Gene expression time series modeling with principal component and neural network

In this work, gene expression time series models have been constructed by using principal component analysis (PCA) and neural network (NN). The main contribution of this paper is to develop a methodology for modeling numerical gene expression time series. The PCA-NN prediction models are compared with other popular continuous prediction methods. The proposed model can give us the extracted features from the gene expressions time series and the orders of the prediction accuracies. Therefore, the model can help practitioners to gain a better understanding of a cell cycle, and to find the dependency of genes, which is useful for drug discoveries. Based on the results of two public real datasets, the PCA-NN method outperforms the other continuous prediction methods. In the time series model, we adapt Akaike's information criteria (AIC) tests and cross-validation to select a suitable NN model to avoid the overparameterized problem.     

Asynchronism-based principal component analysis for time series data mining

Principal component analysis (PCA) is often applied to dimensionality reduction for time series data mining. However, the principle of PCA is based on the synchronous covariance, which is not very effective in some cases. In this paper, an asynchronism-based principal component analysis (APCA) is proposed to reduce the dimensionality of univariate time series. In the process of APCA, an asynchronous method based on dynamic time warping (DTW) is developed to obtain the interpolated time series which derive from the original ones. The correlation coefficient or covariance between the interpolated time series represents the correlation between the original ones. In this way, a novel and valid principal component analysis based on the asynchronous covariance is achieved to reduce the dimensionality. The results of several experiments demonstrate that the proposed approach APCA outperforms PCA for dimensionality reduction in the field of time series data mining.     

Collaborative filtering based on iterative principal component analysis

Collaborative filtering (CF) is one of the most popular recommender system technologies, and utilizes the known preferences of a group of users to predict the unknown preference of a new user. However, the existing CF techniques has the drawback that it requires the entire existing data be maintained and analyzed repeatedly whenever new user ratings are added. To avoid such a problem, Eigentaste, a CF approach based on the principal component analysis (PCA), has been proposed. However, Eigentaste requires that each user rate every item in the so called gauge set for executing PCA, which may not be always feasible in practice. Developed in this article is an iterative PCA approach in which no gauge set is required, and singular value decomposition is employed for estimating missing ratings and dimensionality reduction. Principal component values for users in reduced dimension are used for clustering users. Then, the proposed approach is compared to Eigentaste in terms of the mean absolute error of prediction using the Jester, MovieLens, and EachMovie data sets. Experimental results show that the proposed approach, even without a gauge set, performs slightly better than Eigentaste regardless of the data set and clustering method employed, implying that it can be used as a useful alternative when defining a gauge set is neither possible nor practical.     

基于PCA的GABP神经网络入侵检测方法*

为克服BP算法易陷入局部最小的缺点,同时为减少样本数据维数,提出一种基于主成分分析(PCA)的遗传神经网络方法。通过降维和去相关加快收敛速度,采用改进的遗传算法优化神经网络权值,利用自适应学习速率动量梯度下降算法对神经网络进行训练。MATLAB仿真实验结果表明,该方法在准确性和收敛性方面都优于BP算法,应用于入侵检测系统中的检测率和误报率明显优于传统方法。     

A comparison of three methods for principal component analysis of fuzzy interval data

Vertices Principal Component Analysis (V-PCA), and Centers Principal Component Analysis (C-PCA) generalize Principal Component Analysis (PCA) in order to summarize interval valued data. Neural Network Principal Component Analysis (NN-PCA) represents an extension of PCA for fuzzy interval data. However, also the first two methods can be used for analyzing fuzzy interval data, but they then ignore the spread information. In the literature, the V-PCA method is usually considered computationally cumbersome because it requires the transformation of the interval valued data matrix into a single valued data matrix the number of rows of which depends exponentially on the number of variables and linearly on the number of observation units. However, it has been shown that this problem can be overcome by considering the cross-products matrix which is easy to compute. A review of C-PCA and V-PCA (which hence also includes the computational short-cut to V-PCA) and NN-PCA is provided. Furthermore, a comparison is given of the three methods by means of a simulation study and by an application to an empirical data set. In the simulation study, fuzzy interval data are generated according to various models, and it is reported in which conditions each method performs best.     

Highly accurate energy consumption forecasting model based on parallel LSTM neural networks

The main challenges of the energy consumption forecasting problem are the concerns for reliability, stability, efficiency and accuracy of the forecasting methods. The existing forecasting models suffer from the volatility of the energy consumption data. It is desired for AI models that predict irregular sudden changes and capture long-term dependencies in the data. In this study, a novel hybrid AI empowered forecasting model that combines singular spectrum analysis (SSA) and parallel long short term memory (PLSTM) neural networks is proposed. The decomposition with the SSA enhanced the performance of the PLSTM network. According to the experimental results, the proposed model outperforms the state-of-the-art models at different time intervals in terms of both prediction accuracy and computational efficiency.     

基于PCA和神经网络的识别方法研究

在计算机集成制造系统环境下,质量控制图是统计过程控制的重要工具,实际应用中最困难的是识别出控制图中由于异常因素造成的不同异常模式。针对这一问题展开研究,用主成分分析法作为前处理过程进行样本集的选择与优化,提出了基于PCA_改进BP算法的控制图模式智能识别方法。     

Process identification based on last principal component analysis

A simple linear identification algorithm is presented in this paper. The last principal component (LPC), the eigenvector corresponding to the smallest eigenvalue of a non-negative symmetric matrix, contains an optimal linear relation of the column vectors of the data matrix. This traditional, well-known principal component analysis is extended to the generalized last principal component analysis (GLPC). For processes with colored measurement noise or disturbances, consistency of the GLPC estimator is achieved without involving iteration or non-linear numerical optimization. The proposed algorithm is illustrated by a simulated example and application to a pilot-scale process.     

Quality prediction and analysis for large-scale processes based on multi-level principal component modeling strategy

This paper proposed a multi-level principal component regression (PCR) modeling strategy for quality prediction and analysis of large-scale processes. Based on decomposition of the large data matrix, the first level PCR model divides the process into different sub-blocks through uncorrelated principal component directions, with a related index defined for determination of variables in each sub-block. In the second level, a PCR model is developed for local quality prediction in each sub-block. Subsequently, the third level PCR model is constructed to combine the local prediction results in different sub-blocks. For process analysis, a sub-block contribution index is defined to identify the critical-to-quality sub-blocks, based on which an inside sub-block contribution index is further defined for determination of the key variables in each sub-block. As a result, correlations between process variables and quality variables can be successfully constructed. A case study on Tennessee Eastman (TE) benchmark process is provided for performance evaluation.     

基于主成分分析的多传感器数据融合

针对多个传感器对某一特性指标进行测量实验的数据融合问题,根据多元统计理论,提出了一种基于主成分分析的融合方法。该方法把各传感器的测量数据作为一总体,定义总体的各主成分,利用测量值与主成分的相关关系,给出了各传感器的综合支持程度和数据融合公式。该方法不需要知道总体的分布和先验概率,避免定义距离矩阵和受主观因素作用的关系矩阵。应用实例验证了该方法的有效性和具有较强的抗干扰能力。     

主成分分析与神经网络的结合在多变量序列预测中的应用

目前预测方法的研究主要集中在单变量时间序列上,本文建立起一种针对多元变量非线性时间序列建模和预测的方法框架.首先,同时考虑序列状态间的线性相关性和非线性相关性,建立初始延迟窗以包含充分的预测信息;然后,利用主成分分析(PCA)方法寻找不同变量在数据空间中的最大方差方向,扩展PCA应用于提取多个变量的综合信息,重构多元变量输入状态相空间;最后,利用神经网络逼近不同变量之间以及当前状态和将来状态之间的函数映射关系,实现多元变量预测.对Ro¨ssler混沌方程和大连降雨、气温序列的预测仿真说明了本文方法的有效性,为多元变量时间序列分析提供了一条新的途径.     

基于储备池主成分分析的多元时间序列预测研究

提出一种基于回声状态网络储备池的非线性ＰＣＡ 方法,并将其应用于多元时间序列的预测中．由于多维输入变量间的相关性会影响建模效果,通过储备池将输入在原空间的非线性特征转化成高维空间的线性特征．在其中运用线性ＰＣＡ 技术寻找输入在储备池空间的最大方差方向,提取有效的多元变量综合信息．经储备池主成分分析处理后的输入与预测点呈动态线性映射,可使用线性方法建模．仿真结果表明了该方法的有效性．     

A new subspace identification approach based on principal component analysis

Principal component analysis (PCA) has been widely used for monitoring complex industrial processes with multiple variables and diagnosing process and sensor faults. The objective of this paper is to develop a new subspace identification algorithm that gives consistent model estimates under the errors-in-variables (EIV) situation. In this paper, we propose a new subspace identification approach using principal component analysis. PCA naturally falls into the category of EIV formulation, which resembles total least squares and allows for errors in both process input and output. We propose to use PCA to determine the system observability subspace, the A, B, C, and D matrices and the system order for an EIV formulation. Standard PCA is modified with instrumental variables in order to achieve consistent estimates of the system matrices. The proposed subspace identification method is demonstrated using a simulated process and a real industrial process for model identification and order determination. For comparison the MOESP algorithm and N4SID algorithm are used as benchmarks to demonstrate the advantages of the proposed PCA based subspace model identification (SMI) algorithm.     

基于主成分分析的高速网络IDS性能研究

随着高速网络的快速发展,如何在高速网络中快速有效地捕捉到异常的攻击特征,成为研究IDS所面临的首要问题。利用主成分分析技术的不同主成分互不相关和主成分是原始特征的线性组合的特性,有效地将高维特征向量映射到低维的空间中,既保持了原始数据的特征,又减少了高速网络环境下系统的丢包率,通过对KDD Cup99数据集进行实验,并运用BP神经网络分类器进行了验证,证明该方法是正确有效的。同时提出了数据管理功能模块,不但使算法与实际应用结合的更加紧密,而且也改善了入侵检测系统的整体性能。     

基于动态概率主元分析的统计过程监测

概率主元分析(PPCA)已广泛应用于工业过程监测.然而,PPCA法仅构造了生产过程的静态线性关系,处理具有较强动态特性的实际工业生产过程效果较差.为此提出动态概率主元分析(DPPCA)法,对经过时谱扩展后的变量数据阵,通过期望最大化(EM)算法建立生成模型,从而将静态PPCA推广到动态多变量过程.最后将此法应用于TE过程的仿真研究,结果表明该法有效.     

Filtering method of rock points based on BP neural network and principal component analysis

Filtering is an essential step in the process of obtaining rock data. To the best of our knowledge, there are no special algorithms for use in the point clouds of rock masses. Existing filtering methods remove noisy points by fitting the surface of the ground and deleting the points above the surface around a range of values. This type of methods has certain limitations in rock engineering owing the uniqueness of the particular rockmass being studied. In this paper, a method for filtering the rock points is proposed based on a backpropagation (BP) neural network and principal component analysis (PCA). In the proposed method, a PCA is applied for feature extraction, and for obtaining the dimensional information, which can be used to effectively distinguish the rock and other points at different scales. A BP neural network, which has a strong nonlinear processing capability, is then used to obtain the exact points of rock with the above characteristics. In the present paper, the efficiency of the proposed technique is illustrated by classifying steep rocky slopes as rock and vegetation. A comparison with existing methods indicates the superiority of the proposed method in terms of the point cloud filtering of rock masses.     

Dynamic process fault monitoring based on neural network and PCA

A newly developed method, NNPCA, integrates two data driven techniques, neural network (NN) and principal component analysis (PCA), for process monitoring. NN is used to summarize the operating process information into a nonlinear dynamic mathematical model. Chemical dynamic processes are so complex that they are presently ahead of theoretical methods from a fundamental physical standpoint. NN functions as the nonlinear dynamic operator to remove processes' nonlinear and dynamic characteristics. PCA is employed to generate simple monitoring charts based on the multivariable residuals derived from the difference between the process measurements and the neural network prediction. It can evaluate the current performance of the process. Examples from the recent monitoring practice in the industry and the large-scale system in the Tennessee Eastman process problem are presented to help the reader delve into the matter.     

基于改进二维主成分分析及神经网络的人耳识别方法

针对人耳识别特征提取阶段二维主成分分析算法(2DPCA)所提取的人耳特征维数较大,从而造成实时性差、数据存储空间不足等问题提出了一种改进方法。该方法首先对人耳图片进行预处理,然后采用改进的两级2DPCA算法,进一步压缩提取的人耳特征维数,最后采用BP神经网络进行分类识别。实验表明,将改进的两级2DPCA算法同BP神经网络相结合,具有较好的实时性,同时节约了特征数据的存储空间,并保持了较好的识别率。     

基于核主成分分析的数据流降维研究

分析了数据流降维算法PCA和KPCA的原理和实现方法。针对在大型数据集上PCA线性降维无法有效实现降维且KPCA的降维效率差,提出了一种新的降维策略GKPCA算法。该算法将数据集先分组,对每一组执行KPCA,然后过滤重新组合数据集,再次应用KPCA算法,达到简化样本空间,降低了时间复杂度和空间复杂度。实验分析表明,GKPCA算法不仅能取得良好的降维效果,而且时间消耗少。     

基于主分量分析的缺陷识别研究

为了解决传统的人工定义方法和小波包分解方法在超声信号特征提取方面的不足,提出了将主分量分析方法应用于信号的特征提取,并据此进行超声检测的缺陷识别.这种方法不但大大降低了数据量,减少了计算复杂度,同时也能够保证压缩后的数据能够有效的代表原数据特性.通过对提取到的特征建立特征向量,利用模糊模式判别方法进行测试,并和现有的两种方法进行对比.与目前采用的方法相比,该方法在识别效率和准确性上都表现非常优秀,能对各种模式有效识别.