A Y-Branch Photonic Crystal Slab Waveguide with an Ultrashort Interport Interval

We fabricated two-dimensional photonic crystal slab Y-branch waveguides with different intervals between the two output ports and measured their light guiding characteristics. The field intensity distributions of the TE polarized wave modes are also calculated by means of a transfer matrix method. Both the theoretical and experimental results show that the minimum interval between the two output ports is about 1.4 times the transport wavelength of 1.55μm. If the interval becomes smaller, light waves in the two branches will couple each other seriously. The result will be helpful for designs of ultracompact wave demultiplexers and all-optical integrated circuits.     

翅片长度对纵向翅片扁管换热器换热性能的影响

纵向翅片扁管换热器是一种新型换热器。气体沿扁管轴向方向流动,与管内介质的流动路径平行,可强化传热,减少气侧阻力,不易积灰结垢,维护方便。利用数值模拟方法,以纵向翅片扁管换热器为研究对象,分析翅片长度对换热性能的影响,对换热器的翅片长度进行优化。研究表明,不同进口风速对应不同的有效纵向翅片长度。随着进口风速的增大,翅片的有效长度越大。     

对称蕴涵推理方法的鲁棒性分析北大核心CSCD

模糊推理方法已经被成功地应用于模糊控制器设计,模糊专家系统集成等诸多领域.作为对传统模糊推理方法的改进,我国学者提出了基于三Ⅰ方法的对称蕴涵推理方法.对于模糊推理方法性质的研究,尤其是对推理方法鲁棒性的研究是模糊逻辑领域的一个重要的研究方向.基于规范的Minkowski距离讨论对称蕴涵方法的鲁棒性,给出了针对不同蕴涵算子的四个算法的鲁棒性结论,为模糊推理方法的选择与应用提供科学依据.     

Optimization of the Loading Process of the QUIC Magnetic Trap for the Experiment of Bose-Einstein Condensation

The magnetic quadrupole-Ioffe configuration (QUIC) trap in our Bose-Einstein condensation experiment is introduced. The magnetic trap loading process after laser cooling is ana/ysed and the optimization of the loading process is studied experimentally, Calculation of the magnetic field explains the loss of the atoms during the loading process of the QUIC trap. The number of atoms loaded in the QUIC trap is increased by 40% after optimization in comparison with the normal loading process.     

环周进汽型超声速汽液两相流升压装置性能计算分析

对环周进汽型的变截面通道内超声速汽液两相流升压装置进行了实验及理论研究,实验中进汽压力为0.15～0.4MPa,进水压力为0.2～0.6 MPa。实验结果表明在不同的汽水参数条件下,混合腔内压力与温度分布呈现出相似的规律。在同一工况下,激波前混合腔内各点的压力基本保持不变,随着凝结激波的产生,压力突然增大。激波过程中蒸汽几乎全部凝结,激波过后温度分布趋于平缓。并在实验结果的基础上分别建立了水喷嘴、蒸汽喷嘴、混合腔内两相区和扩散段的数学模型,其预测的装置出口压与实验值之间的误差小于15%。     

Negative Refraction and Imaging in a Triangular-Lattice Metallic Photonic-Crystal Slab

Imaging properties of a two-dimensional photonic crystal （PC） slab consisting of a triangular lattice of metallic cylinders immersed in a dielectric background are investigated by the finite-difference time-domain technique. With the calculated field patterns of a point source placed in the vicinity of the PC slab and the corresponding equifrequency-surface contours, we find that a high-quality image ca.n form in the opposite side of the slab in the lowest TM-polarized photonic band, and this near-field image is formed mainly by the self-collimation effect.     

一类时滞Logistic方程周期解的存在性

We consider the existence of single and multiple positive periodic solutions for the general periodic Logistic equation     

求解退化单调线性互补问题极大互补解的复杂性

本文考虑求解退化单调线性互补问题的一类不可行内点算法，其中嵌入一个恢复算法，给出了用这类算法产生所考虑问题的一个精确极大互补解的复杂性．     

EAST纵场线圈在稳定状态下热负荷的计算

文章分析了EAST托卡马克核聚变装置在正常运行情况下产生的各种热负荷。计算过程考虑了核热沉积以及热传导、热辐射、对流引起的换热过程。其中稀薄气体对流热、辐射热和核沉积热是热负荷的重要组成部分。这些结果对于分析整个液氦系统消耗量,降低低温系统的成本有着重要的作用。