基于FTA与BAM神经网络融合的飞机故障诊断方法

飞机由大量彼此关联的组件组合而成,其大规模特性使得基于故障树(FTA)和基于神经网络的故障诊断方法在应用于其故障诊断时分别存在空间爆炸问题和训练样本整理困难问题.本文融合故障树和BAM神经网络,由故障树归纳出系统所有的故障模式,整理出BAM神经网络所需的具有规范性、独立性、正交性的训练样本,然后用BAM神经网络实现飞机故障的快速和准确诊断.实验评估结果表明,融合方法有良好的可扩展性,而且故障判别率提升了20%.     

二次谐波光谱和布鲁斯特角显微镜研究二棕榈酰磷脂酰胆碱和维生素B2的相互作用

二棕榈酰磷脂酰胆碱（DPPC）分子在气液界面上形成的Langmuir膜是一种重要的生物膜模拟体系,其手性结构及其与外来物质的相互作用一直是相关学科研究的前沿问题。维生素B₂（VB₂）是人体中一种重要的营养物质,它在代谢障碍引起的脂质沉积性类疾病中有大量的实例应用,经常在一些特殊的临床症状中有出乎意料的治疗奇效。目前,VB₂如何参与到膜上生物事件的过程和细胞乃至生命的作用过程中的研究报道较少,特别是VB₂分子与磷脂分子靶标的立体相互作用,其可能发生的手性分子识别现象会在许多生物事件中起着关键作用。综合二次谐波-线二色光谱（SHG-LD）、Langmuir膜天平和布鲁斯特角显微镜(BAM)技术初步研究了VB₂和DPPC分子在气液界面上的相互作用,分别从气液界面上介观水平和宏观水平上互补表征脂质分子在气液界面上的分子骨架自组装的结构。压缩等温线发现纯水界面L-DPPC和D-DPPC液态扩展相/液态凝聚相(LE/LC)共存阶段的膜压几乎不变,race-DPPC的共存相膜压区域稍微缩短,VB₂水溶液界面上race-DPPC的LE/LC共存相消失。此外,弹性模量研究表明VB₂分子可以提高L-DPPC单分子层膜的弹性模量,但降低D-DPPC和race-DPPC单层膜的弹性模量。结合SHG-LD研究发现,在膜压13 mN·m-1下,L-DPPC在纯水和VB₂水溶液界面上表面手性过量值（DCE）保持不变。与纯水界面相比较,D-DPPC在VB₂水溶液上DCE值出现反转,而race-DPPC的DCE值则不随亚相改变而变化。相同膜压下,BAM观察到单一手性相互作用使得L-DPPC和D-DPPC在纯水界面上各自组装成不同枝臂弯曲方向的手性三叶草微畴(microdomain)。VB₂诱导D-DPPC微畴,使其直径增大1～2倍。同时,VB₂也诱导了race-DPPC单层膜上近似圆形状的微畴伸展,并长出了三条有曲率的枝臂。对此可以解释为VB₂降低了非单一手性相互作用的能量,使得race-DPPC出现手性相分离。与此同时,VB₂也诱导了race-DPPC单层膜微畴的手性结构发生变化。该研究有助于理解VB₂调节磷脂膜横向组织结构的分子机理,在细胞膜界面发生的过程中,脂层单层的二维特性和生物分子之间的相互作用可能决定了生物分子的亲和力。     

The production and verification of pristine semi-fluorinated thiol monolayers on gold

In this work the interaction between human serum albumin (HSA) and a monofluorinated phospholipid, 1-palmitoyl-2-[16-fluoropalmitoyl-phosphatidylcholine] (F-DPPC), was studied by using Langmuir monolayer and Brewster angle microscopy (BAM) techniques. Different amounts of F-DPPC were spread on a previously formed HSA monolayer located at the air/water interface at 25 °C and the mixed monolayers thus obtained showed the existence of a liquid expanded-liquid condensed (LE-LC) phase transition (at 14 mN/m), attributed to the pure F-DPPC monolayer, coexisting with a second transition (at 22-24 mN/m) corresponding to the protein conformational change from an unfolded state to another in “loops” configuration. Relative thickness measurements recorded during the compression of the mixed monolayers showed the existence of an “exclusion” surface pressure (π_exc), above which the protein is squeezed out the interface, but not totally. BAM images reveal that some protein molecules in a packed “loops” configuration remain at the interface at surface pressures higher than the “exclusion” surface pressure. The application of the Defay-Crisp phase rule to the phase diagram of the F-DPPC/HSA system can explain the existence of certain regions of surface pressure in which the mixed monolayer components are miscible, as well as those others that they are immiscible.     

分数阶BAM神经网络的全局渐进稳定性

研究了分数阶BAM神经网络平衡点的唯一存在性和全局渐近稳定性,利用压缩映像原理得到了系统平衡点唯一存在的充分条件;通过构造Lyapunov函数,运用Lyapunov函数理论、矩阵不等式法和Laplace积分变换法,得到了所研究模型平衡点的全局渐进稳定的充分条件,以矩阵不等式的形式给出了更为严格和更易验证的条件,并通过数值仿真验证了结论的正确性。     

Exponential stability for stochastic BAM networks with discrete and distributed delays

In this paper, we investigate exponential stability for stochastic BAM networks with mixed delays. The mixed delays include discrete and distributed time-delays. The purpose of this paper is to establish some criteria to ensure the delayed stochastic BAM neural networks are exponential stable in the mean square. A sufficient condition is established by consructing suitable Lyapunov functionals. The condition is expressed in terms of the feasibility to a couple LMIs. Therefore, the exponential stability of the stochastic BAM networks with discrete and distributed delays can be easily checked by using the numerically efficient Matlab LMI toobox. A simple example is given to demonstrate the usefulness of the derived LMI-based stability conditions.     

Global asymptotic stability of BAM neural networks with mixed delays and impulses

In this paper, BAM neural networks with mixed delays and impulses are considered. A new set of sufficient conditions are derived by constructing suitable Lyapunov functional with matrix theory for the global asymptotic stability of BAM neural networks with mixed delays and impulses. Moreover, an example is also provided to illustrate the effectiveness of the results.     

White light-emitting diodes using blue and yellow-orange-emitting phosphors

A blue-emitting phosphor, BaMgAl₁₀O₁₇:Eu²⁺ (BAM) and a yellow-orange phosphor, Ba²⁺-codoped Sr₃SiO₅:Eu²⁺ were prepared by the solid-state reaction. Excitation and emission spectra results showed that BAM and Ba²⁺-codoped Sr₃SiO₅:Eu²⁺ can be efficiently excited by near-ultraviolet (n-UV)-visible light from 250 to 440 nm. The effects of the doped-Eu²⁺ concentration in BAM and Ba²⁺-codoped Sr₃SiO₅:Eu²⁺ on the photoluminescence were investigated in detail. White light-emitting diodes (LED) was obtained by combining n-UV LED chip (GaN-based 380 nm emitting) with BaMgAl₁₀O₁₇:0.09Eu²⁺ and 0.1Ba²⁺-codoped Sr₃SiO₅: 0.2Eu²⁺ phosphors with the characteristic of color-rendering index of 86, CIE chromaticity coordinates (x,y) of (0.3216,0.3096), and color temperature T_c of 5700 K. As the current increases, the relative intensity simultaneously increases. The CIE chromaticity coordinates (x,y) of the white LED tends to decrease. The correlated color temperature T_c increases from 4100 to 7500 K and the color-rendering index R_a increases from 82 to 87 simultaneously.     

反应扩散BAM神经网络的全局指数稳定性

利用拓扑度技巧、 M-矩阵和变分理论, 得到了考虑扩散因素在内的双向联想记忆人工神经网络系统的全局指数稳定性判定定理. 结果表明, 所给判据得出的指数稳定收敛速率估计比传统结果更精细.     

BaMgAl_(10)O_(17)∶Eu~(2+)发射光谱的谱峰形状(英文)

BaMgAl10O17∶Eu2+(BAM)是三基色荧光灯和等离子显示用荧光粉中的蓝色组分。用晶格弛豫和多声子跃迁理论研究了BAM发射光谱的谱峰分布。结果表明可以用三个高斯函数很好地拟合BAM的宽带发射。BAM的宽带发射可能由分布在BaMgAl10O17晶格中三个不同位置的Eu2+的能级跃迁构成。三个Eu的发光中心分别是Beevers-Ross位和anti-Beevers-Ross位,第三个Eu2+的发光中心可能是位于尖晶石基块中的mid-oxygen(mo)位。     

BaMgAl_(10)O_(17)∶Eu~(2 )的MgF_2表面包覆(英文)

采用溶胶-凝胶法对蓝色荧光粉BaMgAl10O17∶Eu2 (BAM)进行表面包膜处理,获得了表面均匀包覆MgF2膜层的BAM荧光粉。并用SEM、XRD和IR手段对其表面形貌、晶格结构性能进行了表征;用EDS对BAM粉体的表面元素进行了定性分析;用荧光光谱测试对荧光粉的发光性能进行了研究。结果表明,在BAM粉体表面均匀包覆MgF2层后,BAM的晶格结构,发光性能没有改变,初始亮度较未包覆的荧光粉有所降低,经过相同条件的热处理后,包覆MgF2荧光粉的亮度热衰减程度明显低于未包覆的荧光粉,且色坐标偏移现象不明显。