全球河流入海沙量估算述评

全球河流入海沙量作为地球系统运行变化的重要而敏感的指标,在一定程度上会对全球社会、经济和环境问题产生重要影响,从而引起国内外研究者的高度关注。针对由于缺乏可靠、完整的河流输沙量数据,很难准确估算全球河流入海沙量的数值及其变化,且已有文献估算值差别很大,缺乏统一认识的问题,收集整理了20世纪50年代至今国内外27篇文献中全球河流入海沙量的估算值,并对近期相关典型研究成果进行述评。调查发现,早期估算的入海沙量数值差异很大,随着人们对这一问题的深入研究,近年来全球入海沙量估算值日趋合理,大多集中在120亿~200亿t/a。分析认为,人类活动影响前后的河流入海沙量宜分别按190亿t/a和130亿t/a考虑。     

Algorithm of gaussian sum filter based on high-order UKF for dynamic state estimation

In this work we consider the state estimation problem in nonlinear/non-Gaussian systems. A new version of Gaussian sum estimation algorithm is developed here based on high-order unscented Kalman filter (HUKF). A sigma point selection method, high-order unscented transformation (HUT) technique is proposed for the HUKF, which can approximate the Gaussian distributions more accurately. We present the systematic formulation of Gaussian filters and develop efficient and accurate numerical integration of the optimal filter. We then go on to extend the use of the HUKF to discrete-time, nonlinear systems with additive, possibly non-Gaussian noise. The resulting filtering algorithm, called the Gaussian sum high-order unscented Kalman filter (GS-HUKF) approximates the predicted and posterior densities as a finite number of weighted sums of Gaussian densities. It is corroborated in the theoretical analysis and the simulation that the proposed Gaussian sum HUKF has integrated advantages with respect to computational accuracy and time complexity for nonlinear non-Gaussian filtering problems.     

Design optimization of a runflat structure based on multi-objective genetic algorithm

Runflat structure plays an important role in determining the sustainable mileage after the tire is shot. Lightweight, stiffness and strength are highly relevant to the overall performance of the structure. A parameterized model was built based on the full study of the structure, and a new adaptive meshing method is proposed to ensure the quality of the model. The accuracy of the new model was verified by comparing to the traditional finite element model. The parameter study was carried out to investigate the response of the performance and mass. Multi-objective optimization model was established by applying optimal Latin square design method and response surface model approach. Non-dominated sorting genetic algorithm-II (NSGA-II) was applied to obtain the optimization design. The results indicate that the combination of parameterized model and multi-objective genetic algorithms successfully achieve the goal of multi-objective optimization for mass and displacement while ensuring the stress. Meanwhile, the optimal topology, shape and thickness optimization for the runflat structure have been achieved at the same time.     

改进的分层A*算法在停车场路径寻优中的应用

在大型停车场车位路径寻优中,传统的评价指标是把距离最短作为最优指标,并没有考虑实际路况,为此引入了切实可行的时间较优评价指标,既能简化引导系统硬件设计,又能节省软件开销;首先,建立了停车场网络图R (P,C,D,V)数学模型,并把网络中的所有节点分成两层,分别构建了不同的估价函数,采用改进的A*算法,提高了以时间较优为评价指标的路径搜索效率和搜索精度;最后,程序运行结果表明,针对不同的路段属性参数,算法总能较快的找到时间较优路径.     

基于智能视觉的透明液体可见异物检测软件设计

目前在国内的透明液体生产线上,液体通常采用人工检测,效率低、准确率,所以基于图形处理算法以及QT,设计了一套基于智能视觉的透明液体杂质颗粒检测软件,重点实现了软件与算法的改进优化;获取的连续图像经自适应中值滤波预处理去除图像噪声后,通过改进的序列图像二次差分算法提取出序列图中的细小的异物,然后根据通过SIFT特征度量的MeanShift目标跟踪算法,跟踪液体图像中的细小异物;并根据异物的运动轨迹及大小,检测到有无异物以及异物的类型,进而进一步判断透明药品质量是否合格;结果测试表明,软件的准确率达到95%以上,检测分辨率达到了44μm,基本可以替代透明液体生产线上的人工检测。     

执行依赖启发式动态规划PMSM控制策略研究

永磁同步电机算法中的PID参数固定不变,自适应能力较差;近似动态规划具有自学习能力,能动态调整参数,增强系统的自适应能力;文章将近似动态规划中的代表性算法——执行依赖启发式动态规划与类PI网络相结合,根据环境反馈对各个策略进行评价,选取评价最优的策略在线调整动作网络参数,对永磁同步电机进行自适应最优控制;仿真结果表明,执行依赖启发式动态规划加PI控制算法在系统速度变化和负载变化过程中,动态效果和稳态精度优于传统PID控制.