民用飞机机载软件复用适航审定方法研究

复用不同来源的软件数据至民用飞机机载软件及其不同的复用方式均对机载软件表明整体符合性存在影响.为降低软件复用带来的项目成本和合格审定风险,首先,对民用飞机机载软件复用进行分类,识别软件复用评估要素;其次,建立软件复用评估框架和流程,明确软件复用评估活动和次序;最后,从实际审查角度给出机载软件复用的审定要求,并给出软件复...     

子脉冲序列模式Er∶YAG激光消融牙本质的实验观察

研制了一台子脉冲序列模式Er∶YAG激光器,获得了每秒80个和100个子脉冲高能量激光输出,开展了不同脉冲宽度的子脉冲对离体牙本质的激光消融实验。实验中使用的是子脉冲序列模式激光器,其重复频率为20 Hz,脉冲包络能量为45 mJ,子脉冲宽度分别为20,30,40,50μs,在无冷却水雾条件下分别对比了子脉冲宽度对牙本质消融量、牙髓腔温升和坑洞组织形貌的影响。结果表明:在相同的激光脉冲能量下,较窄的子脉冲宽度不仅能够增加消融量,降低牙髓腔温升,从而延长操作时间,而且可以获得更好的消融坑洞组织形貌,牙小管的开放程度较高,有利于黏接修复治疗。     

基于目标检测与模糊匹配的非标船牌识别研究

基于卷积神经网络的YOLOv3(You Only Look Once v3)目标检测算法设计了一种基于目标检测及模糊匹配机制的非标船牌识别软件系统,并通过在船舶视频监控系统中的实际应用,验证了该船牌识别系统的可行性,提高了船舶铭牌识别的可靠性。YOLOv3目标检测算法将检测简化为一个回归问题,通过仅仅一个网络,就能从图像中得到物体的类别与概率,确保了识别的准确性与实时性。针对船舶非标铭牌锈蚀、遮挡等问题,创新点是在基于YOLOv3的非标船牌识别系统的实现框架之上,设计船名有限中文库与模糊匹配机制,有效解决了船牌识别准确率过低的问题,取得了较好的识别效果。     

基于同步电荷提取的高效多压电能俘获电路设计

本文提出了一种基于同步电荷提取的高效多压电能俘获电路(High Efficiency Multi-piezoelectric Energy Harvesting Circuit Based on Synchronous Electric Charge Extraction,EM-SECE).所提出的电路利用改进的正负峰...     

基于能力培养的“电路分析基础”课程教学过程设计

安徽三联学院是一所以培养学生各项能力为主要目标的应用型本科高校,教师在教授学生理论知识的同时更应注重培养学生的各项能力,文章以"电路分析基础"课程为例,说明在日常教学活动中如何通过对教学过程的设计,包括课前、课中及课后三部分的设计管理,体现对学生独立思考、分析计算、科学归纳等各项能力的培养,将能力提升融入课程教学里。     

基于大规模天线系统的多通道校准算法研究

文章首先详细地给出大规模天线系统技术优势,并详细给出宽带信号多通道校准基本原理和步骤;然后提出一种新的应用于大规模天线系统的多通道算法,算法实现性能能够将多路待校准通道准确按照参考通道进行校准拟合,并满足系统对多通道幅相一致性的指标要求。实测数据分析表明:多通道校准校准结果可以满足时延、幅度和相位指标要求,保证大规模天线系统的波束赋形和空分复用性能最优。     

认知双向中继网络在κ-μ衰落信道下的中断性能分析

针对认知双向中继网络在进行数据传输时面临的复杂无线信道场景问题,采用广义κ-μ分布构建认知双向中继网络中的视距和非视距无线传输信道,推导次网络在κ-μ衰落信道下的统一中断概率,并分析次网络在多种单一和混合衰落信道情况下的中断性能.仿真结果表明,无线信道的衰落程度对次网络的中断概率影响显著,依据衰落信道类型合理设置网络参...     

Parameter Blind Estimation of Frequency-Hopping Signal Based on Time–Frequency Diagram Modification

To effectively estimate the parameters of the multiple frequency-hopping signals, a blind parameter estimation method based on time–frequency diagram modification is proposed. Firstly, the observed signal is transformed to the time–frequency domain, using short time Fourier transform with overlapping windows. Then an energy detection method based on adaptive threshold is used to modify the time–frequency diagram, and the parameters of the frequency-hopping signals are finally obtained from the modified spectrogram. Theoretical analysis and simulation results show that the method proposed can get a clear time–frequency diagram at low signal-to-noise ratio (SNR), and its accuracy of parameter estimated is higher than that of previous methods. When SNR is ?10 dB, estimation errors of frequency, hopping time and hop duration is 0.0002, 0.0008 and 0.0013, respectively, which are about 1–2 orders of magnitude lower over the previous method.

     

一种适用于北斗短报文通信的天线波束指向算法

针对北斗短报文通信中载体天线波束指向北斗卫星的问题,该文提出一种天线波束指向算法。该算法根据载体所处的地理位置和姿态,计算出指向北斗卫星的天线波束指向角。根据载体天线的合成波束增益和所处地理位置的北斗卫星波束增益,选择出最优的北斗卫星,并将天线波束指向该卫星。该方法可以保证载体运动过程中,天线合成波束实时指向最优北斗卫星,最大限度地提高了北斗短报文通信性能。     

Intrinsic Structure Modification of Electrode Materials for Aqueous Metal-Ion and Metal-Air Batteries

In consideration of low cost, simple operation, safe reliability, and environmental benignity, aqueous rechargeable batteries (ARBs) have attracted great interest among portable electronic devices, energy storage, and power source batteries. As the key components of ARBs, the electrode materials lead to a crucial effect for the overall battery properties, such as working voltage, electrocatalytic activity, capacity, and cycling stability. However, owing to the highly reactive aqueous environment, the electrode materials typically demonstrate a series of issues, including active material dissolution, structural instability, and poor catalytic activity, restricting their application. So far, several researchers have devoted much effort to improve the properties of electrode materials for ARBs. In particular, intrinsic structure modification in terms of vacancy regulation, interlayer engineering, and element doping have been applied to optimize the electronic and phase structure of electrode materials, contributing to elevated ion diffusion, fast charge transfer, and adequate active sites for electrochemical reaction. In this review, recent reports are demonstrated about the intrinsic structure modification of electrode materials in aqueous metal-ion and metal-air batteries, focusing on various regulation strategies and functional mechanisms. Finally, a brief conclusion and perspective is presented to demonstrate constructive suggestions and opinions for further research.