单相光伏并网逆变器无差拍控制的研究与仿真

光伏并网逆变器是光伏发电系统的主要部件,为了达到更好的效率输出更高质量的电能,对逆变器电流进行快速有效的控制尤为关键。该文简单介绍了当前光伏并网逆变器的几种常用控制方法及其基本思想,分析了并网逆变器的工作原理和无差拍控制方法的原理,给出了逆变器脉冲宽度的计算和参考电流的获取方法,通过MATLAB/Simulink软件仿真表明,无差拍控制在单相光伏并网逆变器控制中动态响应特性好,控制方便,电流跟踪电网电压波形好。     

LDMOS 功率器件在固态雷达发射系统中应用研究与实践

介绍了LDMOS 功率器件的特性,通过与传统Si 功率器件相比较,LDMOS 器件具有低成本、高增益、高线性度、热稳定性好和高可靠性等特点,在固态雷达发射系统中有广阔的应用前景,本文对LDMOS 功率器件在固态雷达发射系统中应用进行理论分析,并利用LDMOS 功率器件设计制作了P 波段300W 功放组件,对LDMOS 功率放大组件进行性能测试,根据试验数据分析应用LDMOS 功率器件对固态雷达发射系统的影响。     

TEOS LPCVD技术在SiC功率器件工艺中的应用

应用正硅酸乙酯(TEOS)LPCVD技术实现二氧化硅在SiC晶片表面的淀积,在一定程度上弥补了SiC氧化层过薄和PECVD二氧化硅层过于疏松的弊端。采用TEOS LPCVD技术与高温氧化技术的合理运用,既保证了氧化层介质的致密性和与SiC晶片的粘附能力,又提高了器件的电性能和成品率,同时避免了为获得一定厚度氧化层长时间高温氧化的不足。采用此技术后,SiC芯片的直流成品率得到提高,微波功率器件的对比流片结果显示微波性能也得到了明显的提升,功率增益比原工艺提高了1.5 dB左右,功率附加效率提升了近10%。     

等距多项式插值公式计算法

在分析了传统多项式数插值基础上,对等距情况的插值问题进行了研究,得到了等距情况的简单差商计算公式,计算量比传统方法小.最后通过实例,说明了该计算方法.     

Prestoring Lithium into Stable 3D Nickel Foam Host as Dendrite‐Free Lithium Metal Anode

Lithium metal is considered a “Holy Grail” of anode materials for high‐energy‐density batteries. However, both dendritic lithium deposition and infinity dimension change during long‐term cycling have extremely restricted its practical applications for energy storage devices. Here, a thermal infusion strategy for prestoring lithium into a stable nickel foam host is demonstrated and a composite anode is achieved. In comparison with the bare lithium, the composite anode exhibits stable voltage profiles (200 mV at 5.0 mA cm^?2) with a small hysteresis beyond 100 cycles in carbonate‐based electrolyte, as well as high rate capability, significantly reduced interfacial resistance, and small polarization in a full‐cell battery with Li₄Ti₅O₁₂ or LiFePO₄ as counter electrode. More importantly, in addition to the fact that lithium is successfully confined in the metallic nickel foam host, uniform lithium plating/stripping is achieved with a low dimension change (merely ≈3.1%) and effective inhibition of dendrite formation. The mechanism for uniform lithium stripping/plating behavior is explained based on a surface energy model.     

基于物联网的矿井温、湿度检测系统设计

为了实现对矿井温、湿度检测,提出了一种基于物联网的矿井温、湿度检测系统,并完成了系统的软硬件测试。硬件包括由分布在矿井中的测量节点组成的无线传感网络,由基站节点和监控终端设备相连接形成的监控装置,软件采用MSP430进行编程,并实现了温湿度信号检测。实际应用表明,该系统具有体积小,部署方便,成本低廉等优点。     

基于二维ISAR图像序列的雷达目标三维重建方法

该文基于刚体目标3维运动过程中的几何不变性,将因子分解法引入ISAR图像处理领域,成功实现了雷达目标从2维到3维的重建。文中基于卡尔曼滤波和最邻近数据关联准则完成不同姿态下2维散射中心的关联,应用因子分解法进行目标结构的分层重建,最后给出评判准则检验重建性能。仿真实验证明,该文方法简单易行,能够有效实现单天线ISAR 3维成像。     

基于ARM的矿井下漏电保护装置的研究

针对当前矿井下漏电保护问题,设计了以ARM作为核心的矿井下电网的漏电保护装置,该装置可以解决矿井下总馈电开关和分支馈电开关的漏电保护问题,同时改善了漏电保护装置的动作性能,弥补了过去许多保护装置的不足,应用价值很高。     

医院网络信息管理系统应急处理的探究

目前医院也逐渐开始智能化、网络化,医院网络信息管理系统的使用也越来越多。医生以及相应的管理人员再也不需要填写病例,开收各种单据了。很多医院都是采用一卡通形式,病人只需办理一张卡,里面就包含了病人的所有信息,包括病例信息,缴费信息等等,使用起来相当方便,也为医院节省了不少开支。伴随着医院网络信息管理系统的普遍使用,网络信息安全等问题也逐渐暴露出来,走入人们的视线。如何保证医院网络信息管理系统的安全同时也成为了业界所关注的问题。     

Enhanced Photocatalytic Hydrogen Evolution from Organic Ternary Heterojunction Nanoparticles Featuring a Compact Alloy-Like Phase

Organic semiconductor nanoparticles (NPs) are attractive photocatalysts to produce hydrogen from water splitting. Herein, a ternary strategy of incorporating crystalline n-type molecule IDMIC-4F into the host system made of p-type polymer PM6 and n-type molecule ITCC-M is demonstrated. ITCC-M and IDMIC-4F form compact alloy-like composite with shorter lattice spacing in the ternary p/n heterojunction NPs, resulting in enhanced exciton dissociation and charge transfer characteristics. As the result, an unprecedented hydrogen evolution rate (HER) of 307 mmol h⁻¹ g⁻¹ and a maximum apparent quantum efficiency of 5.9% at 600 nm are achieved in the optimized ternary NPs (PM6:ITCC-M:IDMIC-4F = 1:1.3:0.2), which is among the highest HER from organic photocatalysts to the best of the authors’ knowledge. The alloy-like composite also improves the operational stability of ternary NP photocatalysts. This study shows that synergizing two compatible n-type small molecules to form alloy-like composite is a promising approach to design novel organic photocatalysts for boosting the photocatalytic hydrogen evolution efficiency.