黏性液体中单个气泡上升的形状特性

采用基于Level Set方法的直接数值模拟技术对黏性液体中单个气泡的上升运动进行三维模拟.数值模拟采用拟单相流模型处理气泡内外的气液两相流动,应用Level Set方法捕捉运动气泡的变形.针对Eo数从O(0)～O(2),Mo数从O(-11)～O(2)的流动范围,重点研究了上升气泡的形状特性,并与经典的气泡形状图谱进行了比较.模拟结果表明,上升气泡的形状与无量纲参数(Eo、Mo和Re)密切相关.在高Re的扁椭球区域,数值发现了气泡形状的周期性振荡行为.     

三维射流中颗粒与流体的双向耦合作用

采用基于欧拉一拉格朗日的双向耦合模型对三维气固两相平面射流中颗粒与流体的双向耦合作用进行了直接数值模拟.在考虑颗粒相的反作用后,气相运动采用直接耦合求解,计算颗粒场时,选取Stokes数为0.1的较小颗粒,采用Lagrangian方法跟踪其运动.重点考察了颗粒相与流体相之间的相互作用,分析了不同固相载率的颗粒对流场特性以及对自身扩散的影响.模拟结果表明由于颗粒的影响,在射流入口处流场最初生成的两个大涡沿横向被拉伸,而在射流下游区域,涡结构则沿流向被拉伸;在射流的下游,颗粒降低了流场中心区域的流向平均速度,削弱了流场中心区域的湍流强度.此外,跟单向耦合相比,双向耦合情况下的颗粒分布更加均匀,并且均匀程度随固相载率的增加而增大.     

Quantum Secure Direct Communication with Four-Particle Genuine Entangled State and Dense Coding

A quantum secure direct communication scheme using dense coding is proposed. At first, the sender （Alice） prepares four-particle genuine entangled states and shares them with the receiver （Bob） by sending two particles in each entangled state to him. Secondly, Alice encodes secret information by performing the unitary transformations on her particles and transmits them to Bob. Finally, Bob performs the joint measurements on his particles to decode the secret information. The two-step security test guarantees the security of communication.     

Similarity Reductions of Nonisospectral BKP Equation

Basing on the direct method developed by Clarkson and Kruskal, the nonisospectral BKP equation can be reduced to three types of （1＋1）-dimensional variable coefficients partial differential equations （PDEs）. Furthermore, on the basis of the idea of the symmetry group direct method by Lou et al., three types of reduction PDEs are all reduced to the related constant coefficients PDEs by some transformations.     

Direct Measurement of Branching Fraction for Inclusive Semimuonic Decay of Neutral D Mesons

Using a data sample of about 33pb^-1 collected at and around √s = 3.773 GeV with the BES-Ⅱ detector at the BEPC, we have directly measured the branching fraction for inclusive semimuonic decay of neutral D mesons to be BF（D^0 → μ^＋X） = （7.2 ± 1.5 ± 0.8）%.     

Optical Four-Wave Mixing Operator, Fresnel Operators and Three-Mode Entangled State Representation

We analyse the optical four-wave mixing operator S and relate it to the two-mode Fresnel operator. It is shown that the direct product of the two-mode Fresnel operator and the single-mode Fresnel operator has a natural representation on the basis of a three-mode entangled state, which is constructed by S and a beam splitter transform.     

Silicon Purification by a New Type of Solar Furnace

We propose a new method to reveal a direct transformation from solar energy to solar electricity. Instead of using electricity in the process, we use concentrated solar rays with a crucibleless process to upgrade metallurgical silicon into solar-grade silicon feedstock.     

温度对直接甲醇燃料电池动态性能的影响

利用可计算机控制的电子负载单元,本文实验研究了电池温度对液态进料直接甲醇燃料电池单体电池的稳态和动态性能的影响,并考察了该电池对电池温度变化的动态响应。实验结果表明:电池稳态性能随着电池温度的升高而提升,电池对动态负载的响应随着电池的温度的升高而变得更快和更稳定,升温过程中电池对电池温度变化的响应值要高于降温过程中对应的响应值。     

对具有平均标量梯度的被动标量的直接模拟

采用直接数值模拟方法,对具有平均标量梯度的被动标量场在稳定、均匀各向同性湍流中的统计特性进行了研究(计算Reλ为25和48,Pr数从0.3到4.0)。模拟结果表明:标量的概率密度函数是高斯分布的;标量耗散率的概率分布是不对称性的,在它的左枝还存在明显的拖尾现象,并非对数正态分布;在Re数相同的情况下,随着Pr数的增加, 沿着平均标量梯度方向上的标量梯度其概率分布的偏斜度是减少的,反映出回归各向同性的趋势,而且在以涡量为条件的标量梯度的偏斜度变化曲线中发现涡量影响的饱和现象,我们认为这是由于涡量通过对标量场小尺度结构进行旋转作用来影响标量场的结果。     

RuO2/TiO2复合光催化剂的制备及性能研究

采用溶胶-凝胶-浸渍法制备了RuO2/TiO2复合光催化剂, 以紫外灯为光源, 直接耐晒黑G溶液的光催化降解为模型反应, 研究了RuO2/TiO2的光催化性能. 结果表明 掺杂量ω(RuO2)为0.16%、煅烧温度500 ℃、催化剂投加量为5.00 g·L-1时, RuO2/TiO2复合光催化剂催化活性最高. 直接耐晒黑G降解反应遵从Langmuir-Hinshelwood动力学模型, 测得反应速率常数为4.94×10-3 mmol(L·min)-1和吸附常数14.2 L·mmol-1.