On Lemon Defect Recognition with Visual Feature Extraction and Transfers Learning

Applying machine learning to lemon defect recognition can improve the efficiency of lemon quality detection. This paper proposes a deep learning-based classification method with visual feature extraction and transfer learning to recognize defect lemons (i.e., green and mold defects). First, the data enhancement and brightness compensation techniques are used for data prepossessing. The visual feature extraction is used to quantify the defects and determine the feature variables as the bandit basis for classification. Then we construct a convolutional neural network with an embedded Visual Geometry Group 16 based (VGG16-based) network using transfer learning. The proposed model is compared with many benchmark models such as K-nearest Neighbor (KNN) and Support Vector Machine (SVM). Results show that the proposed model achieves the highest accuracy (95.44%) in the testing data set. The research provides a new solution for lemon defect recognition.

Design and Analysis of Novel Ka Band NOMA Uplink Relay System for Lunar Farside Exploration

This paper proposes a novel Ka band non-orthogonal multiple access(NOMA)uplink relay system for Lunar farside exploration,where a satellite relay node with the help of NOMA scheme,amplifies and forwards the signal from the Earth Base Station(EBS)to a Lunar rover and a lander.We assume that the signal undergoes shadowed-Rician fading for the source-relay link and Rayleigh fading for the relay-destination link.Then,the analytical expressions for the outage probability(OP)and ergodic capacity are derived for the satellite relay node equipped with single and multiple antennas,respectively.In addition,we obtain the optimal power allocation coefficients by maximizing the sum ergodic capacity of the system,and we calculate the power consumption of the NOMA uplink relay system to achieve the same OP performance of OMA system and provide some useful guides for the design of the Earth-to-Lunar communication system.Simulations are provided to confirm the reliability of our analytical results and show the impact of various parameters on the system performance.

Point Cloud Classification Network Based on Graph Convolution and Fusion Attention Mechanism

The classification of point cloud data is the key technology of point cloud data information acquisition and 3D reconstruction, which has a wide range of applications. However, the existing point cloud classification methods have some shortcomings when extracting point cloud features, such as insufficient extraction of local information and overlooking the information in other neighborhood features in the point cloud, and not focusing on the point cloud channel information and spatial information. To solve the above problems, a point cloud classification network based on graph convolution and fusion attention mechanism is proposed to achieve more accurate classification results. Firstly, the point cloud is regarded as a node on the graph, the k-nearest neighbor algorithm is used to compose the graph and the information between points is dynamically captured by stacking multiple graph convolution layers;then, with the assistance of 2D experience of attention mechanism, an attention mechanism which has the capability to integrate more attention to point cloud spatial and channel information is introduced to increase the feature information of point cloud, aggregate local useful features and suppress useless features. Through the classification experiments on ModelNet40 dataset, the experimental results show that compared with PointNet network without considering the local feature information of the point cloud, the average classification accuracy of the proposed model has a 4.4% improvement and the overall classification accuracy has a 4.4% improvement. Compared with other networks, the classification accuracy of the proposed model has also been improved.