DSP Based Optimal Switching Pattern SVPWM Technique Study and Realization

This paper presents a DSP based optimal switching pattern SVPWM （Space vector pulse width modulation） technique. Under this switching mode, the inverter PWM period begins and ends with zero voltage vector, which can effectively avoid the voltage vector sharp change problem in the PWM period and inverter voltage sector. The optimal switching pattern SVPWM technique reduced the inverter switching depletion and smoothed vector change in the PWM period. The inverter output distortion was been reduced. To prove the equivalence of optimal switching pattern SVPWM and carrier-based PWM, the carrier-based PWM form and zero-sequence signal of the optimal switching pattern SVPWM has been deduced. Finally, experiment has been taken to prove those ideal analysed in this paper.     

不同表面基团的纤维素纳米晶体薄膜在不同磁场下的光学特性响应

本文探究了磁场对不同表面基团的纤维素纳米晶体(Cellulose Nanocrystal,CNC)薄膜光学特性的影响。以硫酸化纤维素纳米晶体(S-CNC)为原料,通过2,2,6,6-四甲基哌啶-1-氧基自由基(TEMPO)氧化制备表面带有羧基的纳米纤维素(T-CNC),并采用傅里叶红外光谱、扫描电子显微镜和Zeta电位对其基本结构进行表征。并在无磁场、垂直磁场、倾斜磁场、水平磁场四种模式下观察磁场对不同表面电荷CNC薄膜的影响。结果表明,T-CNC表面带有羧基,S-CNC表面带有硫酸酯基。由于表面电荷不同,使得T-CNC电位绝对值低于S-CNC。两种CNC由于表面电荷差异表现出不同的自组装模式,其中T-CNC为同心自组装,S-CNC为手性向列自组装,且自组装模式的差异不因磁场而改变。但T-CNC与S-CNC在自组装过程中的排列均受到磁场影响。随着磁场取向的不同,两种薄膜的颜色因CNC的排列发生变化而受到影响,其中垂直磁场对两种CNC薄膜的影响最为显著,能使薄膜中CNC的排列更加均匀紧密,从而提升薄膜颜色的均匀性。不同表面基团CNC的自组装薄膜在不同磁场下的颜色响应研究为后续对CNC虹彩...     

Mesoporous Nanoarchitectures for Electrochemical Energy Conversion and Storage

Mesoporous materials have attracted considerable attention because of their distinctive properties, including high surface areas, large pore sizes, tunable pore structures, controllable chemical compositions, and abundant forms of composite materials. During the last decade, there has been increasing research interest in constructing advanced mesoporous nanomaterials possessing short and open channels with efficient mass diffusion capability and rich accessible active sites for electrochemical energy conversion and storage. Here, the synthesis, structures, and energy-related applications of mesoporous nanomaterials are the main focus. After a brief summary of synthetic methods of mesoporous nanostructures, the delicate design and construction of mesoporous nanomaterials are described in detail through precise tailoring of the particle sizes, pore sizes, and nanostructures. Afterward, their applications as electrode materials for lithium-ion batteries, supercapacitors, water-splitting electrolyzers, and fuel cells are discussed. Finally, the possible development directions and challenges of mesoporous nanomaterials for electrochemical energy conversion and storage are proposed.     

Giant dielectric phenomenon of Ba0.5Sr0.5TiO3/CaCu3Ti4O12 multilayers due to interfacial polarization for capacitor applications

Ba_0.5Sr_0.5TiO₃/CaCu₃Ti₄O₁₂ (BST/CCTO) multilayers with different stack sequences were deposited on LaNiO₃(LNO)/SiO₂/Si substrates by a sol-gel process. The dielectric properties of BST/CCTO multilayers are significantly affected by the deposition sequence, the layer thickness and the impurities, effects that are interpreted using the Maxwell-Wagner interfacial polarization model. Impurities are generated by elemental interdiffusion at the interfaces of BST/CCTO, and less at the interfaces of BST/LNO and CCTO/LNO. The dielectric permittivity of the CCTO/BST/LNO/SiO₂/Si sample reaches 352,200 at 10 kHz, and stabilizes above 20,000 in the range of 100 kHz to 1 MHz. This work demonstrates an effective approach to enhance dielectric properties for film capacitor applications by constructing multilayers with specific deposition sequences and layer thicknesses.     

大型阵列天线铝骨架制造工艺

概述了某型号雷达天线骨架的结构特点，分析了制造工艺难点，论述了该骨架的制造工艺过程。产品满足了设计要求，并且适宜批量生产。     

板壳结构开拓应用的一些方案

从结构杂交的思想出发,针对空间结构研究和应用中的某些情况,探讨板壳结构改进性能,开拓应用的问题,提出板壳结构杂交应用的一些方案。     

曲,直光纤导波的比较分析

利用矢量场法,在弯曲半径大于芯半径的条件下,较为精确求解了Ｍａｘｗｅｌｌ方程,得到了导模表达式,并与直光纤进行了比较,得出了它们之间的相同的相与相异。为光纤弯曲损耗的理论分析及计算提供了依据。     

LDH-热膨胀微胶囊的合成及发泡EVA复合材料的综合性能

在悬浮聚合的条件下,以壳层负载的形式合成水滑石LDH-热膨胀微胶囊,并将其作为发泡剂制备发泡乙烯-醋酸乙烯酯(EVA)复合材料.采用扫描电镜与能谱联用仪(SEM-EDS)、热重分析仪(TG)等研究了LDH-热膨胀微胶囊的膨胀性能及发泡EVA复合材料综合性能的变化规律.结果表明:存在于微胶囊表面的LDH提高了其膨胀温度,膨胀倍率增大五倍以上,稳泡温程达到了36℃左右.添加LDH-微胶囊明显改善了发泡EVA复合材料的发泡质量和力学性能,其泡孔平均直径为52.4μm,拉伸强度较添加未改性微胶囊时提高了26.3％.LDH-微胶囊/EVA复合材料具有优良的保温性能,导热系数为0.0908 W/(m·K).     

穿线钢管防腐工艺自动化生产线的研究

针对穿线多管现行涂锌工艺存在的问题和管内防腐层喷涂工艺及ＰＬＣ控制自动喷涂机进行分析和研究,提出用高能浸涂,工艺取代镀锌工艺和管内喷涂工艺的设想。