小型宽带微带天线的设计研究

针对移动通信终端小型化、集成化的发展趋势,本文提出一种中心频率为7.3 GHz的小尺寸宽频带天线.基于微带天线理论及单极天线的典型结构,改变三维结构、平面形状及介质的宽度,设计出一种新型的小型天线.考虑到影响天线特性的相关因素,利用HFSS11软件进行仿真优化,结果表明,该天线大小仅为16 mm×17 mm,绝对带宽可达3.2 GHz(S11＜-10 dB),远远超过了500 MHz.为一宽带小型天线.     

六相感应电动机制动仿真及分析

建立六相感应电动机在两相同步旋转d-q坐标系下的动态数学模型,并分析六相电压源型逆变器的空间矢量脉宽调制(SVPWM)技术。在MATLAB/SIMULINK环境下,构建SVPWM电压源型逆变器供电的六相感应电动机的仿真模型,分别进行六相感应电动机能耗制动、反接制动和回馈制动的动态仿真,并分析这三种制动方式的特点,为电力传动系统的设计提供理论依据。     

基于AD7150微位移电容传感器的研究

利用了集成芯片AD7150完成了对微位移电容传感器的电容采样。对AD7150芯片设计了相应的外接电路,为了增强电路的抗干扰能力,加入相应滤波电路;通过单片机模拟I2C通信方式来进行AD7150的读写控制。测量结果给出了10 pF以下不同标称电容值的电容,误差在2.5%以内。初步实验结果表明,当接入双叉电容传感器探头时,电容值随测量距离的增大而增加;在不同位移量下,传感器的灵敏度不同,距离越近,灵敏度越高,最大灵敏度为686 fF/mm,给出了不同情况下的灵敏度分布,并总结了影响电容传感器工作的电路要点。     

全息双频光栅及其应用

本文介绍全息双频光栅用于光场相干性,透镜几何象差,物体表面形状和物体振动等测量方面的原理,并给出相应的实验结果。     

应用PSCAD软件对有源电力滤波器进行设计与仿真

有源电力滤波器功能强大,作为电力电子设备中重要的组成部分,可以较好的实现谐波的滤除,实现无功的补偿.并且其补偿特性优于无源滤波器.本文用PSCAD对投入有源电力滤波器的电力系统的运行过程进行仿真,控制系统基于瞬时无功功率理论设计,给出负荷电流发生突变时的动态响应曲线.通过仿真得出:APF在电网的谐波抑制以及无功补偿方面特性优良、模型正确、控制系统可行.     

用户设备分类的毫米波异构网络性能研究

针对多层异构网络中基站簇造成的干扰问题,本文提出了一种对用户设备(user equipment,UE)进行分类建模的方法。首先,将处在通信热点区域的毫米波双层异构网络中密集部署的微微基站、毫微微基站以及UE构建成独立的非齐次泊松簇过程;然后,根据毫米波的特点建立了扇形天线模型和视距球传播模型并给出了簇内和簇间干扰的分布距离;此外,通过干扰的拉普拉斯变换以及信号与干扰加噪声比推导出基于UE分类和无UE分类的下行链路频谱效率解析表达式。仿真结果表明,所提出的基于UE分类方案的性能优于无UE分类方案的性能,显著提升了频谱效率。      

Peroxidase‐Like Nanozymes Induce a Novel Form of Cell Death and Inhibit Tumor Growth In Vivo

Nanomaterials with intrinsic enzyme‐like properties, termed nanozymes, have attracted significant interest, although limited information is available on their biological characteristics in cells or in vivo. Here, it is shown that nanomaterials with peroxidase‐like activity trigger a novel form of cell death through an ATP‐citrate lyase (ACLY)‐dependent rat sarcoma viral oncogene (RAS) signaling mechanism. The peroxidase nanozyme‐induced cell lethality, which is termed as nanoptosis, is morphologically and biochemically distinct from the currently well‐defined apoptosis, necrosis, autophagy, pyroptosis, and ferroptosis. It is revealed that nanoptosis is typically characterized by the massive accumulation of cellular vesicles, swelling mitochondria, and distinct chromatin condensation and margination. Using RNA sequencing and protein quantitative mass spectrometry, an ACLY‐dependent RAS signaling pathway is identified that mainly mediates this nanozyme lethality process, and it is observed that RAS‐knockout cells are highly resistant to nanoptosis. Finally, it is demonstrated that this newly discovered nanozyme lethality can be used as an effective therapeutic strategy for inhibiting tumor growth in vivo.     

光学扫描全息系统中提高光电探测系统测量精度的方法

给出了光扫描全息术的基本原理,记录时用实时ＦＺＰ与物理强度透射率发生卷积从而产生扫描全息图,再现时用与记录时相对应的ＦＺＰ与全息图信号发生卷积即可再现出物理的信息,提出了单光源、双光路的光源补偿光路,以消除由于光源的不稳定带来的实验误差。     

ICF固体激光驱动器前级系统中的脉冲整形

本文就国内外ＩＣＦ固体激光驱动器前级系统脉冲整形方案进行了综述,并报导了我们实验室关于脉冲整形的最新进展。     

Surface etching of 6H-SiC (0001) and surface morphology of the subsequently grown GaN via MOCVD

The correlation between surface morphological properties of the GaN epilayers and the surface conditions of 6H-SiC (0001) substrates etched in H₂, C₂H₄/H₂, and HCl/H₂ was studied. Etching 6H-SiC in H₂ produced a high quality surface with steps and terraces, while etching in HCl/H₂ produced either a rough surface with many pits and hillocks or a smooth surface similar to that etched in H₂, depending on the HCl concentration and temperature. The GaN epilayers were subsequently deposited on these etched substrates using either a low temperature GaN or a high temperature AlN buffer layer via MOCVD. The substrate surface defects increased the density and size of the “giant” pinholes (2–4 μm) on GaN epilayers grown on a LT-GaN buffer layer. Small pinholes (<100 nm) were frequently observed on the samples grown on a HT-AlN buffer layer, and their density decreased with the improved surface quality. The non-uniform GaN nucleation caused by substrate surface defects and the slow growth rate of planes of the islands were responsible for the formation of “giant” pinholes, while the small pinholes were believed to be caused by misfit dislocations.