基于LSTM的海洋表面短期风速预测研究

为实现对海面风速精确的短期预测,提出了一种基于长短期记忆(LSTM,longshort-termmemory)神经网络的短期风速预测模型,选取OceanSITES数据库中单个浮标站点采集的风速历史数据作为模型输入,经过训练设置最佳参数等步骤,实现了以LSTM方法,对该站点所在海区海面风速在各季节性代表月份海面风速的24 h短期预测。同时通过不同预测时长的实验以及与BP(back propagation)神经网络神经网络和径向基函数神经网络(radialbasisfunctionneuralnetwork,RBF)的预测效果对比实验,证明了LSTM预测方法相比上述两种神经网络预测方法,在海表面风速预测应用中的优越性。最后通过多个海域对应的站点风速数据预测实验,证明了LSTM神经网络模型的普遍适用性,由相关系数和预测误差的分析可知该方法具备应对急剧变化数据的预测稳定性,可以作为海洋表面风速短期预测的一种可靠方法。     

基于Java Applet的网络地图服务平台设计与实施

网络地图平台设计是数字地图应用的一个重要发展方向。作者着重论述了采用Java Applet建立网络地图服务平台的实现思路、基本框架、数据组织及系统实施的关键技术,在此基础上介绍了地图发布软件的基本功能设计、结合COM组件技术实现公交换乘功能设计、界面设计等,最后给出具体实例。     

基于我国农村经济改革与农民收入变化的新农村建设实质分析

本文通过探讨我国1949 年以来三次重要农村经济改革及其对我国农民收入变化的影 响, 明晰我国农村经济改革与农民收入三起三落的相互关系以及农村经济发展过程中存在的相 关问题: (1)每次改革都发生在农村经济发展停滞不前, 甚至影响到全国经济发展之时; (2)每次农 村经济改革都带来了农村经济的快速发展, 但持续时间不长, 且随之而来的是农民负担过重, 农 村经济陷入困境; (3)农民收入增长的幅度略有下降。本文认为新农村建设是我国1949 年以来三 次农村经济改革的延续, 基于已有三次改革以及新农村建设提出背景的分析, 指出: (1)农村经济 发展现状再一次提出了对农村经济改革的需求; (2)土地改革、家庭联产承包责任制属开源之策; 税费改革属节流之需; 新农村建设应该是在市场经济背景下, 从根本上实现广开财源之举。基于 以上分析并借鉴国外农村建设的经验, 阐释新农村建设的实质, 从而就我国新农村建设提出相关 建议。     

基于空间自相关的闽台城镇建设用地分布研究

空间自相关是一种重要的空间统计方法, 用来检验某种地理现象或某一属性值的整体分 布状况, 判断此现象或属性值在空间上是否有聚集特性存在。本文利用2002 年ASTER 影像数据 作为遥感数据源提取闽台建设用地信息, 闽台建设用地密度的分布呈现出沿台湾海峡呈对称集 聚分布的态势。通过建设用地密度的空间自相关分析, 显示闽台建设用地空间分布整体上呈显著 的空间正相关, 集聚现象明显; 而在局部上则呈现出不同的空间结构形态, 建设用地高密度区主 要集聚分布在闽东南沿海的闽江口、厦门湾和泉州湾三大城镇密集区及台湾西部的台北、台中和 高雄三大都会区。这种空间相关关系的探讨对于认识闽台人口和社会经济的空间分布及福建省 建设用地未来的发展具有重要的意义, 也对福建省社会经济发展政策的制定提供重要参考依据。     

极端干旱荒漠区典型晴天大气热力边界层结构分析

利用极端干旱区敦煌野外观测试验资料,分析了极端干旱荒漠区夏季典型晴天位温、风速、比湿等主要物理要素的垂直结构特征及其地表热力和近地层大气运动特征的日变化规律。发现在极端干旱地区夏季晴天大气热力边界层结构十分独特。在夜间,贴地逆温层最低在900 m以上,最厚可以达到1 750 m,逆温层上面的残余层一般能达到4 000 m左右的高度。在白天,位温超绝热递减层高达1 000 m,超绝热递减层上面的混合层最高达3 700 m,混合层顶上还有大约450 m甚至更厚的夹卷层。当白天对流层发展达到残余层以后,混合层的发展明显加快。风速和比湿垂直廓线特征很好地印证了大气热力边界层独特的结构特征,地表热力和近地层大气运动特征也为这种独特的大气热力边界层结构提供了较好的物理支持。     

鲅鱼圈地区污染气象特征分析

利用近3a的鲅鱼圈地区地面常规气象资料和2005年3～4月鲅鱼圈地区低空污染气象探测资料,分析了鲅鱼圈地区低空污染气象特征。结果表明:鲅鱼圈地区各类型风速廓线出现频率比较均匀,而且由于地面粗糙度较大,因此风速廓线指数比平原地区稍大。     

Engineering characteristics and uses of duricrusts in Australia

The uses and shortcomings of duricrusts (ferricrete, calcrete and silcrete) in engineering construction (as used for road‐base, aggregate, foundation materials and aquifers) are reviewed. Australian production of these materials represents about one‐third of all unprocessed road‐base and they are especially important as pavement courses for lightly trafficked, low‐cost rural and outback roads. However, duricrusts are regarded as marginal materials at best because of their typically poor grading, particle unsoundness, high fines plasticity, and absorption of water and bitumen. These materials are used because they are available locally in areas that are otherwise lacking in hard rock materials, such as deeply weathered and sedimentary rock terrains. The weathering profiles of which they form part are characterized by high permeability (despite being clay‐rich), variable cementation, low compressibility and a tendency to become weaker with depth. Although the more indurated layers are unrippable, they are also difficult to blast. Pedogenic (nodular) duricrusts were formerly sought for natural road‐base, because they occur widely and require only rudimentary processing. However, well‐cemented groundwater (vadose) duricrusts are now the preferred deposits, even though they require crushing and screening. Ferricrete is the most widely exploited of the duricrusts for engineering purposes, especially in northern and southwestern Australia, although calcrete is important in South Australia and in the Murray Basin. Silcrete is only a minor source of aggregate and road‐base, mainly in western Queensland.     

Historical development of the saltmarsh at Wells,Maine

Comparisons of maps and aerial photographs dating from the late 1700s to the present document the recent development of an 8 km² saltmarsh that is situated behind a barrier spit in southern Maine. Tidal channels that were relatively narrow in 1794 became wider by 1872. The reduction of marsh bordering tidal channels is interpreted as evidence that marsh accretion could not keep pace with rising sea-level. This suggests that the rate of sea-level rise had increased, although a change in discharge or sediment load caused by extensive settlement and land clearance may also have been involved. Meander patterns of the tidal streams changed considerably throughout the time period covered by the maps, demonstrating that the streams of this marsh are more dynamic than some others that have been widely reported in the literature. These differences in stream dynamics are probably related to the differences in sedimentological structure of the marshes. Between 1872 and 1956 the barrier spit eroded on its inside (shoreward) edge, probably in response to the construction of riprapping and houses along the spit, and the subsequent reduction of overwash and aeolian transport of sediment. Modification of the tidal inlet and adjacent marsh during the 1960s, including jetty construction, dredging, and filling of portions of the marsh surface, affected the marsh only locally. One tidal stream has been migrating rapidly apparently in response to compaction of peat by dredge spoils and consequent local disruption of the marsh hydrology. Except for this migration, erosion of the marsh edge occurred immediately after the inlet modifications; planimetric changes in the marsh and its streams have been minor since then.     

Settling-velocity distributions and sorting processes on a longitudinal dune: A case study

The processes acting on a longitudinal dune are inferred from the response in the area size-sorting characteristics of the sediment of the active layer. The sediment size distributions are determined by settling and are best described by a log-hyperbolic model which provides the most information on size-sorting processes. Size-sorting characteristics are markedly different across the low round-crested part of the dune from cross-sections of the high more sharp-crested part. This results in changes in textural parameters along the lee-side consistent with changes in the lee-side separation vortex. This is the first time that the effect of wind speed up on the lee-side is observed to be reflected in the sediment; it can only be detected with the very sensitive log-hyperbolic parameters.     

新疆塔西河流域水利开发现状及投资效益分析

本文在对塔西河流域水利建设、水土开发的调查分析基础上，从不同时期流域水利投资项目、投资结构及农业生产发展等方面对流域水利投资效益进行了分析研究，同时还对流域近期的重点投资建设项目的效益作了分析比较和评估。