scholarly journals An Ensemble Empirical Mode Decomposition, Self-Organizing Map, and Linear Genetic Programming Approach for Forecasting River Streamflow

Water ◽  
2016 ◽  
Vol 8 (6) ◽  
pp. 247 ◽  
Author(s):  
Jonathan Barge ◽  
Hatim Sharif
2018 ◽  
Vol 20 (2) ◽  
pp. 468-485 ◽  
Author(s):  
Kiyoumars Roushangar ◽  
Farhad Alizadeh

Abstract This study proposes an ensemble empirical mode decomposition (EEMD)-based multiscale entropy (EME) approach. The proposed model is used to analyze and gage variability of the annual precipitation series and spatially classify raingauges in Iran. For this end, historical annual precipitation data during 1960–2010 from 31 raingauges are decomposed using EEMD. Decomposed series of precipitation series present different periods and trends. Next, entropy concept is applied to the components obtained from EEMD to measure dispersion of multiscale components. It is observed that entropy values of intrinsic mode functions (IMFs) 1–5 and residual component show different behaviors. IMF 5 and residual components have highest values of entropy, whereas IMF 3 and 4 present highest entropy variation among all components. Based on spatial distribution of EME values, EME 3 and 1 have a downward variation from north to south, whereas EME 1 presents increasing variation. Spatial classification of raingauges is performed using EME values as input data to self-organizing map (SOM) and k-means clustering techniques. Finally, spatial structure of annual precipitation variation is investigated. It is observed that EME values have a downward trend with latitude, whereas it is observed that EME shows an upward relationship with longitude in Iran.


Electronics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1248
Author(s):  
Rafia Nishat Toma ◽  
Cheol-Hong Kim ◽  
Jong-Myon Kim

Condition monitoring is used to track the unavoidable phases of rolling element bearings in an induction motor (IM) to ensure reliable operation in domestic and industrial machinery. The convolutional neural network (CNN) has been used as an effective tool to recognize and classify multiple rolling bearing faults in recent times. Due to the nonlinear and nonstationary nature of vibration signals, it is quite difficult to achieve high classification accuracy when directly using the original signal as the input of a convolution neural network. To evaluate the fault characteristics, ensemble empirical mode decomposition (EEMD) is implemented to decompose the signal into multiple intrinsic mode functions (IMFs) in this work. Then, based on the kurtosis value, insignificant IMFs are filtered out and the original signal is reconstructed with the rest of the IMFs so that the reconstructed signal contains the fault characteristics. After that, the 1-D reconstructed vibration signal is converted into a 2-D image using a continuous wavelet transform with information from the damage frequency band. This also transfers the signal into a time-frequency domain and reduces the nonstationary effects of the vibration signal. Finally, the generated images of various fault conditions, which possess a discriminative pattern relative to the types of faults, are used to train an appropriate CNN model. Additionally, with the reconstructed signal, two different methods are used to create an image to compare with our proposed image creation approach. The vibration signal is collected from a self-designed testbed containing multiple bearings of different fault conditions. Two other conventional CNN architectures are compared with our proposed model. Based on the results obtained, it can be concluded that the image generated with fault signatures not only accurately classifies multiple faults with CNN but can also be considered as a reliable and stable method for the diagnosis of fault bearings.


Forecasting ◽  
2021 ◽  
Vol 3 (3) ◽  
pp. 460-477
Author(s):  
Sajjad Khan ◽  
Shahzad Aslam ◽  
Iqra Mustafa ◽  
Sheraz Aslam

Day-ahead electricity price forecasting plays a critical role in balancing energy consumption and generation, optimizing the decisions of electricity market participants, formulating energy trading strategies, and dispatching independent system operators. Despite the fact that much research on price forecasting has been published in recent years, it remains a difficult task because of the challenging nature of electricity prices that includes seasonality, sharp fluctuations in price, and high volatility. This study presents a three-stage short-term electricity price forecasting model by employing ensemble empirical mode decomposition (EEMD) and extreme learning machine (ELM). In the proposed model, the EEMD is employed to decompose the actual price signals to overcome the non-linear and non-stationary components in the electricity price data. Then, a day-ahead forecasting is performed using the ELM model. We conduct several experiments on real-time data obtained from three different states of the electricity market in Australia, i.e., Queensland, New South Wales, and Victoria. We also implement various deep learning approaches as benchmark methods, i.e., recurrent neural network, multi-layer perception, support vector machine, and ELM. In order to affirm the performance of our proposed and benchmark approaches, this study performs several performance evaluation metric, including the Diebold–Mariano (DM) test. The results from the experiments show the productiveness of our developed model (in terms of higher accuracy) over its counterparts.


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