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14 pages, 8825 KiB  
Article
Synthesis and Structural Modulation of Nanoporous Copper Films by Magnetron Sputtering and One-Step Dealloying
by Jinglei Li, Bin Yu, Yunfei Ran, Yalong Liu, Xiangyu Fei, Jiameng Sun, Fuquan Tan, Guanhua Cheng, Ying Zhang, Jingyu Qin and Zhonghua Zhang
Materials 2024, 17(23), 5705; https://doi.org/10.3390/ma17235705 - 21 Nov 2024
Abstract
Nanoporous copper (np-Cu) has attracted much more attention due to its lower cost compared to other noble metals and high functionality in practical use. Herein, Al100−xCux(x = 13–88 at.%) precursor films with thicknesses of 0.16–1.1 μm were fabricated by [...] Read more.
Nanoporous copper (np-Cu) has attracted much more attention due to its lower cost compared to other noble metals and high functionality in practical use. Herein, Al100−xCux(x = 13–88 at.%) precursor films with thicknesses of 0.16–1.1 μm were fabricated by varying magnetron co-sputtering parameters. Subsequently, utilizing a one-step dealloying strategy, a series of np-Cu films with ligament sizes ranging from 11.4–19.0 nm were synthesized. The effects of precursor composition and substrate temperature on the microstructure of np-Cu films were investigated. As the atomic ratio of Cu increases from 15 to 34, the np-Cu film detached from the substrate gradually transforms into a bi-continuous ligament-channel structure that is well bonded to the substrate. Furthermore, the novel bi-layer hierarchical np-Cu films were successfully prepared based on single-layer nanoporous films. Our findings not only contribute to the systematic understanding of the modification of the morphology and structure of np-Cu films but also offer a valuable framework for the design and fabrication of other non-noble nanoporous metals with tailored properties. Full article
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<p>Compositions (Al contents) and sputtering loadings of the Al-Cu films fabricated by adjusting the power of the Cu target while maintaining the power of the Al target at (<b>a</b>) DC 150 W and (<b>b</b>) DC 50 W. The deposition time parameter was set to 3600 s.</p>
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<p>(<b>a</b>–<b>f</b>) Plan-view SEM images of (<b>a</b>) Al<sub>87</sub>Cu<sub>13</sub>, (<b>b</b>) Al<sub>85</sub>Cu<sub>15</sub>, (<b>c</b>) Al<sub>80</sub>Cu<sub>20</sub>, (<b>d</b>) Al<sub>66</sub>Cu<sub>34</sub>, (<b>e</b>) Al<sub>17</sub>Cu<sub>83</sub>, and (<b>f</b>) Al<sub>12</sub>Cu<sub>88</sub> on the RA Cu foil substrates. (<b>g</b>,<b>h</b>) Cross-sectional SEM images of (<b>g</b>) Al<sub>80</sub>Cu<sub>20</sub> and (<b>h</b>) Al<sub>66</sub>Cu<sub>34</sub> on the ED Cu foil substrates. These films were deposited at room temperature and sputtered for 3600 s.</p>
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<p>XRD patterns of the Al<sub>85</sub>Cu<sub>15</sub>, Al<sub>80</sub>Cu<sub>20</sub>, Al<sub>66</sub>Cu<sub>34</sub>, and Al<sub>12</sub>Cu<sub>88</sub> films (<b>a</b>) before and (<b>b</b>) after dealloying.</p>
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<p>(<b>a</b>–<b>d</b>) Optical images of (<b>a</b>) Al<sub>85</sub>Cu<sub>15</sub>, (<b>b</b>) Al<sub>80</sub>Cu<sub>20</sub>, (<b>c</b>) Al<sub>66</sub>Cu<sub>34</sub>, and (<b>d</b>) Al<sub>12</sub>Cu<sub>88</sub> before and after dealloying. (<b>e</b>–<b>l</b>) SEM images of the np-Cu films dealloyed from (<b>e</b>,<b>i</b>) Al<sub>85</sub>Cu<sub>15</sub>, (<b>f</b>,<b>j</b>) Al<sub>80</sub>Cu<sub>20</sub>, (<b>g</b>,<b>k</b>) Al<sub>66</sub>Cu<sub>34</sub>, and (<b>h</b>,<b>l</b>) Al<sub>12</sub>Cu<sub>88</sub>. These films were deposited onto ED Cu foils at room temperature with a sputtering time of 3600 s. (<b>m</b>) Schematic illustrations showing the microstructure evolution of Al<sub>66</sub>Cu<sub>34</sub> during dealloying.</p>
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<p>Plan-view SEM images of the np-Cu films dealloyed from (<b>a</b>,<b>d</b>) Al<sub>85</sub>Cu<sub>15</sub>, (<b>b</b>,<b>e</b>) Al<sub>80</sub>Cu<sub>20</sub>, and (<b>c</b>,<b>f</b>) Al<sub>66</sub>Cu<sub>34</sub>. These thin films were deposited onto the ED Cu foils at (<b>a</b>–<b>c</b>) at room temperature and (<b>d</b>–<b>f</b>) 170 °C for 1800 s.</p>
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<p>(<b>a</b>) Cross-sectional SEM image of the Al<sub>66</sub>Cu<sub>34</sub>-on-Al<sub>80</sub>Cu<sub>20</sub> film. (<b>b</b>,<b>c</b>) Plan-view and (<b>d</b>–<b>f</b>) cross-sectional SEM images of the np-Cu film dealloyed from Al<sub>66</sub>Cu<sub>34</sub>-on-Al<sub>80</sub>Cu<sub>20</sub>. Each layer was sputtered at room temperature for 3600 s.</p>
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<p>(<b>a</b>) Cross-sectional SEM image of the Al<sub>80</sub>Cu<sub>20</sub>-on-Al<sub>66</sub>Cu<sub>34</sub> film. (<b>b</b>–<b>d</b>) Plan-view and (<b>e</b>,<b>f</b>) cross-sectional SEM images of the np-Cu film dealloyed from Al<sub>80</sub>Cu<sub>20</sub>-on-Al<sub>66</sub>Cu<sub>34</sub>. Each layer was sputtered at room temperature for 3600 s.</p>
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28 pages, 1589 KiB  
Article
Optimizing Renewable Energy Systems Placement Through Advanced Deep Learning and Evolutionary Algorithms
by Konstantinos Stergiou and Theodoros Karakasidis
Appl. Sci. 2024, 14(23), 10795; https://doi.org/10.3390/app142310795 - 21 Nov 2024
Abstract
As the world shifts towards a low-carbon economy, the strategic deployment of renewable energy sources (RESs) is critical for maximizing energy output and ensuring sustainability. This study introduces GREENIA, a novel artificial intelligence (AI)-powered framework for optimizing RES placement that holistically integrates machine [...] Read more.
As the world shifts towards a low-carbon economy, the strategic deployment of renewable energy sources (RESs) is critical for maximizing energy output and ensuring sustainability. This study introduces GREENIA, a novel artificial intelligence (AI)-powered framework for optimizing RES placement that holistically integrates machine learning (gated recurrent unit neural networks with swish activation functions and attention layers), evolutionary optimization algorithms (Jaya), and Shapley additive explanations (SHAPs). A key innovation of GREENIA is its ability to provide natural language explanations (NLEs), enabling transparent and interpretable insights for both technical and non-technical stakeholders. Applied in Greece, the framework addresses the challenges posed by the interplay of meteorological factors from 10 different meteorological stations across the country. Validation against real-world data demonstrates improved prediction accuracy using metrics like root mean squared error (RMSE), mean absolute error (MAE), and mean absolute percentage error (MAPE). SHAP analysis enhances transparency by identifying key meteorological influences, such as temperature and humidity, while NLE translates these insights into actionable recommendations in natural language, improving accessibility for energy planners and policymakers. The resulting strategic plan offers precise, intelligent, and interpretable recommendations for deploying RES technologies, ensuring maximum efficiency and sustainability. This approach not only advances renewable energy optimization but also equips stakeholders with practical tools for guiding the strategic deployment of RES across diverse regions, contributing to sustainable energy management. Full article
33 pages, 8578 KiB  
Article
A Secure IIoT Environment That Integrates AI-Driven Real-Time Short-Term Active and Reactive Load Forecasting with Anomaly Detection: A Real-World Application
by Md. Ibne Joha, Md Minhazur Rahman, Md Shahriar Nazim and Yeong Min Jang
Sensors 2024, 24(23), 7440; https://doi.org/10.3390/s24237440 - 21 Nov 2024
Abstract
The Industrial Internet of Things (IIoT) revolutionizes both industrial and residential operations by integrating AI (artificial intelligence)-driven analytics with real-time monitoring, optimizing energy usage, and significantly enhancing energy efficiency. This study proposes a secure IIoT framework that simultaneously predicts both active and reactive [...] Read more.
The Industrial Internet of Things (IIoT) revolutionizes both industrial and residential operations by integrating AI (artificial intelligence)-driven analytics with real-time monitoring, optimizing energy usage, and significantly enhancing energy efficiency. This study proposes a secure IIoT framework that simultaneously predicts both active and reactive loads while also incorporating anomaly detection. The system is optimized for real-time deployment on an edge server, such as a single-board computer (SBC), as well as on a cloud or centralized server. It ensures secure and reliable industrial operations by integrating smart data acquisition systems with real-time monitoring, control, and protective measures. We propose a Temporal Convolutional Networks-Gated Recurrent Unit-Attention (TCN-GRU-Attention) model to predict both active and reactive loads, which demonstrates superior performance compared to other conventional models. The performance metrics for active load forecasting are 0.0183 Mean Squared Error (MSE), 0.1022 Mean Absolute Error (MAE), and 0.1354 Root Mean Squared Error (RMSE), while for reactive load forecasting, the metrics are 0.0202 (MSE), 0.1077 (MAE), and 0.1422 (RMSE). Furthermore, we introduce an optimized Isolation Forest model for anomaly detection that considers the transient conditions of appliances when identifying irregular behavior. The model demonstrates very promising performance, with the average performance metrics for all appliances using this Isolation Forest model being 95% for Precision, 98% for Recall, 96% for F1 Score, and nearly 100% for Accuracy. To secure the entire system, Transport Layer Security (TLS) and Secure Sockets Layer (SSL) security protocols are employed, along with hash-encoded encrypted credentials for enhanced protection. Full article
(This article belongs to the Section Internet of Things)
13 pages, 2625 KiB  
Article
DeepAT: A Deep Learning Wheat Phenotype Prediction Model Based on Genotype Data
by Jiale Li, Zikang He, Guomin Zhou, Shen Yan and Jianhua Zhang
Agronomy 2024, 14(12), 2756; https://doi.org/10.3390/agronomy14122756 - 21 Nov 2024
Abstract
Genomic selection serves as an effective way for crop genetic breeding, capable of significantly shortening the breeding cycle and improving the accuracy of breeding. Phenotype prediction can help identify genetic variants associated with specific phenotypes. This provides a data-driven selection criterion for genomic [...] Read more.
Genomic selection serves as an effective way for crop genetic breeding, capable of significantly shortening the breeding cycle and improving the accuracy of breeding. Phenotype prediction can help identify genetic variants associated with specific phenotypes. This provides a data-driven selection criterion for genomic selection, making the selection process more efficient and targeted. Deep learning has become an important tool for phenotype prediction due to its abilities in automatic feature learning, nonlinear modeling, and high-dimensional data processing. Current deep learning models have improvements in various aspects, such as predictive performance and computation time, but they still have limitations in capturing the complex relationships between genotype and phenotype, indicating that there is still room for improvement in the accuracy of phenotype prediction. This study innovatively proposes a new method called DeepAT, which mainly includes an input layer, a data feature extraction layer, a feature relationship capture layer, and an output layer. This method can predict wheat yield based on genotype data and has innovations in the following four aspects: (1) The data feature extraction layer of DeepAT can extract representative feature vectors from high-dimensional SNP data. By introducing the ReLU activation function, it enhances the model’s ability to express nonlinear features and accelerates the model’s convergence speed; (2) DeepAT can handle high-dimensional and complex genotype data while retaining as much useful information as possible; (3) The feature relationship capture layer of DeepAT effectively captures the complex relationships between features from low-dimensional features through a self-attention mechanism; (4) Compared to traditional RNN structures, the model training process is more efficient and stable. Using a public wheat dataset from AGT, comparative experiments with three machine learning and six deep learning methods found that DeepAT exhibited better predictive performance than other methods, achieving a prediction accuracy of 99.98%, a mean squared error (MSE) of only 28.93 tones, and a Pearson correlation coefficient close to 1, with yield predicted values closely matching observed values. This method provides a new perspective for deep learning-assisted phenotype prediction and has great potential in smart breeding. Full article
(This article belongs to the Section Precision and Digital Agriculture)
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<p>The proposed DeepAT framework. (<b>a</b>) Dataset sources, (<b>b</b>) genotype data processing, (<b>c</b>) allele encoding, (<b>d</b>) experimental procedure, (<b>e</b>) data feature extraction layer, (<b>f</b>) feature relationship capture layer, (<b>g</b>) DeepAT model architecture.</p>
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<p>Training loss variation comparison of DeepAT with the other genotype prediction methods.</p>
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<p>Prediction accuracy comparison of DeepAT with the other genotype prediction methods with different evaluation metrics.</p>
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<p>Correlation between yield predicted and observed values comparison of DeepAT with the other genotype prediction methods.</p>
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21 pages, 10113 KiB  
Article
An Improved Bird Detection Method Using Surveillance Videos from Poyang Lake Based on YOLOv8
by Jianchao Ma, Jiayuan Guo, Xiaolong Zheng and Chaoyang Fang
Animals 2024, 14(23), 3353; https://doi.org/10.3390/ani14233353 - 21 Nov 2024
Viewed by 27
Abstract
Poyang Lake is the largest freshwater lake in China and plays a significant ecological role. Deep-learning-based video surveillance can effectively monitor bird species on the lake, contributing to the local biodiversity preservation. To address the challenges of multi-scale object detection against complex backgrounds, [...] Read more.
Poyang Lake is the largest freshwater lake in China and plays a significant ecological role. Deep-learning-based video surveillance can effectively monitor bird species on the lake, contributing to the local biodiversity preservation. To address the challenges of multi-scale object detection against complex backgrounds, such as a high density and severe occlusion, we propose a new model known as the YOLOv8-bird model. First, we use Receptive-Field Attention convolution, which improves the model’s ability to capture and utilize image information. Second, we redesign a feature fusion network, termed the DyASF-P2, which enhances the network’s ability to capture small object features and reduces the target information loss. Third, a lightweight detection head is designed to effectively reduce the model’s size without sacrificing the precision. Last, the Inner-ShapeIoU loss function is proposed to address the multi-scale bird localization challenge. Experimental results on the PYL-5-2023 dataset demonstrate that the YOLOv8-bird model achieves precision, recall, [email protected], and [email protected]:0.95 scores of 94.6%, 89.4%, 94.8%, and 70.4%, respectively. Additionally, the model outperforms other mainstream object detection models in terms of accuracy. These results indicate that the proposed YOLOv8-bird model is well-suited for bird detection and counting tasks, which enable it to support biodiversity monitoring in the complex environment of Poyang Lake. Full article
(This article belongs to the Section Birds)
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<p>Comparison of datasets: (<b>a</b>) Caltech-UCSD Birds-200-2011; (<b>b</b>) North America Birds; and (<b>c</b>) PYL-5-2023.</p>
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<p>YOLOv8 network structure. (1) The YOLOv8 network model is composed of three parts: the backbone, the neck, and the head. (2) YOLOV8 includes CBS module, the Cross Stage Partial with two fusion (C2f) module, the Spatial Pyramid Pooling-Fast (SSFF) module, and Head module. The CBS module consists of convolution, batchnorm, and a sigmoid linear unit (SiLu) function, and it is named after the initials of these components. The Head module is used for the final classification and regression tasks. (3) The Concat is used to concatenate multiple data tensors along a specified dimension.</p>
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<p>YOLOv8-bird network structure. (1) The YOLOv8-bird network model is composed of three parts: the backbone, the neck, and the head. (2) The YOLOV8-bird includes CBS module, the Cross Stage Partial with two fusion (C2f) module, the Spatial Pyramid Pooling-Fast (SSFF) module, the scale sequence feature fusion module combined with dynamic upsampling (DySSFF), a triple feature-encoding (TFE) module, and a lightweight, shared-detail-enhanced detection head (LSDECD). The CBS module consists of convolution, batchnorm, and a sigmoid linear unit (SiLu) function, and it is named after the initials of these components. (3) The concat is used to concatenate multiple data tensors along a specified dimension. The Add is an operation that overlays feature information of the same dimension.</p>
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<p>The overall structure of Receptive-Field Attention with a 3 × 3 kernel. C, H, and W denote the number of channels and the height and width of the feature map, respectively. The parameters are different between the group convolution’s kernels. Different colors represent different feature information extracted through different receptive fields. The 3 × 3 Group Conv represents the group convolution operation with a kernel size of 3 × 3. The AvgPool represents average pooling operation.</p>
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<p>The overall structure of scale sequence feature fusion based on the dynamic sampling module. The CBS module consists of convolution, batchnorm, and a sigmoid linear unit function. The Unsqueeze and Squeeze are operations used to increase and dacrease the dimensions of data, respectively. The concat is used to concatenate multiple data tensors along a specified dimension.</p>
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<p>The overall structure of the lightweight, shared-detail-enhanced detection head. Conv_GN and DConv_GN denote the group-normalized convolution and group-normalized, detail-enhanced convolution, respectively. Con_Reg and Con_cls denote the convolutional modules for box regression and classification, respectively.</p>
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<p>Comparison of the normalized confusion matrices: (<b>a</b>) YOLOv8; (<b>b</b>) YOLOv8-bird. In the confusion matrix, the elements on the main diagonal represent the number of correctly detected samples; the elements in the lower triangular region indicate the number of missed detections by the model; and the elements in the upper triangular region correspond to the number of false detections by the model.</p>
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<p>Precision–Recall curves. Precision–Recall curve is a graphical representation of a model’s precision and recall across different threshold settings. The The RT-DETR represents the Real-time Detection Transformer.</p>
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<p>Comparison of YOLOv8 and YOLOv8-bird heat maps in each stage. The heatmap obtained from the YOLOv8 algorithm is on the left, the original image is in the middle, and the heatmap obtained by our proposed algorithm is on the right.</p>
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<p>Comparison of YOLOv8 and YOLOv8-bird detection performance in each scenario: (<b>a</b>) occluded scene; (<b>b</b>) dense samll target scene; (<b>c</b>) multi-scale scene. The left image is the original, while the middle and right images show the detection results from the YOLOv8 and YOLOv8-bird models, respectively. The blue boxes highlight areas with a significant number of missed detections. The orange, red and yellow represent the detected Tundra Swan, Greater White-fronted Goose and Oriental White Stork.</p>
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22 pages, 6594 KiB  
Article
Rice Growth-Stage Recognition Based on Improved YOLOv8 with UAV Imagery
by Wenxi Cai, Kunbiao Lu, Mengtao Fan, Changjiang Liu, Wenjie Huang, Jiaju Chen, Zaoming Wu, Chudong Xu, Xu Ma and Suiyan Tan
Agronomy 2024, 14(12), 2751; https://doi.org/10.3390/agronomy14122751 - 21 Nov 2024
Viewed by 135
Abstract
To optimize rice yield and enhance quality through targeted field management at each growth stage, rapid and accurate identification of rice growth stages is crucial. This study presents the Mobilenetv3-YOLOv8 rice growth-stage recognition model, designed for high efficiency and accuracy using Unmanned Aerial [...] Read more.
To optimize rice yield and enhance quality through targeted field management at each growth stage, rapid and accurate identification of rice growth stages is crucial. This study presents the Mobilenetv3-YOLOv8 rice growth-stage recognition model, designed for high efficiency and accuracy using Unmanned Aerial Vehicle (UAV) imagery. A UAV captured images of rice fields across five distinct growth stages from two altitudes (3 m and 20 m) across two independent field experiments. These images were processed to create training, validation, and test datasets for model development. Mobilenetv3 was introduced to replace the standard YOLOv8 backbone, providing robust small-scale feature extraction through multi-scale feature fusion. Additionally, the Coordinate Attention (CA) mechanism was integrated into YOLOv8’s backbone, outperforming the Convolutional Block Attention Module (CBAM) by enhancing position-sensitive information capture and focusing on crucial pixel areas. Compared to the original YOLOv8, the enhanced Mobilenetv3-YOLOv8 model improved rice growth-stage identification accuracy and reduced the computational load. With an input image size of 400 × 400 pixels and the CA implemented in the second and third backbone layers, the model achieved its best performance, reaching 84.00% mAP and 84.08% recall. The optimized model achieved parameters and Giga Floating Point Operations (GFLOPs) of 6.60M and 0.9, respectively, with precision values for tillering, jointing, booting, heading, and filling stages of 94.88%, 93.36%, 67.85%, 78.31%, and 85.46%, respectively. The experimental results revealed that the optimal Mobilenetv3-YOLOv8 shows excellent performance and has potential for deployment in edge computing devices and practical applications for in-field rice growth-stage recognition in the future. Full article
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<p>A schematic diagram of the proposed method.</p>
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<p>The study site and rice field experiment designs. (<b>a</b>) Spring rice field experiment, EXP.1. (<b>b</b>) Autumn rice field experiment, EXP.2.</p>
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<p>Unmanned Aerial Vehicle photography.</p>
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<p>Diagram of YOLOv8 model. Note: The color block in the figure simulates the process of YOLOv8 image input: the image enters the backbone network for feature extraction, passes through the standard convolution and the new C2F convolution structure, and finally enters the image classification function module.</p>
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<p>Diagram of Mobilenetv3-YOLOv8 model. Note: Like <a href="#agronomy-14-02751-f004" class="html-fig">Figure 4</a>, the backbone part of YOLOv8 in the figure is replaced by Mobilenetv3: Conv2d is a two-dimensional convolution layer. Bneck is a special bottleneck structure of Mobilenetv3.</p>
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<p>Overview diagram of CBAM mechanism.</p>
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<p>Overview diagram of CA mechanism.</p>
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<p>Recognition effect of Mobilenetv3-YOLOv8 model on images of different input sizes.</p>
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<p>Performance comparison of different Mobilenet networks.</p>
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<p>Performance comparison of different models.</p>
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<p>Location map of CA mechanism. Notes: Subfigures (<b>a</b>–<b>e</b>) are five different discussions on adding one layer of attention mechanism, two layers, three layers, four layers and five layers to the backbone network. The blue color block is the backbone network work layer. The first layer adopts a bottleneck, which includes a 3 × 3 convolution, and the input feature has a spatial dimension of 320 × 320 and consists of 16 channels. The second layer adopts a bottleneck, which includes a 3 × 3 convolution, and the input feature has a spatial dimension of 160 × 160 and consists of 16 channels. The third layer adopts a bottleneck, which includes a 5 × 5 convolution, and the input feature has a spatial dimension of 80 × 80 and consists of 24 channels. The forth layer adopts a bottleneck, which includes a 5 × 5 convolution, and the input feature has a spatial dimension of 40 × 40 and consists of 48 channels. The fifth layer adopts a bottleneck, which includes a 5 × 5 convolution, and the input feature has a spatial dimension of 20 × 20 and consists of 96 channels. The red color block is the added CA attention mechanism layer.</p>
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<p>Confusion matrix for Mobilenetv3-YOLOv8 evaluated on the test dataset.</p>
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<p>False-positive detection with (<b>a</b>) booting stage being falsely recognized as tillering stage and (<b>b</b>) filling stage being falsely recognized as jointing stage.</p>
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<p>False-positive detection with booting stage being falsely recognized as tillering stage.</p>
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12 pages, 2488 KiB  
Article
A Polycarbonate-Assisted Transfer Method for van der Waals Contacts to Magnetic Two-Dimensional Materials
by Kunlin Yang, Guorui Zhao, Yibin Zhao, Jie Xiao, Le Wang, Jiaqi Liu, Wenqing Song, Qing Lan, Tuoyu Zhao, Hai Huang, Jia-Wei Mei and Wu Shi
Micromachines 2024, 15(11), 1401; https://doi.org/10.3390/mi15111401 - 20 Nov 2024
Viewed by 175
Abstract
Magnetic two-dimensional (2D) materials have garnered significant attention for their potential to revolutionize 2D spintronics due to their unique magnetic properties. However, their air-sensitivity and highly insulating nature of the magnetic semiconductors present substantial challenges for device fabrication with effective contacts. In this [...] Read more.
Magnetic two-dimensional (2D) materials have garnered significant attention for their potential to revolutionize 2D spintronics due to their unique magnetic properties. However, their air-sensitivity and highly insulating nature of the magnetic semiconductors present substantial challenges for device fabrication with effective contacts. In this study, we introduce a polycarbonate (PC)-assisted transfer method that effectively forms van der Waals (vdW) contacts with 2D materials, streamlining the fabrication process without the need for additional lithography. This method is particularly advantageous for air-sensitive magnetic materials, as demonstrated in Fe3GeTe2. It also ensures excellent interface contact quality and preserves the intrinsic magnetic properties in magnetic semiconductors like CrSBr. Remarkably, this method achieves a contact resistance four orders of magnitude lower than that achieved with traditional thermally evaporated electrodes in thin-layer CrSBr devices and enables the observation of sharp magnetic transitions similar to those observed with graphene vdW contacts. Compatible with standard dry-transfer processes and scalable to large wafer sizes, our approach provides a straightforward and effective solution for developing complex magnetic heterojunction devices and expanding the applications of magnetic 2D materials. Full article
(This article belongs to the Special Issue 2D-Materials Based Fabrication and Devices)
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<p>Schematic diagram of the PC-assisted transfer method for vdW contacts. Blue arrows indicate the sequence of operations, and red dashed lines highlight the magnified areas. (<b>a</b>) Au electrode arrays fabricated on a silicon wafer using thermal evaporation after lithography. (<b>b</b>) A silicon wafer spin-coated with a PC film, where the black rectangular frame indicates the area cut with a blade, representing the portion to be used. The right panel shows an optical image under a microscope, with a scale bar of 200 μm. (<b>c</b>) Illustration of the process where the PC film with electrodes is flipped and placed onto a PDMS stamp. Left panel: schematic of the operation. The middle optical image shows the Au electrodes transferred onto the PC film during the process, with a scale bar of 200 μm. Right panel: an image of the electrodes/PC on the PDMS stamp, with bubbles near the large electrode pads that will be removed during the heated transfer. Scale bar: 200 μm. (<b>d</b>) Alignment process. The target flake of 2D materials on a substrate is precisely aligned with the electrodes on the PDMS stamp and carefully stacked together using an XYZR transfer stage. Right panel shows a photograph of the motorized transfer stage inside a glovebox. (<b>e</b>) The transferred electrodes establish van der Waals contact with the sample. The PC film is melted when heating the sample to 180 °C and then dissolved in chloroform to complete the transfer.</p>
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<p>Transfer process in a glove box and optical images on different 2D materials. (<b>a</b>) (<b>i</b>–<b>iiii</b>) Sequential images showing the entire PC-assisted transfer process for establishing vdW contacts to air-sensitive ferromagnet Fe<sub>3</sub>GeTe<sub>2</sub> inside the glovebox: (<b>i</b>) Optical image of the Au electrodes on a sacrificial silicon wafer layer, covered with spin-coated PC film. (<b>ii</b>) Cleaved few-layer Fe<sub>3</sub>GeTe<sub>2</sub> sample on a SiO<sub>2</sub>/Si substrate. (<b>iii</b>) Optical image after the transfer process, showing the electrodes and the Fe<sub>3</sub>GeTe<sub>2</sub> sample in van der Waals contact, with the melted PC film on top. (<b>iiii</b>) Optical image of the Fe<sub>3</sub>GeTe<sub>2</sub> sample with transferred Au electrodes after removing the PC film in chloroform. (<b>b</b>–<b>e</b>) Optical images of devices with transferred Au electrodes for various 2D materials, including conventional 2D material graphene (<b>b</b>) and transition metal dichalcogenide WSe<sub>2</sub> (<b>c</b>) as well as antiferromagnetic 2D materials CoPS<sub>3</sub> (<b>d</b>) and NiPS<sub>3</sub> (<b>e</b>). All scale bars are indicated in the images.</p>
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<p>Electrical transport characterization of air-sensitive ferromagnet Fe<sub>3</sub>GeTe<sub>2</sub> device with the PC-assisted transferred Au electrodes. (<b>a</b>) Four-terminal resistance Rxx versus temperature curve of the Fe<sub>3</sub>GeTe<sub>2</sub> device, showing metallic behavior with good contact properties. The optical image of the device is shown in <a href="#micromachines-15-01401-f002" class="html-fig">Figure 2</a>e. (<b>b</b>) Hall resistance Rxy as a function of magnetic field measured at various temperatures from 2 K to 180 K (indicated on the right), showing clear anomalous Hall effect in the Fe<sub>3</sub>GeTe<sub>2</sub> device. As the temperature increases, the coercive field gradually decreases, and the hysteresis is minimal at 160 K. This trend reflects the material’s robust ferromagnetic properties at lower temperatures.</p>
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<p>Comparison of contacts in CrSBr-based antiferromagnetic semiconductor devices. (<b>a</b>,<b>b</b>) Optical images of CrSBr devices with thermally evaporated Au electrodes (<b>a</b>) and PC-assisted transferred Au electrodes (<b>b</b>), with the crystal axes “a” and “b” marked in each image. All electrodes are numbered for easy identification of measurement configurations. (<b>c</b>,<b>d</b>) I–V curves measured using the central electrodes for the devices displayed above, from which the two-terminal contact resistance (<span class="html-italic">R</span><sub>2T</sub>) is determined based on the slope. (<b>e</b>,<b>f</b>) Four-terminal channel resistance (<span class="html-italic">R</span><sub>4T</sub>) for each device, calculated as <span class="html-italic">R</span><sub>4T</sub> = V/I. Here, a voltage (V<sub>DS</sub>) is applied across the outermost electrodes to measure the channel current (I), while voltage (V) is monitored at the central electrodes, which are labeled in the figure inserts.</p>
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<p>Transport properties of the antiferromagnetic semiconductor CrSBr measured with different types of contacts. (<b>a</b>) Normalized conductance (defined as G/G (T = 300 K)) as a function of temperature (T) measured for CrSBr devices with various thicknesses and types of contacts. (<b>b</b>) Comparison of normalized conductance-vs.-temperature curve for the initial cooling-down process with the curve for the warming-up process after prolonged low-temperature measurements for a few-layer CrSBr device with PC-assisted transferred electrodes. (<b>c</b>) Magnetoresistance ratio, defined as MR (%) = (<span class="html-italic">R</span>(B) − <span class="html-italic">R</span>(0T))/<span class="html-italic">R</span>(0T) measured at various temperatures for the same few-layer CrSBr devices in (<b>b</b>). The external magnetic field applied along the c-axis (perpendicular to the a,b-plane). (<b>d</b>) Magnetoresistance ratio measured at 10 K for the bilayer CrSBr devices with PC-assisted transferred Au electrodes, graphene electrodes, and thermally evaporated Au electrodes. The external magnetic field applied along the easy axis (b-axis of CrSBr).</p>
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9 pages, 5523 KiB  
Article
Gravure-Printed Anodes Based on Hard Carbon for Sodium-Ion Batteries
by Maria Montanino, Claudia Paoletti, Anna De Girolamo Del Mauro and Giuliano Sico
Batteries 2024, 10(11), 407; https://doi.org/10.3390/batteries10110407 - 20 Nov 2024
Viewed by 200
Abstract
Printed batteries are increasingly being investigated for feeding small, wearable devices more and more involved in our daily lives, promoting the study of printing technologies. Among these, gravure is very attractive as a low-cost and low-waste production method for functional layers in different [...] Read more.
Printed batteries are increasingly being investigated for feeding small, wearable devices more and more involved in our daily lives, promoting the study of printing technologies. Among these, gravure is very attractive as a low-cost and low-waste production method for functional layers in different fields, such as energy, sensors, and biomedical, because it is easy to scale up industrially. Thanks to our research, the feasibility of gravure printing was recently proved for rechargeable lithium-ion batteries (LiBs) manufacturing. Such studies allowed the production of high-quality electrodes involving different active materials with high stability, reproducibility, and good performance. Going beyond lithium-based storage devices, our attention was devoted on the possibility of employing highly sustainable gravure printing for sodium-ion batteries (NaBs) manufacturing, following the trendy interest in sodium, which is more abundant, economical, and ecofriendly than lithium. Here a study on gravure printed anodes for sodium-ion batteries based on hard carbon as an active material is presented and discussed. Thanks to our methodology centered on the capillary number, a high printing quality anodic layer was produced providing typical electrochemical behavior and good performance. Such results are very innovative and relevant in the field of sodium-ion batteries and further demonstrate the high potential of gravure in printed battery manufacturing. Full article
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<p>Operating roll-based gravure printing principle, showing inking (1), doctoring (2), transfer (3), spreading (4), and drying (5) sub-processes. Adapted with permission from Ref. [<a href="#B8-batteries-10-00407" class="html-bibr">8</a>].</p>
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<p>Viscosity versus shear rate for the prepared inks at different solid content (14, 15, 18 wt%).</p>
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<p>SEM images of the gravure printed layers: 15 min ball-milled ink (<b>A</b>,<b>A′</b>) and 60 min ball milled (<b>B</b>,<b>B′</b>) at different magnifications.</p>
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<p>SEM images of the gravure printed layers: 3 h ball-milled ink overlapping 10 layers (<b>A</b>,<b>A′</b>) and 15 layers (<b>B</b>,<b>B′</b>) at different magnifications.</p>
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<p>Voltage vs. specific capacity in discharge for gravure printed electrodes based on HC obtained using ball-milled inks at 15 min (<b>A</b>) and 3 h (<b>B</b>) for selected cycles (5th, 10th, 20th, 50th, 100th).</p>
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<p>Discharge-specific capacity for gravure printed electrodes based on HC obtained using ball-milled inks at 15 min and 3 h.</p>
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15 pages, 2979 KiB  
Article
Assessing the Degradation of Levofloxacin in Aqueous Media by Metal-Free g-C3N4 Photocatalyst Under Simulated Solar Light Irradiation
by Truong Nguyen Xuan, Dien Nguyen Thi, Cong Le Thanh, Thu Mai Thi, Thu Le Dieu, Trung Nguyen Duc and Ottó Horváth
Catalysts 2024, 14(11), 837; https://doi.org/10.3390/catal14110837 - 20 Nov 2024
Viewed by 257
Abstract
Graphitic carbon nitride (g-C3N4) as a fascinating conjugated polymer has attracted considerable attention due to its outstanding electronic properties, high physicochemical stability, and unique structure. In this work, we reported the characterization of g-C3N4, which [...] Read more.
Graphitic carbon nitride (g-C3N4) as a fascinating conjugated polymer has attracted considerable attention due to its outstanding electronic properties, high physicochemical stability, and unique structure. In this work, we reported the characterization of g-C3N4, which was simply synthesized by thermal polymerization of thiourea, the photocatalytic degradation kinetics, and the pathway of levofloxacin (LEV) using the prepared g-C3N4. The XRD and SEM results confirmed a crystalline graphite structure with a tri-s-triazine unit and stacked sheet-like layers of g-C3N4. The efficacy factor (EF) was compared to different photocatalytic processes to assess the LEV removal performance. g-C3N4 exhibits good stability as a photocatalyst during LEV photodegradation. Radical scavenger experiments revealed that in the oxidative degradation of LEV, O2 and h+ played the determining roles. Moreover, based on the identification of intermediates using liquid chromatography with tandem mass spectrometry (LC-MS/MS), the degradation pathway of LEV was proposed. Full article
(This article belongs to the Special Issue Environmental Catalysis in Advanced Oxidation Processes, 2nd Edition)
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<p>XRD pattern of g-C<sub>3</sub>N<sub>4</sub> catalyst.</p>
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<p>SEM images of g-C<sub>3</sub>N<sub>4</sub> catalyst with different resolutions. (<b>a</b>) 50,000× magnification, (<b>b</b>) 20,000× magnification.</p>
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<p>(<b>a</b>) Effect of initial solution pH on the photocatalytic activity and (<b>b</b>) first-order kinetic curves.</p>
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<p>pH<sub>pzc</sub> determination for g-C<sub>3</sub>N<sub>4</sub>.</p>
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<p>Comparison between photolysis, adsorption and photocatalysis by g-C<sub>3</sub>N<sub>4</sub>.</p>
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<p>(<b>a</b>) Effect of photocatalyst content on the photocatalytic activity and (<b>b</b>) first-order kinetic curves.</p>
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<p>(<b>a</b>) Effect of initial LEV concentration on the photocatalytic activity and (<b>b</b>) first-order kinetic curves.</p>
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<p>Recycle experiments of the LEV degradation using g-C<sub>3</sub>N<sub>4</sub> photocatalyst.</p>
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<p>Reactive species trapping experiments: (<b>a</b>) effect of quenching agent IPA and AO (observed by UV-Vis spectrophotometry); (<b>b</b>) effect of quenching agent BQ (obtained by photoluminescence measurements); (<b>c</b>) degradation efficiency.</p>
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<p>Photocatalytic mechanism of levofloxacin by g-C3N4 photocatalyst.</p>
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<p>The proposed degradation pathway of LEV.</p>
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17 pages, 11814 KiB  
Article
Recognition of Maize Tassels Based on Improved YOLOv8 and Unmanned Aerial Vehicles RGB Images
by Jiahao Wei, Ruirui Wang, Shi Wei, Xiaoyan Wang and Shicheng Xu
Drones 2024, 8(11), 691; https://doi.org/10.3390/drones8110691 - 19 Nov 2024
Viewed by 389
Abstract
The tasseling stage of maize, as a critical period of maize cultivation, is essential for predicting maize yield and understanding the normal condition of maize growth. However, the branches overlap each other during the growth of maize seedlings and cannot be used as [...] Read more.
The tasseling stage of maize, as a critical period of maize cultivation, is essential for predicting maize yield and understanding the normal condition of maize growth. However, the branches overlap each other during the growth of maize seedlings and cannot be used as an identifying feature. However, during the tasseling stage, its apical ear blooms and has distinctive features that can be used as an identifying feature. However, the sizes of the maize tassels are small, the background is complex, and the existing network has obvious recognition errors. Therefore, in this paper, unmanned aerial vehicle (UAV) RGB images and an improved YOLOv8 target detection network are used to enhance the recognition accuracy of maize tassels. In the new network, a microscale target detection head is added to increase the ability to perceive small-sized maize tassels; In addition, Spatial Pyramid Pooling—Fast (SPPF) is replaced by the Spatial Pyramid Pooling with Efficient Layer Aggregation Network (SPPELAN) in the backbone network part to connect different levels of detailed features and semantic information. Moreover, a dual-attention module synthesized by GAM-CBAM is added to the neck part to reduce the loss of features of maize tassels, thus improving the network’s detection ability. We also labeled the new maize tassels dataset in VOC format as the training and validation of the network model. In the final model testing results, the new network model’s precision reached 93.6% and recall reached 92.5%, which was an improvement of 2.8–12.6 percentage points and 3.6–15.2 percentage points compared to the mAP50 and F1-score values of other models. From the experimental results, it is shown that the improved YOLOv8 network, with high performance and robustness in small-sized maize tassel recognition, can accurately recognize maize tassels in UAV images, which provides technical support for automated counting, accurate cultivation, and large-scale intelligent cultivation of maize seedlings. Full article
(This article belongs to the Special Issue Advances of UAV in Precision Agriculture)
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<p>Study area.</p>
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<p>Image data collection process.</p>
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<p>Data augmentation: (<b>A</b>) luminance and geometric distortion and (<b>B</b>) mosaic.</p>
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<p>Spatial Pyramid Pooling—Fast (SPPF) schematic diagram.</p>
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<p>Spatial Pyramid Pooling with Efficient Layer Aggregation Network (SPPELAN) schematic diagram.</p>
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<p>A diagram illustrating the structure of the convolutional block attention module (CBAM).</p>
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<p>The structural diagram of the global attention mechanism (GAM).</p>
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<p>Basic YOLOv8 network architecture diagram.</p>
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<p>Improved YOLOv8 network architecture diagram.</p>
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<p>Improved structure of the attention module.</p>
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<p>Improved YOLOv8 workflow.</p>
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<p>(<b>A</b>) Trends in various accuracy metrics throughout the model training process. (<b>B</b>) Performance evaluation results of the improved YOLOv8 with various IoU thresholds.</p>
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<p>Visualization results.</p>
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<p>Comparison of different deep learning algorithms for maize tassels detection and recognition performance.</p>
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30 pages, 1150 KiB  
Review
Methods for Detection, Extraction, Purification, and Characterization of Exopolysaccharides of Lactic Acid Bacteria—A Systematic Review
by Manoj Kumar Yadav, Ji Hoon Song, Robie Vasquez, Jae Seung Lee, In Ho Kim and Dae-Kyung Kang
Foods 2024, 13(22), 3687; https://doi.org/10.3390/foods13223687 - 19 Nov 2024
Viewed by 731
Abstract
Exopolysaccharides (EPSs) are large-molecular-weight, complex carbohydrate molecules and extracellularly secreted bio-polymers released by many microorganisms, including lactic acid bacteria (LAB). LAB are well known for their ability to produce a wide range of EPSs, which has received major attention. LAB-EPSs have the potential [...] Read more.
Exopolysaccharides (EPSs) are large-molecular-weight, complex carbohydrate molecules and extracellularly secreted bio-polymers released by many microorganisms, including lactic acid bacteria (LAB). LAB are well known for their ability to produce a wide range of EPSs, which has received major attention. LAB-EPSs have the potential to improve health, and their applications are in the food and pharmaceutical industries. Several methods have been developed and optimized in recent years for producing, extracting, purifying, and characterizing LAB-produced EPSs. The simplest method of evaluating the production of EPSs is to observe morphological features, such as ropy and mucoid appearances of colonies. Ethanol precipitation is widely used to extract the EPSs from the cell-free supernatant and is generally purified using dialysis. The most commonly used method to quantify the carbohydrate content is phenol–sulfuric acid. The structural characteristics of EPSs are identified via Fourier transform infrared, nuclear magnetic resonance, and X-ray diffraction spectroscopy. The molecular weight and composition of monosaccharides are determined through size-exclusion chromatography, thin-layer chromatography, gas chromatography, and high-performance liquid chromatography. The surface morphology of EPSs is observed via scanning electron microscopy and atomic force microscopy, whereas thermal characteristics are determined through thermogravimetry analysis, derivative thermogravimetry, and differential scanning calorimetry. In the present review, we discuss the different existing methods used for the detailed study of LAB-produced EPSs, which provide a comprehensive guide on LAB-EPS preparation, critically evaluating methods, addressing knowledge gaps and key challenges, and offering solutions to enhance reproducibility, scalability, and support for both research and industrial applications. Full article
(This article belongs to the Section Food Microbiology)
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<p>A schematic diagram of various steps involved in the detection, production, extraction, purification, and characterization of exopolysaccharides (EPSs) of lactic acid bacteria (LAB).</p>
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<p>A schematic diagram of various methods used for the determination of different structural characteristics of exopolysaccharides (EPSs) of lactic acid bacteria (LAB).</p>
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21 pages, 2991 KiB  
Article
Gypsum: From the Equilibrium to the Growth Shapes—Theory and Experiments
by Dino Aquilano, Marco Bruno and Stefano Ghignone
Minerals 2024, 14(11), 1175; https://doi.org/10.3390/min14111175 - 19 Nov 2024
Viewed by 321
Abstract
The gypsum crystals (CaSO4·2H2O) crystallizes in a low symmetry system (monoclinic) and shows a marked layered structure along with a perfect cleavage parallel to the {010} faces. Owing to its widespread occurrence, as a single or twinned crystal, here [...] Read more.
The gypsum crystals (CaSO4·2H2O) crystallizes in a low symmetry system (monoclinic) and shows a marked layered structure along with a perfect cleavage parallel to the {010} faces. Owing to its widespread occurrence, as a single or twinned crystal, here the gypsum equilibrium (E.S.) and growth shapes (G.S.) have been re-visited. In making the distinction among E.S. and G.S., in the present work, the basic difference between epitaxy and homo-taxy is clearly evidenced. Gypsum has also been a fruitful occasion to recollect the general rules concerning either contact or penetration twins, for free growing and for twinned crystals nucleating onto pre-existing substrates. Both geometric and crystal growth aspects have been considered as well, by unifying theory and experiments of crystallography and crystal growth through the intervention of βadh, the physical quantity representing the specific adhesion energy between gypsum and other phases. Hence, the adhesion energy allowed us to systematically use the Dupré’s formula. In the final part of the paper, peculiar attention has been paid to sediments (or solution growth) where the crystal size is very small, in order to offer a new simple way to afford classical (CNT) and non-classical nucleation (NCNT) theories, both ruling two quantities commonly used in the industrial crystallization: the total induction times (tindtotal) and crystal size distribution (CSD). Full article
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<p>The separation work W<sub>AB</sub> comes from the balance of two works: (i) that for separating each of the two phases (W<sub>A</sub>, W<sub>B</sub>) and (ii) the work recovered (−2E<sub>AB</sub>) by coupling the two phases. To achieve the sense of “specific”, all works must be divided by 2S. <a href="#minerals-14-01175-t001" class="html-table">Table 1</a> is for twinning.</p>
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<p>The drawing refers to Equation (1). Furthermore, it comments that the E.S. of a crystal embryo is able to make a twin. Case (a): <math display="inline"><semantics> <mrow> <msub> <mrow> <mi mathvariant="sans-serif">γ</mi> </mrow> <mrow> <mi mathvariant="normal">t</mi> <mi mathvariant="normal">w</mi> <mi mathvariant="normal">i</mi> <mi mathvariant="normal">n</mi> </mrow> </msub> </mrow> </semantics></math> = 2<math display="inline"><semantics> <mrow> <msub> <mrow> <mi mathvariant="sans-serif">γ</mi> </mrow> <mrow> <mn>0</mn> </mrow> </msub> </mrow> </semantics></math>, for two separated crystals. Case (c): 0 &lt; <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>γ</mi> </mrow> <mrow> <mi>t</mi> <mi>w</mi> <mi>i</mi> <mi>n</mi> </mrow> </msub> </mrow> </semantics></math> &lt; 2<math display="inline"><semantics> <mrow> <msub> <mrow> <mi>γ</mi> </mrow> <mrow> <mn>0</mn> </mrow> </msub> </mrow> </semantics></math>, for a non-perfect adhesion between P and T. Case (b): <math display="inline"><semantics> <mrow> <msub> <mrow> <mi mathvariant="sans-serif">γ</mi> </mrow> <mrow> <mi mathvariant="normal">t</mi> <mi mathvariant="normal">w</mi> <mi mathvariant="normal">i</mi> <mi mathvariant="normal">n</mi> </mrow> </msub> </mrow> </semantics></math> = 0, when one cannot distinguish P from T.</p>
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<p>The Gibbs–Wulff–Kaischew theorem. In the Figure, the O point, called the Wulff’s point [<a href="#B19-minerals-14-01175" class="html-bibr">19</a>], represents the completely random origin.</p>
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<p>Twinned crystal: the free i-faces are not interested with the original contact plane (OCP- dashed line), and then can grow “homothetically”. Instead, the j-faces adjacent to the OCP, will have an extension depending on the twin energy. The OCP has the constant (<math display="inline"><semantics> <mrow> <msub> <mrow> <mi>c</mi> </mrow> <mrow> <mn>0</mn> </mrow> </msub> </mrow> </semantics></math>) related to <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>γ</mi> </mrow> <mrow> <mn>0</mn> </mrow> </msub> <mo>,</mo> </mrow> </semantics></math> its specific surface energy, as in <a href="#minerals-14-01175-f003" class="html-fig">Figure 3</a>.</p>
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<p>(<b>a</b>) The activation energy for twin nucleation ΔG*<sub>twin</sub> is always higher than that needed to nucleate a normal crystal (Δϕ = 0) and lower than that due for two normal crystals; (<b>b</b>) The J<sub>3D</sub> function: twins can be observed only at higher supersaturation values (<math display="inline"><semantics> <mrow> <msubsup> <mrow> <mi mathvariant="sans-serif">β</mi> </mrow> <mrow> <mi mathvariant="normal">t</mi> <mi mathvariant="normal">w</mi> <mi mathvariant="normal">i</mi> <mi mathvariant="normal">n</mi> </mrow> <mi mathvariant="normal">*</mi> </msubsup> </mrow> </semantics></math>) with respect to β* = <math display="inline"><semantics> <mrow> <msubsup> <mrow> <mi mathvariant="sans-serif">β</mi> </mrow> <mrow> <mi mathvariant="normal">n</mi> <mi mathvariant="normal">o</mi> <mi mathvariant="normal">r</mi> <mi mathvariant="normal">m</mi> <mi mathvariant="normal">a</mi> <mi mathvariant="normal">l</mi> </mrow> <mrow> <mi mathvariant="normal">*</mi> </mrow> </msubsup> </mrow> </semantics></math> needed to nucleate normal crystals; (<b>c</b>) The value (<math display="inline"><semantics> <mrow> <msub> <mrow> <mi mathvariant="normal">J</mi> </mrow> <mrow> <mi mathvariant="normal">T</mi> </mrow> </msub> </mrow> </semantics></math>/<math display="inline"><semantics> <mrow> <msub> <mrow> <mi mathvariant="normal">J</mi> </mrow> <mrow> <mi mathvariant="normal">N</mi> </mrow> </msub> </mrow> </semantics></math>) = 100% is reached only when: ΔG*<sub>twin</sub> = ΔG*.</p>
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<p>The homemade drawing, representing the gypsum projected along its [001] direction, is a strict application of the HP method [<a href="#B22-minerals-14-01175" class="html-bibr">22</a>]. Ca-atoms (blue) are located on the tetrahedra tops (and bottom), while <math display="inline"><semantics> <mrow> <msubsup> <mrow> <mi mathvariant="normal">S</mi> <mi mathvariant="normal">O</mi> </mrow> <mrow> <mn>4</mn> </mrow> <mrow> <mn>2</mn> <mo>−</mo> </mrow> </msubsup> </mrow> </semantics></math> ions are square-shaped. Each <math display="inline"><semantics> <mrow> <msubsup> <mrow> <mi mathvariant="normal">S</mi> <mi mathvariant="normal">O</mi> </mrow> <mrow> <mn>4</mn> </mrow> <mrow> <mn>2</mn> <mo>−</mo> </mrow> </msubsup> </mrow> </semantics></math> ion is only linked to its two water molecules. The limits of the d<sub>020</sub> spacing are located in between the water molecules. The screw 2<sub>1</sub> axes, parallel to [010], lie in between A and B layers of thickness d<sub>200</sub>. The d <sub>040</sub> thickness is also indicated as a private communication by L. Pastero.</p>
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<p>Scheme of an observed growth spiral along with the nanometric interstep distances and step directions. The measured step height is ∼7.5 Å, which is the thickness d<sub>020</sub> = ½ b<sub>0</sub>. Working data: pure gypsum–water solutions; T<sub>cryst.</sub> = 80 °C; very low supersaturation: β = 1.062. Modified from [<a href="#B31-minerals-14-01175" class="html-bibr">31</a>].</p>
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<p>Historical gypsum twins, inspired by [<a href="#B4-minerals-14-01175" class="html-bibr">4</a>]. The twin percent (ordinate axis) is a function of both the twin laws and σ<sub>v</sub>, the exceeding supersaturation. On the abscissa axis, one has: σ<sub>v</sub> = β − 1 = (C − C<sub>eq</sub>)/C<sub>eq</sub>, where C<sub>eq</sub> is here related to T = 20 °C.</p>
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20 pages, 31175 KiB  
Article
An Optimization Method for PCB Surface Defect Detection Model Based on Measurement of Defect Characteristics and Backbone Network Feature Information
by Huixiang Liu, Xin Zhao, Qiong Liu and Wenbai Chen
Sensors 2024, 24(22), 7373; https://doi.org/10.3390/s24227373 - 19 Nov 2024
Viewed by 245
Abstract
Printed Circuit Boards (PCBs) are essential components in electronic devices, making defect detection crucial. PCB surface defects are diverse, complex, low in feature resolution, and often resemble the background, leading to detection challenges. This paper proposes the YOLOv8_DSM algorithm for PCB surface defect [...] Read more.
Printed Circuit Boards (PCBs) are essential components in electronic devices, making defect detection crucial. PCB surface defects are diverse, complex, low in feature resolution, and often resemble the background, leading to detection challenges. This paper proposes the YOLOv8_DSM algorithm for PCB surface defect detection, optimized based on the three major characteristics of defect targets and feature map visualization. First, to address the complexity and variety of defect shapes, we introduce CSPLayer_2DCNv3, which incorporates deformable convolution into the backbone network. This enhances adaptive defect feature extraction, effectively capturing diverse defect characteristics. Second, to handle low feature resolution and background resemblance, we design a Shallow-layer Low-semantic Feature Fusion Module (SLFFM). By visualizing the last four downsampling convolution layers of the YOLOv8 backbone, we incorporate feature information from the second downsampling layer into SLFFM. We apply feature map separation-based SPDConv for downsampling, providing PAN-FPN with rich, fine-grained shallow-layer features. Additionally, SLFFM employs the bi-level routing attention (BRA) mechanism as a feature aggregation module, mitigating defect-background similarity issues. Lastly, MPDIoU is used as the bounding box loss regression function, improving training efficiency by enhancing convergence speed and accuracy. Experimental results show that YOLOv8_DSM achieves a mAP (0.5:0.9) of 63.4%, representing a 5.14% improvement over the original model. The model’s Frames Per Second (FPS) reaches 144.6. To meet practical engineering requirements, the designed PCB defect detection model is deployed in a PCB quality inspection system on a PC platform. Full article
(This article belongs to the Special Issue Sensing and Imaging for Defect Detection: 2nd Edition)
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<p>Proportions of PCB Applications in Various Fields.</p>
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<p>A detailed network architecture diagram of YOLOv8n, where (<b>a</b>) represents the backbone of the network, (<b>b</b>) outlines the structure of the network’s Neck, (<b>c</b>) illustrates the detailed structure of the SPPF module, (<b>d</b>) showcases the detailed structure of the CSPLayer_2Conv, (<b>e</b>) displays the detailed diagram of the CBS convolutional model, and (<b>f</b>) presents two detailed structures of the Bottleneck.</p>
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<p>A detailed YOLOv8_DSM network architecture diagram, where (<b>a</b>) represents the network’s backbone, (<b>b</b>) illustrates the detailed structure of the SLFFM, (<b>c</b>) is the network’s Neck, (<b>d</b>) denotes the network’s detection head, (<b>e</b>) showcases the detailed structure of the network’s Bottleneck, (<b>f</b>) presents the detailed structure of the CSPLayer_2Dcnv3, and (<b>g</b>) elucidates the detailed structure of the DCNV3 convolution.</p>
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<p>Visualization of Heatmaps for Different Layer Feature Maps in the backbone, with red boxes indicating the location of defects.</p>
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<p>Illustration of SPD-Conv when scale equals to two.</p>
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<p>(<b>a</b>) Structure of the Bi-Level Routing Attention; (<b>b</b>) Structure of the BRA.</p>
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<p>Depicts the statistical information of the dataset. Where (<b>a</b>) represents the number of various defects in the dataset, and (<b>b</b>) represents the distribution of width, height, and area of various defects in the dataset.</p>
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<p>Heatmap visualization of the fourth layer feature map in the original backbone and Scheme C, with red boxes indicating the location of defects.</p>
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<p>Main interface of the PCB defect detection quality inspection system: (<b>a</b>) is the initial state, and (<b>b</b>) is the running state.</p>
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18 pages, 4823 KiB  
Article
ME-FCN: A Multi-Scale Feature-Enhanced Fully Convolutional Network for Building Footprint Extraction
by Hui Sheng, Yaoteng Zhang, Wei Zhang, Shiqing Wei, Mingming Xu and Yasir Muhammad
Remote Sens. 2024, 16(22), 4305; https://doi.org/10.3390/rs16224305 - 19 Nov 2024
Viewed by 380
Abstract
The precise extraction of building footprints using remote sensing technology is increasingly critical for urban planning and development amid growing urbanization. However, considering the complexity of building backgrounds, diverse scales, and varied appearances, accurately and efficiently extracting building footprints from various remote sensing [...] Read more.
The precise extraction of building footprints using remote sensing technology is increasingly critical for urban planning and development amid growing urbanization. However, considering the complexity of building backgrounds, diverse scales, and varied appearances, accurately and efficiently extracting building footprints from various remote sensing images remains a significant challenge. In this paper, we propose a novel network architecture called ME-FCN, specifically designed to perceive and optimize multi-scale features to effectively address the challenge of extracting building footprints from complex remote sensing images. We introduce a Squeeze-and-Excitation U-Block (SEUB), which cascades multi-scale semantic information exploration in shallow feature maps and incorporates channel attention to optimize features. In the network’s deeper layers, we implement an Adaptive Multi-scale feature Enhancement Block (AMEB), which captures large receptive field information through concatenated atrous convolutions. Additionally, we develop a novel Dual Multi-scale Attention (DMSA) mechanism to further enhance the accuracy of cascaded features. DMSA captures multi-scale semantic features across both channel and spatial dimensions, suppresses redundant information, and realizes multi-scale feature interaction and fusion, thereby improving the overall accuracy and efficiency. Comprehensive experiments on three datasets demonstrate that ME-FCN outperforms mainstream segmentation methods. Full article
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<p>Architecture of the proposed ME-FCN method. (Blue represents the encoder and orange represents the decoder.)</p>
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<p>Overall architecture of the SEUB. SEUB adopts a simple U-shaped structure, with the bottom layer utilizing atrous convolution to achieve a larger receptive field, while the skip connections incorporate squeeze-and-excitation attention to enhance network stability.</p>
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<p>Residual structure schematic of SEUB.</p>
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<p>Schematic diagram of the Adaptive Multi-scale feature Enhancement Block. The AMEB consists of atrous convolutions with multiple dilation rates and introduces an auxiliary branch, allowing high-level feature maps to autonomously select information utilization, reducing the randomness of feature utilization.</p>
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<p>Dual Multi-scale Attention structure. DMSA performs feature alignment at three scales to alleviate semantic differences and achieve feature interaction and fusion.</p>
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<p>The set of predicted results obtained from different algorithms on the WHU aerial dataset (blue indicates the number of false negatives, red represents the number of false positives, white indicates the correct identification of positive samples, and black shows the correct identification of negative samples).</p>
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<p>The set of predicted results obtained from different algorithms on the Massachusetts dataset (blue indicates the number of false negatives, red represents the number of false positives, white indicates the correct identification of positive samples, and black shows the correct identification of negative samples).</p>
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<p>The set of predicted results obtained from different algorithms on the GF-2 building dataset (blue indicates the number of false positives, red represents the number of false negatives, white indicates the correct identification of positive samples, and black shows the correct identification of negative samples).</p>
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<p>Ablation experiment results with different module combinations. (<b>a</b>) Image, (<b>b</b>) ground truth, (<b>c</b>) baseline, (<b>d</b>) Baseline + SEUB (<b>e</b>) baseline + SEUB + DMSA, and (<b>f</b>) baseline + SEUB + DMSA + AMEB.</p>
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17 pages, 8896 KiB  
Article
MST-YOLO: Small Object Detection Model for Autonomous Driving
by Mingjing Li, Xinyang Liu, Shuang Chen, Le Yang, Qingyu Du, Ziqing Han and Junshuai Wang
Sensors 2024, 24(22), 7347; https://doi.org/10.3390/s24227347 - 18 Nov 2024
Viewed by 264
Abstract
Autonomous vehicles operating in public transportation spaces must rapidly and accurately detect all potential hazards in their surroundings to execute appropriate actions such as yielding, lane changing, and overtaking. This capability is a prerequisite for achieving advanced autonomous driving. In autonomous driving scenarios, [...] Read more.
Autonomous vehicles operating in public transportation spaces must rapidly and accurately detect all potential hazards in their surroundings to execute appropriate actions such as yielding, lane changing, and overtaking. This capability is a prerequisite for achieving advanced autonomous driving. In autonomous driving scenarios, distant objects are often small, which increases the risk of detection failures. To address this challenge, the MST-YOLOv8 model, which incorporates the C2f-MLCA structure and the ST-P2Neck structure to enhance the model’s ability to detect small objects, is proposed. This paper introduces mixed local channel attention (MLCA) into the C2f structure, enabling the model to pay more attention to the region of small objects. A P2 detection layer is added to the neck part of the YOLOv8 model, and scale sequence feature fusion (SSFF) and triple feature encoding (TFE) modules are introduced to assist the model in better localizing small objects. Compared with the original YOLOv8 model, MST-YOLOv8 demonstrates a 3.43% improvement in precision (P), an 8.15% improvement in recall (R), an 8.42% increase in mAP_0.5, a reduction in missed detection rate by 18.47%, a 70.97% improvement in small object detection AP, and a 68.92% improvement in AR. Full article
(This article belongs to the Section Intelligent Sensors)
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<p>Model structure of YOLOv8.</p>
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<p>MST-YOLOv8 structure diagram.</p>
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<p>C2f Module structure diagram.</p>
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<p>MLCA structure diagram.</p>
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<p>C2f-MLCA structure diagram.</p>
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<p>Neck structure diagram of YOLOv8.</p>
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<p>SSFF module structure diagram.</p>
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<p>TEE module structure diagram.</p>
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<p>Model training and validation loss curves.</p>
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<p>Model performance during training.</p>
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<p>Comparison of experimental model performance.</p>
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<p>Model detection effect comparison chart. (<b>a</b>) These images represent the output of the YOLOV8 model; (<b>b</b>) these images represent the output of MST-YOLO. Red represents missed detection, blue represents false detection. Green represents the correct detection of the target to be detected.</p>
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<p>The detection effect of the model under dense traffic flow conditions. (<b>a</b>) This image represents the original image; (<b>b</b>) this image represents the output of MST-YOLO.</p>
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<p>The detection performance of the MST-YOLOv8 model on the BDD100K dataset: (<b>a</b>) the original image, (<b>b</b>) the result output by YOLOV8; (<b>c</b>) the result output by MST-YOLO.</p>
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