中央空调传感器双重降噪模糊故障检测方法

针对现有降噪方法存在噪声残留以及异常检测指标受噪声影响较大的问题,提出中央空调传感器双重降噪和模糊指标 的故障检测方法。 自适应噪声的完整经验模态分解(complete EEMD with adaptive noise,CEEMDAN)所具有的噪声残余等问题, 用局部均值估计提取 k 阶模态替换模态估计完成初次降噪;而早期出现的虚假模式,先通过相关系数准则筛选含噪分量尽可能 保留有效信息,然后计算奇异值差分谱确定降噪阶次进行奇异值分解(singular value decomposition,SVD)完成二次降噪。 最后, 结合能量和峭度系数提出模糊指标作为异常信号控制限进行故障检测。 采用中央空调实验系统运行数据对所提方法进行验 证,结果表明,该方法具有良好的降噪及敏感特征筛选能力,信噪比提升 20. 203 7 dB,均方误差平均减小 48. 75%,故障检测准 确率平均提升 8. 67%,响应速度提升 33. 3%,抗噪性及检测效果提升明显。     

一种紧凑型三陷波 UWB-MIMO 天线的设计

提出了一种紧凑型的三陷波超宽带多输入多输出(ultra wideband multiple-input multiple,UWB-MIMO)天线,将半圆形与 正六边形结合作为辐射贴片,接地板引入带“梳子”缝隙状 T 型枝节来实现较高的隔离度,天线尺寸为 36 mm×18 mm×1. 6 mm。 通过在辐射贴片上刻蚀倒“Ω” 形槽,在馈线上刻蚀类“U” 形槽以及贴片旁引入类“U” 形枝节的方式实现 WiMAX( 3. 3 ~ 3. 6 GHz)、WLAN 部分频段(5. 725~ 5. 825 GHz)和 X 波段下行频率(7. 25 ~ 7. 75 GHz) 3 个频段的陷波。 仿真与实测结果均表 明,该 UWB-MIMO 天线的工作带宽为 1. 9 ~ 10. 6 GHz,相对带宽达到 139%,3 个陷波频段为 2. 9 ~ 3. 7 GHz、5. 6 ~ 6. 0 GHz 和 7. 05~ 7. 76 GHz,且隔离度大于 20 dB,包络相关系数 ECC<0. 003,说明天线在各方面特性良好,可以满足 UWB-MIMO 天线的 要求。     

基于DeblurGAN的运动模糊图像盲复原算法研究

DeblurGAN方法利用条件生成对抗网络解决了端到端的图像去模糊问题,但存在图像边缘细节恢复不足以及鲁棒性不高的问题,针对此问题,提出一种基于DeblurGAN的运动模糊图像盲复原方法。在生成网络中,采用多尺度卷积核神经网络提取特征,并使用级联空洞卷积扩大神经元的感受野;采用自适配归一化方法代替原来生成器中使用的实例归一化方法。其次,引入了梯度图像L1损失,结合对抗损失和感知损失,将其作为图像去模糊的正则约束,使得生成图像的边缘特征更加清晰。实验结果表明,提出方法复原的图像峰值信噪比数值较DeblurGAN算法高出5.4%,结构相似性指标高出1%;在主观上清晰化效果较好,且消除了网格效应。     

自适应加权的多特征融合ECT图像重建算法

为了解决电容层析成像(electrical cpacitance tomography, ECT)图像重建中电容值与介电常数这一非线性病态问题,提出一种自适应加权的多特征融合(adaptive weighted multi-feature fusion, AWMF) ECT图像重建算法,利用网络模型拟合电容张量和介电常数的非线性映射关系。首先,在网络模型中采用密集卷积网络(DenseNet),不仅缓解梯度消失现象,还融合不同通道的特征信息;添加挤压激励网络(squeeze excitation network, SENet)自适应调整特征通道的权重,用以提取不同通道的关键特征,提高重建图像的精度。其次,构建树形聚合结构（tree aggregation structure network, TASN）网络模块,扩大感受野并提取丰富的多尺度特征信息,消除普通卷积所带来的伪影现象。在COMSOL5.3软件上建模仿真后,通过MATLAB2014a对图像进行重建。实验结果表明,重建图像误差系数降低至0.0256,相关系数提高至0.9717,与传统算法和CNN算法相比,具有更高的图像重建质量。     

On measuring network robustness for weighted networks

Knowledge and Information Systems - Network robustness measures how well network structure is strong and healthy when it is under attack, such as vertices joining and leaving. It has been widely...     

Saliency guided self-attention network for pedestrian attribute recognition in surveillance scenarios

Pedestrian attribute recognition is often considered as a multi-label image classification task. In order to make full use of attribute-related location information, a saliency guided sel-attention network ( SGSA-Net) was proposed to weakly supervise attribute localization, without annotations of attribute-related regions. Saliency priors were integrated into the spatial attention module ( SAM ). Meanwhile,channel-wise attention and spatial attention were introduced into the network. Moreover, a weighted binary cross-entropy loss ( WCEL) function was employed to handle the imbalance of training data. Extensive experiments on richly annotated pedestrian ( RAP) and pedestrian attribute ( PETA) datasets demonstrated that SGSA-Net outperformed other state-of-the-art methods.     

双脉冲激光诱导铝等离子体的双波长干涉诊断

双脉冲激光诱导等离子体在激光加工、元素检测、材料去除等领域有广阔的应用前景和发展空间,对其进行诊断具有重要意义。针对延迟双脉冲激光诱导铝等离子体的作用效果和影响机理,采用双波长干涉法对其时间演化规律展开研究。基于马赫-曾德尔干涉仪搭建了双波长干涉诊断系统,得到了双脉冲激光诱导等离子体干涉图。通过对干涉图的处理和分析,得到了等离子体电子密度随双脉冲激光延迟时间的变化规律。结果表明,随着双脉冲激光延迟时间的增加,第二束脉冲激光对等离子体电子密度的增强效果先加强后减弱。其中,双脉冲激光延迟时间为10 ns时,对等离子体电子密度的增强效果最强,在30 ns时刻,其中心区域平均电子密度可达6.49×1019 cm?3,相较于同等能量单脉冲激光诱导等离子体提升了26%。同时研究了延迟时间对第二束脉冲激光作用机制的影响。研究结果为双脉冲激光诱导等离子体的优化方向提供了参考。     

In Situ Management of Ions Migration to Control Hysteresis Effect for Planar Heterojunction Perovskite Solar Cells

As one of the most promising photovoltaic materials, the efficiency of inorganic–organic hybrid halide perovskite solar cells (PSCs) has reached 25.5% in 2020. However, the stability and hysteresis remain primary challenges before it can become a commercial photovoltaic technology. Therefore, those issues have drawn significant attention for photovoltaic applications. In this work, a study of the PSCs hysteresis improvement is presented based on a combination of first-principles simulations, scanning electron microscopy images, and time-dependent photocurrent measurements. It indicates the hysteresis led by the ion migration and accumulation is mainly localized at the two interfaces: one is between electron transport layer and active layer, and the other is between active layer and hole transport layer. Considering the massive defects at the grain boundaries (GBs), they lower the potential barriers significantly. The defect density at GBs is therefore reduced via the in situ passivation of PbI₂ crystals. The hysteresis index is decreased from 22.43% down to 1.04%, and results in an improvement in efficiency from 17.12% up to 20.10%. Following the understanding of defect-induced hysteresis, an approach to improve the hysteresis is provided, which can be integrated into the fabrication process and widely applied to enhance the performance of PSCs.     

n型单晶硅片的电阻率和扩散方阻对IBC太阳电池电性能的影响

叉指背接触式(IBC)太阳电池因正面没有金属栅线遮挡,具有较高的短路电流,且组件外观更加美观。但由于IBC太阳电池正负电极在背面交叉式分布,在制备过程中需要采用光刻掩模技术进行隔离,难以实现大规模生产。采用Quokka软件仿真模拟了电阻率和扩散方阻对n型IBC太阳电池效率的影响,并对不同电阻率和扩散方阻的电池片进行了实验验证,从n型单晶硅片电阻率的选择和扩散工艺优化方面为IBC太阳电池的规模化生产提供了理论基础。实验结果表明,电阻率为3~5Ω·cm、扩散方阻为70Ω/时,小批量生产的IBC太阳电池平均光电转换效率可达23.73%,开路电压为693 mV,短路电流密度为42.44 mA/cm²,填充因子为80.69%。