利用多通道的光学超晶格产生对, 纠缠的连续变量频率梳

提出了一种实验上可行的,通过光学谐振腔内多通道参量下转换过程直接产生多色连续变量对纠缠频率梳的方案,腔内增益介质为周期极化的准相位匹配的钽酸锂(LiTaO₃)一维光学超晶格.通过连续变量纠缠判据证明了每个通道中产生的每对参量光之间是相互纠缠的.讨论了对纠缠频率梳的纠缠特性随系统参数的变化.此方案在量子通信网络中有着一定的应用前景.     

Evidence from the Historical Record to Support Projection of Future Wind Regimes: An Application to Canada

In the field of climate change impact analysis, bidirectional changes in projections of future wind regimes varying among studies, locations, and models have been described in the literature, which is understandable from a global perspective. However, we should attempt to find evidence in the historical record to support these projections. This paper attempts to address this issue by analyzing historical wind gust observations for up to 57 years (1953–2009) over Canada. Two wind gust analysis techniques were used: the speed of daily wind gust events ≥50?km?h^?1 was compared with (1) the climatological daily temperature anomaly and (2) the climatological daily sea level air pressure anomaly. In addition, the frequency of daily wind gust events ≥90?km?h^?1 was compared with both daily temperature and pressure anomalies. The results indicate that during the past five decades gust wind speed over Canada increased significantly as the daily temperature anomaly increased and the daily pressure anomaly decreased. About 50–60% of daily wind gust events ≥90?km?h^?1 occurred with positive daily temperature anomalies and negative daily pressure anomalies. One major conclusion is that the methods used in and results derived from this study might be applied to climate change impact analysis to support projections of future wind regimes.     

顾及步行习惯的室内导航网络及其生成算法

室内导航网络是实现室内路径规划和导航的基础。针对现有室内导航网络存在拓扑连通结构不合理、生成路径几何形态不自然等问题,本文依据人类长期以来形成的“抄近路”习性及“避碰”安全需求,提出了一种符合人行走习惯的室内导航网络及其自动生成算法。该导航网络将室内可通行空间划分为普通房间和走廊,普通房间内网络映射为房间结点与门结点的直线连接;形状复杂的走廊空间则依据空间尺度和凹凸性被细分为狭窄走廊空间和开阔走廊空间,狭窄走廊空间以中轴线作为路线,开阔走廊空间则将门结点和通道口结点连接形成完全图;最后将房门结点连接到走廊路线,形成完整室内导航网络。试验结果表明:该模型及其生成算法能够依据室内空间尺度对复杂通行空间进行合理分区,生成与空间特征一致的导航网络结构,使得规划生成的最短路径形态更符合人们的行走习惯。     

耦合GF-2遥感影像与街景影像的广州市城中村识别

及时准确地获取城中村的空间分布及其环境质量信息对于优化城市空间、改善人居环境具有重要意义。本文以广州市越秀区为例,提出了耦合GF-2高分遥感影像和百度街景影像的城中村识别方法。首先,从街景影像中提取越秀区的街道空间品质特征;其次,在对高分遥感影像预处理并进行多尺度分割的基础上计算光谱、形状、纹理、场景特征和建筑结构5类共计23个特征;最后,融合两种影像的特征用于构建随机森林分类器进行城中村识别。结果表明,基于高分影像和基于街景影像的城中村识别整体精度分别为94.5%和85.7%,Kappa系数分别为0.58和0.31,而两者融合后的分类精度和Kappa系数为96.1%和0.67;其中基于街景影像获取的度量街道空间品质的5个指标贡献了31.6%的特征重要性。鸟瞰视野高分影像和人本视角街景影像提供的信息综合互补,构建了更有区分度的特征空间,减少了城中村的错分现象。本文证实了高分影像和街景影像在特征尺度的融合提升了城中村识别精度。街景影像中的信息可以融入到高分遥感影像等数据源中,辅助进行城中村等非正规居住空间的识别。     

安徽省绩溪县上金山地区钨钼矿矿化类型及找矿前景分析

上金山钨钼矿位于安徽省绩溪县与旌德县交界地带,是扬子准地台南缘新发现的一处大型层控型矿床。南华系休宁组上段上部地层及燕山早期的花岗闪长岩是本矿床主要控矿因素,赋矿地层岩性为锰钙质砂岩—粉砂岩,该赋矿层位是皖南地区找矿新发现。该矿床已达大型规模,地质、物化探综合信息显示,上金山地区具进一步找矿前景,且在已控制的层控型矿床深部及外围,存在寻找斑岩型钨钼矿及石英脉型钨矿的良好条件,经进一步勘查,矿床资源量将显著增加。     

黔北务川—正安—道真地区下二叠统大竹园组和梁山组孢粉学研究

文中材料采自黔北务川—正安—道真地区下二叠统大竹园组和梁山组。大竹园组孢粉化石类型单调,保存较差;而梁山组孢粉化石丰富,保存良好。孢粉组合特征为:(1)大竹园组包含丰富的Calamospora和Florinites及少量Torispora verrucosa,Gulisporites,Alisporites,Hamiapollenites和Striatopodocarpites,这一孢粉组合主要出现在上石炭统至下二叠统。按照大竹园组层位和孢粉化石特征,其地质时代应为早二叠世Asselian期—Artinskian期(相当于紫松期—隆林期)。(2)梁山组中可建立孢粉组合Laevigatosporites vulgaris-Gulisporites-Florinites ovalis,共计发现孢粉化石34属49种,其中蕨类植物孢子含量为51.6％～56.1％,裸子植物花粉含量为43.9％～48.4％。与大竹园组沉积时期相比,这一时期植被极为繁盛。根据孢粉组合特征,梁山组地质时代可能为早二叠世隆林期,即Kungurian期。     

基于模糊综合评判和GIS技术的矿山地质环境影响评价

蒲白矿产资源集中开采区分布于渭北黑腰带地区的蒲城和白水县,煤炭、石灰岩、铝土矿和粘土等多种矿产的持续开发,产生了各类的矿山地质环境问题,其中煤矿采空区塌陷及裂缝最为突出。选取了地形相对高差、岩土体特征、开采方式、有效深厚比、采空区面积比、矿山地质灾害发育密度、地下水位、压占破坏土地资源等11个指标作为评价因子,构建了矿山地质环境影响评价指标体系。采用模糊综合评判法对研究区矿山地质环境影响进行评价,并结合GIS空间分析技术划分为矿山地质环境影响严重区12个,较严重区4个,较轻区2个。评价结果与实际调查情况较为相近,较客观的反映了采矿活动对矿山地质环境的影响,并结合区内实际提出了矿山地质环境恢复治理措施建议,为矿山地质环境保护与恢复治理提供了依据。     

Multi-level analysis of field synergy in the displacement mechanisms of heavy oil thermal recovery

One of the major problems of heavy oil thermal recovery is the inadequacy of understanding the multi-field coupling displacement mechanisms to improve the oil production and extraction ratio. From the perspective of “force” and “flow” in thermodynamics, oil displacement fields are divided into three groups: destination, driving and resistance potential fields. Based on the seepage law, the compositional structure of driving and resistance potential fields has been established by making use of non-equilibrium thermodynamics. In addition, coupling indexes among driving, resistance and a combination of both potential fields can be deduced. Then, the main process of multi-level analysis of oil displacement mechanism of field synergy in the process of heavy oil thermal recovery can be put forward. A practical multi-level case study of typical hot-water flooding displacement can provide useful information and guidance to enhance the displacement process.     

Evaluation of I-wall in New Orleans with back-calculated total stress soil parameters

This study back-calculated moduli and shear strength of soils in London Canal Ave., New Orleans, using full-scale load test data, and re-evaluated the behavior of the I-wall to explore how the existing levees and floodwalls may be reliably retrofitted and future levees and floodwalls may be designed. From the back-calculation, it turned out that the moduli of the field soils were mostly higher (1–12 times) than magnitudes appeared in Interagency Performance Evaluation Task Force (IPET). But the shear strength of a water-glazed Marsh layer in the gap turned out to be substantially lower (0.2–0.25 times) than the magnitude appeared in IPET. This much strength reduction was confirmed by field vane shear tests: tests with artificial water infiltration into the field vane hole presented immeasurably low disturbed strength and resulted in very high sensitivity that might contributed to the failure. This study also shows that the gap development and strength reduction in the water-glazed Marsh layer are two main causes of levee failure, which have been predicted in previous research. The stiffer-than-expected moduli of underlain layers did not affect the failure mechanism of the levee substantially because these underlain layers remained elastic. Therefore, retrofitting solutions should be the ones that may prevent the gap development and to reinforce the Marsh layer.