采用门控循环神经网络估计锂离子电池健康状态

锂离子电池健康状态（State of Health，SOH）描述了电池当前老化程度，对于提前对电池的故障及失控做出预警避免电池的不安全行为具有重要意义。其估计难点在于难以确定数量合适、相关性高的估计输入以及设计合适的估计算法。通过对现有电池老化数据集的研究发现，电池充电过程中电压曲线数据相对稳定，且随着电池的老化出现规律性变化。因此，文中直接采用充电过程中电压数据作为估计SOH的输入，并在数据驱动的框架下，提出了一种基于门控循环神经网络（Recurrent Neural Networks with Gated Recurrent Unit, GRU-RNN）的锂电池SOH估计方法。该方法能够挖掘出一维电压数据中的时序特征和SOH之间的映射规律。在两个公开的电池老化数据集上的实验结果表明，提出的方法达到了1.25%的均方绝对误差和低于5.62%的最大误差，在估计精度上达到现有技术发展水平。     

采用混合核支持向量机的DOA估计

人工神经网络( ANN)进行建模时通常需要准备大量的数据样本,同时网络结构一般都比较复杂;而采用支持向量机( SVM)进行建模时,不同核函数有不同的效果,各有利弊,且选取SVM模型参数的理论支撑尚不完整。为了解决这些问题,提出了一种基于混合核函数的支持向量机来改善来波到达角( DOA)的估计性能,并结合二进制粒子群算法( PSO)来对混合核函数进行参数寻优。该混合核函数由全局核函数和局部核函数构成,提高了SVM的泛化能力和学习能力。首先通过拟合多项式函数,验证了该混合核SVM的有效性。将该方法用于DOA估计建模,在不同信噪比和快拍数下,通过与径向基函数( RBF)神经网络、基于各单一核函数的SVM和MUSIC算法预测结果对比,混合核SVM均方差有所降低,提高了DOA估计的精度且有更好的稳定性。     

A novel prediction method based on the support vector regression for the remaining useful life of lithium-ion batteries

Traditional approaches to lithium-ion battery health management mostly focus on the state of charge (SOC) estimation issues, whereas the state of health (SOH) estimation is also critical to lithium-ion batteries for safe operation. For online battery prognostics, it is critical to make timely and accurate response to SOH. The loss of rated capacity of a battery is usually used to determine the battery SOH, whereas the measurement of the capacity of an operating battery is quite challenging. Normally, the rated capacity fading largely relies on laboratory measurements and offline analysis. In this paper, two real-time measurable health indicators (HI) - one is the time interval of an equal charging voltage difference (TIECVD), and the other is the time interval of an equal discharging voltage difference (TIEDVD) - are extracted. A novel method which combines feature vector selection (FVS) with SVR is utilized to model the relationship between these two HIs and capacity, then the online capacity can be evaluated, more accurate prognostics of SOH and remaining useful life (RUL) can be made. Besides, compared to standard SVR, the proposed method takes FVS to cut down the training data size, which improves the efficiency of model training and prediction. In the end, two datasets demonstrated this approach performs both well in accuracy and efficiency.     

基于支持向量机的网络参数模型研究

使用模糊层次分析法对支持向量机的两个参数进行寻优,并用寻找到的最优参数训练支持向量机,建立网络参数模型。首先使用模糊层次分析法对支持向量机两个参数进行寻优,然后用寻找到的最优参数训练支持向量机,最后建立预测模型,预测网络流量。实验结果表明,该方法不但可以较好地跟踪网络流量变化趋势,使网络流量的预测值与实际值非常接近,而且预测误差变化范围波动小,是一种有效且预测精度高的网络参数模型。     

基于支持向量机的缓存预估模型的设计与实现

采用支持向量机(SVM)对网络业务流数据进行预测估计，通过训练样本，从而获得样本以外数据的分布规律。在此基础上，设计了一种网络排队队列缓存的预估模型。实验表明，该模型具有较高的训练效率和很高的估计精确度。     

动力型锂电池SOC与SOH协同估计

锂电池及其应用近年来逐渐成为研究热点。以提高电池管理系统(BMS)对电池荷电状态(SOC)和健康状态(SOH)的估算精确度为目标,在建立二阶Thevenin等效电路模型基础上提出一种能在线协同估算电池荷电状态和健康状态的改进扩展卡尔曼滤波算法。通过分阶段脉冲放电实验,并利用最小二乘法求得模型参数。在动态应力测试工况(DST)下借助Matlab对比分析了改进扩展卡尔曼算法在SOC和SOH估计精确度、错误初值时算法收敛性、算法复杂度等方面的性能。实验表明,利用该算法可以精确估计出各采样点处的SOC和SOH,误差低于1%;且在初值不准确情况下,运行算法可快速收敛至真值附近,算法估算结果的准确性与模型参数的微调无关,鲁棒性较好。     

基于神经网络与UKF结合的锂离子电池组SOC估算方法

锂离子电池组作为电动汽车的主要动力能源,对荷电状态的准确估计是电动汽车的关键技术之一。准确的SOC估计,对锂离子电池组的寿命维持及电动汽车的行车安全,具有十分重要的意义。基于此设计一种基于神经网络与无迹卡尔曼滤波器(UKF)相结合的SOC估算方法,既克服了UKF需要等效电池组电路模型的缺点,也能显著减小神经网络估算方法的最大误差。该实验数据来源于高级车辆仿真器(ADVISOR2002)基于实际工况的仿真结果,经实验数据证明,该方法具有有效性和实用性。     

Modeling of pneumatic artificial muscle using a hybrid artificial neural network approach

Pneumatic Artificial Muscle (PAM) actuator has been widely used in medical and rehabilitation robots, owing to its high power-to-weight ratio and inherent safety characteristics. However, the PAM exhibits highly non-linear and time variant behavior, due to compressibility of air, use of elastic-viscous material as core tube and pantographic motion of the PAM outer sheath. It is difficult to obtain a precise model using analytical modeling methods. This paper proposes a new Artificial Neural Network (ANN) based modeling approach for modeling PAM actuator. To obtain higher precision ANN model, three different approaches, namely, Back Propagation (BP) algorithm, Genetic Algorithm (GA) approach and hybrid approach combing BP algorithm with Modified Genetic Algorithm (MGA) are developed to optimize ANN parameters. Results show that the ANN model using the GA approach outperforms the BP algorithm, and the hybrid approach shows the best performance among the three approaches.     

利用改进的半正定规划的支持向量机识别车牌

针对现有车牌识别系统效率低的问题,提出了一种改进的支持向量机算法。首先对车牌进行预处理和定位,将每个特征区域构建一个多核心组合。以半定规划求解最佳的权系数。使用改进的半定规划来解决多核学习算法,降低搜索空间。最后构建车牌识别模型。仿真实验表明,该算法效率高,稳定性好。     

灰色关联分析与支持向量机相融合的网络安全态势评价

为了提高网络安全态势的评价准确性,提出一种灰色关联分析与支持向量机相融合的网络安全态势评价模型.首先采用灰色关联分析对网络安全态势评价指标进行筛选,并根据对评价结果贡献赋予评价指标权值,然后将重要的评价指标作为支持向量机的输入向量,并采用社会力模型算法选择模型的参数,最后采用仿真实例分析了模型的评价性能.实验结果表明,本文模型通过灰色关联分析选择支持向量机的输入向量和社会力模型算法选择了最合理的型参数,可以准确描述网络安全态势与评价指标之间的变化关系,不仅提高了网络安全态势评价的正确率,加快了建模速度,而且获得比经典模更优的评价结果.     

人工鱼群优化最小二乘支持向量机的视频字幕定位

征选择是视频字幕定位的关键,为了提高视频字幕定位正确率,提出一种人工鱼群算法(AFSA)和最小二乘支持向量机(LSSVM)相融合的视频字幕定位模型(AFSA-LSSVM)。首先提取视频字幕特征,然后通过模拟鱼群的觅食、聚群及追尾行为找到最优视频字幕特征子集,最后采用LSSVM建立最优视频字幕定位模型,并进行仿真对比实验。结果表明,相对其它视频字幕定位模型,AFSA-LSSVM提高了视频字幕定位正确率和效率,可为后续视频内容的安全分析提供技术支持.     

Prognostics of aluminum electrolytic capacitors using artificial neural network approach

In this work, an effort is being made to monitor the condition of in-circuit aluminum electrolytic capacitor using artificial neural network (ANN). Recent industrial surveys on the reliability of power electronic systems shows that most of faults occur due to the wear out of aluminum electrolytic capacitors and thermal stress is the major cause for its parametric degradation. The condition of target capacitors can be estimated by monitoring variation in equivalent series resistance (ESR) from the initial pristine state value. ANN is used to estimate ESR of pristine and weak target capacitors at the test conditions. The data set for training and testing of proposed back-propagation trained artificial neural network are experimentally obtained from the developed test bed. Using the test bed, target capacitors are subjected to different operating frequency and temperature in the output section of DC/DC buck converter circuit to determine the effect of variation in electrical and thermal stress on ESR value. After off-line training, the proposed ANN is implemented using National Instruments LabVIEW software. A low cost microcontroller is programmed for real time data acquisition of target capacitors and the serial transmission of acquired dataset to the LabVIEW software installed at host computer. The performance of the proposed method is evaluated in real time by comparing the resulting ESR with the experimental values of in-circuit target capacitors. The proposed ANN, once trained properly, can be used for different circuits and in different operating conditions because of its generalization capability.     

Remaining useful life prediction of lithium-ion batteries using a fusion method based on Wasserstein GAN

Lithium-ion batteries are the main power supply equipment in many fields due to their advantages of no memory, high energy density, long cycle life and no pollution to the environment. Accurate prediction for the remaining useful life (RUL) of lithium-ion batteries can avoid serious economic and safety problems such as spontaneous combustion. At present, most of the RUL prediction studies ignore the lithium-ion battery capacity recovery phenomenon caused by the rest time between the charge and discharge cycles. In this paper, a fusion method based on Wasserstein generative adversarial network (GAN) is proposed. This method achieves a more reliable and accurate RUL prediction of lithium-ion batteries by combining the artificial neural network (ANN) model which takes the rest time between battery charging cycles into account and the empirical degradation models which provide the correct degradation trend. The weight of each model is calculated by the discriminator in the Wasserstein GAN model. Four data sets of lithium-ion battery provided by the National Aeronautics and Space Administration (NASA) Ames Research Center are used to prove the feasibility and accuracy of the proposed method.     

基于最小二乘支持向量机的线性特征地物亚像元定位(英文)

BP神经网络已被证明能有效实现遥感图像的亚像元定位,但其训练时间较长,容易陷入局部最优且依赖于大量的训练样本。而在实际应用中,训练样本即先验信息较难获取。然而,建筑物及道路等地物具有规则的线性空间分布。针对这些线性特征地物,研究了一种训练样本的几何合成方法,消除对先验信息的依赖,并提出利用最小二乘支持向量机实现亚像元定位。实验表明,这种结合合成训练样本与最小二乘支持向量机的亚像元定位方法是合理可行的,且与BP神经网络实现方法相比,训练过程明显加快,定位精度更高。     

Digital watermark extraction using support vector machine with principal component analysis based feature reduction

This paper proposes a new approach for watermark extraction using support vector machine (SVM) with principal component analysis (PCA) based feature reduction. In this method, the original cover image is decomposed up to three level using lifting wavelet transform (LWT), and lowpass subband is selected for data hiding purpose. The lowpass subband is divided into small blocks, and a binary watermark is embedded into the original cover image by quantizing the two maximum coefficients of the block. In order to extract watermark bits with maximum correlation, SVM based binary classification approach is incorporated. The training and testing patterns are constructed by employing a reduced set of features along with block coefficients. Firstly, different features are obtained by evaluating the statistical parameters of each block coefficients, and then PCA is utilized to reduce this feature set. As far as security is concerned, randomization of coefficients, blocks, and watermark bits enhances the security of system. Furthermore, energy compaction property of LWT increases the robustness in comparison to conventional wavelet transform. A comparison of the proposed method with some of the recent techniques shows remarkable improvement in terms of robustness and security of the watermark.     

粒子群算法优化支持向量机的网络流量混沌预测

针对传统网络流量预测方法存在预测平均绝对误差较大的问题,提出基于粒子群算法优化支持向量机的网络流量混沌预测方法。采用粒子群算法对支持向量机方法进行优化,利用优化后的支持向量机方法对网络流量进行混沌预测,预测结果表明,采用改进预测方法时,其预测的平均绝对误差值相比FCM-LSSVM网络流量预测方法、Morlet-SVR和ARIMA组合预测方法分别降低了65.3%,34.3%,具有一定的优势。     

Automated recognition of obstructive sleep apnea syndrome using support vector machine classifier

Obstructive sleep apnea (OSA) is a common sleep disorder that causes pauses of breathing due to repetitive obstruction of the upper airways of the respiratory system. The effect of this phenomenon can be observed in other physiological signals like the heart rate variability, oxygen saturation, and the respiratory effort signals. In this study, features from these signals were extracted from 50 control and 50 OSA patients from the Sleep Heart Health Study database and implemented for minute and subject classifications. A support vector machine (SVM) classifier was used with linear and second-order polynomial kernels. For the minute classification, the respiratory features had the highest sensitivity while the oxygen saturation gave the highest specificity. The polynomial kernel always had better performance and the highest accuracy of 82.4% (Sen: 69.9%, Spec: 91.4%) was achieved using the combined-feature classifier. For subject classification, the polynomial kernel had a clear improvement in the oxygen saturation accuracy as the highest accuracy of 95% was achieved by both the oxygen saturation (Sen: 100%, Spec: 90.2%) and the combined-feature (Sen: 91.8%, Spec: 98.0%). Further analysis of the SVM with other kernel types might be useful for optimizing the classifier with the appropriate features for an OSA automated detection algorithm.     

Linear and nonlinear ARMA model parameter estimation using anartificial neural network

Addresses parametric system identification of linear and nonlinear dynamic systems by analysis of the input and output signals. Specifically, the authors investigate the relationship between estimation of the system using a feedforward neural network model and estimation of the system by use of linear and nonlinear autoregressive moving-average (ARMA) models. By utilizing a neural network model incorporating a polynomial activation function, the authors show the equivalence of the artificial neural network to the linear and nonlinear ARMA models. They compare the parameterization of the estimated system using the neural network and ARMA approaches by utilizing data generated by means of computer simulations. Specifically, the authors show that the parameters of a simulated ARMA system can be obtained from the neural network analysis of the simulated data or by conventional least squares ARMA analysis. The feasibility of applying neural networks with polynomial activation functions to the analysis of experimental data is explored by application to measurements of heart rate (HR) and instantaneous lung volume (ILV) fluctuations     

Fault detection and diagnosis in asymmetric multilevel inverter using artificial neural network

The increased component requirement to realise multilevel inverter (MLI) fallout in a higher fault prospect due to power semiconductors. In this scenario, efficient fault detection and diagnosis (FDD) strategies to detect and locate the power semiconductor faults have to be incorporated in addition to the conventional protection systems. Even though a number of FDD methods have been introduced in the symmetrical cascaded H-bridge (CHB) MLIs, very few methods address the FDD in asymmetric CHB-MLIs. In this paper, the gate-open circuit FDD strategy in asymmetric CHB-MLI is presented. Here, a single artificial neural network (ANN) is used to detect and diagnose the fault in both binary and trinary configurations of the asymmetric CHB-MLIs. In this method, features of the output voltage of the MLIs are used as to train the ANN for FDD method. The results prove the validity of the proposed method in detecting and locating the fault in both asymmetric MLI configurations. Finally, the ANN response to the input parameter variation is also analysed to access the performance of the proposed ANN-based FDD strategy.     

Epileptic seizures detection in EEG using DWT-based ApEn and artificial neural network

There are numerous neurological disorders such as dementia, headache, traumatic brain injuries, stroke, and epilepsy. Out of these epilepsy is the most prevalent neurological disorder in the human after stroke. Electroencephalogram (EEG) contains valuable information related to different physiological state of the brain. A scheme is presented for detecting epileptic seizures from EEG data recorded from normal subjects and epileptic patients. The scheme is based on discrete wavelet transform (DWT) analysis and approximate entropy (ApEn) of EEG signals. Seizure detection is performed in two stages. In the first stage, EEG signals are decomposed by DWT to calculate approximation and detail coefficients. In the second stage, ApEn values of the approximation and detail coefficients are calculated. Significant differences have been found between the ApEn values of the epileptic and the normal EEG allowing us to detect seizures with 100 % classification accuracy using artificial neural network. The analysis results depicted that during seizure activity, EEG had lower ApEn values compared to normal EEG. This gives that epileptic EEG is more predictable or less complex than the normal EEG. In this study, feed-forward back-propagation neural network has been used for classification and training algorithm for this network that updates the weight and bias values according to Levenberg–Marquardt optimization technique.