward significantly in September–October(SO0). However, centers of anomalous TC activity barely change from JA0 to SO0 during CPW years. In January–February–March(JFM1) of the decaying years of warming events, TC frequency and intensity both have positive anomaly over the South Pacific. The anoma- lies in EPW years have larger amplitude and wider spatial distribution than those in CPW years. These anomalous activities of TC are associated with GPI anomaly and the key factors affecting GPI anomaly for each ocean basin are quite different.     

模糊综合评判法在多层气层测试井产能劈分中的应用

多层测试井的产能劈分是油气藏勘探开发中的一个关键问题。影响产能的储层参数很多,不同的物性参数对储层产能影响的大小不同;模糊系统理论将综合评价的定性问题转化为定量问题,层次分析法将不同因素按照相关性大小计算其权值。利用综合评价系数对多层试气中的小层进行综合评判和优选,进而对产能进行合理劈分。给出了评价因素对等级区间隶属度的求取方法以及不同因素之间相对权值的计算方法。通过实例给出了模糊综合评判法进行产能劈分的原理和具体步骤,进一步验证了该方法在鄂尔多斯盆地苏里格气田的应用效果。