频谱稀疏OFD-LFM弹头自旋微动特征重构方法

针对基于高分辨雷达技术的弹头自旋微多普勒特征问题展开研究。首先通过理论推导详细分析了OFD-LFM信号体制弹头自旋微多普勒在谱图上的表现形式,并得出相关结论,再结合压缩感知理论提出一种频谱稀疏OFD-LFM微多普勒谱图合成方法,该方法可在大幅减少OFD-LFM子载波数的前提下,准确重构出弹头自旋微多普勒特征曲线;同时有效抑制了谱图中的旁瓣影响。仿真实验结果表明了理论推导的正确性,证明了该文重构方法的有效性。     

基于特征金字塔和多任务学习的绝缘子图像检测

作为输电线路巡检中的关键技术,绝缘子的高效检测在维护输电系统安全稳定运行中发挥着重要作用.针对现有方法存在的易丢失目标位置信息,对于复杂背景下的绝缘子检测精度低等缺点,提出一种基于特征金字塔和多任务学习的绝缘子检测方法.通过融合高、低维度特征信息来构筑特征金字塔,避免目标位置等细节信息的丢失,实现复杂背景中绝缘子的高效检测;引入多任务学习算法,进一步提升模型的泛化能力,提升绝缘子检测精度.利用无人机航拍所得的绝缘子实际图像进行实验,结果表明所提方法可将绝缘子检测精度提升至95.3％,具备较高的工程应用价值.     

Optical properties of nanosize aggregation of phenylene vinylene oligomers

In this paper, we report the experimental results on the optical properties of oligo-phenylene vinylenes (OPVs) formed in nanosize pores of porous silicon substrates. Strong modifications of the photoluminescence properties of nanosize aggregation of OPVs were observed at room temperature, such as a blue shift of the PL spectra, whereas the structure of the oligomers is preserved as proved by Raman scattering experiments. However, the penetration of the oligomers into the nanopores was found to depend on the conformation of the chains, which is, in turn, conditioned by the solvents, used to dissolve the oligomer powder.     

Expectations of indoor climate control

This paper discusses reassessment of indoor climate control in the context of current thermal comfort practice and research. We review the limitations of comfort models and standards with several examples. We examine how people's thermal sensation and preference may be influenced by culture and climate and associated issues of thermal expectations and adaptation. Finally, we discuss how incorporating these factors into future comfort standards might yield more ‘effective’ indoor climate control.     

电网电压不平衡条件下MMC控制策略的仿真比较研究

当电网电压不平衡时,交流侧的电流会出现不对称,有功功率和无功功率在模块化多电平变流器(MMC)外部出现二次波动,严重影响系统的稳定性和电源质量。因此,在电网电压不平衡条件下控制MMC是非常必要的。针对电网电压不平衡状态下的MMC交流侧三相电流不对称、有功功率二次脉动、无功功率二次脉动问题,对这3种控制目标下的参考电流分别进行了求解,并制定了传统PI控制、滑模控制、无源控制等控制策略。最后,在MATLAB/Simulink平台上仿真并比较3种控制策略的优缺点。     

氨制冷压力管道焊接接头质量检测及分析

氨制冷系统中压力管道是特种设备安全监管的核心,管道的焊接接头质量将直接影响整个氨制冷系统的运行安全。对氨制冷压力管道焊接接头进行缺陷及显微组织检测,分析焊接缺陷产生的原因以及对氨制冷管道服役安全造成的危害,并提出提高氨制冷管道焊接质量的建议。     

Mesenchymal stem cells differentiate into tenocytes by bone morphogenetic protein (BMP) 12 gene transfer

Rhesus bone marrow mesenchymal stem cells (MSCs) were transfected with the BMP12 gene by electroporation, and the phenotype of the transfected cells was identified by morphological observation and molecular biological assay. After transfection, cells became slender, and their processes became thinner and were interwoven into a network. There were more organelles in the transfected cells than in the parental MSCs. The transfected cells exhibited mRNA expressions of BMP12, collagen type I and scleraxis, but not collagen type III mRNA expression. Immunocytochemical analysis also showed the presence of collagen type I, but not collagen type III in the transfected cells. The transfected cells were positive for CD44 and negative for HLA-DR. Therefore, MSCs can be introduced to differentiate into tenocytes by BMP12 gene transfection, and bone marrow MSCs can serve as an alternative seed cell for application in tendon tissue engineering.     

DNA-based methods for food authentication

A variety of methods exist whereby the residual DNA content of food material can be used to unequivocally identify the nature of the product. Various techniques are described and discussed, mainly with reference to meat and fish. An attempt has been made to collate the species identified, comprehensively but not exhaustively. Emerging technologies have the potential to simplify the protocols involved with food authentication testing in the future, although the uptake of these by the food industry is liable to be limited by factors such as cost.