拟线性椭圆型方程奇摄动边值问题

本文讨论了拟线性椭圆型方程奇摄动Robin边值问题。在适当的条件下，利用不动点定理，研究了边值问题解的存在唯一性及其渐近性态。     

Approximate analytic solutions for a generalized Hirota—Satsuma coupled KdV equation and a coupled mKdV equation

<正>This paper applies the variational iteration method to obtain approximate analytic solutions of a generalized Hirota-Satsuma coupled Korteweg-de Vries(KdV) equation and a coupled modified Korteweg-de Vries(mKdV) equation. This method provides a sequence of functions which converges to the exact solution of the problem and is based on the use of the Lagrange multiplier for the identification of optimal values of parameters in a functional.Some examples are given to demonstrate the reliability and convenience of the method and comparisons are made with the exact solutions.     

基于多物理场模拟的低水甲烷燃料固体氧化物燃料电池的抗积碳阳极设计

本文采用与实验I-V曲线高度吻合的多物理场全耦合数值模型来模拟低水甲烷燃料SOFC的运行过程. 基于抗积碳电流密度实验数据推导出的动力学积碳活性判据,利用多场耦合数值模型系统研究了电池工作参数和阳极扩散阻碍层厚度对阳极积碳倾向的影响. 仿真模拟揭示了燃料利用率、电流密度、扩散阻碍层厚度和电池工作电压的相互关系. 结果表明,在阳极添加400 um厚的扩散阻碍层是实现SOFC高功率密度和不积碳运行的最优设计. 这种阳极结构设计对实现高效率低成本的SOFC技术具有重要意义.     

基于超导纳米线单光子探测器深空激光通信模型及误码率研究

高速深空通信是深空探测的关键技术之一,具备单光子灵敏度的激光通信系统将大大提高现有的深空通信速度.然而,单光子条件下的激光通信不仅需要考虑传输环境的影响,还需要考虑实际单光子探测器性能和光子数量子态的分布.本文在不考虑大气湍流影响的情况下,以光电探测模型为基础,引入超导纳米线单光子探测器(SNSPD)系统的探测效率和暗计数,建立了反应系统差错性能的数学模型,提出了系统误码率的计算公式.先对公式中的光强和激光脉冲重复频率对误码率的影响进行仿真,再通过实验结果验证仿真模型.结果表明,光强对误码率的影响最明显,随着光强从0.01光子/脉冲到1000光子/脉冲的增加,误码率从10~(-1)到10~(-7)量级明显下降;激光脉冲重复频率对误码率的影响受到不同光强的制约,但都随着脉冲重复频率的增加呈下降趋势.与此同时,当增加光强或者提高速度时,误码率高于仿真结果,约在10~(-4)量级,其原因可能是实际通信中调制光信号的消光比不足和光纤引入背景噪声提高了系统暗计数.以上模型和实验结果为进一步开展基于SNSPD的月球-地球、火星-地球等高速深空激光通信奠定了基础.     

基于多物理场模拟的阳极支撑微管燃料电池的结构优化设计

High volumetric power density (VPD) is the basis for the commercial success of micro-tubular solid oxide fuel cells (mtSOFCs). To find maximal VPD (MVPD) for anode-supported mtSOFC (as-mtSOFC), the effects of geometric parameters on VPD are analyzed and the anode thickness, t_an, and the cathode length, l_ca, are identified as the key design parameters. Thermo-fluid electrochemical models were built to examine the dependence of the electrical output on the cell parameters. The multiphysics model is validated by reproducing the experimental I-V curves with no adjustable parameters. The optimal l_ca and the corresponding MVPDs are then determined by the multiphysics model for 20 combinations of r_in, the inner tube radius, and t_an. And all these optimization are made at 1073.15 K. The results show that:(i) significant performance improvement may be achieved by geometry optimization, (ii) the seemingly high MVPD of 11 and 14 W/cm³ can be easily realized for as-mtSOFC with single-and double-terminal anode current collection, respectively. Moreover, the variation of the area specific power density with l_ca2(2 mm, 40 mm) is determined for three representative (r_in, t_an) combinations. Besides, it is demonstrated that the current output of mtSOFC with proper geometric parameters is comparable to that of planar SOFC.     

混凝土框架结构中楼板抗连续性倒塌效应的分析

针对钢筋混凝土框架结构,采用解析法,结合混凝土框架结构连续倒塌过程和抗力机制,分析了现浇楼板对结构抗连续性倒塌性能的影响,提出了考虑楼板效应的抗力计算方法。采用非线性静力Pushover方法分析现浇楼板对混凝土框架结构抗连续倒塌性能的影响,验证了解析法分析的正确性。结果表明,楼板对梁机制抗力的影响不明显,但对悬链线机制抗力的影响显著。对于边中柱初始失效情形,同时存在梁机制和悬链线机制两种抗连续倒塌机制,楼板可明显提高结构抗倒塌能力;对于角柱初始失效情形,仅存在梁机制而不能形成悬链线机制,楼板对结构的抗倒塌能力基本无影响。更多还原     

The nonlinear nonlocal singularly perturbed problems for reaction diffusion equations

A class of nonlinear nonlocal for singularly perturbed Robin initial boundary value problems for reaction diffusion equations is considered. Under suitable conditions, firstly, the outer solution of the original problem is obtained, secondly, using the stretched variable, the composing expansion method and the expanding theory of power series the initial layer is constructed, finally, using the theory of differential inequalities the asymptotic behavior of solution for the initial boundary value problems are studied and educing some relational inequalities the existence and uniqueness of solution for the original problem and the uniformly valid asymptotic estimation is discussed. Foundation items: the National Natural Science Foundation of China (10071048); the “Hunfred Talents Project” by Chinese Academy of Sciences Biography: Mo Jia-qi (1937−)     

定常的Navier-Stokes方程的非线性Galerkin混合元法及其后验估计

提出了定常的Navier-Stokes方程的一种非线性Galerkin混合元法,并导出非线性Galerkin混合元解的存在性和误差估计及其后验误差估计.     

定常的磁流体力学方程的非线性Galerkin混合元法

提出了定常的磁流体动力学方程的一种非线性Galerkin混合元法,并导出非线性Galerkin混合元解的存在性和误差估计．     

全息照相实验中图像采集数码装置的应用

在全息照相实验教学过程中,在＂再现＂环节引入CCD等图像观测和采集功能的数码辅助装置,对于记录物体的再现观测有一定的帮助,有利于学生对全息记录和＂再现＂的理解。