Effect of electric fields on the ion current signals in a constant volume combustion chamber

Ion current sensing has the potential to become a promising combustion diagnostic technique for mass productive engines. In this paper, the effect of electric fields on ion current signals measured from a series of methane/air flames in a constant volume combustion chamber (CVCC) is investigated both experimentally and numerically. Based on simultaneous flame Schlieren imaging and ion current measurement, the relation between the flame/electrodes contact area and the ion current signal waveform is explored under different electric field configurations. A CFD model, which incorporates flame plasma hydrodynamics, neutral/charged species reaction kinetics and ion-electric field interactions, is constructed. The effect of the electric field on the ion distribution and the charged species flux are analyzed, and the signal amplitude and timing are well predicted under the equivalence ratio range of Ф?=?0.7–1.1. Besides, the behavior of electrons, which is normally neglected in previous studies, is also analyzed in this work. The results show that it will affect the signal as well. The electron produced in the flame front zone can hardly diffuse into the pre-flame zone (<?350?K) even its mobility is 3-4 order higher than those of the positive ions. Therefore, the anode of the ion probe, which placed in the pre-flame zone, cannot detect the ion current signal until it contacts the flame front.     

Periodic solution of a two-species competitive system with toxicant and birth pulse

In this paper, we study the existence of positive periodic solution of two-species competitive system with toxicant and birth pulse. A set of easily verifiable sufficient conditions are derived for the existence of at least one positive periodic solution of the above system by using the method of coincidence degree. Numerical simulations are also presented to illustrate the feasibility of our main results.     

The photodetector of Ge nanocrystals/Si for 1.55 μm operation deposited by pulsed laser deposition

The photodetector properties of a Ge nanocrystals detector fabricated by pulsed laser deposition and in situ rapid thermal annealing treatment at 600 °C have been studied. Strong optical absorption and photocurrent response of the detector are measured in the wavelength range 1.3-1.55 μm. The detector possesses a low dark current of 61.4 nA and a photocurrent responsivity of 56 mA/W at the reverse bias 5 V. The external quantum efficiency at 1.55 μm is estimated to be 15%. The stop wavelength of absorption spectra extends to 1.65 μm. It indicates that these kind of Ge nanocrystals devices can be used as a 1.3-1.55 μm near infrared detector.     

奇异二阶拟线性椭圆型方程Dirichlet问题（Ⅲ）

本文应用摄动方法、上下解方法、截断函数方法，得到了一类带奇异项的二阶拟线性椭圆型方程Ｄｉｒｉｃｈｌｅｔ问题正解的存在性和正则性，发展了文献［１］－［７］的相应工作．     

亚波长消反射光栅

为了降低消反射光栅的偏振敏感性，将等效介质理论推广到二维亚波长结构，对一种特定的矩形柱状结构进行了分析。构造了一种分析方法，然后利用光栅结构的有关表达式得到这种二维结构的近似等效系数。并设计了适用于10．6μm红外波段的二维亚波长消反射光栅，用二元光学的制作工艺在si衬底上进行了实验制备。测试结果表明：对中心波长为10．6μm的红外光，这种光栅象单层消反射膜一样，具有很好的增透效果。     

油溶性Ag纳米微粒的制备及表征

以双十八烷氧基二硫代磷酸吡啶盐为修饰剂 ,以单宁酸为还原剂 ,在水醇混合溶剂中合成了表面修饰的Ag纳米微粒 ,采用X射线粉末衍射仪、透射电子显微镜、傅立叶变换红外光谱仪、热分析仪等对其进行了结构表征 ,在四球摩擦试验机上测试了其抗磨性能 .结果表明 ,表面修饰的Ag纳米微粒粒径分布均匀 ,平均粒径约为15nm ,无团聚现象 ,可溶于液体石蜡等有机溶剂 ,作为润滑油添加剂 ,具有良好的抗磨作用 ,可显著提高基础油的承载力 .     

Synthesis and electrochemical properties of amphiphilic crown ether langmuir-blodgett films [1]

4-Octadecanoylbenzo-15-crown-5 (I) and four 4-alkylbenzo-15-crown-5 ligands [4-XB15C5 where X =n-C₁₈H₃₇ (II), X =n-C₁₆H₃₃ (III), X =n-C₁₄H₂₉ (IV), and X =n-C₁₂H₂₅ (V)] have been synthesized. The -A isotherms ofI andII were systematically investigated. The results indicated that the Langmuir-Blodgett (LB) films have high stability where the ratios ofI/SA andII/SA were 1 : 1 and 1 : 10, respectively, with a 6.2 pH subphase. The LB films of the crown ethers were deposited onto graphite electrodes pretreated by immersing them in liquid wax. The peak current reached the maximum value when the electrode surface was modified with five layers of the amphiphilic crown ethers.     

TiO2/EDTA-rich carbon composites: Synthesis,characterization and visible-light-driven photocatalytic reduction of Cr(VI)

TiO₂/EDTA-rich carbon composites exhibits excellent photoreduction of Cr(VI) activity via ligand-to-metal charge transfer process.     

基于超高效液相色谱-四极杆飞行时间质谱联用技术的血瘀模型大鼠血浆代谢组学分析

采用盐酸肾上腺素加冰水浴建立急性血瘀大鼠模型，使用超高效液相色谱-四极杆飞行时间质谱（UPLC-Q-TOF/MS）检测空白对照组与血瘀模型组中血浆代谢物，用主成分分析（PCA）、有监督偏最小二乘法判别分析（PLS-DA）及正交偏最小二乘法判别分析（OPLS-DA）对代谢组学数据进行多维统计分析，筛选潜在生物标志物。与对照组相比，在血瘀模型组大鼠血浆中检测出46个差异代谢物，血瘀模型组中乙酰胆碱、N6，N6，N6-三甲基-L-赖氨酸、胞嘧啶、乙酰肉碱等21个代谢物显著上调，吲哚丙酸、LysoPC（14：0）等25个代谢物显著下调，可能与脂质代谢、半乳糖代谢、亚油酸代谢、不饱和脂肪酸生物合成、糖酵解、花生四烯酸代谢等通路有关。代谢产物可作为血瘀证研究中的重要标记物，该研究结果有助于揭示血瘀证的发病机制，可为临床血瘀疾病的诊断及选用药物治疗提供思路，为后续治疗手段提供参考依据。     

PW1700X射线衍射仪织构分析应用软件的功能开发

由Ｐｈｉｌｉｐｓ引进的ＰＷ１７００Ｘ射线衍射仪织构测量系统只能用反射法，按螺旋线扫测极目数据，测绘极角。α≤８５°的不完整极图。经功能开发后，建立了织构分析测算系统，织构分析应用软件包，包括不完整极图测量与ＯＤＦ（取向分布函数）计算，回算全极图与反极图，可彩色屏显考贝，并能进行织构的定量分析。适用于立方和六方品系多晶织构材料分析。近两年应用表明，软件功能优异。