Preparation and Characterization of Hydrophobic Nano Silver Film on Butterfly Wings as Bio-template

Hydrophobic nano silver films were fabricated on butterfly wings as bio-template. The micrometric/nano structures and hydrophobicity of the surfaces were investigated with the help of scanning electron microscope（SEM） and video-based contact angle meter. The hydrophobic mechanism of silver film was analyzed with the aid of Cas- sie＇s formula. On the nano silver films of various thicknesses（5, 10, 20, 40, 60, 80, 100 nm）, all the contact an- gles（CAs） of water were bigger than 120°. When the silver film was 5 nm, the CAs of water on it on the wing surfa- ces of Mimathyma nycteis and Speyeria aglaja were 143.2° and 139.2°, respectively. Coated with the sliver film of the same thickness, butterfly wing surface exhibited the CA remarkably bigger than glass slide surface, exhibiting its high hydrophobicity. With the increase of silver film thickness on butterfly wing surface, the hydrophobicity kept de- creasing. The micrometric/nano hierarchical structures on butterfly wing surface result in the transition of metal silver from hydrophilicity to hydrophobicity.     

Time-resolved spectral wing emission kinetics and optical imaging of human cancerous and normal prostate tissues

Time-resolved polarization-dependent kinetics of near infrared (NIR) spectral wing (SW) emission from human cancerous and normal prostate tissues was investigated. The differences between the temporal profiles, intensities and polarization properties of SW emission from cancerous and normal prostate tissues were observed. The intensity of SW emission from cancerous prostate tissue at peak position was found ∼2 times stronger than the normal prostate tissue indicating changes of fluorophores contained in the cancerous tissue compared with normal tissue. The decay time of anisotropy of SW emission from cancerous tissue was found ∼1.4 times longer than that of normal tissue reflecting changes of the micro-environment of fluorophores in the cancerous tissue as compared with the normal tissue. The stronger intensity of SW emission from cancerous tissue was used to image and identify cancerous areas surrounded by normal tissue.     

Identification of Anthocyanin Compounds in Butterfly Pea Flowers (Clitoria ternatea L.) by Ultra Performance Liquid Chromatography/Ultraviolet Coupled to Mass Spectrometry

Butterfly pea flower have great sensory attraction, but they have not yet been used widely in Vietnam. Extracts of butterfly pea flowers can be used conveniently as a natural blue colorant for food products. In this study, the identification of anthocyanin compounds in butterfly pea flowers was performed by UPLC coupled with a UV and Mass spectrometer instrument. Positive and negative ion electrospray MS/MS chromatograms and spectra of the anthocyanin compounds were determined. By analyzing the chromatograms and spectra for each ion, five anthocyanins were identified in the butterfly pea flower extract; these were delphinidin-3-(6″-p-coumaroyl)-rutinoside, cyanidin 3-(6″-p-coumaroyl)-rutinoside, delphinidin-3-(p-coumaroyl) glucose in both cis- and trans- isomers, cyanidin-3-(p-coumaroyl-glucoside) and delphinidin-3-pyranoside. Additionally, based on their intensity, it was determined that cyanidin-3-(p-coumaroyl-glucoside) was the most abundant anthocyanin, followed by cyanidin 3-(6″-p-coumaroyl)-rutinoside, delphinidin-3-(p-coumaroyl-glucoside), delphinidin-3-(6″-p-coumaroyl)-rutinoside and delphinidin-3-pyranoside. In this study, cyanidin derivatives were discovered in butterfly pea flower extract, where these compounds had not been detected in previous studies.     

Effects of flexibility on aerodynamic performance of delta wings with different sweep angles

Force measurement and surface oil flow visualization experiments were conducted in a wind tunnel to investigate the effects of flexibility on aerodynamic performance of delta wings with different sweep angles.The experimental results indicate that the maximum lift coefficient is increased and the stall angle is delayed as the sweep angle increases for both rigid and flexible wings.It is also found that the maximum lift coefficients of the flexible wings with a sweep angle from 35° to 50° are higher than those of the rigid ones.The increment of the maximum lift coefficient in particular achieves 32.9% compared with the case without lift enhancement for the 40° flexible delta wing.Moreover,the surface oil flow visualization experiments show that the stall of the flexible wing of the moderate low sweep angle is accompanied by helical flow structure,while the vortex bursting appears on the corresponding rigid wing.     

二维地效翼及地效流动特性数值研究

用数值模拟的方法,对二维NACA0012翼型在地面效应下的空气动力特性和地效流动特性进行研究,得到地效翼的升力、阻力和翼型表面压力分布随攻角及相对飞行高度的变化情况.通过对计算结果的分析,可以看出,在一定的攻角,靠近地面飞行,机翼的升力得到提高;随着飞行高度的降低,地面效应增强,机翼的失速攻角减小;地面附近的粘性流动对机翼的空气动力特性影响很小;当相对飞行高度小于0.1时,应该考虑空气的可压缩性.     

三维机翼表面水滴撞击特性计算

系统研究机翼结冰计算中水滴轨迹和撞击特性的计算方法,将网格扇形分区和单元拓扑结构思想应用于水滴轨迹计算,引入欧拉法、预估-校正、四步Runge-Kutta法离散求解水滴运动方程.基于三维NACA 0012机翼模型,讨论水滴所在位置判断、速度插值和表面收集系数的计算方法,分析方程离散格式、水滴释放位置对计算结果的影响.采用三维机翼计算收集系数分布,并与试验结果进行对比,分析水滴直径对收集系数的影响;最后,将水滴计算模块DROP3D集成于结冰软件计算平台,计算不同工况参数下,机翼表面的气流流场和水滴撞击特性及结冰冰形,进-步验证程序的运行性能.     

基于螺旋桨滑流效应的大展弦比机翼气动弹性分析

以高空长航时大展弦比太阳能无人机机翼为研究对象,针对分布式电驱螺旋桨滑流和大展弦比机翼之间耦合的复杂气动干涉问题,采用滑移网格方法、动网格技术、SST k-ω RANS湍流模型和CFD/CSD （Computational Fluid Dynamics/Computational Structural Dynamics）双向流固耦合技术,研究了螺旋桨不同转速、布局方式和气动阻尼对机翼气动弹性响应的影响。数值计算结果表明,螺旋桨滑流会改变机翼表面的压力分布;螺旋桨流场对机翼的扰动频率接近机翼的结构固有频率时,机翼会发生共振;螺旋桨的位置越靠近翼尖,或螺旋桨的数量增多,都将增加机翼气动弹性响应的幅值。     

一类多翼蝴蝶混沌吸引子及其电路实现

提出了一种构造多翼蝴蝶混沌吸引子的新方法,在Liu混沌系统的基础上,通过设计一种新的分段线性函数,构造了一个产生多翼蝴蝶混沌吸引子的混沌系统,对系统的平衡点、Lyapunov指数谱、分岔图、相图、频谱和Poincare截面进行了分析。最后,设计了相应的硬件电路,电路实验结果与数值仿真结果一致,验证了该方法的可行性和有效性。     

偏振复用光纤通信系统色散均衡器及算法的研究

设计了一种适用于偏振复用相干解调光纤通信系统的色散均衡器,用于补偿信道传输的色散损伤。该均衡器采用半码元间隔的蝶形有限脉冲响应滤波器结构,与此结构配合的自适应算法分别采用最小均方算法和递归最小二乘算法。通过仿真实验,分析了两种算法对残留色度色散和偏振模色散的补偿容限。仿真结果表明,递归最小二乘算法的补偿效果优于最小均方算法,它可以同时补偿1760ps/nm的残留色度色散和104.9ps偏振模色散引起的差分群时延,比同等条件的最小均方算法提升性能2.23dB。