北极地区200海里外大陆架划界法律问题研究

随着北极冰盖的融化,开采北极蕴藏丰富的石油、矿产资源越来越具有现实可行性,北极地区200海里外大陆架划界问题日益成为各国关注的热点.分析北极地区200海里外大陆架划界的国际法基础、主要法律问题以及学界对解决该问题的建议,认为200海里外大陆架划界不可能通过某一特定程序一次性解决,而是现有国际法框架内各国共同参与、区分不...     

基于地理信息系统的数字环境模型研究

本文提出了以遥感与地理信息系统为技术手段,用有序数值阵列的方法建立数字环境模型的新思路,具体阐述了建立数字环境模型的意义、方法和应用范围。并在建立数字环境模型的基础上,对西藏“一江两河”地区的环境综合状况进行了定量评价。     

用气象卫星资料估算吉林省主要农作物产量

净第一性生产力（Npp）分析是全球变化研究中广为利用的方法,利用气象卫星资料获得年际植被指数（Iv）估算Npp建立不同作物的Npp与其产量的关系模型,即可实现对粮食总产和不同作物产量的估算。文中介绍了应用净第一性生产力遥感（NPP—RS）模型对吉林省粮食总产和主要作物产量进行估算的方法。采用NPP—RS模型,对1995～2000年吉林省的粮食总产及主要农作物玉米、水稻产量进行了动态估算。对粮食总产估产的平均相对误差为13．6％,玉米的平均相对误差为17．6％,水稻的平均相对误差为6．7％。要提高用此方法进行遥感估产的精度,还需要对当年的种植制度、种植结构的变化有所了解,注意当年的灾情,增加灾害影响系数。     

内蒙古东南部地区夏季旱涝的环流特征分析及预测

主要从与内蒙古东南部地区(指赤峰市和通辽市)夏季旱涝关系密切的西太平洋副高、亚洲地区环流和蒙古冷涡三个主要的天气系统入手,分析旱涝年的环流差异。结果表明:⑴夏季蒙古冷涡偏多、副热带高压偏强和北半球盛行经向环流,是造成夏季降水偏多的主要环流形势;⑵冬季北半球极涡纬度和亚洲地区的环流指数对夏季环流形势有一定的指示意义;二者相互动态地影响了夏季旱涝,据此建立夏季旱涝预测模型。经过1995—2008年14年的实际应用,趋势准确率为85.7%。     

Land use change under conditions of high population pressure: the case of Java

A long history of increases in population pressure in Java has caused agricultural land use to expand and intensify. More recent land use changes caused the conversion of prime agricultural land into residential and industrial area. Results of a dynamic, regional-scale, land use change model are presented, defining the spatial distribution of these land use changes. The model is based on multi-scale modelling of the relations between land use and socio-economic and biophysical determinants. Historical validation showed that the model can adequately simulate the pattern of land use change. Future patterns of land use change between 1994 and 2010 are simulated assuming further urbanization. The results suggest that most intensive land use changes will occur in Java's lowland areas.     

Experimental analysis on the risk of vortex ventilation and the free surface ventilation of marine propellers

The paper presents a discussion of the ventilation inception and air drawing prediction of ships propellers, aiming to predict under what conditions ventilation will happen, and the actual physical mechanism of the ventilation.Three different types of ventilation inception mechanisms are included in our discussion: free surface vortex ventilation, ventilation by sucking down the free surface without forming a vortex as well as ventilation by propeller coming out of the water. Ventilation prediction is based on a series of model tests, where the propeller is tested in different levels of intermittent ventilation. The use of underwater video gives a visual understanding of the ventilation phenomena.Ventilation by vortex formation has analogies with other phenomena, such as the inlet vortex in pump sumps, ground vortex at the inlet of the aircraft engines and the Propeller Hull Vortex Cavitation (PHVC). The paper includes comparison between Propeller Hull Vortex Cavitation (PHVC) and Propeller Free Surface Vortex Ventilation (PFSVV) as well as comparison between PFSVV and vortex formations of aero engines during high power operation near a solid surface.Experimental data based on several different model tests shows the boundary between the vortex forming, non-vortex forming and free surface ventilation flow regimes. For comparison the following parameters, which determined the intensity of the hydrodynamic interaction between the propeller and free surface have been used: propeller load coefficient c_T, tip clearance ratio c/D, propeller submergence ratio h/R, ambient velocity V_i and flow cavitation/ventilation number σ_cav/σ_vent.     

Experimental and numerical study on vortex-induced motions of a deep-draft semi-submersible

An experimental study on vortex-induced motions (VIM) of a deep-draft semi-submersible (DDS) was carried out in a towing tank, with the aim to investigate the VIM effects on the overall hydrodynamics of the structure. In order to study the fluid physics associated with VIM of the DDS, a comprehensive numerical simulation was conducted to examine the characteristics of vortex shedding processes and their interactions due to multiple cylindrical columns. The experimental measurements were obtained for horizontal plane motions including transverse, in-line and yaw motions as well as drag and lift forces on the structure. Spectral analysis was further carried out based on the recorded force time history. These data were subsequently used to validate the numerical model. Detailed numerical results on the vortex flow characteristics revealed that during the “lock-in”, the vortex shedding processes of the upstream columns enhance the vortex shedding processes of the downstream columns leading to the rapid increase of the magnitude of VIM. In addition to the experimental measurements, for the two uniform flow incidences (0° and 45°) investigated, comprehensive numerical data of the parametric study on the VIM characteristics at a wide range of current strength will also serve as quality benchmarks for future study and provide guidance for practical design.     

冬季大风影响下的渤黄海水交换特征

利用ROMS海洋数值模式对2006年冬季渤黄海的海洋动力环境进行模拟,基于温度、盐度模拟结果,使用谱混合模型进行水团分析,定义了渤海海峡地区的水交换区。并进一步讨论了冬季大风事件对水交换区的影响,给出了冬季大风影响下的渤黄海水交换特征。研究得出,冬季的黄海水团以“舌”形分布于渤海海峡地区,水交换区则表现为沿“舌”形边缘呈带状分布,具有西北——东南的走向趋势,并且在“舌”尖处的水交换面积最大。通过缩小研究范围,发现位于黄海最北部的沿岸海域并不参与渤黄海之间的水体交换。最后研究发现,冬季大风事件对渤海水交换具有促进作用,具体表现为：大风过程使黄海暖流对渤海的入侵更加深入,水交换区向渤海方向伸展,南部的水交换带变宽,河流径流进入渤海后与渤海水的混合区加大,并发生北移。     

King Canute muses in the South Seas: Why aren’t Pacific Islands transitioning to low carbon sea transport futures?

Transition to low carbon sea transport is a logical response to the extreme dependency of the Pacific Islands region on imported fossil fuel, its significant vulnerability to the effects of climate change and the critical shipping needs of Pacific Island countries (PICs). Building on previous work in low carbon sea transport in the Pacific, this paper further considers the barriers to achieving such transition by assessing, through a ‘post-Paris Agreement’ lens, the Intended Nationally Determined Contributions (INDCs) submitted by PICs and contrasting these to the near total lack of investment and planning for low carbon transition in the transport sector with the parallel occurrence in the electricity sector where ~USD 2 billion of donor investment is deployed or queued despite electricity using only ~20% of fossil fuel across the region. Consistent with recent international studies, inadequate and inappropriate financing and policy have been identified as dominant transition barriers for low carbon sea transport development in PICs. This paper further examines the regional level barriers to policy development, and finds them inhibited by the silo nature of the major regional actors. The implications that the Paris Agreement has for climate financing to support the essential research and capacity development needed to underpin a successful low carbon sea transport transition strategy at any useful scale and speed are also considered in this paper.     

多相离散随机介质模型及其探地雷达波场特征研究

沥青混凝土是由骨料、沥青胶浆、空气按照一定的体积百分比混合而成的多相非匀质混合物,其骨料、沥青胶浆和空气的体积不等、形状各异、介电特性不同、空间位置随机分布,具有明显的多相、离散、随机介质特征.本文基于随机介质模型理论,(1)测量与统计了介电常数在典型沥青混凝土芯样空间上的随机分布统计特征;(2)估算了沥青混凝土介质的自相关函数及其特征参数(自相关长度、自相关角度等),确定其随机介质类型;(3)提出了量化约束下的多相离散随机介质建模算法,以混合型椭圆自相关函数为基础,构建了不同粗糙度因子的多相离散随机介质模型;(4)构建了不同空隙率的多相离散随机介质模型,正演模拟与对比分析了探地雷达波在均匀介质、连续型随机介质和多相离散随机介质中的传播特征.结果表明:多相离散随机介质模型不仅描述了沥青混凝土的多相、离散与空间随机分布统计特征,而且进一步描述了其各组成物质体积百分比,能更全面、准确地描述沥青混凝土的介质特征,同时也为描述其他类似材料或介质提供了新的方法和途径;在多相离散随机介质模型中,探地雷达波散射强烈,随机、无序传播的散射波相互叠加干涉,形成了明显的随机扰动和"噪声",致使异常体反射波扭曲变形、不连续,降低了探地雷达回波的信噪比和分辨率.研究探地雷达波的随机扰动特征与多相离散随机介质模型参数之间的关系,将为定量评价多相离散随机介质的属性参数提供参考和帮助.