软开关技术的发展及其现状

详细地介绍了软开关技术发展的历史及最新研究现状,其中包括准谐振电路、零开关PWM电路和零转换PWM电路,指出了软开关技术的新进展,并给出了部分典型电路。     

用于空间光通信的宽带LiNbO3行波调制器

用于空间光通信的宽带LiNbO3行波调制器,采用变频技术将Ka频段的信号变频到较低频率,再直接调制光波.并通过理论分析、分布电容求解及CPW结构的优化得到Ka波段微波光调制器的主要技术参数.其跟踪和数据中继卫星之间采用激光链路,并论证了宽带LiNbO3行波调制器用于空间光通信的可行性.     

基于正交编码的M元非正弦扩频调制方法

为了提高非正弦时域正交调制通信系统的性能,增强抗干扰能力,将M元扩频技术引入到非正弦时域正交调制通信系统,提出了一种基于正交编码的M元非正弦时域正交扩频调制方法.采用理论推导和数值仿真的方法,分析了该系统在加性高斯白噪声信道下的误码性能和频带利用率.结果表明：该方法能够有效提高系统的误码性能,增强系统的抗干扰能力.     

一种电磁环境量化分析方法

提出了一种电磁环境量化分析的新方法.该方法充分考虑了电磁环境信号的极化方式、调制方式,给出了极化因子、调制因子的内涵和定义基于不同极化方式、调制方式之间影响特性的理论分析和仿真,给出了典型电磁环境的极化因子、调制因子及其变化特性.所得成果为深入研究复杂电磁环境的量化分析和评估方法提供了积极的理论探索.     

宽带高斯型功率谱噪声信号相关特性分析

宽带噪声雷达具有良好的抗干扰和低截获性能.传统的窄带相关函数由于忽略了运动目标的多普勒色散效应而无法准确分析宽带信号的相关特性.本文以宽带噪声调频雷达测量高速目标为研究背景,推导了宽带相关函数均值的解析表达式,并对其进行了仿真验证.在此基础上分析得出,当多普勒色散积较大时宽带相关函数具有双峰特性,并揭示了其产生原因,指出了双峰位置与多普勒色散积及相对带宽之间的关系.为宽带高斯谱噪声雷达的分辨力和检测性能分析以及系统的参数设计提供了理论基础.     

基于双调频斜率的分布式星载雷达波形设计

在分布式星载雷达系统中,为了获得分集增益和高分辨性能,要求各雷达发射的波形具有较强的正交性和较低的多普勒敏感性.通过对双调频斜率(Double Frequency Slope,DFS)信号的自相关性、距离分辨率、互相关性以及多普勒容忍性等性能的研究,推导出该波形各参数之间的关系.在此基础上,结合分布式星载雷达系统的要求提出了基于DFS信号的波形参数设计方法,并设计出具有正交性和低多普勒敏感性的DFS信号波形.研究结果表明：在信号时宽不变的情况下,增大各子信号间的调频斜率差可以提高多个DFS波形间的正交性;而要使DFS波形具有较低的多普勒敏感性,则可以通过增大信号带宽或减小调频斜率差来达到.仿真结果表明：利用波形参数间的相互关系设计出的DFS信号波形,能够较好地满足分布式星载雷达系统的要求.     

Red and Blue Light Differently Influence Actinidia chinensis Performance and Its Interaction with Pseudomonas syringae pv. Actinidiae

Light composition modulates plant growth and defenses, thus influencing plant–pathogen interactions. We investigated the effects of different light-emitting diode (LED) red (R) (665 nm) and blue (B) (470 nm) light combinations on Actinidia chinensis performance by evaluating biometric parameters, chlorophyll a fluorescence, gas exchange and photosynthesis-related gene expression. Moreover, the influence of light on the infection by Pseudomonas syringae pv. actinidiae (Psa), the etiological agent of bacterial canker of kiwifruit, was investigated. Our study shows that 50%R–50%B (50R) and 25%R–75%B (25R) lead to the highest PSII efficiency and photosynthetic rate, but are the least effective in controlling the endophytic colonization of the host by Psa. Monochromatic red light severely reduced ΦPSII, ETR, Pn, TSS and photosynthesis-related genes expression, and both monochromatic lights lead to a reduction of DW and pigments content. Monochromatic blue light was the only treatment significantly reducing disease symptoms but did not reduce bacterial endophytic population. Our results suggest that monochromatic blue light reduces infection primarily by modulating Psa virulence more than host plant defenses.     

Siponimod Modulates the Reaction of Microglial Cells to Pro-Inflammatory Stimulation

Siponimod (Mayzent^®), a sphingosine 1-phosphate receptor (S1PR) modulator which prevents lymphocyte egress from lymphoid tissues, is approved for the treatment of relapsing-remitting and active secondary progressive multiple sclerosis. It can cross the blood–brain barrier (BBB) and selectively binds to S1PR1 and S1PR5 expressed by several cell populations of the central nervous system (CNS) including microglia. In multiple sclerosis, microglia are a key CNS cell population moving back and forth in a continuum of beneficial and deleterious states. On the one hand, they can contribute to neurorepair by clearing myelin debris, which is a prerequisite for remyelination and neuroprotection. On the other hand, they also participate in autoimmune inflammation and axonal degeneration by producing pro-inflammatory cytokines and molecules. In this study, we demonstrate that siponimod can modulate the microglial reaction to lipopolysaccharide-induced pro-inflammatory activation.     

三电平变换器PWM控制通态损耗分析

为了进一步优化变换器的热设计,分析研究了电压源中点钳位式三电平变换器的通态损耗,并提供了分析多电平变换器通态损耗的思路:根据电流、电压关系确定器件导通规律,进而求出器件通态占空比,并在此基础上推导出用于分析计算的通态损耗表达式.由所推导的表达式对正弦脉宽调制和空间矢量脉宽调制下的三电平变换器通态损耗进行了分析比较,并得到一些有意义的结论.     

基于虚拟电网磁链定向的电压型PWM变换器研究

为了简化电压型PWM变换器采样电路的复杂程度,提高其抗扰动性能及降低成本,研究了一种基于虚拟电网磁链定向的电压型PWM变换器网侧无电网电压传感器控制策略,给出了一种虚拟磁链观测器误差补偿方法。仿真结果表明系统有很好的控制性能,给出的误差补偿方法可以很好地解决虚拟磁链定向时的稳态误差问题。