scholarly journals Imputação de dados ausentes através de redes neurais recorrentes no monitoramento de integridade estrutural

2021 ◽  
Author(s):  
Luiz Felipe Sousa ◽  
Adam Dreyton Ferreira Santos ◽  
João Weyl Albuquerque Costa
Keyword(s):  
Health Monitoring ◽  
Short Term Memory ◽  
Principal Component ◽  
Kernel Principal Component Analysis ◽  
Percentage Error ◽  
Short Term ◽  
Missing Completely At Random ◽  
De Se ◽  
Long Short Term Memory ◽  
Gated Recurrent Units

Um problema comum em grandes conjuntos de dados é a informação ausente, seja por falha nos sensores de captura, perda no transporte, ou outra situação que culmine com a perda de dados. Diante desta situação, é frequente que a decisão do pesquisador seja desconsiderar os dados ausentes, removê-los do conjunto, no entanto, essa exclusão pode gerar inferências que não são válidas, principalmente se os dados que permanecem na análise são diferentes daqueles que foram excluídos. Para lidar com este problema em conjuntos de dados de monitoramento de integridade estrutural (Structural health monitoring – SHM), este trabalho faz uso de redes neurais recorrentes Gated Recurrent Units (GRU) e Long Short-Term Memory (LSTM), para realizar a tarefa de imputação de dados ausentes. Em uma etapa anterior à imputação, foi realizada a amputação artificial dos dados, assumindo o mecanismo de dados ausentes Missing Completely at Random (MCAR), em percentuais de 25, 50 e 75%. As técnicas de imputação foram avaliadas com o uso da métrica Mean Absolute Percentage Error (MAPE). Posteriormente, foi aplicada a etapa de detecção de dano, as bases imputadas foram submetidas aos algoritmos Mahalanobis Square Distance (MSD) e Kernel Principal Component Analysis (KPCA) a fim de se obter as taxas de erros T1 e T2 detectadas. A partir dos resultados obtidos, foi possível observar que o uso da LSTM na imputação dos dados, alcançou resultados melhores que a GRU em todas as taxas de amputação, este melhor desempenho pode também ser notado na etapa de detecção de dano, onde as bases imputadas por LSTM alcançam melhores resultados de detecção de erros T1 e T2.

scholarly journals Forecasting Energy Consumption of Wastewater Treatment Plants with a Transfer Learning Approach for Sustainable Cities

Electronics ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 1149
Author(s):  
Pedro Oliveira ◽  
Bruno Fernandes ◽  
Cesar Analide ◽  
Paulo Novais
Keyword(s):  
Wastewater Treatment ◽  
Energy Consumption ◽  
Transfer Learning ◽  
Short Term Memory ◽  
Wastewater Treatment Plants ◽  
Learning Approach ◽  
Sustainable Cities ◽  
Short Term ◽  
Long Short Term Memory ◽  
Gated Recurrent Units

A major challenge of today’s society is to make large urban centres more sustainable. Improving the energy efficiency of the various infrastructures that make up cities is one aspect being considered when improving their sustainability, with Wastewater Treatment Plants (WWTPs) being one of them. Consequently, this study aims to conceive, tune, and evaluate a set of candidate deep learning models with the goal being to forecast the energy consumption of a WWTP, following a recursive multi-step approach. Three distinct types of models were experimented, in particular, Long Short-Term Memory networks (LSTMs), Gated Recurrent Units (GRUs), and uni-dimensional Convolutional Neural Networks (CNNs). Uni- and multi-variate settings were evaluated, as well as different methods for handling outliers. Promising forecasting results were obtained by CNN-based models, being this difference statistically significant when compared to LSTMs and GRUs, with the best model presenting an approximate overall error of 630 kWh when on a multi-variate setting. Finally, to overcome the problem of data scarcity in WWTPs, transfer learning processes were implemented, with promising results being achieved when using a pre-trained uni-variate CNN model, with the overall error reducing to 325 kWh.

scholarly journals Anomaly Detection in Moving Crowds through Spatiotemporal Autoencoding and Additional Attention

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Biao Yang ◽  
Jinmeng Cao ◽  
Rongrong Ni ◽  
Ling Zou
Keyword(s):  
Anomaly Detection ◽  
Short Term Memory ◽  
Principal Component ◽  
Temporal Variations ◽  
Robust Principal Component Analysis ◽  
Short Term ◽  
Detection Approach ◽  
Convolutional Autoencoder ◽  
Long Short Term Memory ◽  
Lstm Network

We propose an anomaly detection approach by learning a generative model using deep neural network. A weighted convolutional autoencoder- (AE-) long short-term memory (LSTM) network is proposed to reconstruct raw data and perform anomaly detection based on reconstruction errors to resolve the existing challenges of anomaly detection in complicated definitions and background influence. Convolutional AEs and LSTMs are used to encode spatial and temporal variations of input frames, respectively. A weighted Euclidean loss is proposed to enable the network to concentrate on moving foregrounds, thus restraining background influence. Moving foregrounds are segmented from the input frames using robust principal component analysis decomposition. Comparisons with state-of-the-art approaches indicate the superiority of our approach in anomaly detection. Generalization of anomaly detection is improved by enforcing the network to focus on moving foregrounds.

scholarly journals Implementation of Long Short-Term Memory and Gated Recurrent Units on Grouped Time-Series Data to Predict Stock Prices Accurately

2021 ◽  
Author(s):  
Armin Lawi ◽  
Hendra Mesra ◽  
Supri Amir
Keyword(s):  
Time Series ◽  
Stock Prices ◽  
Stock Price ◽  
Time Series Data ◽  
Short Term Memory ◽  
Series Data ◽  
Percentage Error ◽  
Short Term ◽  
Term Memory ◽  
Long Short Term Memory

Abstract Stocks are an attractive investment option since they can generate large profits compared to other businesses. The movement of stock price patterns on the stock market is very dynamic; thus it requires accurate data modeling to forecast stock prices with a low error rate. Forecasting models using Deep Learning are believed to be able to accurately predict stock price movements using time-series data, especially the Long Short-Term Memory (LSTM) and Gated Recurrent Unit (GRU) algorithms. However, several previous implementation studies have not been able to obtain convincing accuracy results. This paper proposes the implementation of the forecasting method by classifying the movement of time-series data on company stock prices into three groups using LSTM and GRU. The accuracy of the built model is evaluated using loss functions of Rooted Mean Squared Error (RMSE) and Mean Absolute Percentage Error (MAPE). The results showed that the performance evaluation of both architectures is accurate in which GRU is always superior to LSTM. The highest validation for GRU was 98.73% (RMSE) and 98.54% (MAPE), while the LSTM validation was 98.26% (RMSE) and 97.71% (MAPE).

scholarly journals Video-Based Sentiment Analysis with hvnLBP-TOP Feature and bi-LSTM

2019 ◽  
Vol 33 ◽  
pp. 9963-9964 ◽  
Author(s):  
Haoran Li ◽  
Hua Xu
Keyword(s):  
Sentiment Analysis ◽  
Extraction Method ◽  
Short Term Memory ◽  
Recognition Accuracy ◽  
Principal Component ◽  
Short Term ◽  
Term Memory ◽  
Feature Extraction Method ◽  
Long Short Term Memory ◽  
New Feature

In this paper, we propose a new feature extraction method called hvnLBP-TOP for video-based sentiment analysis. Furthermore, we use principal component analysis (PCA) and bidirectional long short term memory (bi-LSTM) for dimensionality reduction and classification. We achieved an average recognition accuracy of 71.1% on the MOUD dataset and 63.9% on the CMU-MOSI dataset.

scholarly journals Prediction of Wind Turbine-Grid Interaction Based on a Principal Component Analysis-Long Short Term Memory Model

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3221 ◽  
Author(s):  
Yining Wang ◽  
Da Xie ◽  
Xitian Wang ◽  
Yu Zhang
Keyword(s):  
Principal Component Analysis ◽  
Wind Turbine ◽  
Short Term Memory ◽  
Principal Component ◽  
Wind Farms ◽  
Short Term ◽  
Term Memory ◽  
Long Short Term Memory ◽  
Lstm Network ◽  
Oscillation Frequencies

The interaction between the gird and wind farms has significant impact on the power grid, therefore prediction of the interaction between gird and wind farms is of great significance. In this paper, a wind turbine-gird interaction prediction model based on long short term memory (LSTM) network under the TensorFlow framework is presented. First, the multivariate time series was screened by principal component analysis (PCA) to reduce the data dimensionality. Secondly, the LSTM network is used to model the nonlinear relationship between the selected sequence of wind turbine network interactions and the actual output sequence of the wind farms, it is proved that it has higher accuracy and applicability by comparison with single LSTM model, Autoregressive Integrated Moving Average (ARIMA) model and Back Propagation Neural Network (BPNN) model, the Mean Absolute Percentage Error (MAPE) is 0.617%, 0.703%, 1.397% and 3.127%, respectively. Finally, the Prony algorithm was used to analyze the predicted data of the wind turbine-grid interactions. Based on the actual data, it is found that the oscillation frequencies of the predicted data from PCA-LSTM model are basically the same as the oscillation frequencies of the actual data, thus the feasibility of the model proposed for analyzing interaction between grid and wind turbines is verified.

scholarly journals Rotational Unit of Memory: A Novel Representation Unit for RNNs with Scalable Applications

2019 ◽  
Vol 7 ◽  
pp. 121-138 ◽  
Author(s):  
Rumen Dangovski ◽  
Li Jing ◽  
Preslav Nakov ◽  
Mićo Tatalović ◽  
Marin Soljačić
Keyword(s):  
Short Term Memory ◽  
State Of The Art ◽  
Language Modeling ◽  
Text Summarization ◽  
Short Term ◽  
Memory State ◽  
Long Short Term Memory ◽  
Gated Recurrent Units ◽  
Better Than ◽  
Real World Problems

Stacking long short-term memory (LSTM) cells or gated recurrent units (GRUs) as part of a recurrent neural network (RNN) has become a standard approach to solving a number of tasks ranging from language modeling to text summarization. Although LSTMs and GRUs were designed to model long-range dependencies more accurately than conventional RNNs, they nevertheless have problems copying or recalling information from the long distant past. Here, we derive a phase-coded representation of the memory state, Rotational Unit of Memory (RUM), that unifies the concepts of unitary learning and associative memory. We show experimentally that RNNs based on RUMs can solve basic sequential tasks such as memory copying and memory recall much better than LSTMs/GRUs. We further demonstrate that by replacing LSTM/GRU with RUM units we can apply neural networks to real-world problems such as language modeling and text summarization, yielding results comparable to the state of the art.

scholarly journals Remaining Useful Life Prediction of Airplane Engine Based on PCA–BLSTM

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4537
Author(s):  
Shixin Ji ◽  
Xuehao Han ◽  
Yichun Hou ◽  
Yong Song ◽  
Qingfu Du
Keyword(s):  
Principal Component Analysis ◽  
Hybrid Model ◽  
Short Term Memory ◽  
Principal Component ◽  
Remaining Useful Life ◽  
Short Term ◽  
Term Memory ◽  
Airplane Engine ◽  
Useful Life ◽  
Long Short Term Memory

The accurate prediction of airplane engine failure can provide a reasonable decision basis for airplane engine maintenance, effectively reducing maintenance costs and reducing the incidence of failure. According to the characteristics of the monitoring data of airplane engine sensors, this work proposed a remaining useful life (RUL) prediction model based on principal component analysis and bidirectional long short-term memory. Principal component analysis is used for feature extraction to remove useless information and noise. After this, bidirectional long short-term memory is used to learn the relationship between the state monitoring data and remaining useful life. This work includes data preprocessing, the construction of a hybrid model, the use of the NASA’s Commercial Aerodynamic System Simulation (C-MAPSS) data set for training and testing, and the comparison of results with those of support vector regression, long short-term memory and bidirectional long short-term memory models. The hybrid model shows better prediction accuracy and performance, which can provide a basis for formulating a reasonable airplane engine health management plan.

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