石家庄盛夏一次暴雨空报诊断分析

实时天气系统的时空分布、多个物理量要素都表明2007年7月18日河北省石家庄市东、南和北部将有暴雨天气发生的可能,结果暴雨并没有发生.为了找到暴雨空报的原因,对常规资料和各种数值预报产品进行诊断分析.结果表明:(1)石家庄地区处于2条切变线的中间区域,导致缺少强降水的垂直条件(中、低层的切变线),这是暴雨空报的最主要原因;(2)利用离石家庄最近的邢台探空站的物理量特征来判断石家庄对流发展程度效果较差,这和探空站空间尺度较大有关,这是空报原因之二;(3)缺少有效的数值预报产品是预报失误原因之三:(4)这次邢台、邯郸的暴雨天气系统可定为西南涡类暴雨.利用卫星水汽云图和雷达、国家级自动站要素资料相结合可以大大提高灾害性天气预警能力.     

河西走廊一次区域性大风强沙尘暴天气诊断

应用常规和自动加密站观测资料,对2009年4月29日发生在河西走廊的一次区域性强沙尘暴天气过程,从天气学成因、物理量要素等方面进行了诊断分析.结果表明:这是一次冷锋后大风引发的沙尘暴;沙尘暴发生在强气压梯度区;地面气象要素对冷锋过境及沙尘暴爆发有强烈反应,可以在沙尘暴预报中作为一个参考依据;沙尘暴爆发区低层辐合,高层辐散,有明显的上升运动;锋生函数和螺旋度对沙尘暴爆发区有较好的指示意义.     

基于BP神经网络与数学形态学的彩色地质图面要素信息智能提取

地质图是一个区域地质研究的重要成果,也是前人留下的宝贵资料,更融合了地质专家的丰富知识。本研究的目的是通过新的思路将彩色地质图信息提取出来,使其结果能直接进行数据分析,并用于决策和分析。以机器学习为指导,在分析半结构化（栅格）地质图特征的基础上,根据图例信息,提出一种彩色地质图信息提取新思路,对彩色地质图进行分层信息提取,并结合数学形态学和多层前向反馈式神经网络,探索半结构化数据转换为结构数据的有效技术方法。利用图像信息提取技术将半结构化地质图转化为结构化数据,可用于成矿预测等研究。这一变化将改变传统地质数据的结构,地质研究的信息基础和来源将会增加,对于获取更多的数据源和信息源,进一步开展地质分析研究具有重要意义。     

基于HRCT诊断模型鉴别纯磨玻璃结节样肺腺癌浸润程度研究进展

鉴别肺纯磨玻璃结节样肺腺癌的浸润程度对于临床管理及改善患者预后有重要的指导意义,目前已开发出多种诊断模型用于此。本文结合国内外相关文献,介绍基于HRCT表现的诊断模型在鉴别肺纯磨玻璃结节样肺腺癌的浸润程度研究现状及价值评估等,对其研究进展及临床应用前景进行综述。     

基于LiDAR数据和航空影像的水体自动提取

提出将LiDAR数据对水体的敏感性与航空影像的高分辨率特征相结合的水体自动提取方法。利用SIFT算法对LiDAR强度图像和航空影像进行配准,在LiDAR高程图像上提取无回波信号的黑色区域,构建几何约束条件,排除由遮挡产生的无效区域;将水体初始位置映射到航空影像上,结合边缘信息进行区域生长,并对生长区域进行数学形态学运算,最终获取水体区域。实验结果表明,该方法可以获得很好的水体提取效果。     

Diffusive mass exchange of non‐reactive substances in dual‐porosity porous systems – column experiments under saturated conditions

Diffusive mass exchange into immobile water regions within heterogeneous porous aquifers influences the fate of solutes. The percentage of immobile water is often unidentified in natural aquifers though. Hence, the mathematical prediction of solute transport in such heterogeneous aquifers remains challenging. The objective of this study was to find a simple analytical model approach that allows quantifying properties of mobile and immobile water regions and the portion of immobile water in a porous system. Therefore, the Single Fissure Dispersion Model (SFDM), which takes into account diffusive mass exchange between mobile and immobile water zones, was applied to model transport in well‐defined saturated dual‐porosity column experiments. Direct and indirect model validation was performed by running experiments at different flow velocities and using conservative tracer with different molecular diffusion coefficients. In another column setup, immobile water regions were randomly distributed to test the model applicability and to determine the portion of immobile water. In all setups, the tracer concentration curves showed differences in normalized maximum peak concentration, tailing and mass recovery according to their diffusion coefficients. These findings were more pronounced at lower flow rates (larger flow times) indicating the dependency of diffusive mass exchange into immobile water regions on tracers' molecular diffusion coefficients. The SFDM simulated all data with high model efficiency. Successful model validation supported the physical meaning of fitted model parameters. This study showed that the SFDM, developed for fissured aquifers, is applicable in porous media and can be used to determine porosity and volume of regions with immobile water. Copyright © 2015 John Wiley & Sons, Ltd.     

Computer-aided design of bus route maps

The bus route map is a diagram that aims to convey necessary information for map readers to find an appropriate way of moving from an origin to a destination. Design of bus route map is a complicated and time-consuming task that requires careful consideration of readability and aesthetics. This paper proposes a new computational method for designing bus route maps. The method helps us to reduce six types of undesirable elements in bus route maps, i.e., gap, shift, crossing, overlap, misalignment, and acute bend. The method consists of two phases: line layout phase determines the relative order of bus routes on each road segment and map layout phase calculates the actual position of bus routes drawn on a map. This paper applies the method to the design of bus route maps of Chiba City, Japan. The result supports the effectiveness of the method as well as reveals open topics for future research.     

Electrical analogy for modelling thermal regime and moisture distribution in sandy soils

The soil mass is subjected to temperature variation due to several human activities (viz. tanks storing heated fluids, buried cables and pipelines, air-conditioning ducts, disposal of nuclear and thermal power plant wastes etc.), which result in heat-induced migration of the moisture in it. Though several studies have been conducted in the past to investigate the mechanism of heat migration through the soil mass, a methodology for ‘real-time measurement of the variations in temperature, flux and moving moisture front, in tandem, with respect to space' has rarely been attempted. In this context, extensive laboratory investigations were conducted to measure real-time flux and temperature variations in the sandy soils, and the validation of results has been done by employing an equivalent electrical circuit programme, LTspice. Subsequently, a mathematical model PHITMDS (i.e. Prediction of Heat-Induced Temperature and Moisture Distribution in Soil) has been developed and its utility and efficacy, for predicting the depth-wise temperature and heat-induced moisture migration, due to evaporation, in terms of position of moving moisture front in the sandy soil has been critically discussed and demonstrated.     

谈地下水数学模型在南干渠灌区中的预测与应用

地下水数学模型是用数学方法表述,经过概化地下水系统,在系统分析地下水补、径、排的基础上,对地下水预测分析的一种有效方法.随着南干渠灌区建成后水量的变化,本文通过选用适宜的数学模型,对灌区地下水资源量进行模拟计算,根据模拟计算结果对灌区地下水升幅进行预测,对灌区生态环境的变化做出评价.