Pixel level image fusion scheme based on accumulated gradient and PCA transform

A new image fusion scheme based on local accumulated gradient and PCA transform is presented. The image fusion process begins by taking the Dual tree complex wavelet transform of the source images. Then, the fused local detailed coefficients are chosen according to local accumulated gradient rule, and the fused approximate coefficients are acquired by selection or averaging rule based on PCA. Finally, the fused image can be obtained by taking the inverse dual tree complex wavelet transform of the fused composite coefficients. The experimental results show that the proposed method is an efficient approach to image fusion.     

基于灰色RBF神经网络模型的电梯层间交通分布预测

为了有效预测电梯的层间交通分布状态,提出一种层间交通O-D矩阵的预测方法．该方法融合灰色预测和神经网络方法各自的优点,将灰色预测方法与RBF神经网络有机结合,构造灰色神经网络预测模型．利用灰色预测中的累加生成运算（accumulatedgeneratingoperation,AGO）对原始观测数据进行变换,得到规律性较强的累加数据,作为神经网络的建模和训练样本．还提出了对不良交通需求数据的修正方法,以进一步降低观测数据的随机性．所提方法既避免了灰色预测方法存在的理论误差,又提高了神经网络的训练速度和预测精度,适用于短期层间交通分布预测．仿真试验验证了该方法的有效性．     

不同土壤湿度和雨强下径流曲线模型的改进

前期土壤湿度条件和降雨强度是影响径流曲线（SCS-CN）模型径流量预测精度的重要因素。分析不同流域下二者对SCS-CN模型性能的影响,对提高模型预测精度至关重要。基于5个半干旱半湿润和湿润流域的降雨径流资料,利用偏相关分析和K-均值聚类改进SCS-CN模型。结果表明：在重新划分前期土壤湿度条件区间后,模型预测能力大幅度提升,有效降低模型平均偏差,纳什效率系数平均提高42.8%。基于最大10 min雨强对SCS-CN模型改进后,纳什效率系数得到一定提高,且半干旱半湿润流域的提升幅度略大于湿润流域。改进的模型在研究流域都取得较好的效果,平均偏差均低于7 mm;除呈村流域非汛期外纳什效率系数均达到0.93,平均提升89%;均方根误差平均降低29.2 mm。     

网络改变教与学

因评价体系的导向所致,国内重点院校计算机专业教师在教学投入上严重不足,并导致教育质量不高。针对该问题,本文结合7年的教学实践和分析总结,提出累加式考核、抄袭问题对策、交互式课堂、考试作为学习过程等系列颇具成效的建设性解决方案。这些方案只有在网络支撑下才能有效实施。教学结果表明,依靠网络的力量,不仅能节省教师的时间和精力,而且能促进学生主动学习,显著提升教学质量。     

并行Hough变换快速航迹起始

Hough变换在航迹起始领域得到广泛应用,但在扫描次数较少时起始效果不佳。通过转变Hough变换处理结构和改变计数器累加方式,提出了一种并行Hough变换快速航迹起始算法。利用Hough变换将不同时刻的量测集合分别映射到参数空间,继而将空间中具有相同索引的各次累加结果构成累加向量,统计其非零元素的个数,如大于预先设定的门限,则用向量各元素求和作为累加结果,否则置零。将利用该方法获得最终的累加结果进行门限检测来确定是否起始航迹。仿真实验表明,该算法可在密集环境下快速准确地起始航迹。     

Hidden Markov models with arbitrary state dwell-time distributions

A hidden Markov model (HMM) with a special structure that captures the ‘semi’-property of hidden semi-Markov models (HSMMs) is considered. The proposed model allows arbitrary dwell-time distributions in the states of the Markov chain. For dwell-time distributions with finite support the HMM formulation is exact while for those that have infinite support, e.g. the Poisson, the distribution can be approximated with arbitrary accuracy. A benefit of using the HMM formulation is that it is easy to incorporate covariates, trend and seasonal variation particularly in the hidden component of the model. In addition, the formulae and methods for forecasting, state prediction, decoding and model checking that exist for ordinary HMMs are applicable to the proposed class of models. An HMM with explicitly modeled dwell-time distributions involving seasonality is used to model daily rainfall occurrence for sites in Bulgaria.     

南方红壤区马尾松林下水土流失与降雨量关系研究

为了更好地研究马尾松林水土流失规律,从水土流失主要控制因子——降雨因子出发,通过对红壤侵蚀区不同林下配置模式马尾松林径流试验小区2009—2011年的产流、产沙与降雨量的关系研究。得到如下结论：①各小区的产流量和产沙量均与降雨量呈显著性相关,回归模型主要以一元二次回归最优,个别小区以幂函数和对数函数最优,其中以马尾松地表裸露小区模拟方程可决系数最大;②各雨型在同一郁闭度条件下,除去郁闭度为0％的小区外,各小区基本满足乔＋地表裸露〉乔＋百喜草〉乔＋胡枝子,伴随着降雨量的增加,各小区的径流系数总体上呈增加的趋势,尤其在暴雨和大暴雨以上的雨型更加明显;③产沙方面,各雨型条件下,除去郁闭度为O％的小区和个别郁闭度为24％的小区外,基本上满足乔＋地表裸露〉乔＋胡枝子〉乔＋百喜草。     

江苏太湖流域降雨径流年际变化分析

以江苏太湖流域（1956—2012）降雨为基础,分析江苏太湖流域径流及时空变化特征,研究该流域降雨径流的年际年内变化及两者的变化关系。结果表明：降雨径流都呈增长趋势。降雨平均每10年增加29mm,径流平均每10年增加26mm;降雨在年内季节分配上,夏季、冬季呈加大趋势,春季、秋季呈减小趋势;加大的降水年内分配的不均导致径流在年内分配的更加不均匀,径流集中在汛期,汛期径流量约达年径流量的84．8％,加大了某季节内的洪水、干旱风险。     

降雨入渗对非饱和土边坡稳定性的影响

研究降雨入渗对边坡稳定性的影响规律。采用有限元法进行非饱和土边坡的二维非稳态渗流计算,考虑基质吸作用利用极限平衡法进行非饱和土边坡稳定安全系数计算,进而通过算例计算,分析了降雨过程中及降雨之后,边坡内孔隙水压分布、潜在滑裂面位置以及边坡稳定安全系数的变化情况。着重分析了降雨强度和降雨持续时间的影响,并特别注意分析降雨结束后的边坡稳定性。算例表明某些情况下边坡安全系数最小值出现在降雨之后的数小时或数天,而非降雨的过程中或降雨刚刚结束之时。     

Monthly Joint Operations for the Nakdong Multi-reservoir System in Korea

Abstract

This study applies a state-of-art optimization technique, SSDP/ESP (Sampling Stochastic Dynamic Programming with Ensemble Streamflow Prediction), to derive a monthly joint operating policy for the Nakdong multi-reservoir system in Korea. A rainfall-runoff model, SSARR (Streamflow Synthesis And Reservoir Regulation), is linked to the SSDP/ESP model to provide ESP scenarios for runoff during the next month in the Nakdong River basin. The primary advantage of the SSDP/ESP is that it updates the derived operating policy as new ESP forecasts become available. Another SSDP model that employs historical runoff scenarios (SSDP/Hist) is also developed. The main difference between the two SSDP models is that SSDP/Hist is an off-line model whereas the SSDP/ESP is on-line. The developed operating policies are tested with a simulation model using an object-oriented simulation software, STELLA. The simulation results show that SSDP/ESP is superior to SSDP/Hist with respect to the water supply criterion, although both models perform similarly with respect to the hydroelectric energy production criterion.