LED汽车前大灯散热器正交优化设计与分析

设计了一种LED汽车前大灯散热器结构,该结构主要由一条通风管和一台无叶风扇组成.在SolidWorks软件中建立该散热结构模型,并导入FloEFD软件进行散热仿真,得到LED结温温度为148℃.提出在通风管中填充矩形翅片和填充蜂窝结构两种改进方案.仿真结果表明,采用两种改进方案后LED汽车前大灯的结温温度分别下降至102.01℃和86.20℃.对填充蜂窝结构方案进行正交优化试验,分析得出影响该系统散热性能的因素依次为:蜂窝等效直径、蜂窝类型、填充长度、壁厚和通风管长度.按照该顺序优化参数值,得到最优散热结构.仿真结果表明,经过正交优化后,LED汽车前大灯的温度降为75.17℃,进一步提高了整体结构的散热性能.最后分析了该结构的基板温度与风速的关系,结果表明当风速低于5m/s时,温度随着风速的增大急剧降低,当风速高于5m/s时,温度下降趋势相对缓慢.     

Bi2Te3/Sb超晶格纳米线的外延生长和热电测量

通过脉冲电沉积,外延生长出小单元长度的Bi₂Te₃/Sb超晶格纳米线.借助哈曼方法,测量了超晶格纳米线阵列的热电性能,330 K时的ZT值可达0.15.研究了Bi₂Te₃/Sb超晶格纳米线阵列器件的制冷或者加热能力,发现器件的上下表面的最大温差可以达到6.6 K.     

基于二阶Loyt-Sagnac干涉仪的灵敏度增强温度传感器

通过在基于高双折射光纤Sagnac干涉仪的Sagnac环内增加一段高双折射光纤并控制两段高双折射光纤的熔接角度,设计制作了二阶Loyt-Sagnac干涉仪结构.利用Jones矩阵对反射谱特性进行了理论推导,对光束入射角度和高双折射光纤长度进行了优化,并对两种结构的干涉仪温度传感器进行仿真和实验.仿真结果表明,利用二阶Loyt-Sagnac干涉仪结构的游标效应,能提高其作为温度传感器时的灵敏度;实验结果证明,单段Sagnac环干涉仪温度传感器灵敏度为-1.46nm/℃,而使用二阶Loyt-Sagnac干涉仪的温度传感灵敏度为-17.99nm/℃,提高了约12.32倍.     

温度对奶粉荧光光谱的影响

采用荧光光谱和荧光寿命技术研究了温度对奶粉荧光特征的影响.通过比较奶粉与酪蛋白、乳糖及维生素的荧光光谱,确定了奶粉的荧光主要来自酪蛋白的贡献.随着温度的升高,奶粉和酪蛋白的荧光强度减小,其中幼儿配方奶粉和成人普通奶粉的荧光强度随温度升高减小的趋势基本相同,而婴儿配方奶粉的荧光强度随温度的升高出现了一个相对变化缓慢的平台区,酪蛋白的荧光强度随温度升高呈缓慢下降的趋势,下降的速度比奶粉的要缓.酪蛋白加热到90℃然后冷却至25℃,荧光强度部分恢复,说明一部分蛋白质的结构变化或者荧光基团的活性变化是可逆的.测量了不同温度下奶粉和酪蛋白的荧光寿命.奶粉和酪蛋白的荧光寿命曲线在双指数拟合之后,都有两个寿命,这两个寿命可能来自于色氨酸和苯丙氨酸.随着温度的升高,奶粉和酪蛋白的两个荧光寿命都减小.     

可双参量同时测量的光纤磁场传感器

设计并制作了一种马赫-曾德尔干涉仪(Mach-Zehnder Interferometer,MZI)与光纤布喇格光栅级联的光纤磁场传感器,其中MZI由相当于分光器的锥结构和相当于耦合器的花生锥结构级联组成,封装在填充了磁流体的毛细管中.由于磁流体的有效折射率会随着外界磁场强度的改变而变化,故可通过观察干涉谱的特征波长的变化来测量外界磁场强度,而光纤布喇格光栅透射峰对磁场强度不敏感.当磁场强度由0mT变化到20mT时,马赫-曾德尔干涉峰的灵敏度为0.11nm/mT.温度特性实验测得马赫-曾德尔干涉峰和光纤布喇格光栅透射峰的温度灵敏度分别为0.401 5nm/℃和0.011 4nm/℃.因此,可利用敏感矩阵实现双参量同时测量.     

法布里-珀罗标准具和共焦球面扫描干涉仪的调节

观察法布里—珀罗标准具和共焦球面扫描干涉仪在共焦前后的多光束干涉图像,根据干涉条纹的变化和干涉仪频谱信号强弱进行精确调焦的方法,提高了实验效率并且得到了较好的实验结果。     

模型飞行验证系统测控与信息传输技术研究

模型飞行验证系统是为更加有效地开展模型自由飞试验研究而设计的通用试验系统,测控(TT C)与信息传输系统是其信息保障的核心。本文在充分考虑模型自由飞试验特点的基础上,重点研究了模型飞行验证系统研制过程中的测控与信息传输技术,介绍了其工作原理及实现方法,并对部分结果进行分析。     

Full-fledged proteomic analysis of bioactive wheat amylase inhibitors by a 3-D analytical technique: Identification of new heterodimeric aggregation states

Wheat proteinaceous alpha-amylase inhibitors (alpha-AIs) are increasingly investigated for their agronomical role as natural defence molecules of plants against the attack of insects and pests, but also for their effects on human health. The wheat genomes code for several bioactive alpha-AIs that share sequence homology, but differ in their specificity against alpha-amylases from different species and for their aggregation states. Wheat alpha-AIs are traditionally classified as belonging to the three classes of tetrameric, homodimeric and monomeric forms, each class being constituted by a number of polypeptides that display different electrophoretic mobilities. Here we describe a proteomic approach for the identification of bioactive alpha-AIs from wheat and, in particular, a 3-D technique that allows to best identify and characterize the dimeric fraction. The technique takes advantage of the thermal resistance of alpha-AIs (resistant to T > 70 degrees C) and consists in the separation of protein mixtures by 2-D polyacrylamide/starch electrophoresis under nondissociating PAGE (ND-PAGE, first dimension) and dissociating (urea-PAGE or U-PAGE second dimension) conditions, followed by in-gel spontaneous reaggregation of protein complexes and identification of the alpha-amylase inhibitory activity (antizymogram, third dimension) using enzymes from human salivary glands and from the larvae of Tenebrio molitor coleopter (yellow mealworm). Dimeric alpha-AIs from Triticum aestivum (bread wheat) were observed to exist as heterodimers. The formation of heterodimeric complexes was also confirmed by in vitro reaggregation assays carried out on RP-HPLC purified wheat dimeric alpha-AIs, and their bioactivity assayed by antizymogram analysis. The present 3-D analytical technique can be exploited for fast, full-fledged identification and characterization of wheat alpha-AIs.     

Influence of temperature on performance of an anaerobic sequencing biofilm batch reactor with circulation applied to treatment of low-strength wastewater

The effect of temperature on the performance of an anaerobic sequencing biofilm batch reactor (ASBBR) with liquid-phase recirculation was assessed. Assays were performed using a recirculation velocity of 0.20 cm/s, 8-h cycles, and an average treated synthetic wastewater volume of 2 L/cycle with a concentration of 500 mg of Chemical Oxygen Demand (COD)/L. Operation temperatures were 15, 20, 25, 30, and 35°C. At 25, 30, and 35°C, organic matter removal efficiencies for filtered samples ranged from 81 to 83%. At lower temperatures, namely 15 and 20°C, removal efficiency decreased significantly to 61 and 65%, respectively. A first-order model could be fitted to the experimental concentration profile values. The first-order kinetic parameter value of this model varied from 0.46 to 0.81 h¹ considering the lowest and highest temperature studied. Moreover, analysis of the removal profile values allowed fitting of an Arrhenius-type equation with an activation energy of 5715 cal/mol.     

Enantiomeric quality control of antihistamines in pharmaceuticals by affinity electrokinetic chromatography with human serum albumin as chiral selector

The present paper deals with the enantiomeric separation of six antihistaminic enantiomers by affinity electrokinetic chromatography (AEKC)-partial filling technique using human serum albumin (HSA) as chiral selector. A multivariate optimization approach of the most critical experimental variables in enantioresolution, running pH, HSA concentration and HSA plug length (SPL) was carried out since there are interactions between variables that could not be considered in an univariate optimization. The estimated and experimental resolution values obtained for antihistaminic enantiomers varied from 1.13 (for orphenadrine) to 2.15 (for brompheniramine). The optimum experimental conditions for enantioresolution of each compound were: brompheniramine, pH 8.5, [HSA] 180 μM, SPL 180 s; chlorcyclizine, pH 6.5, [HSA] 180 μM, SPL 150 s; chlorpheniramine, pH 8.25, [HSA] 160 μM, SPL 150 s; hydroxyzine, pH 7.0, [HSA] 180 μM, SPL 150 s; and orphenadrine, pH 7.8, [HSA] 160 μM, SPL 150 s. pH and the quadratic term of pH seem to be the most critical factors that determine enantioresolution of antihistamines. The validity of the developed methodologies to enantiomeric quality control of antihistamines in pharmaceutical formulations is demonstrated analyzing the content of brompheniramine, chlorpheniramine and hyroxyzine enantiomers in commercially available pharmaceutical formulations containing racemic mixtures of compounds. Resolution, accuracy, reproducibility, cost and sample throughput of the proposed methodologies make them suitable for quality control of the enantiomeric composition of antihistamines in pharmaceutical preparations.