水浸出物是茶叶质量评价的重要指标之一。该研究提出利用近红外光谱法结合偏最小二乘算法(Partial least squares,PLS)快速检测乌龙茶中水浸出物含量。利用近红外光谱仪采集60份乌龙茶样品的光谱信息,通过Savitzky-Golay(SG)滤波器对原...水浸出物是茶叶质量评价的重要指标之一。该研究提出利用近红外光谱法结合偏最小二乘算法(Partial least squares,PLS)快速检测乌龙茶中水浸出物含量。利用近红外光谱仪采集60份乌龙茶样品的光谱信息,通过Savitzky-Golay(SG)滤波器对原始光谱数据进行预处理;采用连续投影算法(Successive projections algorithm,SPA)对采集的SG预处理光谱进行特征波长选择,基于SG预处理光谱和SPA法优化的特征光谱建立乌龙茶中水浸出物含量的PLS定量模型。结果显示,利用SPA法优化出14个特征波长建立SPA-PLS模型的性能最佳。在预测集中的相关系数为0.8966,预测均方根误差为0.8034%,剩余预测偏差为4.11。结果表明采用近红外光谱结合SPAPLS算法快速检测乌龙茶中水浸出物含量是可行的。展开更多
Based on the framework of method of successive averages(MSA), a modified stochastic user-equilibrium assignment algorithm was proposed, which can be used to calculate the passenger flow distribution of urban rail tran...Based on the framework of method of successive averages(MSA), a modified stochastic user-equilibrium assignment algorithm was proposed, which can be used to calculate the passenger flow distribution of urban rail transit(URT) under network operation. In order to describe the congestion's impact to passengers' route choices, a generalized cost function with in-vehicle congestion was set up. Building on the k-th shortest path algorithm, a method for generating choice set with time constraint was embedded, considering the characteristics of network operation. A simple but efficient route choice model, which was derived from travel surveys for URT passengers in China, was introduced to perform the stochastic network loading at each iteration in the algorithm. Initial tests on the URT network in Shanghai City show that the methodology, with rational calculation time, promises to compute more precisely the passenger flow distribution of URT under network operation, compared with those practical algorithms used in today's China.展开更多
文摘水浸出物是茶叶质量评价的重要指标之一。该研究提出利用近红外光谱法结合偏最小二乘算法(Partial least squares,PLS)快速检测乌龙茶中水浸出物含量。利用近红外光谱仪采集60份乌龙茶样品的光谱信息,通过Savitzky-Golay(SG)滤波器对原始光谱数据进行预处理;采用连续投影算法(Successive projections algorithm,SPA)对采集的SG预处理光谱进行特征波长选择,基于SG预处理光谱和SPA法优化的特征光谱建立乌龙茶中水浸出物含量的PLS定量模型。结果显示,利用SPA法优化出14个特征波长建立SPA-PLS模型的性能最佳。在预测集中的相关系数为0.8966,预测均方根误差为0.8034%,剩余预测偏差为4.11。结果表明采用近红外光谱结合SPAPLS算法快速检测乌龙茶中水浸出物含量是可行的。
基金Project(2007AA11Z236) supported by the National High Technology Research and Development Program of ChinaProject(2012M5209O1) supported by China Postdoctoral Science Foundation
文摘Based on the framework of method of successive averages(MSA), a modified stochastic user-equilibrium assignment algorithm was proposed, which can be used to calculate the passenger flow distribution of urban rail transit(URT) under network operation. In order to describe the congestion's impact to passengers' route choices, a generalized cost function with in-vehicle congestion was set up. Building on the k-th shortest path algorithm, a method for generating choice set with time constraint was embedded, considering the characteristics of network operation. A simple but efficient route choice model, which was derived from travel surveys for URT passengers in China, was introduced to perform the stochastic network loading at each iteration in the algorithm. Initial tests on the URT network in Shanghai City show that the methodology, with rational calculation time, promises to compute more precisely the passenger flow distribution of URT under network operation, compared with those practical algorithms used in today's China.
文摘采用自主水下航行器(Autonomous Underwater Vehicle,AUV)磁测平台可开展海洋地磁场测量、水下磁性目标探测和识别等工作,AUV磁测平台具有广阔的应用前景,但目前AUV载体磁干扰补偿技术研究尚不成熟,制约着水下航行器测磁精度。基于磁测平台抗磁干扰基本原理,提出一种基于线性种群规模缩减和成功历史的参数自适应差分进化(Success History-based Adaptive Differential Evolution with Linear Population Size Reduction,L-SHADE)算法的AUV载体磁干扰参数辨识的数值模拟方法。用磁偶极子和旋转椭球壳混合模型来等效模拟AUV载体磁干扰,通过模拟航行获得多组磁测数据,据此建立磁干扰参数辨识模型,并采用L-SHADE算法求解。通过数值模拟实验定量分析研究磁测平台测磁精度随磁传感器、平台姿态及航向等误差的传播规律。研究结果表明:当磁传感器测量精度为10 nT、姿态测量精度为0.01°、航向测量精度为0.1°时,测磁误差可小于100 nT。设计的AUV磁测平台抗干扰试验表明,地磁场总量最大相对误差为1.07%。
