强对流天气临近预报技术研究

强对流天气是严重危害人民生活的危险性天气,特别是对于空中飞行有重大影响。目前,国内外主要的临近预报技术包括利用雷达资料的雷暴识别和跟踪技术、利用卫星资料的强降水估计,概率预报技术、概念模型和数值模式预报技术等。本文重点介绍近年来发展起来的强对流天气临近预报方法和主要业务系统,分析了临近预报技术中存在的主要问题并对未来发展趋势进行了展望。     

一种新的预报晴空湍流综合算法

介绍了晴空湍流及其相关的湍流指数,以及通过对9个指数进行加权综合得到的一个综合预报算法。利用T213模式资料,计算了9个湍流指数,并分别用12个北京地区的飞机颠簸个例进行验证,得到各湍流指数的预报结果;在此基础上,应用新的综合算法,得到一个综合预报结果。计算结果表明,虽然理查孙数和风相关指数、MOSCAT概率预报因子指数的预报效果相对较好,但是这三个指数的预报范围和强度均偏大,容易出现空报;综合算法则较好地综合各个指数,预报区域相对集中,预报强度也较符合实际情况,空报的情况也得到了相应的改善,总体预报效果较好     

A Preliminary Application of the Differential Evolution Algorithm to Calculate the CNOP

A projected skill is adopted by use of the differential evolution （DE） algorithm to calculate a conditional nonlinear optimal perturbation （CNOP）. The CNOP is the maximal value of a constrained optimization problem with a constraint condition, such as a ball constraint. The success of the DE algorithm lies in its ability to handle a non-differentiable and nonlinear cost function. In this study, the DE algorithm and the traditional optimization algorithms used to obtain the CNOPs are compared by analyzing a theoretical grassland ecosystem model and a dynamic global vegetation model. This study shows that the CNOPs generated by the DE algorithm are similar to those by the sequential quadratic programming （SQP） algorithm and the spectral projected gradients （SPG2） algorithm. If the cost function is non-differentiable, the CNOPs could also be caught with the DE algorithm. The numerical results suggest the DE algorithm can be employed to calculate the CNOP, especially when the cost function is non-differentiable.     

基于ARM与Linux的姿态角测量系统的研制

选取旋转矢量算法作为姿态角测量系统的姿态矩阵更新算法.针对三子样算法采样周期长的特点,提出了重复使用采样数据的方案以保证系统的实时性.选取陶瓷静电陀螺仪CG-L53为角速率传感器,设计了以AT89S51为MCU的信号采集板,搭建了以ARM芯片为CPU的计算机平台,完成了系统各模块的软件设计.仿真测试结果表明,系统能较稳定地输出姿态角信息.     

Statistical inverse analysis based on genetic algorithm and principal component analysis: Applications to excavation problems and pressuremeter tests

This study concerns the identification of constitutive models from geotechnical measurements by inverse analysis. Soil parameters are identified from measured horizontal displacements of sheet pile walls and from a measured pressuremeter curve. An optimization method based on a genetic algorithm (GA) and a principal component analysis (PCA), developed and tested on synthetic data in a previous paper, is applied. These applications show that the conclusions deduced from synthetic problems can be extrapolated to real problems. The GA is a robust optimization method that is able to deal with the non‐uniqueness of the solution in identifying a set of solutions for a given uncertainty on the measurements. This set is then characterized by a PCA that gives a first‐order approximation of the solution as an ellipsoid. When the solution set is not too curved in the research space, this ellipsoid characterizes the soil properties considering the measured data and the tolerate margins for the response of the numerical model. Besides, optimizations from different measurements provide solution sets with a common area in the research space. This intersection gives a more relevant and accurate identification of parameters. Finally, we show that these identified parameters permit to reproduce geotechnical measurements not used in the identification process. Copyright © 2009 John Wiley & Sons, Ltd.     

Sentinel-2密集时间序列数据和Google Earth Engine的潮间带湿地快速自动分类

潮间带湿地是滨海湿地的重要组成部分,具有维持生物多样性、促进碳汇等重要生态功能.及时、准确地掌握潮间带湿地现状是实现潮间带湿地可持续管理目标的基础.先前的潮间带湿地分类研究依赖于训练样本、人工设定阈值或后处理等,本研究基于GEE (Google Earth Engine)平台开发一种自动、快速、高精度的潮间带湿地分类方...     

路基断面填挖区域快速分割及其面积计算探讨

在路基工程中,计算填挖方量的传统方法误差大效率低,该文针对其主要影响因素提出了一种按断面上设计线和地面线的横坐标是否单调进行分类的计算方法。文章首先给出了能够反应填挖属性的一个更简形式的凹凸多边形面积计算公式,然后提出了在横标单调条件下的求交追赶算法,最后介绍了非单调条件下的填挖区域分割与面积计算方法。该方法实现了填挖方量的精确计算,较好地满足了工程概算要求,同时有效提高了设计效率。     

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???????????У?PECE????????????????????????????Collocation????????????????幫??????????μ?PECE???????????????????ж??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????Adams-PECE????????PECE?????????????????????????????,???????????Collocation-PECE??????????????н???????????????Ч??     

占优问题的通量校正运移解法

描述非饱和土壤中溶质运移的对流弥散方程可分成两部分：对流部分用通量校正运移(FCT)算法求解；弥散部分用常规的隐式差分方法求解.FCT算法包括两个阶段，一个是低阶运移阶段，这一阶段的解，可能会引进过量的数值弥散；另一个是高阶通量校正阶段，通过对反扩散通量进行校正(限定)，可有效地消除数值弥散和数值振荡.而水体积分数用FUCG方法求得，能保持质量守恒.通过数值例子验证了FCT算法的有效性.     

波阻抗遗传算法反演方法的研究及应用

作者介绍的遗传算法是在自然界生物遗传过程优选和进化原理的基础上，针对波阻抗反演的实际问题，对标准的遗传算法进行了改进，引入了模拟退火算法中的热槽法控制初始群体的产生，用逐位迭代的交换方式代替传统的杂交方式即随机选择杂交点进行交换。使用改进的遗传算法对地震波阻抗进行反演，可很好地提高反演的精度。在文中最后，作者通过理论模型和实例验证了上述的思想。