迷宫流道转角对灌水器抗堵塞性能的影响

以转角分别为45.0°、60.0°、67.5°和75.0°的齿形流道灌水器为研究对象,应用CFD流场速度数值分析、PIV颗粒运动轨迹线和速度观测对比以及浑水抗堵塞测试相结合的方法,研究了转角对灌水器水力性能和抗堵塞能力的影响。结果表明转角与流量系数及流态指数均呈负相关关系,而灌水器的抗堵塞能力随着转角的增加呈下降趋势。综合分析转角对水力性能和抗堵塞性能的影响,提出迷宫流道结构灌水器的合理转角为60.0°。

A general route to transform normal hydrophilic cloths into superhydrophobic surfaces

Herein, we describe a simple and inexpensive method for forming superhydrophobic cloths with the highest water contact angle of close to 180 degrees, in which normal commercial cloths serving as pristine materials are modified with suitable gold micro/nanostructures.

A polymer composite film with reversible responsive behaviors

A responsive polymer composite film was generated by the use of reversibly switchable Surface morphology of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) films in response to different block selective solvents on the rough isotactic poly(propylene) (i-PP) substrate. The Maximum difference of the water contact angle of the composite films increased from 22.6 degrees of PS-b-PMMA films on the smooth substrate to 42.6 degrees when they were treated by PS and PMMA selective solvents, respectively. The mechanisms of the responsive extent enhanced and the superhydrophobicity of the composite films were discussed in detail.

Macroporous fluoropolymeric films templated by silica colloidal assembly: A possible route to super-hydrophobic surfaces

A super-hydrophobic surface was obtained on a three-dimensional (313) polyvinylidene fluoride (PVDF) macroporous film. The porous films were fabricated through self-assembled silica colloidal templates. The apparent water contact angle of the surface can be tuned from 106 degrees to 153 degrees through altering the sintering temperature and the diameter of the colloidal templates. A composite structure of micro-cavities and nanoholes on the PVDF surface was responsible for the super-hydrophobicity. The wettability of the porous surfaces was described by the use of the Cassie-Baxter model and Wenzel's equation.

2-[2-(Phenylsulfonyl)ethyl]isoindoline-1,3-dione

In the title compound, C16H13NO4S, the phthalimide ring system makes a dihedral angle of 56.7 (1)degrees with the phenyl ring.

Interparticle distance-temperature-strain rate equivalence for the brittle-tough transition in polymer blends

From the angle of energy transformation an equation was obtained for the brittle transition in polymer blends. The effects of interparticle distance, temperature and strain rate on the brittle-tough transition in polymer blends were characterized by this equation. The calculations show that, for this transition: (1) increasing temperature and decreasing interparticle distance are equivalent and the shift factor increases with increasing temperature; (2) decreasing strain rate and decreasing interparticle distance have equivalent effects on the transition; (3) the strain rate must be optimum in order to find the brittle-tough transition phenomena for a given temperature region. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.

Liquid crystal alignment controlled by LB films

Copper phthalocyanine doped polymethacrylate Langmuir-Blodgett films were transferred to align a nematic liquid crystal 5CB, It is found that the pre-tilt angle of the liquid crystal can be controlled with the variation of the doped copper phthalocyanine molecular ratio and is correlated with the dichroic ratio of the aligning layer. The polarity of the aligning layer is regarded as the most likely underlying factor that causes the different LC alignment configurations. (C) 1997 Elsevier Science B.V.

Red color filter in an organo-soluble polyamide matrix for liquid crystal displays

A red color filter was laminated from a solution of red color pigment and an organo-soluble polyamide, based on 1,4-bis(3,4-dicarboxyphenoxy) benzene dianhydride (HQDPA) and 2,2'-dimethyl-4,4'-methylene dianiline (DMMDA). The red color filter in a polyamide matrix with negative birefringence plays an important role in twisted nematic liquid crystal displays (TN-LCDs). The red color filter, and also compensation films, extend the viewing angle of LCDs. (C) 1997 Elsevier Science S.A.

Wave generation by the falling rock in the two-dimensional wave tank

Wave generation by the falling rock in the two-dimensional wave tank is experimentally and numerically studied, where the numerical model utilizes the boundary element method to solve the fully nonlinear potential flow theory. The wave profiles at different times are measured in the laboratory, which are also used to test the numerical model. Comparisons show that the experimental and numerical results are in good agreement, and the numerical model can be used to simulate the wave generation due to the submarine rock falling. Further numerical tests on the influences of the rock size, density, initial position and the falling angle on the wave elevation of the generated waves are performed, respectively. The results show that the size and density of the rock have strong effects on the maximum elevation of the generated wave, while the effects of the initial position and the falling angle of the rock are also significant. When the size or the density of the rock increases, the maximum elevation of the generated wave increases. The same effect on the generated wave would be produced if the initial position of the rock becomes closer to the surface, or the falling angle between the falling route and the vertical direction turns larger. In addition, the present numerical tests reveal that the submarine rock falling provides a new generation method for the breaking wave in the wave tank.

关于水面形状的分析

对以恒加速度沿光滑平面运动的无盖水箱中的水面形状进行了具体分析,并给出了计算水箱中水稳定时液面与水平面夹角的公式·

基于天际线识别的无人机实时姿态角估计

以无人机天际线识别为背景,提出了一种准确、实时的天际线识别算法,并由此估计姿态角。在结合实际情况的基础上,对天际线建立能量泛函模型,利用变分原理推出相应偏微分方程。在实际应用中出于对实时性的考虑,引入直线约束对该模型进行简化,然后利用由粗到精的思想识别天际线。首先,对图像预处理并垂直剖分,然后利用简化的水平直线模型对天际线进行粗识别,通过拟合获得天际线粗识别结果,最后在基于梯度和区域混合开曲线模型约束下精确识别天际线,并由此估计无人机滚动和俯仰姿态角。实验结果表明,该算法对天际线识别具有较好的鲁棒性、准确性和实时性。