软切换FSO/RF链路混合编码调制算法性能分析

将自由空间光(FSO)通信链路的高速率优势与射频(RF)链路的可靠性优势互补结合,针对FSO/RF混合通信链路组网的物理层数据可靠传输问题,研究软切换机制下采用LDPC混合编码与2-PPM和16QAM调制的系统方案性能。混合系统FSO链路在Gamma-Gamma信道不同湍流强度与RF链路在Rician信道不同信噪比条件下的仿真结果表明,所述方案在软切换下达到1×10~(-6)误比特率时,不同条件下可获得1.3~8.0 dB不等的性能增益改善,显著提高在不同链路条件下FSO/RF混合通信系统的数据传输可靠性。     

锂离子二次电池

锂离子二次电池的体积比能量和质量比能量分别为金属氢化物－镍电池的约１．５倍和２倍。为充分发挥锂离子电池比能量高这一特点，生产电子设备的厂家在设计使用该类电池的整机线路时必须充分考虑到该类电池的有关特性、使用方法及电路设计原则，包括放电电流的控制、充电方式的选择、充电电压的限制以及避免过充放等     

自抗扰控制在永磁同步电机无速度传感器调速系统的应用

在永磁同步电机(PMSM)无速度传感器调速系统中,为解决负载扰动时控制性能变差的问题,提出用自抗扰控制技术的PMSM控制方案,将负载扰动归为未知扰动,用自抗扰控制(ADRC)来进行估计、补偿和控制.另外,为实现无速度传感器运行,利用ADRC中的扩张状态观测器(ESO)对扰动的估计值进行转速的辨识.仿真表明采用自抗扰控制方法不仅能够提高系统的响应速度,减小稳态误差,并且超调很小,能有效的抑制负载扰动带来的影响,而且ESO估计出来的转速精度高,对电机参数变化不敏感,鲁棒性好.     

嵌入式实时操作系统与网络构件的设计

提出了基于32位ARM的嵌入式实时操作系统与网络构件的设计方案，介绍了硬件结构、系统结构以及软件编程技巧。并针对嵌入式设备接入网络提出的“μC/OS-Ⅱ”解决方案：一套基于嵌入式实时操作系统的嵌入式网络软件开发平台。在此平台之上，可以方便进行嵌入式应用系统的开发。本文对系统作洋实的阐述，并重点介绍嵌入式实时操作系统肛μC/OS-Ⅱ应用TCP／IP时应进行合理的裁减。     

基于ZigBee网络的室内甲醛浓度远程实时监测系统设计

针对现有家用甲醛检测手段中存在的测量点单一,无法远程监测的问题,设计了一种基于无线传感器网络ZigBee的室内甲醛浓度远程实时监测系统,给出了整体系统的构建方案,构建了甲醛浓度检测的无线传感网络,通过ZigBee网络实现对家庭空间中多个测量点的实时采集,经过网络远传后通过LabVIEW监测程序实现数据的远程实时显示。经过测试,完成了对家庭环境中多个测量点的室内甲醛浓度的远程实时监测,验证了系统的可行性与可靠性。     

基于BlockChain的电子公文交换加密方法研究

电子公文交换系统,需要信息管理领域和类似于区块链中资源交换机制的相互协作,以此优化电子公文的管理机制。为了实现此目标论文提出了一种授权系统,以便利用区块链(blockchain)技术进行公文处理。所提出的系统可实现更可靠的监控管理功能和授权功能,部门之间相互委托控制器的功能,并具有数据访问安全系数高等特点。文中提出的方案在优化资源监视机制,提高授权安全级别,减少交易所消耗的资源方面,有一定参考价值。     

Degradation state analysis of the IGBT module based on apparent junction temperature

The multi-chip parallel insulated gate bipolar transistor (IGBT) is the core device in large-capacity power electronic equipment, but its operational reliability is of considerable concern to industry. The application of IGBT online degradation state analysis technology can be benefcial to the improvement of system reliability. The failure mechanism of IGBT devices is discussed in this paper, and a technique for analyzing the degradation state of IGBT based on apparent junction temperature is proposed. First, the distortion consistency of the voltage rise time in various failures is discussed, and the junction temperature dependence of the voltage rise time is then demonstrated. Subsequently, an apparent junction temperature model based on the voltage rise time is established (the ftting accuracy is as high as 94.3%). From the high-frequency model in the switching process of the device, an online extraction technology of key parameters (e.g., voltage rise time) is developed. Finally, an experimental platform for IGBT degradation state estimation is established, and the feasibility of IGBT degradation state estimation based on apparent junction temperature is proved, especially the degradation of bonding-wire and the gate-oxide-layer. The experimental results show that the proposed IGBT degradation state estimation technique based on apparent junction temperature is a reliable online estimation method with non-contact, high accuracy, and comprehensiveness.     

Degradation state analysis of the IGBT module based on apparent junction temperature

The multi-chip parallel insulated gate bipolar transistor (IGBT) is the core device in large-capacity power electronic equipment, but its operational reliability is of considerable concern to industry. The application of IGBT online degradation state analysis technology can be benefcial to the improvement of system reliability. The failure mechanism of IGBT devices is discussed in this paper, and a technique for analyzing the degradation state of IGBT based on apparent junction temperature is proposed. First, the distortion consistency of the voltage rise time in various failures is discussed, and the junction temperature dependence of the voltage rise time is then demonstrated. Subsequently, an apparent junction temperature model based on the voltage rise time is established (the ftting accuracy is as high as 94.3%). From the high-frequency model in the switching process of the device, an online extraction technology of key parameters (e.g., voltage rise time) is developed. Finally, an experimental platform for IGBT degradation state estimation is established, and the feasibility of IGBT degradation state estimation based on apparent junction temperature is proved, especially the degradation of bonding-wire and the gate-oxide-layer. The experimental results show that the proposed IGBT degradation state estimation technique based on apparent junction temperature is a reliable online estimation method with non-contact, high accuracy, and comprehensiveness.     

基于双路特征的宫颈细胞核分割

宫颈细胞核的分割问题研究对宫颈癌筛查诊断具有重要意义,但受边缘模糊及存在干扰物影响给分割任务带来了巨大挑战。针对此问题提出一种基于DeepLabV3+网络的细胞核分割方法,首先充分利用主干网络的输出进行多尺度特征融合,并引入注意力机制,构建了细胞团分割模型,以减少背景中干扰物对细胞核分割的影响;基于此设计了融合Transformer与ResNet50的双路特征提取模块,兼顾模型对全局信息的获取及低层上下文特征的敏感度,提高了模型对细胞核与干扰信息的辨别能力。实验结果表明,算法在宫颈细胞核的分割任务中取得了良好的分割效果,均交并比为0.832 9,较DeepLabV3+模型提高了2.33%,且与其他方法相比获得了更优的性能指标。     

基于三相AC/AC直接变换的AC/DC变换器研究

利用AC/AC矩阵式直接变换原理,分析了带有高频隔离变压器的AC/DC变换器电路工作模态。将基本空间矢量进行优化组合,解决了高频变压器双向磁化中的复位问题。从理论上推导了电压传输比,采用PI调节器实现了系统的闭环控制。通过数字仿真与实验验证了分析方法的正确性。