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Search Results (1,402)

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17 pages, 3279 KiB  
Article
TCN-GRU Based on Attention Mechanism for Solar Irradiance Prediction
by Zhi Rao, Zaimin Yang, Xiongping Yang, Jiaming Li, Wenchuan Meng and Zhichu Wei
Energies 2024, 17(22), 5767; https://doi.org/10.3390/en17225767 (registering DOI) - 18 Nov 2024
Abstract
The global horizontal irradiance (GHI) is the most important metric for evaluating solar resources. The accurate prediction of GHI is of great significance for effectively assessing solar energy resources and selecting photovoltaic power stations. Considering the time series nature of the GHI and [...] Read more.
The global horizontal irradiance (GHI) is the most important metric for evaluating solar resources. The accurate prediction of GHI is of great significance for effectively assessing solar energy resources and selecting photovoltaic power stations. Considering the time series nature of the GHI and monitoring sites dispersed over different latitudes, longitudes, and altitudes, this study proposes a model combining deep neural networks and deep convolutional neural networks for the multi-step prediction of GHI. The model utilizes parallel temporal convolutional networks and gate recurrent unit attention for the prediction, and the final prediction result is obtained by multilayer perceptron. The results show that, compared to the second-ranked algorithm, the proposed model improves the evaluation metrics of mean absolute error, mean absolute percentage error, and root mean square error by 24.4%, 33.33%, and 24.3%, respectively. Full article
(This article belongs to the Section A2: Solar Energy and Photovoltaic Systems)
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<p>The framework diagram of TCN.</p>
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<p>The framework diagram of causal convolution.</p>
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<p>The framework diagram of dilated convolution.</p>
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<p>The framework diagram of residual connection.</p>
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<p>The framework diagram of GRU.</p>
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<p>The framework diagram of attention mechanism.</p>
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<p>The framework diagram of MLP.</p>
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<p>The framework diagram of TGAM.</p>
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<p>The prediction fitting plot of TGAM.</p>
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<p>The prediction fitting plot of TGAM and comparison algorithms.</p>
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<p>The evaluation indicators and improvement percentages of TGAM and comparison algorithms: (<b>a</b>) MAE; (<b>b</b>) MAPE; (<b>c</b>) RMSE.</p>
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<p>The impact of missing variables on model prediction: (<b>a</b>) MAE; (<b>b</b>) MAPE; (<b>c</b>) RMSE.</p>
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11 pages, 2427 KiB  
Article
Metabolomic Profiling and Machine Learning Models for Tumor Classification in Patients with Recurrent IDH-Wild-Type Glioblastoma: A Prospective Study
by Rawad Hodeify, Nina Yu, Meenakshisundaram Balasubramaniam, Felipe Godinez, Yin Liu and Orwa Aboud
Cancers 2024, 16(22), 3856; https://doi.org/10.3390/cancers16223856 (registering DOI) - 17 Nov 2024
Viewed by 237
Abstract
Background/Objectives: The recurrence of glioblastoma is an inevitable event in this disease’s course. In this study, we sought to identify the metabolomic signature in patients with recurrent glioblastomas undergoing surgery and radiation therapy. Methods: Blood samples collected prospectively from six patients with recurrent [...] Read more.
Background/Objectives: The recurrence of glioblastoma is an inevitable event in this disease’s course. In this study, we sought to identify the metabolomic signature in patients with recurrent glioblastomas undergoing surgery and radiation therapy. Methods: Blood samples collected prospectively from six patients with recurrent IDH-wildtype glioblastoma who underwent one surgery at diagnosis and a second surgery at relapse were analyzed using untargeted gas chromatography–time-of-flight mass spectrometry to measure metabolite abundance. The data analysis techniques included univariate analysis, correlation analysis, and a sample t-test. For predictive modeling, machine learning (ML) algorithms such as multinomial logistic regression, gradient boosting, and random forest were applied to predict the classification of samples in the correct treatment phase. Results: Comparing samples after the first surgery and after the relapse surgeries to the pre-operative samples showed a significant decrease in sorbitol and mannitol; there was a significant increase in urea, oxoproline, glucose, and alanine. After chemoradiation, two metabolites, erythritol and 6-deoxyglucitol, showed a decrease, with a cut-off of three and a significant reduction for 6-deoxyglucitol, while 2,4-difluorotoluene and 9-myristoleate showed an increase post radiation, with a fold-change cut-off of three. The gradient-boosting ML model achieved a high performance for the prediction of tumor conditions in patients with glioblastoma who had undergone relapse surgery. Conclusions: We developed an ML predictor for tumor phase based on the plasma metabolomic profile. Our study suggests the potential of combining metabolomics with ML as a new tool to stratify the risk of tumor progression in patients with glioblastoma. Full article
(This article belongs to the Section Cancer Biomarkers)
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<p>GC-TOF MS intensities of untargeted plasma metabolomics for pre-surgical and post-surgical samples. (<b>A</b>) Levels of decreased metabolites post surgery (PostS) compared to pre-surgery values (PreS) with a cut-off fold-change of 3. (<b>B</b>) Metabolites with a significant decrease post-surgery (<span class="html-italic">p</span> &lt; 0.05). (<b>C</b>) Comparison of increased metabolite levels pre surgery vs. post surgery, with a cut-off fold-change of 3. (<b>D</b>) Metabolites with a significant increase post surgery (<span class="html-italic">p</span> &lt; 0.05). Statistical significance was determined using an unpaired Student’s <span class="html-italic">t</span>-test, where (****) denotes a <span class="html-italic">p</span>-value &lt; 0.0001, (***) <span class="html-italic">p</span> &lt; 0.001, and (**) a <span class="html-italic">p</span>-value &lt; 0.01.</p>
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<p>MS intensities of plasma metabolites for pre-radiation and post-radiation samples. (<b>A</b>) Levels of decreased metabolites post radiation (PostRad) compared to pre radiation (PreRad), with a cut-off fold-change of 3. Statistical significance was determined using an unpaired Student’s <span class="html-italic">t</span>-test. Metabolites with a significant decrease post radiation (** <span class="html-italic">p</span> &lt; 0.01). (<b>B</b>) Increased metabolites post radiation with a cut-off fold-change of 3. “ns” Not significant.</p>
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<p>Heatmap of Pearson’s correlation coefficients for altered plasma metabolites with a cut-off of r &gt; 0.90. Altered metabolites with high correlations are highlighted in black boxes. The correlation score can be tracked through the scale bar on the right side of the heatmap. Positive correlations are present between several metabolites: between sorbitol and mannitol, indoxyl sulfate and threonic acid, and gluconic acid and gluconic acid lactone.</p>
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<p>Metabolomics with machine learning models for the classification of clinical stages in patients with recurrent glioblastoma undergoing repeat surgery. (<b>A</b>) Comparing the performance of metabolomic-based machine learning algorithms based on accuracy, precision, recall, and F1-score. (<b>B</b>) The learning curve on test samples as a function of the training samples. (<b>C</b>) ROC-AUC curve to assess the performance of the three models. (<b>D</b>–<b>F</b>) Confusion matrix for each of the three models when tested on the test dataset consisting of 12 samples. The color scales (0–5) next to each confusion matrix represent classification accuracies. The actual/prediction labels are mapped as follows: “0” for pre surgery, “1” for post surgery, “2” for pre radiation, and “3” for post radiation.</p>
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15 pages, 2419 KiB  
Article
Deciphering Membrane Proteins Through Deep Learning Models by Revealing Their Locale Within the Cell
by Mehwish Faiz, Saad Jawaid Khan, Fahad Azim, Nazia Ejaz and Fahad Shamim
Bioengineering 2024, 11(11), 1150; https://doi.org/10.3390/bioengineering11111150 - 15 Nov 2024
Viewed by 266
Abstract
Membrane proteins constitute essential biomolecules attached to or integrated into cellular and organelle membranes, playing diverse roles in cellular processes. Their precise localization is crucial for understanding their functions. Existing protein subcellular localization predictors are predominantly trained on globular proteins; their performance diminishes [...] Read more.
Membrane proteins constitute essential biomolecules attached to or integrated into cellular and organelle membranes, playing diverse roles in cellular processes. Their precise localization is crucial for understanding their functions. Existing protein subcellular localization predictors are predominantly trained on globular proteins; their performance diminishes for membrane proteins, explicitly via deep learning models. To address this challenge, the proposed study segregates membrane proteins into three distinct locations, including the plasma membrane, internal membrane, and membrane of the organelle, using deep learning algorithms including recurrent neural networks (RNN) and Long Short-Term Memory (LSTM). A redundancy-curtailed dataset of 3000 proteins from the MemLoci approach is selected for the investigation, along with incorporating pseudo amino acid composition (PseAAC). PseAAC is an exemplary technique for extracting protein information hidden in the amino acid sequences. After extensive testing, the results show that the accuracy for LSTM and RNN is 83.4% and 80.5%, respectively. The results show that the LSTM model outperforms the RNN and is most commonly employed in proteomics. Full article
(This article belongs to the Special Issue Bio-Macromolecular Modeling and Computational Design)
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<p>Transformation of membrane proteins sequences into pseudo amino acid composition.</p>
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<p>Compositional architecture of the proposed RNN model. FC1 = fully connected layer 1, FC2 = fully connected layer 2, FC3 = fully connected layer 3.</p>
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<p>Compositional architecture of the proposed LSTM model. FC1 = fully connected layer 1, FC2 = fully connected layer 2, FC3 = fully connected layer 3.</p>
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<p>Loss evaluation of (<b>a</b>) RNN and (<b>b</b>) LSTM models.</p>
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<p>Accuracy evaluation of (<b>a</b>) RNN and (<b>b</b>) LSTM models.</p>
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<p>Confusion matrices for Long Short-Term Memory (LSTM) and Recurrent neural network (RNN) implemented on membrane proteins for tagging their location.</p>
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<p>Performance evaluators for LSTM and RNN for membrane proteins location recognition where OMP = organelle membrane proteins, IMP = internal membrane proteins, and PMP = plasma membrane proteins.</p>
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16 pages, 2277 KiB  
Review
Drug Discovery in the Age of Artificial Intelligence: Transformative Target-Based Approaches
by Akshata Yashwant Patne, Sai Madhav Dhulipala, William Lawless, Satya Prakash, Shyam S. Mohapatra and Subhra Mohapatra
Int. J. Mol. Sci. 2024, 25(22), 12233; https://doi.org/10.3390/ijms252212233 - 14 Nov 2024
Viewed by 388
Abstract
The complexities inherent in drug development are multi-faceted and often hamper accuracy, speed and efficiency, thereby limiting success. This review explores how recent developments in machine learning (ML) are significantly impacting target-based drug discovery, particularly in small-molecule approaches. The Simplified Molecular Input Line [...] Read more.
The complexities inherent in drug development are multi-faceted and often hamper accuracy, speed and efficiency, thereby limiting success. This review explores how recent developments in machine learning (ML) are significantly impacting target-based drug discovery, particularly in small-molecule approaches. The Simplified Molecular Input Line Entry System (SMILES), which translates a chemical compound’s three-dimensional structure into a string of symbols, is now widely used in drug design, mining, and repurposing. Utilizing ML and natural language processing techniques, SMILES has revolutionized lead identification, high-throughput screening and virtual screening. ML models enhance the accuracy of predicting binding affinity and selectivity, reducing the need for extensive experimental screening. Additionally, deep learning, with its strengths in analyzing spatial and sequential data through convolutional neural networks (CNNs) and recurrent neural networks (RNNs), shows promise for virtual screening, target identification, and de novo drug design. Fragment-based approaches also benefit from ML algorithms and techniques like generative adversarial networks (GANs), which predict fragment properties and binding affinities, aiding in hit selection and design optimization. Structure-based drug design, which relies on high-resolution protein structures, leverages ML models for accurate predictions of binding interactions. While challenges such as interpretability and data quality remain, ML’s transformative impact accelerates target-based drug discovery, increasing efficiency and innovation. Its potential to deliver new and improved treatments for various diseases is significant. Full article
(This article belongs to the Special Issue Techniques and Strategies in Drug Design and Discovery, 2nd Edition)
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<p>Example of algorithms and classifiers in ML models [<a href="#B4-ijms-25-12233" class="html-bibr">4</a>,<a href="#B5-ijms-25-12233" class="html-bibr">5</a>].</p>
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<p>Example of algorithms and classifiers in ML models for small molecule-based approach drug discovery [<a href="#B9-ijms-25-12233" class="html-bibr">9</a>].</p>
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<p>Example of algorithms and classifiers in ML models for a fragment-based approach to drug discovery [<a href="#B24-ijms-25-12233" class="html-bibr">24</a>].</p>
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<p>Example of Algorithms and Classifiers in ML Models for Structure-Based Approach Drug Discovery [<a href="#B46-ijms-25-12233" class="html-bibr">46</a>].</p>
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19 pages, 5737 KiB  
Article
Improving the Quality of Experience of Video Streaming Through a Buffer-Based Adaptive Bitrate Algorithm and Gated Recurrent Unit-Based Network Bandwidth Prediction
by Jeonghun Woo, Seungwoo Hong, Donghyun Kang and Donghyeok An
Appl. Sci. 2024, 14(22), 10490; https://doi.org/10.3390/app142210490 - 14 Nov 2024
Viewed by 377
Abstract
With the evolution of cellular networks and wireless-local-area-network-based communication technologies, services for smart device users have appeared. With the popularity of 4G and 5G, smart device users can now consume larger bandwidths than before. Consequently, the demand for various services, such as streaming, [...] Read more.
With the evolution of cellular networks and wireless-local-area-network-based communication technologies, services for smart device users have appeared. With the popularity of 4G and 5G, smart device users can now consume larger bandwidths than before. Consequently, the demand for various services, such as streaming, online games, and video conferences, has increased. For improved quality of experience (QoE), streaming services utilize adaptive bitrate (ABR) algorithms to handle network bandwidth variations. ABR algorithms use network bandwidth history for future network bandwidth prediction, allowing them to perform efficiently when network bandwidth fluctuations are minor. However, in environments with frequent network bandwidth changes, such as wireless networks, the QoE of video streaming often degrades because of inaccurate predictions of future network bandwidth. To address this issue, we utilize the gated recurrent unit, a time series prediction model, to predict the network bandwidth accurately. We then propose a buffer-based ABR streaming technique that selects optimized video-quality settings on the basis of the predicted bandwidth. The proposed algorithm was evaluated on a dataset provided by Zeondo by categorizing instances of user mobility into walking, bus, and train scenarios. The proposed algorithm improved the QoE by approximately 11% compared with the existing buffer-based ABR algorithm in various environments. Full article
(This article belongs to the Special Issue Multimedia Systems Studies)
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<p>Total volume of app categories in 2022.</p>
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<p>Buffer occupancy calculation.</p>
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<p>Video quality selection in the buffer-based adaptive bitrate algorithm.</p>
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<p>Bandwidth measurement results.</p>
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<p>Ratio of measurements recorded as zero among total measurements.</p>
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<p>Normalized root meant squared error (NRMSE) values with different hyperparameter settings.</p>
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<p>GRU model structure.</p>
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<p>Structure of the proposed scheme.</p>
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<p>Relationship between video rate and buffer occupancy.</p>
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<p>Root mean square error (RMSE) of network bandwidth prediction in different mobility scenarios.</p>
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<p>Comparison of the measured and predicted network bandwidths in the pedestrian scenario.</p>
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<p>Comparison of the measured and predicted network bandwidths in the bus scenario.</p>
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<p>Comparison of the measured and predicted network bandwidths in train scenario.</p>
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<p>Comparison of mean opinion scores in pedestrian scenarios.</p>
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<p>Comparison of video quality in pedestrian scenario 2.</p>
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<p>Comparison of buffer occupancies in pedestrian scenario 2.</p>
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<p>Comparison of mean opinion scores in bus scenarios.</p>
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<p>Comparison of video quality in bus scenario 7.</p>
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<p>Comparison of buffer occupancy in bus scenario 7.</p>
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<p>Comparison of the mean opinion scores in train scenarios.</p>
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<p>Comparison of video quality in train scenario 1.</p>
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<p>Comparison of buffer occupancy in train scenario 1.</p>
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15 pages, 969 KiB  
Article
Double Decomposition and Fuzzy Cognitive Graph-Based Prediction of Non-Stationary Time Series
by Junfeng Chen, Azhu Guan and Shi Cheng
Sensors 2024, 24(22), 7272; https://doi.org/10.3390/s24227272 - 14 Nov 2024
Viewed by 205
Abstract
Deep learning models, such as recurrent neural network (RNN) models, are suitable for modeling and forecasting non-stationary time series but are not interpretable. A prediction model with interpretability and high accuracy can improve decision makers’ trust in the model and provide a basis [...] Read more.
Deep learning models, such as recurrent neural network (RNN) models, are suitable for modeling and forecasting non-stationary time series but are not interpretable. A prediction model with interpretability and high accuracy can improve decision makers’ trust in the model and provide a basis for decision making. This paper proposes a double decomposition strategy based on wavelet decomposition (WD) and empirical mode decomposition (EMD). We construct a prediction model of high-order fuzzy cognitive maps (HFCM), called the WE-HFCM model, which considers interpretability and strong reasoning ability. Specifically, we use the WD and EDM algorithms to decompose the time sequence signal and realize the depth extraction of the signal’s high-frequency, low-frequency, time-domain, and frequency domain features. Then, the ridge regression algorithm is used to learn the HFCM weight vector to achieve modeling prediction. Finally, we apply the proposed WE-HFCM model to stationary and non-stationary datasets in simulation experiments. We compare the predicted results with the autoregressive integrated moving average (ARIMA) and long short-term memory (LSTM) models.For stationary time series, the prediction accuracy of the WE-HFCM model is about 45% higher than that of the ARIMA, about 35% higher than that of the SARIMA model, and about 16% higher than that of the LSTM model. For non-stationary time series, the prediction accuracy of the WE-HFCM model is 69% higher than that of the ARIMA and SARIMA models. Full article
(This article belongs to the Special Issue Emerging Machine Learning Techniques in Industrial Internet of Things)
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<p>Wavelet decomposition and reconstruction: (<b>a</b>) wavelet decomposition (<b>b</b>) wavelet reconstruction.</p>
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<p>(<b>a</b>) Fuzzy cognitive map with five nodes. (<b>b</b>) The weight matrix of FCM.</p>
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<p>Basic framework of the WE-HFCM prediction model.</p>
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<p>Double decomposition frame.</p>
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<p>The learning process of HFCM with four node.</p>
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<p>The RMSE values of HFCM of 2–7 nodes in the four datasets correspond to the order 1–6 HFCM, respectively. (<b>a</b>) k = 1, (<b>b</b>) k = 2, (<b>c</b>) k = 3, (<b>d</b>) k = 4, (<b>e</b>) k = 5, (<b>f</b>) k = 6.</p>
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<p>WE-HFCM predictions on four datasets: (<b>a</b>) wind-speed, (<b>b</b>) open-price, (<b>c</b>) sunspot, (<b>d</b>) min-temp.</p>
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<p>WE-HFCM interpretation analysis on the min-temp test dataset.</p>
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46 pages, 4014 KiB  
Article
Robust Human Activity Recognition for Intelligent Transportation Systems Using Smartphone Sensors: A Position-Independent Approach
by John Benedict Lazaro Bernardo, Attaphongse Taparugssanagorn, Hiroyuki Miyazaki, Bipun Man Pati and Ukesh Thapa
Appl. Sci. 2024, 14(22), 10461; https://doi.org/10.3390/app142210461 - 13 Nov 2024
Viewed by 751
Abstract
This study explores Human Activity Recognition (HAR) using smartphone sensors to address the challenges posed by position-dependent datasets. We propose a position-independent system that leverages data from accelerometers, gyroscopes, linear accelerometers, and gravity sensors collected from smartphones placed either on the chest or [...] Read more.
This study explores Human Activity Recognition (HAR) using smartphone sensors to address the challenges posed by position-dependent datasets. We propose a position-independent system that leverages data from accelerometers, gyroscopes, linear accelerometers, and gravity sensors collected from smartphones placed either on the chest or in the left/right leg pocket. The performance of traditional machine learning algorithms (Decision Trees (DT), K-Nearest Neighbors (KNN), Random Forest (RF), Support Vector Classifier (SVC), and XGBoost) is compared against deep learning models (Gated Recurrent Unit (GRU), Long Short-Term Memory (LSTM), Temporal Convolutional Networks (TCN), and Transformer models) under two sensor configurations. Our findings highlight that the Temporal Convolutional Network (TCN) model consistently outperforms other models, particularly in the four-sensor non-overlapping configuration, achieving the highest accuracy of 97.70%. Deep learning models such as LSTM, GRU, and Transformer also demonstrate strong performance, showcasing their effectiveness in capturing temporal dependencies in HAR tasks. Traditional machine learning models, including RF and XGBoost, provide reasonable performance but do not match the accuracy of deep learning models. Additionally, incorporating data from linear accelerometers and gravity sensors led to slight improvements over using accelerometer and gyroscope data alone. This research enhances the recognition of passenger behaviors for intelligent transportation systems, contributing to more efficient congestion management and emergency response strategies. Full article
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<p>Running Activity Accelerometer Data: acceleration values along the x, y, and z axes recorded between 80 and 85 s.</p>
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<p>Running Activity Gyroscope Data: angular velocity along the x, y, and z axes recorded between 80 and 85 s.</p>
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<p>Running Activity Linear Accelerometer Data: linear acceleration values along the x, y, and z axes recorded between 80 and 85 s.</p>
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<p>Running Activity Gravity Sensor Data: gravitational acceleration values along the x, y, and z axes recorded between 80 and 85 s.</p>
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<p>Methodological framework for assessing machine learning and deep learning techniques.</p>
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<p>Architecture of a Gated Recurrent Unit (GRU) Network used in Activity Recognition. Adapted from [<a href="#B37-applsci-14-10461" class="html-bibr">37</a>], showing the flow through the reset and update gates, facilitating efficient sequential data processing.</p>
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<p>Architecture of a Long Short-Term Memory (LSTM) Network utilized in Activity Recognition. Adapted from [<a href="#B38-applsci-14-10461" class="html-bibr">38</a>], showing the flow of information through the forget, input, and output gates to manage long-term dependencies in sequential data.</p>
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<p>Architecture of a Temporal Convolutional Network (TCN) for Activity Recognition, adapted from [<a href="#B28-applsci-14-10461" class="html-bibr">28</a>]. Dilated causal convolutions capture long-term dependencies, with dropout layers to prevent overfitting.</p>
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<p>Architecture of the Transformer Model used in Activity Recognition, illustrating the multi-head attention and feed-forward layers, adapted from [<a href="#B29-applsci-14-10461" class="html-bibr">29</a>]. The positional encoding enables handling of sequential data without recurrence.</p>
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<p>ConfusionMatrices formodels using a two-sensor configuration with non-overlapping data segments: (<b>a</b>) DT, (<b>b</b>) KNN, (<b>c</b>) RF, (<b>d</b>) SVC, (<b>e</b>) XGBoost, (<b>f</b>) GRU, (<b>g</b>) LSTM, (<b>h</b>) TCN, (<b>i</b>) Transformer.</p>
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<p>ConfusionMatrices formodels using a two-sensor configuration with non-overlapping data segments: (<b>a</b>) DT, (<b>b</b>) KNN, (<b>c</b>) RF, (<b>d</b>) SVC, (<b>e</b>) XGBoost, (<b>f</b>) GRU, (<b>g</b>) LSTM, (<b>h</b>) TCN, (<b>i</b>) Transformer.</p>
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<p>Confusion Matrices for models using a two-sensor configuration with 50% overlapping data segments: (<b>a</b>) DT, (<b>b</b>) KNN, (<b>c</b>) RF, (<b>d</b>) SVC, (<b>e</b>) XGBoost, (<b>f</b>) GRU, (<b>g</b>) LSTM, (<b>h</b>) TCN, (<b>i</b>) Transformer.</p>
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<p>Confusion Matrices for models using a two-sensor configuration with 50% overlapping data segments: (<b>a</b>) DT, (<b>b</b>) KNN, (<b>c</b>) RF, (<b>d</b>) SVC, (<b>e</b>) XGBoost, (<b>f</b>) GRU, (<b>g</b>) LSTM, (<b>h</b>) TCN, (<b>i</b>) Transformer.</p>
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<p>Confusion Matrices for models using a four-sensor configuration with Non-overlapping data segments: (<b>a</b>) DT, (<b>b</b>) KNN, (<b>c</b>) RF, (<b>d</b>) SVC, (<b>e</b>) XGBoost, (<b>f</b>) GRU, (<b>g</b>) LSTM, (<b>h</b>) TCN, (<b>i</b>) Transformer.</p>
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<p>Confusion Matrices for models using a four-sensor configuration with Non-overlapping data segments: (<b>a</b>) DT, (<b>b</b>) KNN, (<b>c</b>) RF, (<b>d</b>) SVC, (<b>e</b>) XGBoost, (<b>f</b>) GRU, (<b>g</b>) LSTM, (<b>h</b>) TCN, (<b>i</b>) Transformer.</p>
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<p>Confusion Matrices for models using a four-sensor configuration with 50% overlapping data segments: (<b>a</b>) DT, (<b>b</b>) KNN, (<b>c</b>) RF, (<b>d</b>) SVC, (<b>e</b>) XGBoost, (<b>f</b>) GRU, (<b>g</b>) LSTM, (<b>h</b>) TCN, (<b>i</b>) Transformer.</p>
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<p>Confusion Matrices for models using a four-sensor configuration with 50% overlapping data segments: (<b>a</b>) DT, (<b>b</b>) KNN, (<b>c</b>) RF, (<b>d</b>) SVC, (<b>e</b>) XGBoost, (<b>f</b>) GRU, (<b>g</b>) LSTM, (<b>h</b>) TCN, (<b>i</b>) Transformer.</p>
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19 pages, 1867 KiB  
Article
Bridging the Gap: An Algorithmic Framework for Vehicular Crowdsensing
by Luis G. Jaimes, Craig White and Paniz Abedin
Sensors 2024, 24(22), 7191; https://doi.org/10.3390/s24227191 - 9 Nov 2024
Viewed by 432
Abstract
In this paper, we investigate whether greedy algorithms, traditionally used for pedestrian-based crowdsensing, remain effective in the context of vehicular crowdsensing (VCS). Vehicular crowdsensing leverages vehicles equipped with sensors to gather and transmit data to address several urban challenges. Despite its potential, VCS [...] Read more.
In this paper, we investigate whether greedy algorithms, traditionally used for pedestrian-based crowdsensing, remain effective in the context of vehicular crowdsensing (VCS). Vehicular crowdsensing leverages vehicles equipped with sensors to gather and transmit data to address several urban challenges. Despite its potential, VCS faces issues with user engagement due to inadequate incentives and privacy concerns. In this paper, we use a dynamic incentive mechanism based on a recurrent reverse auction model, incorporating vehicular mobility patterns and realistic urban scenarios using the Simulation of Urban Mobility (SUMO) traffic simulator and OpenStreetMap (OSM). By selecting a representative subset of vehicles based on their locations within a fixed budget, our mechanism aims to improve coverage and reduce data redundancy. We evaluate the applicability of successful participatory sensing approaches designed for pedestrian data and demonstrate their limitations when applied to VCS. This research provides insights into adapting greedy algorithms for the particular dynamics of vehicular crowdsensing. Full article
(This article belongs to the Special Issue Intelligent Transportation Systems: Sensing, Automation and Control)
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<p>Example of coverage per user.</p>
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<p>Radius vs. percent utilization (<b>left</b>) and number of participants (<b>right</b>).</p>
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<p>Cost vs. number of active participants under normal (<b>left</b>), exponential (<b>center</b>), and uniform (<b>right</b>) distributions.</p>
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<p>Number of samples vs. percentage area coverage (<b>left</b>), number of active participants (<b>center</b>), and cost (<b>right</b>).</p>
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<p>Simulation components.</p>
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<p>Normal distribution for trajectory distribution and participants’ true valuations.</p>
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<p>Exponential distribution for trajectory distribution and participants’ true valuations.</p>
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<p>Budget vs. coverage, number of participants, and budget utilization under uniform distribution for trajectory locations and participant true valuations.</p>
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<p>Budget vs. coverage, number of participants, and budget utilization under uniform and normal distributions for trajectory locations and participant true valuations, respectively.</p>
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<p>Budget vs. coverage, number of participants, and budget utilization under normal and uniform distributions for trajectory locations and participant true valuations, respectively.</p>
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13 pages, 2093 KiB  
Article
Speech Enhancement Algorithm Based on Microphone Array and Lightweight CRN for Hearing Aid
by Ji Xi, Zhe Xu, Weiqi Zhang, Li Zhao and Yue Xie
Electronics 2024, 13(22), 4394; https://doi.org/10.3390/electronics13224394 - 9 Nov 2024
Viewed by 441
Abstract
To address the performance and computational complexity issues in speech enhancement for hearing aids, a speech enhancement algorithm based on a microphone array and a lightweight two-stage convolutional recurrent network (CRN) is proposed. The algorithm consists of two main modules: a beamforming module [...] Read more.
To address the performance and computational complexity issues in speech enhancement for hearing aids, a speech enhancement algorithm based on a microphone array and a lightweight two-stage convolutional recurrent network (CRN) is proposed. The algorithm consists of two main modules: a beamforming module and a post-filtering module. The beamforming module utilizes directional features and a complex time-frequency long short-term memory (CFT-LSTM) network to extract local representations and perform spatial filtering. The post-filtering module uses analogous encoding and two symmetric decoding structures, with stacked CFT-LSTM blocks in between. It further reduces residual noise and improves filtering performance by passing spatial information through an inter-channel masking module. Experimental results show that this algorithm outperforms existing methods on the generated hearing aid dataset and the CHIME-3 dataset, with fewer parameters and lower model complexity, making it suitable for hearing aid scenarios with limited computational resources. Full article
(This article belongs to the Special Issue Signal, Image and Video Processing: Development and Applications)
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<p>Overall structure of the model.</p>
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<p>Schematic diagram of CFT-LSTM network structure.</p>
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<p>Intermodal mask estimation module.</p>
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<p>Comparison of ablation experiment results on the hearing aid dataset.</p>
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<p>Comparison of algorithm performance on the hearing aid dataset.</p>
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<p>Comparison of algorithm performance on the CHIME-3 dataset.</p>
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23 pages, 4462 KiB  
Article
Prediction of Lithium-Ion Battery Health Using GRU-BPP
by Sahar Qaadan, Aiman Alshare, Alexander Popp and Benedikt Schmuelling
Batteries 2024, 10(11), 399; https://doi.org/10.3390/batteries10110399 - 8 Nov 2024
Viewed by 408
Abstract
Accurate prediction of lithium-ion batteries’ (LIBs) state-of-health (SOH) is crucial for the safety and maintenance of LIB-powered systems. This study addresses the variability in degradation trajectories by applying gated recurrent unit (GRU) networks alongside principal component analysis (PCA), Granger causality, and K-means clustering [...] Read more.
Accurate prediction of lithium-ion batteries’ (LIBs) state-of-health (SOH) is crucial for the safety and maintenance of LIB-powered systems. This study addresses the variability in degradation trajectories by applying gated recurrent unit (GRU) networks alongside principal component analysis (PCA), Granger causality, and K-means clustering to analyze the relationships between operating conditions—such as temperature and load profiles—and battery performance degradation. This paper uses a publicly accessible dataset derived by aging three prismatic LIB cells under a realistic forklift operation profile. First, we identify the features that are relevant to driving variance, then we employ the winning algorithm of K-means clustering for the classification of operational states. Granger causality later investigates the inter-group relationships. Our GRU-BPP model achieves an RMSE value of 0.167 and an MAE of 0.129 for the reference performance testing (RPT) dataset and an RMSE of 0.032 with an MAE of 0.025 for the aging dataset, thus outperformed benchmark methods such as GRU, LME, and XGBoost. These results further enhance the predictiveness and robustness of this approach and yield a holistic solution to the conventional challenges in battery management and their remaining useful life (RUL) predictions. Full article
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<p>Reference performance testing (RPT) metrics over rounds for Cells 1, 2, and 3.</p>
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<p>Aging metrics over rounds for Cells 1, 2, and 3.</p>
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<p>Distribution of current, voltage, energy, and temperature during reference performance testing (RPT) for Cells 1, 2, and 3.</p>
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<p>Distribution of current, voltage, energy, and temperature during aging for Cells 1, 2, and 3.</p>
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<p>K-means and GMM clustering for RPT data across Cells 1, 2, and 3.</p>
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<p>K-means and GMM clustering for RPT data across Cells 1, 2, and 3.</p>
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<p>K-means and GMM clustering for aging data across Cells 1, 2, and 3.</p>
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<p>K-means and GMM clustering for aging data across Cells 1, 2, and 3.</p>
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<p>Flow Chart Details for RPT Dataset—Cell 1, 2, and 3.</p>
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<p>Flow chart details for aging dataset—Cell 1, 2, and 3.</p>
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<p>PCA, features, and energy contribution of RPT data for Cells 1, 2, and 3.</p>
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<p>PCA, features, and energy contribution of aging data for Cells 1, 2, and 3.</p>
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<p>Feature distributions for RPT data clusters—Cell 1.</p>
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<p>Feature distributions for RPT data clusters—Cell 2.</p>
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<p>Feature distributions for RPT data clusters—Cell 3.</p>
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<p>Feature distributions for aging data clusters—Cell 1.</p>
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<p>Feature distributions for aging data clusters—Cell 2.</p>
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<p>Feature distributions for aging data clusters—Cell 3.</p>
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<p>Validation loss and testing loss results for the GRU-BPP model on the RPT and aging datasets.</p>
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19 pages, 39662 KiB  
Article
Gravity Predictions in Data-Missing Areas Using Machine Learning Methods
by Yubin Liu, Yi Zhang, Qipei Pang, Sulan Liu, Shaobo Li, Xuguo Shi, Shaofeng Bian and Yunlong Wu
Remote Sens. 2024, 16(22), 4173; https://doi.org/10.3390/rs16224173 - 8 Nov 2024
Viewed by 396
Abstract
Gravity data, comprising a key foundational dataset, are crucial for various research, including land subsidence monitoring, geological exploration, and navigational positioning. However, the collection of gravity data in specific regions is difficult because of environmental, technical, and economic constraints, resulting in a non-uniform [...] Read more.
Gravity data, comprising a key foundational dataset, are crucial for various research, including land subsidence monitoring, geological exploration, and navigational positioning. However, the collection of gravity data in specific regions is difficult because of environmental, technical, and economic constraints, resulting in a non-uniform distribution of the observational data. Traditionally, interpolation methods such as Kriging have been widely used to deal with data gaps; however, their predictive accuracy in regions with sparse data still needs improvement. In recent years, the rapid development of artificial intelligence has opened up a new opportunity for data prediction. In this study, utilizing the EGM2008 satellite gravity model, we conducted a comprehensive analysis of three machine learning algorithms—random forest, support vector machine, and recurrent neural network—and compared their performances against the traditional Kriging interpolation method. The results indicate that machine learning methods exhibit a marked advantage in gravity data prediction, significantly enhancing the predictive accuracy. Full article
(This article belongs to the Special Issue Deep Learning for Remote Sensing and Geodata)
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<p>Terrain relief for large-scale dataset area.</p>
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<p>Terrain relief for small-scale dataset area.</p>
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<p>Fixed selection experiment configuration for the large-scale dataset (the black dots represent the data points of the testing set).</p>
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<p>Fixed selection experiment configuration for the small-scale dataset (the black dots represent the data points of the testing set).</p>
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<p>Predicted and true values of the four methods for the large-scale dataset. The blue curve is the true gravity value, and the green, orange, black, and red curves are predicted values for the RNN, RF, SVM, and Kriging methods, respectively. The horizontal axis is the number of samples, and the vertical axis is the predicted values.</p>
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<p>Predicted and true values of the four methods for the small-scale dataset. The blue curve is the true gravity value, and the green, orange, black, and red curves are predicted values for the RNN, RF, SVM, and Kriging methods, respectively. The horizontal axis is the number of samples, and the vertical axis is the predicted values.</p>
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<p>Predicted gravity data for the large-scale dataset; (<b>a</b>–<b>d</b>) the predicted values for RF, RNN, SVM, and Kriging methods, respectively.</p>
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<p>Predicted gravity data for the small-scale dataset; (<b>a</b>–<b>d</b>) the predicted values for RF, RNN, SVM, and Kriging methods, respectively.</p>
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<p>Predicted gravity data for the small-scale dataset; (<b>a</b>–<b>d</b>) the predicted values for RF, RNN, SVM, and Kriging methods, respectively.</p>
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<p>FDD of four methods for the large-scale dataset. The horizontal axis represents the difference, and the vertical axis represents frequency. (<b>a</b>–<b>d</b>) The RNN, RF, SVM, and Kriging methods, respectively.</p>
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<p>FDD of four methods for the large-scale dataset. The horizontal axis represents the difference, and the vertical axis represents frequency. (<b>a</b>–<b>d</b>) The RNN, RF, SVM, and Kriging methods, respectively.</p>
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<p>FDD of four methods for the small-scale dataset. The horizontal axis represents the difference, and the vertical axis represents frequency. (<b>a</b>–<b>d</b>) The RNN, RF, SVM, and Kriging methods, respectively.</p>
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<p>Predicted and true values of the four methods for the large-scale dataset. The blue curve is the true gravity value, and the green, orange, black, and red curves are predicted values for the RNN, RF, SVM, and Kriging methods, respectively. The horizontal axis is the number of samples, and the vertical axis is the predicted values.</p>
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<p>Predicted and true values of the four methods for the small-scale dataset. The blue curve is the true gravity value, and the green, orange, black, and red curves are predicted values for the RNN, RF, SVM, and Kriging methods, respectively. The horizontal axis is the number of samples, and the vertical axis is the predicted values.</p>
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<p>Predicted gravity data for the large-scale dataset. (<b>a</b>–<b>d</b>) The predicted values for RF, RNN, SVM, and Kriging methods, respectively.</p>
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<p>Predicted gravity data for the small-scale dataset. (<b>a</b>–<b>d</b>) The predicted values for RF, RNN, SVM, and Kriging methods, respectively.</p>
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<p>FDD of the four methods for the large-scale dataset. The horizontal axis represents the difference, and the vertical axis represents frequency. (<b>a</b>–<b>d</b>) The RNN, RF, SVM, and Kriging methods, respectively.</p>
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<p>FDD of the four methods for the small-scale dataset. The horizontal axis represents the difference, and the vertical axis represents frequency. (<b>a</b>–<b>d</b>) The RNN, RF, SVM, and Kriging methods, respectively.</p>
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24 pages, 5735 KiB  
Article
Vehicle-To-Grid (V2G) Charging and Discharging Strategies of an Integrated Supply–Demand Mechanism and User Behavior: A Recurrent Proximal Policy Optimization Approach
by Chao He, Junwen Peng, Wenhui Jiang, Jiacheng Wang, Lijuan Du and Jinkui Zhang
World Electr. Veh. J. 2024, 15(11), 514; https://doi.org/10.3390/wevj15110514 - 8 Nov 2024
Viewed by 491
Abstract
With the increasing global demand for renewable energy and heightened environmental awareness, electric vehicles (EVs) are rapidly becoming a popular clean and efficient mode of transportation. However, the widespread adoption of EVs has presented several challenges, such as the lagging development of charging [...] Read more.
With the increasing global demand for renewable energy and heightened environmental awareness, electric vehicles (EVs) are rapidly becoming a popular clean and efficient mode of transportation. However, the widespread adoption of EVs has presented several challenges, such as the lagging development of charging infrastructure, the impact on the power grid, and the dynamic changes in user charging behavior. To address these issues, this paper first proposes a vehicle-to-grid (V2G) optimization framework that responds to regional dynamic pricing. It also considers power balancing in charging and discharging stations when a large number of EVs are involved in scheduling, with the aim of maximizing the benefits for EV owners. Next, by leveraging the interaction between environmental states and the dynamic behavior of EVs, we design an optimization algorithm that combines the recurrent proximal policy optimization (RPPO) algorithm and long short-term memory (LSTM) networks. This approach enhances system convergence and improves grid stability while maximizing benefits for EV owners. Finally, a simulation platform is used to validate the practical application of the RPPO algorithm in optimizing V2G and grid-to-vehicle (G2V) charging strategies, providing significant theoretical foundations and technical support for the development of smart grids and sustainable transportation systems. Full article
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<p>Overall framework diagram.</p>
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<p>Network diagram.</p>
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<p>LSTM network diagram.</p>
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<p>Current distribution at charging stations under the fixed-time strategy.</p>
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<p>Charging optimization under the dynamic pricing strategy.</p>
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<p>Charging optimization under the RPPO algorithm.</p>
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<p>Comparison of charging and discharging prices.</p>
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<p>Set and actual current of EV charging stations under different strategies.</p>
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<p>SOC Management of EV charging stations under different charging algorithms.</p>
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11 pages, 1143 KiB  
Article
A Comparison of Open Ventral Hernia Repair Risk Stratification Systems: A Call for Consensus
by Tamás Talpai, Dumitru Sandu Râmboiu, Cătălin Alexandru Pîrvu, Stelian Pantea, Mircea Șelaru, Dan Cârțu, Silviu Daniel Preda, Ștefan Pătrașcu, Nicolae Dragoș Mărgăritescu, Marius Bică and Valeriu-Marin Șurlin
J. Clin. Med. 2024, 13(22), 6692; https://doi.org/10.3390/jcm13226692 - 7 Nov 2024
Viewed by 639
Abstract
Background/Objectives: Ventral hernia repair (VHR) is a common surgical intervention linked to specific surgical site complications. In such occurrences, the related morbidity is often substantial. Although known risk factors have long been recognized, their systematic inclusion in risk stratification systems lacks universal [...] Read more.
Background/Objectives: Ventral hernia repair (VHR) is a common surgical intervention linked to specific surgical site complications. In such occurrences, the related morbidity is often substantial. Although known risk factors have long been recognized, their systematic inclusion in risk stratification systems lacks universal validation. This study evaluates the effectiveness and correspondence of three risk assessment tools—CeDAR, VHWG, and the modified VHWG—in predicting postoperative wound complications in VHR patients. Methods: We analyzed data from 203 patients who underwent VHR for incisional midline or lateral wall hernia across two surgical departments between 2019 and 2023. Each patient was scored using CeDAR, VHWG, and the modified VHWG systems. Outcomes were assessed based on surgical site occurrences (SSOs) such as seroma formation, wound infections, and recurrences. Results: The incidence of SSOs was 8.9%, with two recorded deaths (0.89%). CeDAR scores showed a statistically significant relationship with SSOs but failed to accurately predict complication rates across subgroups. The VHWG grading system effectively predicted higher complication rates for grades III and IV compared to grades I and II, though its modified version did not show significant predictive improvements. Secondary outcomes indicated a higher SSO rate in patients requiring posterior component separation (TAR) and those with larger hernia defects, though the differences were not statistically significant. Major preoperative risk factors, including smoking, diabetes, and obesity, did not show significant correlations with SSO rates in this study. Conclusions: Current risk estimation tools inadequately predict SSOs in VHR. Enhancing prediction accuracy will require incorporating both patient-specific and surgical factors, potentially through advanced algorithms and large-scale studies. Full article
(This article belongs to the Section Pharmacology)
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<p>Flowchart with patient grading systems.</p>
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<p>Unilateral transversus abdominis release (personal archive).</p>
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17 pages, 1680 KiB  
Article
A BiGRU Model Based on the DBO Algorithm for Cloud-Edge Communication Networks
by Zhiyong Zha, Jianwen He, Lei Zhen, Mingyang Yu, Chenxi Dong, Zhikang Li, Geng Wu, Haoran Zuo and Kai Peng
Appl. Sci. 2024, 14(22), 10155; https://doi.org/10.3390/app142210155 - 6 Nov 2024
Viewed by 402
Abstract
With the development of IoT technology, central cloud servers and edge-computing servers together form a cloud–edge communication network to meet the increasing demand for computing tasks. The data transmitted in this network is of high value, so the ability to quickly and accurately [...] Read more.
With the development of IoT technology, central cloud servers and edge-computing servers together form a cloud–edge communication network to meet the increasing demand for computing tasks. The data transmitted in this network is of high value, so the ability to quickly and accurately predict the traffic load of each link becomes critical to ensuring the security and stable operation of the network. In order to effectively counter the potential threat of flood attacks on network stability, we combine the Bi-directional Gated Recurrent Unit (BiGRU) model with the Dung Beetle Optimizer (DBO) algorithm to design a DBO-BiGRU short-term traffic load prediction model. Experimental validation on a public dataset shows that the proposed model has better prediction accuracy and fit than the mainstream models of RNN, LSTM, and TCN. Full article
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<p>Application diagram of edge-computing paradigm.</p>
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<p>Cloud–Edge communication network.</p>
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<p>BiGRU hidden layer structure.</p>
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<p>Structure of BiGRU traffic prediction model.</p>
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<p>Overall architecture of DBO-BiGRU prediction model.</p>
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<p>Comparison of curves for the four models.</p>
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22 pages, 4927 KiB  
Article
Simulation and Optimization of Automated Guided Vehicle Charging Strategy for U-Shaped Automated Container Terminal Based on Improved Proximal Policy Optimization
by Yongsheng Yang, Jianyi Liang and Junkai Feng
Systems 2024, 12(11), 472; https://doi.org/10.3390/systems12110472 - 5 Nov 2024
Viewed by 473
Abstract
As the decarbonization strategies of automated container terminals (ACTs) continue to advance, electrically powered Battery-Automated Guided Vehicles (B-AGVs) are being widely adopted in ACTs. The U-shaped ACT, as a novel layout, faces higher AGV energy consumption due to its deep yard characteristics. A [...] Read more.
As the decarbonization strategies of automated container terminals (ACTs) continue to advance, electrically powered Battery-Automated Guided Vehicles (B-AGVs) are being widely adopted in ACTs. The U-shaped ACT, as a novel layout, faces higher AGV energy consumption due to its deep yard characteristics. A key issue is how to adopt charging strategies suited to varying conditions to reduce the operational capacity loss caused by charging. This paper proposes a simulation-based optimization method for AGV charging strategies in U-shaped ACTs based on an improved Proximal Policy Optimization (PPO) algorithm. Firstly, Gated Recurrent Unit (GRU) structures are incorporated into the PPO to capture temporal correlations in state information. To effectively limit policy update magnitudes in the PPO, we improve the clipping function. Secondly, a simulation model is established by mimicking the operational process of the U-shaped ACTs. Lastly, iterative training of the proposed method is conducted based on the simulation model. The experimental results indicate that the proposed method converges faster than standard PPO and Deep Q-network (DQN). When comparing the proposed method-based charging threshold with a fixed charging threshold strategy across six different scenarios with varying charging rates, the proposed charging strategy demonstrates better adaptability to terminal condition variations in two-thirds of the scenarios. Full article
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<p>Layout of U-shaped ACTs.</p>
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<p>Schematic diagram of U-shaped ACT simulation model.</p>
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<p>Status information summary.</p>
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<p>Charging strategy flowchart.</p>
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<p>(<b>a</b>) GRU structure. (<b>b</b>) GRU.</p>
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<p>Simulation optimization method for AGV dynamic charging threshold strategy based on DRL.</p>
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<p>Policy training process flowchart.</p>
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<p>Schematic diagram of U-shaped automated container terminal simulation model.</p>
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<p>Reward curves for three methods.</p>
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<p>Summary of charging strategy evaluation scores.</p>
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