Predicting river daily flow using wavelet-artificial neural networks based on regression analyses in comparison with artificial neural networks and support vector machine models

This study investigates the ability of wavelet-artificial neural networks (WANN) for the prediction of short-term daily river flow. The WANN model is improved by conjunction of two methods, discrete wavelet transform and artificial neural networks (ANN) based on regression analyses, respectively. The proposed WANN models are applied to the daily flow data of Vanyar station, on the Ajichai River in the northwest region of Iran, and compared with the ANN and support vector machine (SVM) techniques. Mean square error (MSE), mean absolute error (MAE) and correlation coefficient (R) statistics are used for evaluating precision of the WANN, ANN and SVM models. Comparison results demonstrate that the WANN model performs better than the ANN and SVM models in short-term (1-, 2- and 3-day ahead) daily river flow prediction.

     

Prediction of dissolved oxygen in River Calder by noise elimination time series using wavelet transform

Prediction of dissolved oxygen (DO) plays an important role in water resources especially in surface waters such as rivers. The oxygen affects a vast number of other water indicators. In this study, the artificial neural network (ANN) and a hybrid wavelet-ANN (WANN) models were considered to predict thirty minutes dissolved oxygen in the River Calder at the Methley Bridge Station was located in the UK. For the proposed WANN model, the discrete wavelet transform (DWT) was linked to the ANN model for DO prediction. To achieve this aim, the original time series of thirty minutes DO and temperature (T) were decomposed in several sub-time series by DWT, and these new sub-series were imposed to the ANN model. The results were compared with single ANN model. The comparisons were done by some of the widely used relevant physical statistic indices. The Nash–Sutcliffe coefficient values were 0.998 and 0.740 for the WANN and ANN models, respectively. The model computed values of DO by the WANN model were in close agreement with respective measured values in the river water. Elimination noise by DWT model during pre-processing data is one of the abilities of the WANN model to better prediction. Since the results indicate closer approximation of the peak DO values by the WANN model, this model could be used for the simulation of cumulative DO data prediction in thirty minutes ahead.     

Pso-Bp 耦合算法在矿井瓦斯突出预测中的应用

矿井瓦斯含量的预测模型是一个多变量、非线性的函数关系,预测模型建立的准确与否决定于各个影响因素之间的相互作用、相互耦合的特性。将神经网络与粒子群算法有机地结合起来,以神经网络理论为基础,利用粒子群算法优化隐含层神经元个数和网络中的连接权值,建立瓦斯含量预测模型,解决了Bp神经网络收敛速度慢、易陷入局部优化的缺陷。并在历史数据的基础上,建立遗传神经网络训练和检验样本集,利用MATLAB进行仿真,结果表明粒子群神经网络模型可靠性强,预测精度高。     

New robust forecasting models for exchange rates prediction

This paper introduces two robust forecasting models for efficient prediction of different exchange rates for future months ahead. These models employ Wilcoxon artificial neural network (WANN) and Wilcoxon functional link artificial neural network (WFLANN). The learning algorithms required to train the weights of these models are derived by minimizing a robust norm called Wilcoxon norm. These models offer robust exchange rate predictions in the sense that the training of weight parameters of these models are not influenced by outliers present in the training samples. The Wilcoxon norm considers the rank or position of an error value rather than its amplitude. Simulation based experiments have been conducted using real life data and the results indicate that both models, unlike conventional models, demonstrate consistently superior prediction performance under different densities of outliers present in the training samples. Further, comparison of performance between the two proposed models reveals that both provide almost identical performance but the later involved low computational complexity and hence is preferable over the WANN model.     

神经网络和改进粒子群算法在地震预测中的应用

提出了一种基于神经网络与改进粒子群算法的地震预测方法,该方法采用前向神经网络作为地震震级的预测模型,引入改进的粒子群算法对前向网络的连接权值进行修正。为了设计在全局搜索和局部搜索之间取得最佳平衡的惯性权重,基于粒子动态变异思想对粒子群优化算法进行改进,提出了一种动态变异粒子群优化算法,并将其应用于地震震级预测神经网络模型优化。在仿真实验中,将所提出的方法与另外两个采用不同算法的前向网络预测方法进行了比较。结果表明所提出的优化算法收敛速度最快,所得模型的预测误差最小,泛化能力最强,对地震的中期预测有很好的参考作用。     

Prediction of first lactation 305-day milk yield in Karan Fries dairy cattle using ANN modeling

In this paper, an artificial neural network (ANN) model is proposed to predict the first lactation 305-day milk yield (FLMY305) using partial lactation records pertaining to the Karan Fries (KF) crossbred dairy cattle. A scientifically determined optimum dataset of representative breeding traits of the cattle is used to develop the model.Several training algorithms, viz., (i) gradient descent algorithm with adaptive learning rate; (ii) Fletcher–Reeves conjugate gradient algorithm; (iii) Polak–Ribiére conjugate gradient algorithm; (iv) Powell–Beale conjugate gradient algorithm; (v) Quasi-Newton algorithm with Broyden, Fletcher, Goldfarb, and Shanno (BFGS) update; and (vi) Levenberg–Marquardt algorithm with Bayesian regularization; along with various network architectural parameters, i.e., data partitioning strategy, initial synaptic weights, number of hidden layers, number of neurons in each hidden layer, activation functions, regularization factor, etc., are experimentally investigated to arrive at the best model for predicting the FLMY305.Also, a multiple linear regression (MLR) model is developed for the milk-yield prediction. The performances of ANN and MLR models are compared to assess the relative prediction capability of the former model.It emerges from this study that the performance of ANN model seems to be slightly superior to that of the conventional regression model. Hence, it is recommended that the ANNs can potentially be used as an alternative technique to predict FLMY305 in the KF cattle.     

Corrosion current density prediction in reinforced concrete by imperialist competitive algorithm

This study attempted to predict corrosion current density in concrete using artificial neural networks (ANN) combined with imperialist competitive algorithm (ICA) used to optimize weights of ANN. For that reason, temperature, AC resistivity over the steel bar, AC resistivity remote from the steel bar, and the DC resistivity over the steel bar are considered as input parameters and corrosion current density as output parameter. The ICA–ANN model has been compared with the genetic algorithm to evaluate its accuracy in three phases of training, testing, and prediction. The results showed that the ICA–ANN model enjoys more ability, flexibility, and accuracy.     

Overbreak prediction and optimization in tunnel using neural network and bee colony techniques

Overbreak is an undesirable phenomenon in blasting operations. The causing factors of overbreak can be generally divided as blasting and geological parameters. Due to multiplicity of effective parameters and complexity of interactions among these parameters, empirical methods may not be fully appropriated for blasting pattern design. In this research, artificial neural network (ANN) as a powerful tool for solving such complicated problems is developed to predict overbreak induced by blasting operations in the Gardaneh Rokh tunnel, Iran. To develop an ANN model, an established database comprising of 255 datasets has been utilized. A three-layer ANN was found as an optimum model for prediction of overbreak. The coefficient of determination (R²) and root mean square error (RMSE) values of the selected model were obtained as 0.921, 0.4820, 0.923 and 0.4277 for training and testing, respectively, which demonstrate a high capability of ANN in predicting overbreak. After selecting the best model, the selected model was used for optimization purpose using artificial bee colony (ABC) algorithm as one of the most powerful optimization algorithms. Considering this point that overbreak is one of the main problems in tunneling, reducing its amount causes to have a good tunneling operation. After making several models of optimization and variations in its weights, the optimum amount for the extra drilling was 1.63 m², which is 47% lower than the lowest value (3.055 m²). It can be concluded that ABC algorithm can be introduced as a new optimizing algorithm to minimize overbreak induced by tunneling.

     

基于CS-ANN的软件缺陷预测模型研究

为了提高软件缺陷预测的准确率,利用布谷鸟搜索算法(Cuckoo Search,CS)的寻优能力和人工神经网络算法（Artificial Neural Network,ANN）的非线性计算能力,提出了基于CS-ANN的软件缺陷预测方法。此方法首先使用基于关联规则的特征选择算法降低数据的维度,去除了噪声属性;利用布谷鸟搜索算法寻找神经网络算法的权值,然后使用权值和神经网络算法构建出预测模型;最后使用此模型完成缺陷预测。使用公开的NASA数据集进行仿真实验,结果表明该模型降低了误报率并提高了预测的准确率,综合评价指标AUC（area under the ROC curve）、F1值和G-mean都优于现有模型。     

基于QPSO和极限学习的离散过程神经网络及学习算法

连续过程神经元网络在权函数正交基展开时, 基函数个数无法有效确定, 因此逼近精度不高. 针对该问题, 提出一种离散过程神经元网络, 使用三次样条数值积分处理离散样本和权值的时域聚合运算. 模型训练采用双链量子粒子群完成输入权值的全局寻优, 通过量子旋转门和非门完成种群进化. 局部使用极限学习, 通过Moore-Penrose广义逆计算输出权值. 以时间序列预测为例进行仿真实验, 结果验证了模型的有效性, 且训练收敛能力和逼近能力都有一定程度的提高.     

Optimization of neural network model using modified bat-inspired algorithm

The success of an artificial neural network (ANN) strongly depends on the variety of the connection weights and the network structure. Among many methods used in the literature to accurately select the network weights or structure in isolate; a few researchers have attempted to select both the weights and structure of ANN automatically by using metaheuristic algorithms. This paper proposes modified bat algorithm with a new solution representation for both optimizing the weights and structure of ANNs. The algorithm, which is based on the echolocation behaviour of bats, combines the advantages of population-based and local search algorithms. In this work, ability of the basic bat algorithm and some modified versions which are based on the consideration of the personal best solution in the velocity adjustment, the mean of personal best and global best solutions through velocity adjustment and the employment of three chaotic maps are investigated. These modifications are aimed to improve the exploration and exploitation capability of bat algorithm. Different versions of the proposed bat algorithm are incorporated to handle the selection of the structure as well as weights and biases of the ANN during the training process. We then use the Taguchi method to tune the parameters of the algorithm that demonstrates the best ability compared to the other versions. Six classifications and two time series benchmark datasets are used to test the performance of the proposed approach in terms of classification and prediction accuracy. Statistical tests demonstrate that the proposed method generates some of the best results in comparison with the latest methods in the literature. Finally, our best method is applied to a real-world problem, namely to predict the future values of rainfall data and the results show satisfactory of the method.     

基于免疫算法的前馈神经网络权值设计

提出了一种基于免疫算法的前馈神经网络设计方法(ImmuneFeed-forwardNeuralNetwork,INN),用于实现前馈神经网络权值空间的搜索。初步实验结果显示免疫算法具有快速学习网络权值的和脱离局部极小点的能力。     

Robust feedforward and recurrent neural network based dynamic weighted combination models for software reliability prediction

Traditional parametric software reliability growth models (SRGMs) are based on some assumptions or distributions and none such single model can produce accurate prediction results in all circumstances. Non-parametric models like the artificial neural network (ANN) based models can predict software reliability based on only fault history data without any assumptions. In this paper, initially we propose a robust feedforward neural network (FFNN) based dynamic weighted combination model (PFFNNDWCM) for software reliability prediction. Four well-known traditional SRGMs are combined based on the dynamically evaluated weights determined by the learning algorithm of the proposed FFNN. Based on this proposed FFNN architecture, we also propose a robust recurrent neural network (RNN) based dynamic weighted combination model (PRNNDWCM) to predict the software reliability more justifiably. A real-coded genetic algorithm (GA) is proposed to train the ANNs. Predictability of the proposed models are compared with the existing ANN based software reliability models through three real software failure data sets. We also compare the performances of the proposed models with the models that can be developed by combining three or two of the four SRGMs. Comparative studies demonstrate that the PFFNNDWCM and PRNNDWCM present fairly accurate fitting and predictive capability than the other existing ANN based models. Numerical and graphical explanations show that PRNNDWCM is promising for software reliability prediction since its fitting and prediction error is much less relative to the PFFNNDWCM.     

Artificial neural networks with evolutionary instance selection for financial forecasting

In this paper, I propose a genetic algorithm (GA) approach to instance selection in artificial neural networks (ANNs) for financial data mining. ANN has preeminent learning ability, but often exhibit inconsistent and unpredictable performance for noisy data. In addition, it may not be possible to train ANN or the training task cannot be effectively carried out without data reduction when the amount of data is so large. In this paper, the GA optimizes simultaneously the connection weights between layers and a selection task for relevant instances. The globally evolved weights mitigate the well-known limitations of gradient descent algorithm. In addition, genetically selected instances shorten the learning time and enhance prediction performance. This study applies the proposed model to stock market analysis. Experimental results show that the GA approach is a promising method for instance selection in ANN.     

Application of artificial neural network to the rapid feedback of potential ecological risk in flood diversion zone

As one of the ecological consequences due to intensified human activities in the upper catchments of the Yangtze River, the riverbed rising accompanied with soil erosion in the catchments has resulted in the significant increase of water level vs. the same flow discharge, which in turn enhanced the potential frequency of flood diversion and the uncertainty of flood risk in the diversion zone. In this paper, an artificial neural network (ANN) model based on radial-basis-function (RBF) was established for flood risk ranking at five safety polders. The computational speed for potential flood/ecological risk prediction as well as the feedback capability of integrated system was significantly enhanced through key techniques such as combination of the conventional hydrodynamic model and the ANN model, and integration of GIS and model. The site-specific and multi-site-specific RBF-ANN models developed herein not only provide useful tools for rapid prediction of flood routing process, but also show much promise for rapid feedback of the site-specific risk and real-time diversion process control.     

Constructive neural networks with piecewise interpolationcapabilities for function approximations

This paper proposes a constructive neural network with a piecewise linear or nonlinear local interpolation capability to approximate arbitrary continuous functions. This neural network is devised by introducing a space tessellation which is a covering of the Euclidean space by nonoverlapping hyperpolyhedral convex cells. In the proposed neural network, a number of neural network granules (NNG's) are processed in parallel and repeated regularly with the same structures. Each NNG does a local mapping with an interpolation capability for a corresponding hyperpolyhedral convex cell in a tessellation. The plastic weights of the NNG can be calculated to implement the mapping for training data; consequently, this reduces training time and alleviates the difficulties of local minima in training. In addition, the interpolation capability of the NNG improves the generalization for the new data within the convex cell. The proposed network requires additional neurons for tessellation over the standard multilayer neural networks. This increases the network size but does not slow the retrieval response when implemented by parallel architecture.     

Flood forecasting at the Dadu River in China based on ANN

Mappings of the stimuli effects and the input and output estimates of artificial neural networks (ANN) are obtained via combinations of nonlinear functions. This approach offers the advantages of self‐learning, self‐organization, self‐adaptation, and fault tolerance as well as the potential for use in flood forecasting applications. Furthermore, the ANN technology allows the use of multiple variables in both the input and output layers. This capability is very important for flood calculation because the stage, discharge, and other hydrological variables often are functions of many influential variables. Herein, we propose a flood forecasting system with related application, based on ANN. This method offers better performance and efficiency.     

基于SCSO-GRU模型的网络流量预测

网络流量有实时性、不稳定性和时序相关性等特点,传统网络流量预测模型存在泛化能力不强和预测精度低等不足之处。为解决这些不足,本文提出一种结合基于正余弦的群优化（SCSO）算法的GRU神经网络的网络流量预测模型（SCSO-GRU）。首先,介绍SCSO算法的粒子更新原理;然后构建SCSO-GRU神经网络的网络流量预测模型,将SCSO算法用于模型训练,提高训练效果,克服传统GRU神经网络收敛于局部最优的缺点;最后用SCSO-GRU模型进行网络流量预测。实验结果表明,与传统LSTM和GRU模型相比,本文模型具有显著的收敛效果和较好的预测精度,可以更好地刻画网络流量变化趋势。     

基于MEA-BP的微波加热褐煤温度预测

对于微波干燥褐煤的温度采样数据具有多峰非平稳特性,采用小波阈值滤波能够较好地保留原始数据的细节信息。而直接使用反向传播（ BP）神经网络来建立对微波加热物料温度预测模型,具有预测精度低、收敛速度慢且容易陷入局部极小点等缺点。采用具有极强全局寻优能力的思维进化算法（ MEA）来优化BP（ MEA-BP）神经网络的初始权值和阈值。实验结果表明：经MEA-BP神经网络具有更高的预测精度和泛化能力,预测性能得到了显著的提高。     

股票价格预测的建模与仿真研究

研究股票价格准确预测问题,由于股票价格数据具非线性、随机性等变化规律,同时股票市场与国内外经济政治变化有关,传统股票价格预测方法只能对其线性变化规律进行准确预测,无法反映股票价格非线性部分进行有效建模,导致股价预测精度不高。为了提高股票价格预测精度,提出了一种遗传优化BP神经网络的股票价格预测模型。充分利用BP神经网络良好的非线性映射能力,对股票价格变化规律进行建模,并通过遗传算法对BP神经网络模型参数进行优化,从而获最优股票价格最优预测模型。实验结果表明,相对于传统股票价格预测模型,遗传算法优化BP神经网络的股票价格预测模型拟合程度更好,预测精度更高,为股票价格预测提供了依据。