球面折反射成像的内螺纹螺距视觉测量系统

为了实现内螺纹参数的非接触、自动化在线测量,本文以通孔螺母和盲孔螺母为检测对象,提出了一种基于球面折反射全景成像原理的内螺纹螺距参数的机器视觉测量系统。系统采集经球面折反射得到的图像,随后分割出完整的内螺纹区域;采用对比度受限的自适应直方图均衡化算法提高图像对比度,并采用中值滤波与双边滤波的组合来保护螺纹边界信息;再使用Zernike矩边缘检测算法确定每条螺纹的亚像素边缘;最终,基于折反射成像理论计算得到内螺纹螺距尺寸。与计量用螺纹综合测量机的螺距测量值进行了对比,实验结果表明该系统的平均测量误差为0.018 5 mm,满足工业生产中内螺纹螺距精度的要求,检测效率高,可用于内螺纹在线视觉检测。本研究为圆柱形内壁尺寸测量和缺陷检测提供了一种参考方案。     

基于双解码路径DD-UNet的脑肿瘤图像分割算法

针对医学图像中病灶区域尺度不一、边界模糊和周围组织强度不均匀所导致的分割精度降低问题,提出了一种基于双解码器的脑肿瘤图像分割模型。为了增强特征的表征力,提出了高阶微分残差模块并使用不同空洞率的扩张卷积用于提取特征编码,提高了网络模型的分割性能;引入上下文语义信息感知模块(multi scale dilation, MSD),从不同的目标尺度中提取更多的精细信息,提高了对结构细节信息的捕获能力,同时减少了编解码器之间的特征差异;在空间解码路径中使用选择性聚合空间注意力模块(spatial aggregation attention module, SAAM),增加了对有效空间特征的权重比例,减少了无效的特征干扰。在脑肿瘤数据集上进行了实验验证,实验结果表明,所提算法的Dice系数、平均交并比、敏感性、特异性、准确率等指标分别为：93.35%、90.71%、91.15%、99.94%、96.75%。     

基于无监督学习的低照度图像增强算法

针对目前低照度图像增强算法存在恢复细节丢失、网络复杂度高和配对数据集获取难度大等问题,提出了一种基于无监督学习的图像增强算法。在YIQ色彩空间中,通过构建的轻量化网络和幂指函数计算亮度通道Y的增强曲线,从而获得曝光较差区域增强和高光区域遏制的图像。该网络使用的无参考损失函数可以隐式地评估图像增强质量并驱动网络学习。实验对比结果表明,该算法在可训练参数和模型权重仅占9.5 k/88 kB的情形下,在视觉效果与图像质量指标上都取得了具有竞争力的结果。     

蓄意流量攻击下基于确定网络演算的互联电网自适应负荷频率控制策略

蓄意流量攻击通过抢占有限的网络带宽降低正常数据流的时效性。对于网络化负荷频率控制(load frequency control, LFC),流量攻击将造成稳定裕度下降、频率偏差幅度上升甚至越限事故。现有控制方案一般采用单一且固定的控制器保证最大攻击强度下的渐进稳定性,存在设计约束多、保守性大的缺点。因此提出了一种跟随攻击强度自适应调整控制器增益的LFC策略。首先,基于确定性网络演算,得到了无攻击场景下数据流传输延时上边界,并预设了一系列表征不同攻击强度的传输延时范围。其次,通过构造Lyapunov泛函,推导了针对每个攻击强度的控制器设计准则。最后,基于切换控制理论,确定了所提自适应方案所能容忍的最大攻击强度变化频率。仿真表明,与现有控制方案相比,所提方法的频率偏差幅度可下降12.60%,区域控制误差的绝对值误差积分可下降10.85%。     

数据驱动下具备高抗干扰能力的输电线路故障检测技术

为提高安全性和可靠性,提出一种具备高抗干扰能力的故障检测技术。建立典型柔性直流输电系统模型并分析了行波的区内外传播特性;推导行波电流公式并解析其区内外差异,为故障检测技术奠定了理论基础;提出基于行波电流弹性系数的方案并据此建立了故障检测技术。设置不同故障状态对该故障检测技术的可靠性和正确性进行验证,结果表明,所提方案具备较好性能,解决了传统方案高阻故障不灵敏的问题。     

Floating Catalyst Chemical Vapor Deposition Patterning Nitrogen-Doped Single-Walled Carbon Nanotubes for Shape Tailorable and Flexible Micro-Supercapacitors

Micro-supercapacitors (MSCs) as high-power density energy storage units are designed to meet the booming development of flexible electronics, requiring simple and fast fabrication technology. Herein, a fast and direct solvent-free patterning method is reported to fabricate shape-tailorable and flexible MSCs by floating catalyst chemical vapor deposition (FCCVD). The nitrogen-doped single-walled carbon nanotubes (N-SWCNTs) are directly deposited on a patterned filter by FCCVD with designable patterns and facilely dry-transferred on versatile substrates. The obtained MSCs deliver an excellent areal capacitance of 3.6 mF cm⁻² and volumetric capacitance of 98.6 F cm⁻³ at a scan rate of 5 mV s⁻¹ along with excellent long-term cycle stability over 125 000 circles. Furthermore, the MSCs show good performance uniformity, which can be readily integrated via connection in parallel or series to deliver a stable high voltage (4 V with five serially connected devices) and large capacitance (5.1 mF with five parallel devices) at a scan rate of 100 mV s⁻¹, enabling powering the light emitting displays. Therefore, this method blazes the trail of directly preparing flexible, shape-customizable, and high-performance MSCs.     

Ultrahigh Energy Storage Capacitors Based on Freestanding Single-Crystalline Antiferroelectric Membrane/PVDF Composites

Inorganic/organic dielectric composites are very attractive for high energy density electrostatic capacitors. Usually, linear dielectric and ferroelectric materials are chosen as inorganic fillers to improve energy storage performance. Antiferroelectric (AFE) materials, especially single-crystalline AFE oxides, have relatively high efficiency and higher density than linear dielectrics or ferroelectrics. However, adding single-crystalline AFE oxides into polymers to construct composite with improved energy storage performance remains elusive. In this study, high-quality freestanding single-crystalline PbZrO₃ membranes are obtained by a water-soluble sacrificial layer method. They exhibit classic AFE behavior and then 2D–2D type PbZrO₃/PVDF composites with the different film thicknesses of PbZrO₃ (0.1-0.4 µm) is constructed. Their dielectric properties and polarization response improve significantly as compared to pure PVDF and are optimized in the PbZrO₃(0.3 µm)/PVDF composite. Consequently, a record-high energy density of 43.3 J cm⁻³ is achieved at a large breakdown strength of 750 MV m⁻¹. Phase-field simulation indicates that inserting PbZrO₃ membranes effectively reduces the breakdown path. Single-crystalline AFE oxide membranes will be useful fillers for composite-based high-power capacitors.     

Lightweight deep learning methods for panoramic dental X-ray image segmentation

Neural Computing and Applications - Dental X-ray image segmentation is helpful for assisting clinicians to examine tooth conditions and identify dental diseases. Fast and lightweight segmentation...     

The research on channel estimation and signal-noise ratio estimation based on minimum error entropy kalman filter for single carrier frequency domain equalization system

In this paper, the channel estimation and signal-to-noise ratio (SNR) estimation technique of single-carrier frequency domain equalization (SC-FDE) system under low SNR in aeronautical multipath channel are studied, a SNR estimation algorithm which is easy to implement in engineering and an improved LS channel estimation algorithm based on Kalman filter using minimum error entropy (MEE-KF) are proposed. This paper first introduces the SC-FDE system and introduces the principle of MEE-KF, and then, the channel estimation flow based on MEE-KF is obtained by combining it with the traditional LS channel estimation algorithm, which makes the estimation results perform better. Simulation results show that after getting more accurate noise variance, the channel estimation results can better follow the changes of the channel after MEE-KF processing, so as to resist the doppler frequency offset effect and make the channel estimation results more accurate, that is the channel response results of the data part can be closer to the real situation, so that the communication performance of SC-FDE system has also been greatly improved.     

The Edge Effects Boosting Hydrogen Evolution Performance of Platinum/Transition Bimetallic Phosphide Hybrid Electrocatalysts

Platinum (Pt) is regarded as a promising electrocatalyst for hydrogen evolution reaction (HER). However, its application in an alkaline medium is limited by the activation energy of water dissociation, diffusion of H⁺, and desorption of H*. Moreover, the formation of effective structures with a low Pt usage amount is still a challenge. Herein, guided by the simulation discovery that the edge effect can boost local electric field (LEF) of the electrocatalysts for faster proton diffusion, platinum nanocrystals on the edge of transition metal phosphide nanosheets are fabricated. The unique heterostructure with ultralow Pt amount delivered an outstanding HER performance in an alkaline medium with a small overpotential of 44.5 mV and excellent stability for 80 h at the current density of −10 mA cm⁻². The mass activity of as-prepared electrocatalyst is 2.77 A mg⁻¹_Pt, which is 15 times higher than that of commercial Pt/C electrocatalysts (0.18 A mg⁻¹_Pt). The density function theory calculation revealed the efficient water dissociation, fast adsorption, and desorption of protons with hybrid structure. The study provides an innovative strategy to design unique nanostructures for boosting HER performances via achieving both synergistic effects from hybrid components and enhanced LEF from the structural edge effect.