宽带多谐振偶极子天线设计

根据目前无线通信系统发展小型化与宽带化的趋势,设计了一款具有多谐振点的宽带偶极子辐射天线。首先通过特征模理论分析倒T型导体结构得到两个谐振模式;然后在不影响倒T型导体结构谐振特性的前提下,引入寄生谐振偶极子单元;最后在3个谐振模式的电流共同最大处添加集总端口,同时激励3个谐振模式,得到3个谐振点的宽带谐振天线。天线的仿真与实测结果基本吻合,最终的工作带宽为1.8～2.56 GHz (相对带宽为34.9%)。由此,所设计的天线不仅结构简单,且性能方面良好,可广泛应用于无线通信系统中。     

基于电压定向的网侧变换器控制建模及仿真

通过建立三相静止坐标系和两相同步旋转坐标系下的DFIG双PWM网侧变换的数学模型。在电压矢量定向方式基础之上,在Matlab/Simulink中对电压、电流双闭环的控制方式及空间电压矢量脉宽调制方式和锁相环技术进行了模块搭建并仿真。仿真结果表明网侧变换器能够快速调节直流侧电压达到稳定,即能有效的实现整流,并在交流侧发生幅值扰动时,能快速维持在直流侧目标电压不平衡度范围内,且控制输入电流波形正弦。     

地下工程变形缝粘贴式卷材止水带防水新技术

从防水角度分析了建筑物变形缝的特征,提出地下工程变形缝防水的设计原则,介绍了地下工程变形缝防水新技术--粘贴式卷材止水带的性能特点及其应用.     

基于振动声调制的金属微裂纹定位方法研究

针对传统线性超声检测无法检测闭合微裂纹的问题,搭建了铝板的微裂纹振动声调制(VAM)检测系统,提取检测信号中的一阶旁瓣非线性信号和只滤除基波的全部非线性信号并对其时域反转,在ABAQUS有限元软件下,将其加载在铝板的无损模型上实现时间反转聚焦,获取铝板模型能量分布云图和各质点的位移信息,以此对微裂纹进行定位。结果表明,在时反信号的聚焦时刻原裂纹位置处有较强能量聚焦,只滤除基波的全部非线性信号聚焦效果优于一阶旁瓣非线性信号,振动声调制技术与时间反转方法结合能够实现对微裂纹的检测和定位。     

Ag-doped NiO porous network structure on Ni foam as electrode for supercapacitors

Ag-doped NiO porous network structure grown on Ni foam has been synthesized through a facile hydrothermal method. Then network structure is assembled by numerous interconnected superfine nanowires, and Ag is uniformly distributed in the body of NiO network. The unique porous network structure doped by conductive Ag and the direct integration of electrode materials on Ni foam current collector provide efficient pathways for electron transport and electrolyte ions diffusion. The electrochemical results demonstrate that the Ag-doped NiO electrode exhibits a specific capacitance of 570.7 F g^?1 and excellent cycling stability. The Ag-doped NiO electrode with relatively high electrochemical performance is a promising candidate for the supercapacitor electrodes. These results can also provide strategies to develop advanced electrode materials supercapacitor applications.     

基于深度神经网络的电影彩色化研究

针对电影彩色化面临着上色质量和时序稳定性的双重挑战,提出一种带有循环结构的生成对抗网络,可用于电影的自动彩色化,不需要任何参考帧和人工干预.该网络基于经典的条件生成对抗网络:生成器用于生成彩色图像,完成彩色化任务;鉴别器用于鉴别真伪,提升生成器性能.引入循环结构和时序一致性损失,用于整合时序信息,解决上色的稳定性问题.实验结果表明,该方法在保证单帧图像上色的同时,可以有效减少生成的电影序列中的闪烁现象.     

Self-supported N-doped carbon nanonet integrated on carbon paper for gas diffusion electrode

This paper reports a novel synthesis route to prepare an integrated gas diffusion electrode (I-GDE) consisting of self-supported N-doped nanonet by pyrolyzing polyaniline on carbon paper via the electrodeposition of aniline. Electrochemical experiments suggest that the integrated structure apparently improves the mass transport, electrical conductivity in the oxygen reduction reaction performance. The peak current density of the I-GDE achieves 0.71 mA cm^?2, which is almost two times to the conventional ink-based electrode fabricated with the same material under the same conditions.     

Development of Ti bipolar plates with carbon/PTFE/TiN composites coating for PEMFCs

A highly corrosion resistant and conductive carbon/PTFE/TiN composite coating on Ti bipolar plates is prepared by a two-step hydrothermal and impregnation process. The composite coating exhibits a full coverage with uniformly distributed PTFE and TiN particles when 0.1 mol/L of glucose is used as carbon source and 10 wt % PFTE + 3 g/L TiN suspension as impregnating solution. The as-prepared composite coating film shows 0.009 μA cm^?2 of corrosion current density and 13 mΩ cm² of ICR in the simulated solution of proton exchange membrane fuel cells, respectively. Meanwhile, the potentiostatic polarization test shows that the corrosion current density of the composite coating is below 1 μA cm^?2 under real PEMFC working conditions of the cathode (0.6 V) and anode (?0.1 V). Additionally, the composite coating enhances hydrophobic property with a static contact angle of 120.2°and 115.5°before and after polarization test, respectively. In summary, the Ti substrate with carbon/PTFE/TiN composite coating shows a great potential application as bipolar plates of PEMFCs.     

混凝-光催化联用技术处理造纸废水的研究

采用混凝-光催化联用技术对造纸废水进行了处理和研究,讨论了各种铝盐及铁盐无机絮凝剂与有机絮凝剂复配后对造纸废水的处理效果、纳米TiO2光催化剂的制备条件及其对光催化性能的影响以及混凝-光催化联用过程中纳米TiO2投加量和光照时间等因素对造纸废水CODcr去除率的影响。     

电网电压不对称跌落下DFIG的双dq粒子群优化控制

为了改善DFIG机组的故障穿越能力,首先分析了故障下DFIG机组的动态变化过程。针对电网电压不对称跌落中的单相电压跌落,在Simulink环境下搭建了基于双d-q正、负序分解的改进转子侧及网侧变换器模型,应用粒子群算法对PI调节器的参数进行全局优化,并将传统的控制策略与改进控制策略进行仿真对比。仿真结果表明,在跌落后电压k值范围为0.45~1p.u.内,改进的控制策略可以有效地抑制有功、无功的二倍频波动,增强机组对电网故障冲击承受能力,提高DFIG机组运行的稳定性。