方截面鼓泡床气液两相瞬态数值研究

在双流体模型中引入界面浓度输运方程,利用界面浓度和气泡平均Sauter直径模化各相间作用力。引入一附加 湍动能输运方程模化气泡诱导引起的液相湍流。利用该模型对方截面鼓泡床内气液两相流进行三维瞬态数值模拟。计算结 果表明该模型能较好得模拟方截面鼓泡床内气液两相流时均和瞬态流动特征。     

泡状流局部界面浓度实验与理论研究

应用高速数字摄像系统,首先对双头电导探针测量泡状流局部界面浓度的几种模型进行了标定和评价。使用标定好的双头电导探针技术,对垂直上升管内气液两相泡状流局部界面浓度和含气率分布特性进行了深入的实验研究。试验段为内径40 mm的透明有机玻璃管。根据试验数据的分析结果,发展了一种垂直上升管内气液两相泡状流局部界面浓度预测模型。在本文实验条件下,该局部界面浓度模型预测结果能够与实验数据很好地符合。     

采用三角形面积坐标的四边形17节点样条单元

利用二元4次样条插值基和三角形面积坐标构造17节点四边形单元．这个新单元具有4次完备阶,通过一些算例测试表明了该单元有较高精度并对网格畸变不敏感．     

电感耦合等离子体原子发射光谱法分析不同产地大豆中的矿物元素含量

选取江西、黑龙江、吉林和安徽4产地同一种属大豆经硝酸湿法消解后,采用电感耦合等离子体原子发射光谱法同时测定了其中K, P, Mg, Ca, Fe,Al, Zn, Mn 和Na元素的含量,并采用Ducan多重比较方法对结果进行统计分析。结果表明：大豆中含有丰富的矿物元素,其中K,P,Mg,Ca,Fe元素含量较高,且排序不因产地的变化而改变。Mn, Zn,Al,Na元素的排序则受产地影响较大。K, P, Mg的含量受产地的影响不大,表现出某一品种大豆自身生长对主要矿物质的需求是相对稳定的。不同产地大豆中Al, Ca,Fe, Na, Mn,Zn元素的含量差异显著(P<0.05),说明这几种微量元素的含量受土壤及环境的影响较大,其中安徽大豆中的铁元素(70.93 mg·kg-1)和江西大豆中的锰元素(32.69 mg·kg-1)显著高于其他3个样品。     

光子晶体光纤数值孔径的测量和数值研究

光纤的数值孔径是光纤的重要参数,大数值孔径光纤在激光器和激光感应荧光系统中有很好的应用前景。光子晶体光纤的数值孔径与传统阶跃型光纤不同,它与光波长有密切的关系。因此,本文用光谱仪测量了不同结构的折射率引导型光子晶体光纤的数值孔径,并进行了数值模拟,研究了光波长、包层空气孔直径、孔间距等对光子晶体光纤数值孔径的影响,同时对光子晶体光纤的非线性系数、宏弯损耗、截止波长、有效模面积等与光波长有关的参数进行了研究,取得了满意的结果。     

Influence of adatom migration on wrinkling morphologies of AlGaN/GaN micro-pyramids grown by selective MOVPE

Ga N micro-pyramids with AlGaN capping layer are grown by selective metal–organic–vapor phase epitaxy(MOVPE). Compared with bare Ga N micro-pyramids, AlGaN/Ga N micro-pyramids show wrinkling morphologies at the bottom of the structure. The formation of those special morphologies is associated with the spontaneously formed AlGaN polycrystalline particles on the dielectric mask, owing to the much higher bond energy of Al–N than that of Ga–N. When the sizes of the polycrystalline particles are larger than 50 nm, the uniform source supply behavior is disturbed, thereby leading to unsymmetrical surface morphology. Analysis reveals that the scale of surface wrinkling is related to the migration length of Ga adatoms along the AlGaN {1ī01} facet. The migration properties of Al and Ga further affect the distribution of Al composition along the sidewalls, characterized by the μ-PL measurement.     

应用于软X射线成像探测的Angel型龙虾眼光学系统研究

龙虾眼光学聚焦系统是一种模仿龙虾视觉的光学系统,适用于卫星平台上的软X射线成像探测.根据掠入射原理,分析和计算了Angel型龙虾眼光学系统采用不同金属镀膜时光子能量和全反射临界角、反射率的定量关系;提出一种计算龙虾眼光学系统有效探测面积的方法,推导了相关的理论计算公式并进行了蒙特卡罗仿真试验,理论计算值与蒙特卡罗仿真结果吻合很好,龙虾眼X射线光学系统在110keV能段的有效面积与光子能量近似呈负指数关系,具体的参量与镀膜的粗糙度有关.     

高比表面碳化硅制备及其作为催化剂载体的应用

介绍了模板法、溶胶-凝胶法以及聚碳硅烷裂解法制备高比表面积碳化硅的主要过程和结果, 并介绍了碳化硅作为催化剂载体在多相催化中应用的研究进展. 对碳化硅在多相催化中的应用前景进行了展望.     

Mesh Simplification Using an Area-Based Distortion Measure

A new area-based mesh simplification algorithm is described. The proposed algorithm removes the center vertex of a polygon which consists of faces and represents that polygon with faces. A global search method is adapted that iteratively determines which vertex is to be removed using the proposed area-based distortion measurement. Although the global search method requires more computations compared to a local search method, it guarantees better quality of approximation. Various re-triangulations are also considered to improve the perceptual quality of the final approximation. From multiple re-triangulations, one with minimum distortion is selected to represent the original mesh. Experimental results demonstrate the performance of the proposed algorithm for data reduction while maintaining the quality of the rendered objects.*This work was supported by McMaster Manufacturing Research Institute (MMRI).