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Search Results (2,288)

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29 pages, 6970 KiB  
Article
Traumatic Brain Injury Structure Detection Using Advanced Wavelet Transformation Fusion Algorithm with Proposed CNN-ViT
by Abdullah, Ansar Siddique, Zulaikha Fatima and Kamran Shaukat
Information 2024, 15(10), 612; https://doi.org/10.3390/info15100612 - 6 Oct 2024
Viewed by 244
Abstract
Detecting Traumatic Brain Injuries (TBI) through imaging remains challenging due to limited sensitivity in current methods. This study addresses the gap by proposing a novel approach integrating deep-learning algorithms and advanced image-fusion techniques to enhance detection accuracy. The method combines contextual and visual [...] Read more.
Detecting Traumatic Brain Injuries (TBI) through imaging remains challenging due to limited sensitivity in current methods. This study addresses the gap by proposing a novel approach integrating deep-learning algorithms and advanced image-fusion techniques to enhance detection accuracy. The method combines contextual and visual models to effectively assess injury status. Using a dataset of repeat mild TBI (mTBI) cases, we compared various image-fusion algorithms: PCA (89.5%), SWT (89.69%), DCT (89.08%), HIS (83.3%), and averaging (80.99%). Our proposed hybrid model achieved a significantly higher accuracy of 98.78%, demonstrating superior performance. Metrics including Dice coefficient (98%), sensitivity (97%), and specificity (98%) verified that the strategy is efficient in improving image quality and feature extraction. Additional validations with “entropy”, “average pixel intensity”, “standard deviation”, “correlation coefficient”, and “edge similarity measure” confirmed the robustness of the fused images. The hybrid CNN-ViT model, integrating curvelet transform features, was trained and validated on a comprehensive dataset of 24 types of brain injuries. The overall accuracy was 99.8%, with precision, recall, and F1-score of 99.8%. The “average PSNR” was 39.0 dB, “SSIM” was 0.99, and MI was 1.0. Cross-validation across five folds proved the model’s “dependability” and “generalizability”. In conclusion, this study introduces a promising method for TBI detection, leveraging advanced image-fusion and deep-learning techniques, significantly enhancing medical imaging and diagnostic capabilities for brain injuries. Full article
(This article belongs to the Special Issue Real-World Applications of Machine Learning Techniques)
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<p>Classification of different available fusion algorithmic techniques.</p>
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<p>Traumatic brain injury classification.</p>
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<p>TBI dataset classes distribution.</p>
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<p>Traumatic medical brain injury data prepossessing.</p>
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<p>Proposed hybrid image fusion algorithm for medical image fusion.</p>
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<p>Proposed model architecture of hybrid CNN-ViT model.</p>
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<p>Two medical scan images which are to be fused.</p>
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<p>The fused image in the third axis.</p>
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<p>Spatial gradients computed by smoothing the average input images.</p>
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<p>Dice coefficient.</p>
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<p>Sensitivity Rate.</p>
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<p>Specificity (True Negative Rate).</p>
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<p>Entropy.</p>
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<p>Average Pixel Intensity (Mean).</p>
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<p>Standard deviation (SD).</p>
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<p>Correlation Coefficient (CC).</p>
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<p>Edge similarity measure.</p>
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<p>Overall accuracy of all algorithm.</p>
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<p>Average classification Performance Metrics TBI.</p>
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<p>Average Confusion metric for multiclass TBI.</p>
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<p>Average AUC-ROC Curve for multiclass TBI.</p>
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<p>Training and validation accuracy.</p>
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<p>Cross validation Traumatic brain Injury.</p>
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<p>State-of-the-art comparison with existing techniques.</p>
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21 pages, 5497 KiB  
Article
SMOTE-Based Automated PCOS Prediction Using Lightweight Deep Learning Models
by Rumman Ahmad, Lamees A. Maghrabi, Ishfaq Ahmad Khaja, Louai A. Maghrabi and Musheer Ahmad
Diagnostics 2024, 14(19), 2225; https://doi.org/10.3390/diagnostics14192225 - 5 Oct 2024
Viewed by 338
Abstract
Background: The reproductive age of women is particularly vulnerable to the effects of polycystic ovarian syndrome (PCOS). High levels of testosterone and other male hormones are frequent contributors to PCOS. It is believed that miscarriages and ovulation problems are majorly caused by PCOS. [...] Read more.
Background: The reproductive age of women is particularly vulnerable to the effects of polycystic ovarian syndrome (PCOS). High levels of testosterone and other male hormones are frequent contributors to PCOS. It is believed that miscarriages and ovulation problems are majorly caused by PCOS. A recent study found that 31.3% of Asian women have been afflicted with PCOS. Healing women with life-threatening disorders associated with PCOS requires more research. In prior research, methods have involved autonomously classified PCOS using a number of different machine learning techniques. ML-based approaches involve hand-crafted feature extraction and suffer from low performance issues, which cannot be ignored for the accurate prediction and identification of PCOS. Objective: Hence, predicting PCOS using cutting-edge deep learning methods for automated feature engineering with better performance is the prime focus of this study. Methods: The proposed method suggests three lightweight (LSTM-based, CNN-based, and CNN-LSTM-based) deep learning models, incorporating SMOTE for dataset balancing to obtain a valid performance. Results: The proposed three models tend to offer an accuracy of 92.04%, 96.59%, and 94.31%, an ROC-AUC of 92.0%, 96.6%, and 94.3%, the number of parameters of 6689, 297, and 13285, and a training time of 67.27 s, 10.02 s, and 18.51 s, respectively. In addition, the DeLong test is also performed to compare AUCs to assess the statistical significance of all three models. Among all three models, the SMOTE + CNN models performs better in terms of accuracy, precision, recall, AUC, number of parameters, training time, DeLong’s p-value over the other. Conclusions: Moreover, a performance comparison is also carried out with other state-of-the-art PCOS detection studies and methods, which validates the better performance of the proposed model. Thus, the proposed model provides the greatest performance, which can lead to a reduction in the number of failed pregnancies and help in finding PCOS in the early stages. Full article
(This article belongs to the Section Machine Learning and Artificial Intelligence in Diagnostics)
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<p>Heatmap for examining the correlations between all features of the PCOS dataset.</p>
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<p>Heatmap for the correlations between the features with threshold 0.25 of PCOS dataset.</p>
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<p>Schematic diagram of the proposed methodology.</p>
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<p>Typical architectures of the three proposed deep learning models with the size of input and output of each layer.</p>
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<p>Confusion matrices for the proposed models. (<b>a</b>) LSTM, (<b>b</b>) Custom CNN, (<b>c</b>) CNN + LSTM.</p>
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<p>Accuracy and loss plots for the proposed LSTM model.</p>
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<p>Accuracy and loss plots for the proposed custom CNN model.</p>
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<p>Accuracy and loss plots for the proposed custom CNN+LSTM model.</p>
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<p>ROC-AUCs for PCOS prediction using (<b>a</b>) LSTM model, (<b>b</b>) custom CNN model, and (<b>c</b>) CNN-LSTM model.</p>
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<p>Performance comparison of PCOS prediction models [<a href="#B22-diagnostics-14-02225" class="html-bibr">22</a>,<a href="#B27-diagnostics-14-02225" class="html-bibr">27</a>,<a href="#B30-diagnostics-14-02225" class="html-bibr">30</a>,<a href="#B47-diagnostics-14-02225" class="html-bibr">47</a>,<a href="#B48-diagnostics-14-02225" class="html-bibr">48</a>,<a href="#B49-diagnostics-14-02225" class="html-bibr">49</a>,<a href="#B51-diagnostics-14-02225" class="html-bibr">51</a>,<a href="#B52-diagnostics-14-02225" class="html-bibr">52</a>,<a href="#B54-diagnostics-14-02225" class="html-bibr">54</a>].</p>
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23 pages, 1046 KiB  
Article
Forecasting Short- and Long-Term Wind Speed in Limpopo Province Using Machine Learning and Extreme Value Theory
by Kgothatso Makubyane and Daniel Maposa
Forecasting 2024, 6(4), 885-907; https://doi.org/10.3390/forecast6040044 - 4 Oct 2024
Viewed by 430
Abstract
This study investigates wind speed prediction using advanced machine learning techniques, comparing the performance of Vanilla long short-term memory (LSTM) and convolutional neural network (CNN) models, alongside the application of extreme value theory (EVT) using the r-largest order generalised extreme value distribution ( [...] Read more.
This study investigates wind speed prediction using advanced machine learning techniques, comparing the performance of Vanilla long short-term memory (LSTM) and convolutional neural network (CNN) models, alongside the application of extreme value theory (EVT) using the r-largest order generalised extreme value distribution (GEVDr). Over the past couple of decades, the academic literature has transitioned from conventional statistical time series models to embracing EVT and machine learning algorithms for the modelling of environmental variables. This study adds value to the literature and knowledge of modelling wind speed using both EVT and machine learning. The primary aim of this study is to forecast wind speed in the Limpopo province of South Africa to showcase the dependability and potential of wind power generation. The application of CNN showcased considerable predictive accuracy compared to the Vanilla LSTM, achieving 88.66% accuracy with monthly time steps. The CNN predictions for the next five years, in m/s, were 9.91 (2024), 7.64 (2025), 7.81 (2026), 7.13 (2027), and 9.59 (2028), slightly outperforming the Vanilla LSTM, which predicted 9.43 (2024), 7.75 (2025), 7.85 (2026), 6.87 (2027), and 9.43 (2028). This highlights CNN’s superior ability to capture complex patterns in wind speed dynamics over time. Concurrently, the analysis of the GEVDr across various order statistics identified GEVDr=2 as the optimal model, supported by its favourable evaluation metrics in terms of Akaike information criteria (AIC) and Bayesian information criteria (BIC). The 300-year return level for GEVDr=2 was found to be 22.89 m/s, indicating a rare wind speed event. Seasonal wind speed analysis revealed distinct patterns, with winter emerging as the most efficient season for wind, featuring a median wind speed of 7.96 m/s. Future research could focus on enhancing prediction accuracy through hybrid algorithms and incorporating additional meteorological variables. To the best of our knowledge, this is the first study to successfully combine EVT and machine learning for short- and long-term wind speed forecasting, providing a novel framework for reliable wind energy planning. Full article
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<p>Geographic location of Polokwane within Limpopo province. Source: <a href="https://w.wiki/B2us" target="_blank">https://w.wiki/B2us</a>, accessed on 5 May 2024.</p>
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<p>Basic architecture of the Vanilla LSTM network. Source: <a href="https://www.researchgate.net/figure/The-structure-of-LSTM-memory-cell_fig5_342998863" target="_blank">https://www.researchgate.net/figure/The-structure-of-LSTM-memory-cell_fig5_342998863</a>, accessed on 30 June 2024.</p>
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<p>Basic architecture of a CNN. Source: <a href="https://learnopencv.com/wp-content/uploads/2023/01/tensorflow-keras-cnn-vgg-architecture.png" target="_blank">https://learnopencv.com/wp-content/uploads/2023/01/tensorflow-keras-cnn-vgg-architecture.png</a>, accessed on 18 September 2024.</p>
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<p>Seasonal wind speed trend analysis for 2023.</p>
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<p>Trend slope plot.</p>
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<p>Training and testing predictions of Vanilla LSTM and CNN models.</p>
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<p>Boxplot of the residual errors of each method with different ranges of the wind speed.</p>
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<p>Training and validation loss of Vanilla LSTM and CNN models.</p>
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<p>(<b>Top left panel</b>): Vanilla LSTM daily wind speed predictions; (<b>Top right panel</b>): CNN daily wind speed predictions; (<b>Bottom left panel</b>): Vanilla LSTM yearly wind speed predictions; (<b>Bottom right panel</b>): CNN yearly wind speed predictions.</p>
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<p><math display="inline"><semantics> <mrow> <mi>G</mi> <mi>E</mi> <mi>V</mi> <msub> <mi>D</mi> <mrow> <mi>r</mi> <mo>=</mo> <mn>2</mn> </mrow> </msub> </mrow> </semantics></math> diagnostic plots.</p>
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14 pages, 7581 KiB  
Article
Study on Methods Using Multi-Label Learning for the Classification of Compound Faults in Auxiliary Equipment Pumps of Marine Engine Systems
by Byungmoon Yu, Youngki Kim, Taehyun Lee, Youhee Cho, Jihwan Park, Jongjik Lee and Jihyuk Park
Processes 2024, 12(10), 2161; https://doi.org/10.3390/pr12102161 - 4 Oct 2024
Viewed by 373
Abstract
The impact of the Fourth Industrial Revolution has brought significant attention to Condition-based maintenance (CBM) for autonomous ships. This study aims to apply CBM to the fuel supply pump of a ship. Five major failures were identified through reliability analysis, and structural analysis [...] Read more.
The impact of the Fourth Industrial Revolution has brought significant attention to Condition-based maintenance (CBM) for autonomous ships. This study aims to apply CBM to the fuel supply pump of a ship. Five major failures were identified through reliability analysis, and structural analysis was conducted to investigate the mechanisms by which one failure induces another, leading to the identification of three compound failure scenarios. Data were collected on a test bed under normal conditions, five single failure conditions, and three compound failure conditions. The acceleration data from the experiments were transformed into 2D arrays corresponding to a single pump rotation, and a method was proposed to compensate for the errors accumulated during the repeated array generation. The data were vectorized using a simplified CNN structure and applied to six multi-label learning methods, which were compared to identify the optimal approach. Among the six methods, the Label Powerset (LP) was found to be the most effective. Multi-label learning captures correlations between labels, similar to the failure-inducing mechanisms learned from structural analysis. Full article
(This article belongs to the Section Advanced Digital and Other Processes)
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<p>Test bed for the simulation test.</p>
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<p>Three-dimensional modeling of the pump with key components.</p>
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<p>Structural analysis at bearing failure: (<b>a</b>) 10-degree rotation; (<b>b</b>) 20-degree rotation; (<b>c</b>) 30-degree rotation.</p>
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<p>(<b>a</b>) Secondary failure by bearing failure; (<b>b</b>) secondary failure by misalignment.</p>
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<p>(<b>a</b>) Five single failures; (<b>b</b>) three compound failures.</p>
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<p>(<b>a</b>) Before applying compensation method; (<b>b</b>) after applying compensation method.</p>
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<p>Visualization of the arrays of six states: (<b>a</b>) normal; (<b>b</b>) bearing; (<b>c</b>) mechanical seal; (<b>d</b>) elastomer; (<b>e</b>) misalignment; (<b>f</b>) cavitation.</p>
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<p>Flowchart of the proposed method.</p>
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20 pages, 3901 KiB  
Article
Multi-Modal Fusion Network with Multi-Head Self-Attention for Injection Training Evaluation in Medical Education
by Zhe Li, Aya Kanazuka, Atsushi Hojo, Yukihiro Nomura and Toshiya Nakaguchi
Electronics 2024, 13(19), 3882; https://doi.org/10.3390/electronics13193882 - 30 Sep 2024
Viewed by 491
Abstract
The COVID-19 pandemic has significantly disrupted traditional medical training, particularly in critical areas such as the injection process, which require expert supervision. To address the challenges posed by reduced face-to-face interactions, this study introduces a multi-modal fusion network designed to evaluate the timing [...] Read more.
The COVID-19 pandemic has significantly disrupted traditional medical training, particularly in critical areas such as the injection process, which require expert supervision. To address the challenges posed by reduced face-to-face interactions, this study introduces a multi-modal fusion network designed to evaluate the timing and motion aspects of the injection training process in medical education. The proposed framework integrates 3D reconstructed data and 2D images of hand movements during the injection process. The 3D data are preprocessed and encoded by a Long Short-Term Memory (LSTM) network to extract temporal features, while a Convolutional Neural Network (CNN) processes the 2D images to capture detailed image features. These encoded features are then fused and refined through a proposed multi-head self-attention module, which enhances the model’s ability to capture and weigh important temporal and image dynamics in the injection process. The final classification of the injection process is conducted by a classifier module. The model’s performance was rigorously evaluated using video data from 255 subjects with assessments made by professional physicians according to the Objective Structured Assessment of Technical Skill—Global Rating Score (OSATS-GRS)[B] criteria for time and motion evaluation. The experimental results demonstrate that the proposed data fusion model achieves an accuracy of 0.7238, an F1-score of 0.7060, a precision of 0.7339, a recall of 0.7238, and an AUC of 0.8343. These findings highlight the model’s potential as an effective tool for providing objective feedback in medical injection training, offering a scalable solution for the post-pandemic evolution of medical education. Full article
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<p>The multi-camera injection acquisition system. It includes three sets of industrial cameras, which are positioned at the upper left, upper right, and directly above the front of the arm model to clearly capture the hand movements. A general-purpose camera is used for event detection, and an arm model is employed to simulate puncture. A timing button is used to control the start, while a photo sensor detects blood backflow.</p>
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<p>Definition of different stages in time detection. The time parameters are divided into three parts: the start time (when the operator presses the button to start the injection); needle puncture time (when the tip of needle contacts the skin); and blood backflow time (when the needle continues to puncture the vessel, causing blood backflow).</p>
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<p>Mediapipe Hand used to recognize hand injection motions from different camera perspectives and convert the data into 3D space.</p>
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<p>Labeling of the thumb–index finger joints. The information that can be extracted includes the angles between the joints, distances between the joints, and the fingertip distance (distance between points 4 and 8).</p>
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<p>Overall framework of the proposed multi-modal fusion network for evaluating medical injection training. The framework is divided into three main components: (<b>A</b>) the overall process flow, (<b>B</b>) the bidirectional LSTM module, and (<b>C</b>) the multi-head self-attention module.</p>
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<p>Architecture of the LSTM-based predictive model using 3D features.</p>
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<p>Architecture of the CNN-based predictive model using 2D image features.</p>
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<p>Framework of the multi-modal data fusion model.</p>
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<p>Confusion matrix and ROC curve results from the 5-fold cross-validation for the multi-modal fusion and multi-head self-attention model.</p>
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30 pages, 10186 KiB  
Article
An Improved Convolutional Neural Network for Pipe Leakage Identification Based on Acoustic Emission
by Weidong Xu, Jiwei Huang, Lianghui Sun, Yixin Yao, Fan Zhu, Yaoguo Xie and Meng Zhang
J. Mar. Sci. Eng. 2024, 12(10), 1720; https://doi.org/10.3390/jmse12101720 - 30 Sep 2024
Viewed by 572
Abstract
Oil and gas pipelines are the lifelines of the energy market, but due to long-term use and environmental factors, these pipelines are prone to corrosion and leaks. Offshore oil and gas pipeline leaks, in particular, can lead to severe consequences such as platform [...] Read more.
Oil and gas pipelines are the lifelines of the energy market, but due to long-term use and environmental factors, these pipelines are prone to corrosion and leaks. Offshore oil and gas pipeline leaks, in particular, can lead to severe consequences such as platform fires and explosions. Therefore, it is crucial to accurately and swiftly identify oil and gas leaks on offshore platforms. This is of significant importance for improving early warning systems, enhancing maintenance efficiency, and reducing economic losses. Currently, the efficiency of identifying leaks in offshore platform pipelines still needs improvement. To address this, the present study first established an experimental platform to simulate pipeline leaks in a marine environment. Laboratory leakage signal data were collected, and on-site noise data were gathered from the “Liwan 3-1” offshore oil and gas platform. By integrating leakage signals with on-site noise data, this study aimed to closely mimic real-world application scenarios. Subsequently, several neural network-based leakage identification methods were applied to the integrated dataset, including a probabilistic neural network (PNN) combined with time-domain feature extraction, a Backpropagation Neural Network (BPNN) optimized with simulated annealing and particle swarm optimization, and a Long Short-Term Memory Network (LSTM) combined with Mel-Frequency Cepstral Coefficients (MFCC). Corresponding models were constructed, and the effectiveness of leak detection was validated using test sets. Additionally, this paper proposes an improved convolutional neural network (CNN) leakage detection technology named SART-1DCNN. This technology optimizes the network architecture by introducing attention mechanisms, transformer modules, residual blocks, and combining them with Dropout and optimization algorithms, which significantly enhances data recognition accuracy. It achieves a high accuracy rate of 99.44% on the dataset. This work is capable of detecting pipeline leaks with high accuracy. Full article
(This article belongs to the Special Issue Structural Analysis and Failure Prevention in Offshore Engineering)
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<p>Pipeline structure model.</p>
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<p>Pipeline AE detection system.</p>
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<p>LW3-1 CEP platform. (<b>a</b>) LW3-1 framework model; (<b>b</b>) LW3-1 on-site image.</p>
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<p>AE sensor layout on offshore platform pipelines. (<b>a</b>) Sensor installation position 1; (<b>b</b>) sensor installation position 2.</p>
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<p>Laboratory leak signal waveform.</p>
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<p>Measured noise signal on platform and leak signal with noise added. (<b>a</b>) Measured noise signal on platform; (<b>b</b>) leak signal with noise added.</p>
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<p>Frequency spectrum and time–frequency plot of measured noise signal on platform. (<b>a</b>) Frequency spectrum of measured noise signal on platform; (<b>b</b>) time–frequency plot of signal with noise added.</p>
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<p>Frequency spectrum and time–frequency plot of leak signal with noise added. (<b>a</b>) Frequency spectrum of signal with noise added; (<b>b</b>) time–frequency plot of signal with noise added.</p>
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<p>PNN structure diagram.</p>
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<p>PNN classification results diagram (part).</p>
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<p>Confusion matrix for the TDF-PNN method test set.</p>
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<p>SA-PSO parameter optimization process.</p>
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<p>Confusion matrix for the SA-PSO-BPNN method test set.</p>
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<p>Main extraction process of Mel-Frequency Cepstral Coefficients.</p>
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<p>LSTM neuron structure.</p>
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<p>Confusion matrix for the MFCC-LSTM method test set.</p>
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<p>Working principle of one-dimensional CNN.</p>
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<p>Structure of the SART-1DCNN.</p>
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<p>Diagnostic process for the SART-1DCNN model.</p>
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<p>Accuracy and loss function curves for 100 epochs on training and validation sets. (<b>a</b>) training metrics; (<b>b</b>) validation metrics.</p>
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<p>t-SNE plot of the test set data.</p>
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<p>Confusion matrix for test set prediction results.</p>
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<p>Frameworks of LeNet and AlexNet.</p>
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24 pages, 5038 KiB  
Article
UAV Anomaly Detection Method Based on Convolutional Autoencoder and Support Vector Data Description with 0/1 Soft-Margin Loss
by Huakun Chen, Yongxi Lyu, Jingping Shi and Weiguo Zhang
Drones 2024, 8(10), 534; https://doi.org/10.3390/drones8100534 - 29 Sep 2024
Viewed by 393
Abstract
Unmanned aerial vehicles (UAVs) are becoming more widely used in various industries, raising growing concerns about their safety and reliability. The flight data of UAVs can directly reflect their flight health status; however, the rarity of abnormal flight data and the spatiotemporal characteristics [...] Read more.
Unmanned aerial vehicles (UAVs) are becoming more widely used in various industries, raising growing concerns about their safety and reliability. The flight data of UAVs can directly reflect their flight health status; however, the rarity of abnormal flight data and the spatiotemporal characteristics of these data represent a significant challenge for constructing accurate and reliable anomaly detectors. To address this, this study proposes an anomaly detection framework that fully considers the temporal correlations and distribution characteristics of flight data. This framework first combines a one-dimensional convolutional neural network (1DCNN) with an autoencoder (AE) to establish a feature extraction model. This model leverages the feature extraction capabilities of the 1DCNN and the reconstruction capabilities of the AE to thoroughly extract the spatiotemporal features from UAV flight data. Then, to address the challenge of adaptive anomaly detection thresholds, this research proposes a nonlinear model of support vector data description (SVDD) utilizing a 0/1 soft-margin loss, referred to as L0/1-SVDD. This model replaces the traditional hinge loss function in SVDD with a 0/1 loss function, with the goal of enhancing the accuracy and robustness of anomaly detection. Since the 0/1 loss function is a bounded, non-convex, and non-continuous function, this paper proposes the Bregman ADMM algorithm to solve the L0/1-SVDD. Finally, the difference between the reconstructed and the actual value is employed to train the L0/1-SVDD, resulting in a hypersphere classifier that is capable of detecting UAV anomaly data. The experimental results using real flight data show that, compared with methods such as AE, LSTM, and LSTM-AE, the proposed method exhibits superior performance across five evaluation metrics. Full article
(This article belongs to the Special Issue Advances in Detection, Security, and Communication for UAV)
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<p>Autoencoder.</p>
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<p>The overall framework for UAV anomaly detection.</p>
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<p>Diagram of the architecture of the CAE model.</p>
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<p>Feature change curves during UAV engine failure.</p>
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<p>Feature change curves when the UAV’s rudder is stuck to the right.</p>
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<p>Feature change curves when the UAV’s rudder is stuck to the right.</p>
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<p>The impact of different sliding window lengths on the anomaly detection accuracy: (<b>a</b>) engine failure; (<b>b</b>) rudder and aileron at zero.</p>
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<p>Impact of different strides on anomaly detection accuracy: (<b>a</b>) engine failure; (<b>b</b>) rudder and aileron at zero.</p>
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<p>Residuals of the reconstructed data for different types of anomalies: (<b>a</b>) rudder and aileron at zero; (<b>b</b>) rudder stuck to the left; (<b>c</b>) rudder stuck to the right; and (<b>d</b>) left aileron stuck at zero.</p>
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<p>ROC curves for different anomaly detection methods: (<b>a</b>) engine failure; (<b>b</b>) rudder stuck to the left; (<b>c</b>) rudder stuck to the right; (<b>d</b>) elevator stuck at zero; (<b>e</b>) left aileron stuck at zero; (<b>f</b>) right aileron stuck at zero; (<b>g</b>) both ailerons stuck at zero; (<b>h</b>) rudder and aileron at zero.</p>
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<p>ROC curves for different anomaly detection methods: (<b>a</b>) engine failure; (<b>b</b>) rudder stuck to the left; (<b>c</b>) rudder stuck to the right; (<b>d</b>) elevator stuck at zero; (<b>e</b>) left aileron stuck at zero; (<b>f</b>) right aileron stuck at zero; (<b>g</b>) both ailerons stuck at zero; (<b>h</b>) rudder and aileron at zero.</p>
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20 pages, 14487 KiB  
Article
Fault Classification of 3D-Printing Operations Using Different Types of Machine and Deep Learning Techniques
by Satish Kumar, Sameer Sayyad and Arunkumar Bongale
AI 2024, 5(4), 1759-1778; https://doi.org/10.3390/ai5040087 - 27 Sep 2024
Viewed by 536
Abstract
Fused deposition modeling (FDM), a method of additive manufacturing (AM), comprises the extrusion of materials via a nozzle and the subsequent combining of the layers to create 3D-printed objects. FDM is a widely used method for 3D-printing objects since it is affordable, effective, [...] Read more.
Fused deposition modeling (FDM), a method of additive manufacturing (AM), comprises the extrusion of materials via a nozzle and the subsequent combining of the layers to create 3D-printed objects. FDM is a widely used method for 3D-printing objects since it is affordable, effective, and easy to use. Some defects such as poor infill, elephant foot, layer shift, and poor surface finish arise in the FDM components at the printing stage due to variations in printing parameters such as printing speed, change in nozzle, or bed temperature. Proper fault classification is required to identify the cause of faulty products. In this work, the multi-sensory data are gathered using different sensors such as vibration, current, temperature, and sound sensors. The data acquisition is performed by using the National Instrumentation (NI) Data Acquisition System (DAQ) which provides the synchronous multi-sensory data for the model training. To induce the faults, the data are captured under different conditions such as variations in printing speed, temperate, and jerk during the printing. The collected data are used to train the machine learning (ML) and deep learning (DL) classification models to classify the variation in printing parameters. The ML models such as k-nearest neighbor (KNN), decision tree (DT), extra trees (ET), and random forest (RF) with convolutional neural network (CNN) as a DL model are used to classify the variable operation printing parameters. Out of the available models, in ML models, the RF classifier shows a classification accuracy of around 91% whereas, in the DL model, the CNN model shows good classification performance with accuracy ranging from 92 to 94% under variable operating conditions. Full article
(This article belongs to the Special Issue Intelligent Systems for Industry 4.0)
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<p>The overall methodology of fault detection in 3D-printed products.</p>
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<p>Experimental setup for data collection.</p>
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<p>Sensor mounting position and Data Acquisition System (DAQ).</p>
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<p>Collected normalized vibration, current, temperature, and sound sensor signal representation for different operating conditions.</p>
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<p>RFC model confusion matrix for variable temperature condition.</p>
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<p>CNN model learning curve for variable temperature conditions.</p>
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<p>CNN model confusion matrix for variable temperature condition.</p>
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<p>ETC model confusion matrix for variable speed condition.</p>
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<p>CNN model learning curve for variable printing speed conditions.</p>
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<p>CNN model confusion matrix of variable speed condition.</p>
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<p>RFC model confusion matrix for variable jerk condition.</p>
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<p>CNN model Learning curve for variable Jerk conditions.</p>
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<p>CNN model confusion matrix of variable jerk conditions.</p>
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19 pages, 5080 KiB  
Article
Probabilistic Uncertainty Consideration in Regionalization and Prediction of Groundwater Nitrate Concentration
by Divas Karimanzira
Knowledge 2024, 4(4), 462-480; https://doi.org/10.3390/knowledge4040025 - 25 Sep 2024
Viewed by 303
Abstract
In this study, we extend our previous work on a two-dimensional convolutional neural network (2DCNN) for spatial prediction of groundwater nitrate, focusing on improving uncertainty quantification. Our enhanced model incorporates a fully probabilistic Bayesian framework and a structure aimed at optimizing both specific [...] Read more.
In this study, we extend our previous work on a two-dimensional convolutional neural network (2DCNN) for spatial prediction of groundwater nitrate, focusing on improving uncertainty quantification. Our enhanced model incorporates a fully probabilistic Bayesian framework and a structure aimed at optimizing both specific value predictions and predictive intervals (PIs). We implemented the Prediction Interval Validation and Estimation Network based on Quality Definition (2DCNN-QD) to refine the accuracy of probabilistic predictions and reduce the width of the prediction intervals. Applied to a model region in Germany, our results demonstrate an 18% improvement in the prediction interval width. While traditional Bayesian CNN models may yield broader prediction intervals to adequately capture uncertainties, the 2DCNN-QD method prioritizes quality-driven interval optimization, resulting in narrower prediction intervals without sacrificing coverage probability. Notably, this approach is nonparametric, allowing it to be effectively utilized across a range of real-world scenarios. Full article
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<p>The study area of Baden-Württemberg (BaWü). Generalized hydrogeological map of Baden-Württemberg, southwest Germany, showing karst aquifer systems and locations [<a href="#B15-knowledge-04-00025" class="html-bibr">15</a>].</p>
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<p>Frequency density of the nitrate from 2019 from 1566 measuring sites.</p>
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<p>Flowchart showing the methodology.</p>
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<p>The data are provided in two main formats: (<b>a</b>) the predictor variables, represented as raster files containing covariate information, and (<b>b</b>) the target variable, which is the nitrate concentration, presented in the form of a point shapefile.</p>
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<p>Spatial context in the vicinity of a nitrate observation well (<math display="inline"><semantics> <mrow> <mi>P</mi> </mrow> </semantics></math>) for <math display="inline"><semantics> <mrow> <mi>n</mi> </mrow> </semantics></math> number of explanatory raster variables.</p>
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<p>(<b>a</b>) Crops of raster images at the observation wells by a window of size <math display="inline"><semantics> <mrow> <mi>h</mi> <mo>×</mo> <mi>w</mi> </mrow> </semantics></math> and (<b>b</b>) cropped images representing <span class="html-italic">n</span> different input variables at the same point marked by the red square.</p>
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<p>The backbone neural network model based on unimodal 2DCNN architecture.</p>
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<p>The structure of the 2DCNN model modified for uncertainty consideration.</p>
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<p>Measured vs. predicted groundwater nitrate concentrations for (<b>a</b>) 2DCNN, (<b>b</b>) Bayesian 2DCNN and (<b>c</b>) 2DCNN-QD models, and (<b>d</b>) Taylor diagram. The red line represents the ideal predictions and the blue lines the regression line of the point cloud.</p>
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<p>Regionalization results of the three models, (<b>a</b>) 2DCNN, (<b>b</b>) Bayesian 2DCNN, and (<b>c</b>) 2DCNN-QD.</p>
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<p>Uncertainty band of the regionalization by the two developed methods: (<b>a</b>) obtained through bootstrapping of 2DCNN and (<b>b</b>) Bayesian and (<b>c</b>) prediction intervals of the deep learning method, which produces both PIs and specific value predictions (2DCNN-QD) with MPIWs of 48, 59, and 26 mg/L, respectively.</p>
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23 pages, 7912 KiB  
Article
Asymmetric Network Combining CNN and Transformer for Building Extraction from Remote Sensing Images
by Junhao Chang, Yuefeng Cen and Gang Cen
Sensors 2024, 24(19), 6198; https://doi.org/10.3390/s24196198 - 25 Sep 2024
Viewed by 475
Abstract
The accurate extraction of buildings from remote sensing images is crucial in fields such as 3D urban planning, disaster detection, and military reconnaissance. In recent years, models based on Transformer have performed well in global information processing and contextual relationship modeling, but suffer [...] Read more.
The accurate extraction of buildings from remote sensing images is crucial in fields such as 3D urban planning, disaster detection, and military reconnaissance. In recent years, models based on Transformer have performed well in global information processing and contextual relationship modeling, but suffer from high computational costs and insufficient ability to capture local information. In contrast, convolutional neural networks (CNNs) are very effective in extracting local features, but have a limited ability to process global information. In this paper, an asymmetric network (CTANet), which combines the advantages of CNN and Transformer, is proposed to achieve efficient extraction of buildings. Specifically, CTANet employs ConvNeXt as an encoder to extract features and combines it with an efficient bilateral hybrid attention transformer (BHAFormer) which is designed as a decoder. The BHAFormer establishes global dependencies from both texture edge features and background information perspectives to extract buildings more accurately while maintaining a low computational cost. Additionally, the multiscale mixed attention mechanism module (MSM-AMM) is introduced to learn the multiscale semantic information and channel representations of the encoder features to reduce noise interference and compensate for the loss of information in the downsampling process. Experimental results show that the proposed model achieves the best F1-score (86.7%, 95.74%, and 90.52%) and IoU (76.52%, 91.84%, and 82.68%) compared to other state-of-the-art methods on the Massachusetts building dataset, the WHU building dataset, and the Inria aerial image labeling dataset. Full article
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<p>Challenges in the building extraction task: (<b>a</b>) Diversity of building forms. (<b>b</b>) Scale changes in buildings. (<b>c</b>) Interference from complex backgrounds. (<b>d</b>) Blurred remote sensing images.</p>
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<p>General structure of CTANet.</p>
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<p>Detailed structure of ConvNeXt.</p>
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<p>The structure of BHAFormer block. The right side of the figure shows the details of the bilateral hybrid attention (BHA).</p>
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<p>The structure of MSM-AMM. Contains spatial attention branch and channel attention branch.</p>
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<p>Visualizing ablation study results on the Inria aerial image labeling dataset. (<b>a</b>) Images. (<b>b</b>) Labels. (<b>c</b>) CTANet. (<b>d</b>) Only BHAFormer. (<b>e</b>) Only MSM-AMM. (<b>f</b>) Baseline.</p>
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<p>Visualization results of CATNet and state-of-the-art methods on the Inria aerial image labeling dataset. (<b>a</b>) Images. (<b>b</b>) Labels. (<b>c</b>) CTANet. (<b>d</b>) BuildFormer. (<b>e</b>) TransUNet. (<b>f</b>) Swin-Unet.</p>
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<p>Visualization results of CATNet and state-of-the-art methods on the Massachusetts building dataset. (<b>a</b>) Images. (<b>b</b>) Labels. (<b>c</b>) CTANet. (<b>d</b>) BuildFormer. (<b>e</b>) TransUNet. (<b>f</b>) Swin-Unet.</p>
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<p>Visualization results of CATNet and state-of-the-art methods on the WHU building dataset. (<b>a</b>) Images. (<b>b</b>) Labels. (<b>c</b>) CTANet. (<b>d</b>) BuildFormer. (<b>e</b>) TransUNet. (<b>f</b>) Swin-Unet.</p>
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23 pages, 4935 KiB  
Article
FireDA: A Domain Adaptation-Based Method for Forest Fire Recognition with Limited Labeled Scenarios
by Zhengjun Yan, Xing Zheng, Wei Li, Liming Wang, Peng Ding, Ling Zhang, Muyi Yin and Xiaowei Wang
Forests 2024, 15(10), 1684; https://doi.org/10.3390/f15101684 - 24 Sep 2024
Viewed by 540
Abstract
Vision-based forest fire detection systems have significantly advanced through Deep Learning (DL) applications. However, DL-based models typically require large-scale labeled datasets for effective training, where the quality of data annotation is crucial to their performance. To address challenges related to the quality and [...] Read more.
Vision-based forest fire detection systems have significantly advanced through Deep Learning (DL) applications. However, DL-based models typically require large-scale labeled datasets for effective training, where the quality of data annotation is crucial to their performance. To address challenges related to the quality and quantity of labeling, a domain adaptation-based approach called FireDA is proposed for forest fire recognition in scenarios with limited labels. Domain adaptation, a subfield of transfer learning, facilitates the transfer of knowledge from a labeled source domain to an unlabeled target domain. The construction of the source domain FBD is initiated, which includes three common fire scenarios: forest (F), brightness (B), and darkness (D), utilizing publicly available labeled data. Subsequently, a novel algorithm called Neighborhood Aggregation-based 2-Stage Domain Adaptation (NA2SDA) is proposed. This method integrates feature distribution alignment with target domain Proxy Classification Loss (PCL), leveraging a neighborhood aggregation mechanism and a memory bank designed for the unlabeled samples in the target domain. This mechanism calibrates the source classifier and generates more accurate pseudo-labels for the unlabeled sample. Consequently, based on these pseudo-labels, the Local Maximum Mean Discrepancy (LMMD) and the Proxy Classification Loss (PCL) are computed. To validate the efficacy of the proposed method, the publicly available forest fire dataset, FLAME, is employed as the target domain for constructing a transfer learning task. The results demonstrate that our method achieves performance comparable to the supervised Convolutional Neural Network (CNN)-based state-of-the-art (SOTA) method, without requiring access to labels from the FLAME training set. Therefore, our study presents a viable solution for forest fire recognition in scenarios with limited labeling and establishes a high-accuracy benchmark for future research. Full article
(This article belongs to the Section Natural Hazards and Risk Management)
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<p>Framework of the proposed FireDA.</p>
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<p>Sample images of FBD and FLAME.</p>
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<p>Spider diagram of the ablation study on the FLAME validation set.</p>
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<p>Feature visualization of FBD training and FLAME validation samples based on t-SNE. The red and yellow points represent the FBD and FLAME fire samples, respectively. The blue and green points represent the FBD and FLAME non-fire samples, respectively.</p>
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<p>GradCAM-based heatmaps for samples in FLAME. (1–5) are fire samples from the target domain FLAME, with red boxes indicating the location of the fire.</p>
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<p>Grid search results of the hyperparameters.</p>
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<p>GradCAM-based heatmaps for samples of complex scenarios. (<b>1</b>–<b>5</b>) are fire and non-fire samples from complex scenes within the source domain FBD.</p>
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<p>Spider diagram of the evaluation metrics on the FLAME testing set.</p>
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17 pages, 4918 KiB  
Article
Radio Frequency Signal-Based Drone Classification with Frequency Domain Gramian Angular Field and Convolutional Neural Network
by Yuanhua Fu and Zhiming He
Drones 2024, 8(9), 511; https://doi.org/10.3390/drones8090511 - 21 Sep 2024
Viewed by 461
Abstract
Over the past few years, drones have been utilized in a wide range of applications. However, the illegal operation of drones may pose a series of security risks to sensitive areas such as airports and military bases. Hence, it is vital to develop [...] Read more.
Over the past few years, drones have been utilized in a wide range of applications. However, the illegal operation of drones may pose a series of security risks to sensitive areas such as airports and military bases. Hence, it is vital to develop an effective method of identifying drones to address the above issues. Existing drone classification methods based on radio frequency (RF) signals have low accuracy or a high computational cost. In this paper, we propose a novel RF signal image representation scheme that incorporates a convolutional neural network (CNN), named the frequency domain Gramian Angular Field with a CNN (FDGAF-CNN), to perform drone classification. Specifically, we first compute the time–frequency spectrum of raw RF signals based on short-time Fourier transform (STFT). Then, the 1D frequency spectrum series is encoded as 2D images using a modified GAF transform. Moreover, to further improve the recognition performance, the images obtained from different channels are fused to serve as the input of a CNN classifier. Finally, numerous experiments were conducted on the two available open-source DroneRF and DroneRFa datasets. The experimental results show that the proposed FDGAF-CNN can achieve a relatively high classification accuracy of 98.72% and 98.67% on the above two datasets, respectively, confirming the effectiveness and generalization ability of the proposed method. Full article
(This article belongs to the Special Issue Advances in Detection, Security, and Communication for UAV)
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<p>The drone classification framework of the proposed FDGAF-CNN.</p>
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<p>Frequency spectrums calculated by two methods: (<b>a</b>) frequency spectrum by FFT; (<b>b</b>) frequency spectrum by STFT.</p>
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<p>Procedure of FDGAF image generation.</p>
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<p>Time–frequency spectrograms and FDGAF images of three types of drones: (<b>a</b>) Bebop spectrogram; (<b>b</b>) Phantom spectrogram; (<b>c</b>) AR spectrogram; (<b>d</b>) Bebop FDGAF image; (<b>e</b>) Phantom FDGAF image; (<b>f</b>) AR FDGAF image.</p>
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<p>CNN model.</p>
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<p>Illustration of RF samples of DroneRF dataset: (<b>a</b>) background activities without drone; (<b>b</b>) Bebop; (<b>c</b>) AR; (<b>d</b>) Phantom.</p>
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<p>Illustration of RF samples of DroneRFa dataset: (<b>a</b>) Phantom 3; (<b>b</b>) Mini 2.</p>
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<p>Illustration of the visualized FDGAFs between different types of drones: (<b>a</b>) Phantom 3; (<b>b</b>) Phantom 4 Pro; (<b>c</b>) Air 2S; (<b>d</b>) Mini 2; (<b>e</b>) MATRICE 30T; (<b>f</b>) MATRICE 200.</p>
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<p>Learning curves of the proposed model for two open-source drone RF datasets: (<b>a</b>) training accuracy of DroneRF; (<b>b</b>) training accuracy of DroneRFa; (<b>c</b>) training loss of DroneRF; (<b>d</b>) training loss of DroneRFa.</p>
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<p>Confusion matrix showing the recognition rate obtained for two datasets: (<b>a</b>) DroneRF; (<b>b</b>) DronRFa.</p>
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<p>Classification accuracy comparison of different methods on the DroneRF dataset.</p>
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22 pages, 4655 KiB  
Article
Deep-Learning-Based Approach for IoT Attack and Malware Detection
by Burak Taşcı
Appl. Sci. 2024, 14(18), 8505; https://doi.org/10.3390/app14188505 - 20 Sep 2024
Viewed by 1343
Abstract
The Internet of Things (IoT), introduced by Kevin Ashton in the late 1990s, has transformed technology usage globally, enhancing efficiency and convenience but also posing significant security challenges. With the proliferation of IoT devices expected to exceed 29 billion by 2030, securing these [...] Read more.
The Internet of Things (IoT), introduced by Kevin Ashton in the late 1990s, has transformed technology usage globally, enhancing efficiency and convenience but also posing significant security challenges. With the proliferation of IoT devices expected to exceed 29 billion by 2030, securing these devices is crucial. This study proposes an optimized 1D convolutional neural network (1D CNN) model for effectively classifying IoT security data. The model architecture includes input, convolutional, self-attention, and output layers, utilizing GELU activation, dropout, and normalization techniques to improve performance and prevent overfitting. The model was evaluated using the CIC IoT 2023, CIC-MalMem-2022, and CIC-IDS2017 datasets, achieving impressive results: 98.36% accuracy, 100% precision, 99.96% recall, and 99.95% F1-score for CIC IoT 2023; 99.90% accuracy, 99.98% precision, 99.97% recall, and 99.96% F1-score for CIC-MalMem-2022; and 99.99% accuracy, 99.99% precision, 99.98% recall, and 99.98% F1-score for CIC-IDS2017. These outcomes demonstrate the model’s effectiveness in detecting and classifying various IoT-related attacks and malware. The study highlights the potential of deep-learning techniques to enhance IoT security, with the developed model showing high performance and low computational overhead, making it suitable for real-time applications and resource-constrained devices. Future research should aim at testing the model on larger datasets and incorporating adaptive learning capabilities to further enhance its robustness. This research significantly contributes to IoT security by providing advanced insights into deploying deep-learning models, encouraging further exploration in this dynamic field. Full article
(This article belongs to the Special Issue Advances in Internet of Things (IoT) Technologies and Cybersecurity)
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<p>Malware families count by category.</p>
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<p>Graphical representation of the proposed CNN.</p>
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<p>Accuracy and loss curves for the proposed CNN model on the CIC IoT 2023 dataset.</p>
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<p>Accuracy and loss curves for the proposed CNN model on the CIC-MalMem-2022.</p>
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<p>Accuracy and loss curves for the proposed CNN model on the CIC-IDS2017.</p>
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<p>Confusion matrix for the CIC IoT 2023 dataset.</p>
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<p>Confusion matrix for the CIC-MalMem-2022 dataset.</p>
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<p>Confusion matrix for the CIC-IDS2017 dataset.</p>
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<p>Comparison of machine-learning methods.</p>
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26 pages, 767 KiB  
Tutorial
Hands-On Fundamentals of 1D Convolutional Neural Networks—A Tutorial for Beginner Users
by Ilaria Cacciari and Anedio Ranfagni
Appl. Sci. 2024, 14(18), 8500; https://doi.org/10.3390/app14188500 - 20 Sep 2024
Viewed by 422
Abstract
In recent years, deep learning (DL) has garnered significant attention for its successful applications across various domains in solving complex problems. This interest has spurred the development of numerous neural network architectures, including Convolutional Neural Networks (CNNs), Recurrent Neural Networks (RNNs), Generative Adversarial [...] Read more.
In recent years, deep learning (DL) has garnered significant attention for its successful applications across various domains in solving complex problems. This interest has spurred the development of numerous neural network architectures, including Convolutional Neural Networks (CNNs), Recurrent Neural Networks (RNNs), Generative Adversarial Networks (GANs), and the more recently introduced Transformers. The choice of architecture depends on the data characteristics and the specific task at hand. In the 1D domain, one-dimensional CNNs (1D CNNs) are widely used, particularly for tasks involving the classification and recognition of 1D signals. While there are many applications of 1D CNNs in the literature, the technical details of their training are often not thoroughly explained, posing challenges for those developing new libraries in languages other than those supported by available open-source solutions. This paper offers a comprehensive, step-by-step tutorial on deriving feedforward and backpropagation equations for 1D CNNs, applicable to both regression and classification tasks. By linking neural networks with linear algebra, statistics, and optimization, this tutorial aims to clarify concepts related to 1D CNNs, making it a valuable resource for those interested in developing new libraries beyond existing ones. Full article
(This article belongs to the Special Issue Advances in Neural Networks and Deep Learning)
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<p>Our literature review on 1D CNNs has revealed gaps in studies, posing a challenge in fully addressing the theoretical elements required to derive all the equations involved in the training process (i.e., feedforward and backpropagation). The mathematical foundations we refer to include linear algebra, statistics, and optimization.</p>
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<p>(<b>a</b>) 1D single filter convolution, (<b>b</b>) 1D multi-filter convolution. The dimension of the 1D input signal is <span class="html-italic">n</span>, and each filter size is <span class="html-italic">s</span>.</p>
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<p>Convolution of an input signal <span class="html-italic">p</span> columns, each of length <span class="html-italic">n</span>, and a multi-filter represented by a 3D matrix of size <math display="inline"><semantics> <mrow> <mi>s</mi> <mo>×</mo> <mi>p</mi> <mo>×</mo> <mi>q</mi> </mrow> </semantics></math>, where the index <span class="html-italic">u</span> runs from 1 to the filter size <span class="html-italic">s</span>, and <math display="inline"><semantics> <mrow> <mi>p</mi> <mo>×</mo> <mi>q</mi> </mrow> </semantics></math> is the number of filters. This process results in a 2D matrix in which each column <math display="inline"><semantics> <msub> <mi>C</mi> <mi>q</mi> </msub> </semantics></math> is obtained by summing up <span class="html-italic">p</span> convolutions.</p>
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<p>The filter <math display="inline"><semantics> <msup> <mi>K</mi> <mrow> <mo>(</mo> <mn>2</mn> <mo>)</mo> </mrow> </msup> </semantics></math> is a third-order tensor with <math display="inline"><semantics> <mrow> <msup> <mi>s</mi> <mrow> <mo>(</mo> <mn>2</mn> <mo>)</mo> </mrow> </msup> <mo>×</mo> <mi>p</mi> <mo>×</mo> <mi>q</mi> </mrow> </semantics></math> dimension, where <math display="inline"><semantics> <mrow> <msup> <mi>s</mi> <mrow> <mo>(</mo> <mn>2</mn> <mo>)</mo> </mrow> </msup> <mo>=</mo> <mn>3</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>p</mi> <mo>=</mo> <mn>4</mn> </mrow> </semantics></math> and <math display="inline"><semantics> <mrow> <mi>q</mi> <mo>=</mo> <mn>6</mn> </mrow> </semantics></math>. The 2D components of <math display="inline"><semantics> <msup> <mi>K</mi> <mrow> <mo>(</mo> <mn>2</mn> <mo>)</mo> </mrow> </msup> </semantics></math> are represented separately.</p>
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<p>Schematization of the training process.</p>
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<p>The vector <span class="html-italic">f</span> (<math display="inline"><semantics> <mrow> <mn>18</mn> <mo>×</mo> <mn>1</mn> </mrow> </semantics></math>) is reshaped back in order to obtain <math display="inline"><semantics> <mrow> <mo>Δ</mo> <msup> <mi>S</mi> <mrow> <mo>(</mo> <mn>2</mn> <mo>)</mo> </mrow> </msup> </mrow> </semantics></math> (<math display="inline"><semantics> <mrow> <mn>3</mn> <mo>×</mo> <mn>6</mn> </mrow> </semantics></math>).</p>
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<p>Example of an up-sampling operation. The input is the <math display="inline"><semantics> <mrow> <mn>2</mn> <mo>×</mo> <mn>1</mn> </mrow> </semantics></math> array on the left. Down-sampling produces a 1D array based on the average or maximum of the input. During up-sampling, the 1D array is split into a new <math display="inline"><semantics> <mrow> <mn>2</mn> <mo>×</mo> <mn>1</mn> </mrow> </semantics></math> array. If averaging is used, the output is filled by evenly distributing the output value from down-sampling, in this case, dividing by 2. If the max operation is used, the output value is placed where the original maximum value occurred.</p>
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16 pages, 9787 KiB  
Article
Combined ResNet Attention Multi-Head Net (CRAMNet): A Novel Approach to Fault Diagnosis of Rolling Bearings Using Acoustic Radiation Signals and Advanced Deep Learning Techniques
by Xiaozheng Xu, Ying Li and Xuebao Ding
Appl. Sci. 2024, 14(18), 8431; https://doi.org/10.3390/app14188431 - 19 Sep 2024
Viewed by 544
Abstract
The fault diagnosis of rolling bearing acoustic radiation signals holds significant importance in industrial equipment maintenance. It effectively prevents equipment failures and downtime, ensuring the smooth operation of the production process. Compared with traditional vibration signals, acoustic radiation signals have the advantage of [...] Read more.
The fault diagnosis of rolling bearing acoustic radiation signals holds significant importance in industrial equipment maintenance. It effectively prevents equipment failures and downtime, ensuring the smooth operation of the production process. Compared with traditional vibration signals, acoustic radiation signals have the advantage of non-contact measurement. They can diagnose faults in special conditions where sensors cannot be installed and provide more comprehensive equipment status information. Therefore, to extract the fault characteristic information of rolling bearings from complex acoustic signals, this paper proposes an advanced deep learning model combining Gramian Angular Field (GAF), ResNet1D, ResNet2D, and multi-head attention mechanism, named CRAMNet (Combined ResNet Attention Multi-Head Net), to diagnose the faults of rolling bearing acoustic radiation signals. Firstly, this method includes converting one-dimensional signals into GAF images and performing data standardization and segmentation. Then, the method utilizes ResNet1D to extract features from one-dimensional signals and ResNet2D to extract features from GAF images. Further, it combines the multi-head attention mechanism to enhance feature representation and capture dependencies between different channels. Finally, this paper compares the proposed method with several traditional models (including CNN, LSTM, DenseNet, and CNN-Transformers). Experimental results show that the proposed method performs outstandingly in terms of accuracy and robustness. The combination of residual networks and multi-head attention mechanism in the model significantly enhances its ability to accurately diagnose rolling bearing faults, proving the superiority of the algorithm. Full article
(This article belongs to the Section Mechanical Engineering)
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<p>Residual network module.</p>
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<p>One-dimensional signals are converted into two-dimensional signals using the GAF.</p>
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<p>Multi-head attention mechanism module.</p>
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<p>Overall technical flowchart of the CRAMNet.</p>
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<p>Test bench for bearing faults.</p>
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<p>Failure modes of different bearing components.</p>
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<p>Loss and accuracy of the CRAMNet training process.</p>
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<p>Visualized results during training (<b>a</b>) ResNet1D features, (<b>b</b>) ResNet2D features, (<b>c</b>) attention features, (<b>d</b>) FC1 features, (<b>e</b>) FC2 features, and (<b>f</b>) FC3 features.</p>
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<p>Comparison of the results of different methods: (<b>a</b>) train accuracy of different models, (<b>b</b>) train loss of different models, (<b>c</b>) test accuracy of different models, and (<b>d</b>) test loss of different models.</p>
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<p>Confusion matrix results for different models: (<b>a</b>) CNN; (<b>b</b>) LSTM; (<b>c</b>) DenseNet; (<b>d</b>) CNN-Transformers; and (<b>e</b>) CRAMNet.</p>
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<p>The results of 10 experiments with different models compared.</p>
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