Considering that real communication signals corrupted by noise are generally nonstationary, and timefrequency distributions are especially suitable for the analysis of nonstationary signals, time-frequency distributio...Considering that real communication signals corrupted by noise are generally nonstationary, and timefrequency distributions are especially suitable for the analysis of nonstationary signals, time-frequency distributions are introduced for the modulation classification of communication signals： The extracted time-frequency features have good classification information, and they are insensitive to signal to noise ratio （SNR） variation. According to good classification by the correct rate of a neural network classifier, a multilayer perceptron （MLP） classifier with better generalization, as well as, addition of time-frequency features set for classifying six different modulation types has been proposed. Computer simulations show that the MLP classifier outperforms the decision-theoretic classifier at low SNRs, and the classification experiments for real MPSK signals verify engineering significance of the MLP classifier.展开更多
Low-light image enhancement methods have limitations in addressing issues such as color distortion,lack of vibrancy,and uneven light distribution and often require paired training data.To address these issues,we propo...Low-light image enhancement methods have limitations in addressing issues such as color distortion,lack of vibrancy,and uneven light distribution and often require paired training data.To address these issues,we propose a two-stage unsupervised low-light image enhancement algorithm called Retinex and Exposure Fusion Network(RFNet),which can overcome the problems of over-enhancement of the high dynamic range and under-enhancement of the low dynamic range in existing enhancement algorithms.This algorithm can better manage the challenges brought about by complex environments in real-world scenarios by training with unpaired low-light images and regular-light images.In the first stage,we design a multi-scale feature extraction module based on Retinex theory,capable of extracting details and structural information at different scales to generate high-quality illumination and reflection images.In the second stage,an exposure image generator is designed through the camera response mechanism function to acquire exposure images containing more dark features,and the generated images are fused with the original input images to complete the low-light image enhancement.Experiments show the effectiveness and rationality of each module designed in this paper.And the method reconstructs the details of contrast and color distribution,outperforms the current state-of-the-art methods in both qualitative and quantitative metrics,and shows excellent performance in the real world.展开更多
针对无人机在光伏组件巡检任务中红外故障图像识别准确率低、检测速度慢的问题,提出一种特征增强的YOLO v5s故障检测算法。首先对损失函数进行优化,将原有的回归损失计算方法由GIOU(generalized intersection over union)改为功能更加...针对无人机在光伏组件巡检任务中红外故障图像识别准确率低、检测速度慢的问题,提出一种特征增强的YOLO v5s故障检测算法。首先对损失函数进行优化,将原有的回归损失计算方法由GIOU(generalized intersection over union)改为功能更加强大的EIOU(efficient intersection over union)损失函数,并自适应调节置信度损失平衡系数,提升模型训练效果;随后,在每个检测层前分别添加InRe特征增强模块,通过丰富特征表达增强目标特征提取能力。最后,用创建的红外光伏数据集进行对比验证。实验结果表明:本文方法均值平均精度(mean average precision,mAP)为92.76%,检测速度(frame per second,FPS)达到42.37 FPS,其中热斑、组件脱落两种故障类型平均精度分别为94.85%、90.67%,完全能够满足无人机自动巡检的需求。展开更多
文摘Considering that real communication signals corrupted by noise are generally nonstationary, and timefrequency distributions are especially suitable for the analysis of nonstationary signals, time-frequency distributions are introduced for the modulation classification of communication signals： The extracted time-frequency features have good classification information, and they are insensitive to signal to noise ratio （SNR） variation. According to good classification by the correct rate of a neural network classifier, a multilayer perceptron （MLP） classifier with better generalization, as well as, addition of time-frequency features set for classifying six different modulation types has been proposed. Computer simulations show that the MLP classifier outperforms the decision-theoretic classifier at low SNRs, and the classification experiments for real MPSK signals verify engineering significance of the MLP classifier.
基金supported by the National Key Research and Development Program Topics(Grant No.2021YFB4000905)the National Natural Science Foundation of China(Grant Nos.62101432 and 62102309)in part by Shaanxi Natural Science Fundamental Research Program Project(No.2022JM-508).
文摘Low-light image enhancement methods have limitations in addressing issues such as color distortion,lack of vibrancy,and uneven light distribution and often require paired training data.To address these issues,we propose a two-stage unsupervised low-light image enhancement algorithm called Retinex and Exposure Fusion Network(RFNet),which can overcome the problems of over-enhancement of the high dynamic range and under-enhancement of the low dynamic range in existing enhancement algorithms.This algorithm can better manage the challenges brought about by complex environments in real-world scenarios by training with unpaired low-light images and regular-light images.In the first stage,we design a multi-scale feature extraction module based on Retinex theory,capable of extracting details and structural information at different scales to generate high-quality illumination and reflection images.In the second stage,an exposure image generator is designed through the camera response mechanism function to acquire exposure images containing more dark features,and the generated images are fused with the original input images to complete the low-light image enhancement.Experiments show the effectiveness and rationality of each module designed in this paper.And the method reconstructs the details of contrast and color distribution,outperforms the current state-of-the-art methods in both qualitative and quantitative metrics,and shows excellent performance in the real world.
文摘由于低照度图像具有对比度低、细节丢失严重、噪声大等缺点,现有的目标检测算法对低照度图像的检测效果不理想.为此,本文提出一种结合空间感知注意力机制和多尺度特征融合(Spatial-aware Attention Mechanism and Multi-Scale Feature Fusion,SAM-MSFF)的低照度目标检测方法 .该方法首先通过多尺度交互内存金字塔融合多尺度特征,增强低照度图像特征中的有效信息,并设置内存向量存储样本的特征,捕获样本之间的潜在关联性;然后,引入空间感知注意力机制获取特征在空间域的长距离上下文信息和局部信息,从而增强低照度图像中的目标特征,抑制背景信息和噪声的干扰;最后,利用多感受野增强模块扩张特征的感受野,对具有不同感受野的特征进行分组重加权计算,使检测网络根据输入的多尺度信息自适应地调整感受野的大小.在ExDark数据集上进行实验,本文方法的平均精度(mean Average Precision,mAP)达到77.04%,比现有的主流目标检测方法提高2.6%~14.34%.
文摘针对无人机在光伏组件巡检任务中红外故障图像识别准确率低、检测速度慢的问题,提出一种特征增强的YOLO v5s故障检测算法。首先对损失函数进行优化,将原有的回归损失计算方法由GIOU(generalized intersection over union)改为功能更加强大的EIOU(efficient intersection over union)损失函数,并自适应调节置信度损失平衡系数,提升模型训练效果;随后,在每个检测层前分别添加InRe特征增强模块,通过丰富特征表达增强目标特征提取能力。最后,用创建的红外光伏数据集进行对比验证。实验结果表明:本文方法均值平均精度(mean average precision,mAP)为92.76%,检测速度(frame per second,FPS)达到42.37 FPS,其中热斑、组件脱落两种故障类型平均精度分别为94.85%、90.67%,完全能够满足无人机自动巡检的需求。
