Rainfall forecasting is becoming more and more significant and precipitation anomalies would lead to droughts and floods disasters.However,because of the complexity and non-stationary of rainfall data,it is difficult ...Rainfall forecasting is becoming more and more significant and precipitation anomalies would lead to droughts and floods disasters.However,because of the complexity and non-stationary of rainfall data,it is difficult to forecast.In this paper,a novel hybrid model to forecast rainfall is developed by incorporating singular spectrum analysis (SSA) and dragonfly algorithm (DA) into support vector regression (SVR) method.Firstly,SSA is used for extracting the trend components of the hydrological data.Then,SVR is utilized to deal with the volatility and irregularity of the precipitation series.Finally,the parameter of SVR is optimized by DA.The proposed SSA-DA-SVR method is used to forecast the monthly precipitation for Songbai,Panshui,Lanma and Jiulongchi stations.To validate the efficiency of the method,four compared models,DA-SVR,SSA-GWO-SVR,SSA-PSO-SVR and SSA-CS-SVR are established.The result shows that the proposed method has the best performance among all five models,and its prediction has high precision and accuracy.展开更多
Due to the severe and costly problems caused by asphaltene precipitation in petroleum industry,developing a quick and accurate model,to predict the asphaltene precipitation under different conditions,seems crucial.In ...Due to the severe and costly problems caused by asphaltene precipitation in petroleum industry,developing a quick and accurate model,to predict the asphaltene precipitation under different conditions,seems crucial.In this study,a new model,namely genetic algorithm e support vector regression(GA-SVR)is proposed,which is applied to predict the amount of asphaltene precipitation.GA is used to select the best optimal values of SVR parameters and kernel parameter,simultaneously,to increase the generalization performance of the SVR.The GA-SVR model is trained and tested on the experimental data sets reported in literature.The performance of the GASVR model is compared with two scaling equation models,using statistical error measures and graphical analyses.The results show that the prediction performance of the proposed model,is highly reliable and satisfactory.展开更多
A new customization approach based on support vector regression （SVR） is proposed to obtain individual headrelated impulse response （HRIR） without complex measurement and special equipment. Principal component ana...A new customization approach based on support vector regression （SVR） is proposed to obtain individual headrelated impulse response （HRIR） without complex measurement and special equipment. Principal component analysis （PCA） is first applied to obtain a few principal components and corresponding weight vectors correlated with individual anthropometric parameters. Then the weight vectors act as output of the nonlinear regression model. Some measured anthropometric parameters are selected as input of the model according to the correlation coefficients between the parameters and the weight vectors. After the regression model is learned from the training data, the individual HRIR can be predicted based on the measured anthropometric parameters. Compared with a back-propagation neural network （BPNN） for nonlinear regression, better generalization and prediction performance for small training samples can be obtained using the proposed PCA-SVR algorithm.展开更多
Model predictive control(MPC)is an optimal control method that predicts the future states of the system being controlled and estimates the optimal control inputs that drive the predicted states to the required referen...Model predictive control(MPC)is an optimal control method that predicts the future states of the system being controlled and estimates the optimal control inputs that drive the predicted states to the required reference.The computations of the MPC are performed at pre-determined sample instances over a finite time horizon.The number of sample instances and the horizon length determine the performance of the MPC and its computational cost.A long horizon with a large sample count allows the MPC to better estimate the inputs when the states have rapid changes over time,which results in better performance but at the expense of high computational cost.However,this long horizon is not always necessary,especially for slowly-varying states.In this case,a short horizon with less sample count is preferable as the same MPC performance can be obtained but at a fraction of the computational cost.In this paper,we propose an adaptive regression-based MPC that predicts the best minimum horizon length and the sample count from several features extracted from the time-varying changes of the states.The proposed technique builds a synthetic dataset using the system model and utilizes the dataset to train a support vector regressor that performs the prediction.The proposed technique is experimentally compared with several state-of-the-art techniques on both linear and non-linear models.The proposed technique shows a superior reduction in computational time with a reduction of about 35–65%compared with the other techniques without introducing a noticeable loss in performance.展开更多
模型辅助检测概率(model-assisted probability of detection,MAPoD)和灵敏度分析对于量化涡流无损检测(eddy current nondestructive testing,ECNDT)系统的检测能力非常重要。由于不确定性在涡流无损检测的MAPoD和SA问题中的传播,传统...模型辅助检测概率(model-assisted probability of detection,MAPoD)和灵敏度分析对于量化涡流无损检测(eddy current nondestructive testing,ECNDT)系统的检测能力非常重要。由于不确定性在涡流无损检测的MAPoD和SA问题中的传播,传统基于实验方法和物理仿真模型对该问题的分析需要耗费大量的时间和人力成本,为了降低这些成本,提出基于粒子群算法(particle swarm optimization,PSO)的支持向量回归(support vector regression,SVR)模型取代传统的实验方法以及物理仿真模型,对涡流无损检测模型的响应进行预测,从而加速MAPoD和SA问题的分析。此外,创新性地将网格搜索、随机搜索、模拟退火算法和PSO等优化算法与SVR相结合,研究不同的优化算法对SVR的关键参数优化的精度和效率,验证PSO相较于其他优化算法的性能优势。最后,将PSO-SVR模型应用于ECNDT算例中,对表面裂缝长度的不确定性进行MAPoD和SA的分析。结果表明,所提算法在保证求解精度的同时,加速了涡流无损检测系统的MAPoD和SA问题的研究,并减少了计算开销。在计算量方面,对这两个问题的求解,平均分别仅需纯物理模型计算量的3.5%和0.06%。展开更多
The existing optimized performance prediction of carbon fiber protofilament process model is still unable to meet the production needs. A way of performance prediction on carbon fiber protofilament was presented based...The existing optimized performance prediction of carbon fiber protofilament process model is still unable to meet the production needs. A way of performance prediction on carbon fiber protofilament was presented based on support vector regression( SVR) which was optimized by an optimization algorithm combining simulated annealing algorithm and genetic algorithm( SAGA-SVR). To verify the accuracy of the model,the carbon fiber protofilament production test data were analyzed and compared with BP neural network( BPNN). The results show that SAGA-SVR can predict the performance parameters of the carbon fiber protofilament accurately.展开更多
为给小麦的长势监测与农艺决策提供科学依据,利用高光谱技术实现了小麦冠层叶绿素含量的估测。通过分析18种高光谱指数对叶绿素的估测能力,筛选出可敏感表征叶绿素含量的指数REP,利用地面光谱数据为样本集,以最小二乘支持向量回归(least...为给小麦的长势监测与农艺决策提供科学依据,利用高光谱技术实现了小麦冠层叶绿素含量的估测。通过分析18种高光谱指数对叶绿素的估测能力,筛选出可敏感表征叶绿素含量的指数REP,利用地面光谱数据为样本集,以最小二乘支持向量回归(least squares support vector regression,LS-SVR)算法建立了小麦冠层叶绿素含量反演模型,其校正决定系数C-R2与预测决定系数P-R2分别为0.751与0.722,在各指数中反演精度最高。进一步分析表明,REP对叶绿素含量以及LAI值较高与较低的样本均具备良好的预测能力,可有效避免样本取值范围以及冠层郁闭度等因素对叶绿素含量估测的影响。利用LS-SVR反演模型完成了OMIS影像叶绿素含量的遥感填图,并以地面实测值进行检验,其拟合模型R2与RMSE值分别为0.676与1.715。结果表明,高光谱指数REP所建立的LS-SVR模型实现了叶绿素含量的准确估测,可用于小麦叶绿素含量信息的快速、无损获取。展开更多
为改进小麦冠层含氮率的高光谱测定模型,以正交试验筛选出小波去噪的最优参数组合(小波类型取haar,分解层数为5,阈值方案选择Fixed form threshold,噪声结构定为Unscaled white noise),并利用去噪后的小麦冠层光谱建立偏最小二乘回归(P...为改进小麦冠层含氮率的高光谱测定模型,以正交试验筛选出小波去噪的最优参数组合(小波类型取haar,分解层数为5,阈值方案选择Fixed form threshold,噪声结构定为Unscaled white noise),并利用去噪后的小麦冠层光谱建立偏最小二乘回归(PLS)模型,对不同预处理方法进行比较分析。发现采用小波去噪结合一阶导数能最有效消除原始光谱的背景信息,此时PLS模型校正集均方根误差(RMSEC)为0.260,预测集均方根误差(RMSEP)为0.288。对经一阶导数结合小波去噪后的光谱用主成分分析(PCA)进行降维,以前6个主成份为输入变量,建立最小二乘支撑向量机回归模型(LS-SVR),其RMSEC与RMSEP分别为0.154与0.259,具有比PLS模型更高的精度。结果表明:以小波去噪结合一阶导数去除小麦冠层反射光谱中的土壤背景信息以提高模型的精度是可行的,且LS-SVR是建模的优选方法。展开更多
文摘Rainfall forecasting is becoming more and more significant and precipitation anomalies would lead to droughts and floods disasters.However,because of the complexity and non-stationary of rainfall data,it is difficult to forecast.In this paper,a novel hybrid model to forecast rainfall is developed by incorporating singular spectrum analysis (SSA) and dragonfly algorithm (DA) into support vector regression (SVR) method.Firstly,SSA is used for extracting the trend components of the hydrological data.Then,SVR is utilized to deal with the volatility and irregularity of the precipitation series.Finally,the parameter of SVR is optimized by DA.The proposed SSA-DA-SVR method is used to forecast the monthly precipitation for Songbai,Panshui,Lanma and Jiulongchi stations.To validate the efficiency of the method,four compared models,DA-SVR,SSA-GWO-SVR,SSA-PSO-SVR and SSA-CS-SVR are established.The result shows that the proposed method has the best performance among all five models,and its prediction has high precision and accuracy.
文摘Due to the severe and costly problems caused by asphaltene precipitation in petroleum industry,developing a quick and accurate model,to predict the asphaltene precipitation under different conditions,seems crucial.In this study,a new model,namely genetic algorithm e support vector regression(GA-SVR)is proposed,which is applied to predict the amount of asphaltene precipitation.GA is used to select the best optimal values of SVR parameters and kernel parameter,simultaneously,to increase the generalization performance of the SVR.The GA-SVR model is trained and tested on the experimental data sets reported in literature.The performance of the GASVR model is compared with two scaling equation models,using statistical error measures and graphical analyses.The results show that the prediction performance of the proposed model,is highly reliable and satisfactory.
基金Project supported by the Shanghai Natural Science Foundation (Grant No.08ZR1408300)the Shanghai Leading Academic Discipline Project (Grant No.S30108)
文摘A new customization approach based on support vector regression （SVR） is proposed to obtain individual headrelated impulse response （HRIR） without complex measurement and special equipment. Principal component analysis （PCA） is first applied to obtain a few principal components and corresponding weight vectors correlated with individual anthropometric parameters. Then the weight vectors act as output of the nonlinear regression model. Some measured anthropometric parameters are selected as input of the model according to the correlation coefficients between the parameters and the weight vectors. After the regression model is learned from the training data, the individual HRIR can be predicted based on the measured anthropometric parameters. Compared with a back-propagation neural network （BPNN） for nonlinear regression, better generalization and prediction performance for small training samples can be obtained using the proposed PCA-SVR algorithm.
文摘Model predictive control(MPC)is an optimal control method that predicts the future states of the system being controlled and estimates the optimal control inputs that drive the predicted states to the required reference.The computations of the MPC are performed at pre-determined sample instances over a finite time horizon.The number of sample instances and the horizon length determine the performance of the MPC and its computational cost.A long horizon with a large sample count allows the MPC to better estimate the inputs when the states have rapid changes over time,which results in better performance but at the expense of high computational cost.However,this long horizon is not always necessary,especially for slowly-varying states.In this case,a short horizon with less sample count is preferable as the same MPC performance can be obtained but at a fraction of the computational cost.In this paper,we propose an adaptive regression-based MPC that predicts the best minimum horizon length and the sample count from several features extracted from the time-varying changes of the states.The proposed technique builds a synthetic dataset using the system model and utilizes the dataset to train a support vector regressor that performs the prediction.The proposed technique is experimentally compared with several state-of-the-art techniques on both linear and non-linear models.The proposed technique shows a superior reduction in computational time with a reduction of about 35–65%compared with the other techniques without introducing a noticeable loss in performance.
文摘模型辅助检测概率(model-assisted probability of detection,MAPoD)和灵敏度分析对于量化涡流无损检测(eddy current nondestructive testing,ECNDT)系统的检测能力非常重要。由于不确定性在涡流无损检测的MAPoD和SA问题中的传播,传统基于实验方法和物理仿真模型对该问题的分析需要耗费大量的时间和人力成本,为了降低这些成本,提出基于粒子群算法(particle swarm optimization,PSO)的支持向量回归(support vector regression,SVR)模型取代传统的实验方法以及物理仿真模型,对涡流无损检测模型的响应进行预测,从而加速MAPoD和SA问题的分析。此外,创新性地将网格搜索、随机搜索、模拟退火算法和PSO等优化算法与SVR相结合,研究不同的优化算法对SVR的关键参数优化的精度和效率,验证PSO相较于其他优化算法的性能优势。最后,将PSO-SVR模型应用于ECNDT算例中,对表面裂缝长度的不确定性进行MAPoD和SA的分析。结果表明,所提算法在保证求解精度的同时,加速了涡流无损检测系统的MAPoD和SA问题的研究,并减少了计算开销。在计算量方面,对这两个问题的求解,平均分别仅需纯物理模型计算量的3.5%和0.06%。
基金the Key Project of National Natural Science Foundation of China(No.61134009)Program for Changjiang Scholars and Innovation Research Team in University from the Ministry of Education,China(No.IRT1220)+1 种基金Specialized Research Fund for Shanghai Leading Talents,Project of the Shanghai Committee of Science and Technology,China(No.13JC1407500)the Fundamental Research Funds for the Central Universities,China(No.2232012A3-04)
文摘The existing optimized performance prediction of carbon fiber protofilament process model is still unable to meet the production needs. A way of performance prediction on carbon fiber protofilament was presented based on support vector regression( SVR) which was optimized by an optimization algorithm combining simulated annealing algorithm and genetic algorithm( SAGA-SVR). To verify the accuracy of the model,the carbon fiber protofilament production test data were analyzed and compared with BP neural network( BPNN). The results show that SAGA-SVR can predict the performance parameters of the carbon fiber protofilament accurately.
文摘为给小麦的长势监测与农艺决策提供科学依据,利用高光谱技术实现了小麦冠层叶绿素含量的估测。通过分析18种高光谱指数对叶绿素的估测能力,筛选出可敏感表征叶绿素含量的指数REP,利用地面光谱数据为样本集,以最小二乘支持向量回归(least squares support vector regression,LS-SVR)算法建立了小麦冠层叶绿素含量反演模型,其校正决定系数C-R2与预测决定系数P-R2分别为0.751与0.722,在各指数中反演精度最高。进一步分析表明,REP对叶绿素含量以及LAI值较高与较低的样本均具备良好的预测能力,可有效避免样本取值范围以及冠层郁闭度等因素对叶绿素含量估测的影响。利用LS-SVR反演模型完成了OMIS影像叶绿素含量的遥感填图,并以地面实测值进行检验,其拟合模型R2与RMSE值分别为0.676与1.715。结果表明,高光谱指数REP所建立的LS-SVR模型实现了叶绿素含量的准确估测,可用于小麦叶绿素含量信息的快速、无损获取。
文摘为改进小麦冠层含氮率的高光谱测定模型,以正交试验筛选出小波去噪的最优参数组合(小波类型取haar,分解层数为5,阈值方案选择Fixed form threshold,噪声结构定为Unscaled white noise),并利用去噪后的小麦冠层光谱建立偏最小二乘回归(PLS)模型,对不同预处理方法进行比较分析。发现采用小波去噪结合一阶导数能最有效消除原始光谱的背景信息,此时PLS模型校正集均方根误差(RMSEC)为0.260,预测集均方根误差(RMSEP)为0.288。对经一阶导数结合小波去噪后的光谱用主成分分析(PCA)进行降维,以前6个主成份为输入变量,建立最小二乘支撑向量机回归模型(LS-SVR),其RMSEC与RMSEP分别为0.154与0.259,具有比PLS模型更高的精度。结果表明:以小波去噪结合一阶导数去除小麦冠层反射光谱中的土壤背景信息以提高模型的精度是可行的,且LS-SVR是建模的优选方法。
