颗粒趋壁沉积的直接数值模拟

气相采用直接数值模拟方法、颗粒相采用拉格朗日轨道模型方法对摩擦雷诺数为180的充分发展槽道内Stokes数为1～104的颗粒趋壁沉积现象进行了研究.研究表明,惯性颗粒在湍流涡的作用下趋向壁面运动,并以一定速率沉积.在"吸收壁面"条件下沉积速率首先随着颗粒弛豫时间增大而增大,在弛豫时间大于100时,沉积速率保持不变.     

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.     

端氨基聚氨酯-g-聚丙烯的制备及工艺参数研究

通过反应挤出方法将端氨基聚氨酯(ATPU)接枝到聚丙烯(PP)分子链上,并用红外光谱对AT-PU-g-PP进行了表征。研究了ATPU分子量、配比、螺杆转速等对接枝率的影响,确定了合成高接枝率产物的优化工艺条件。将ATPU-g-PP再与通用PP共混挤出,可得到功能化聚丙烯(FPP)。     

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。