全反射镜结构对AlGaInP发光二极管发光效率的影响

采用计算机模拟的方法,计算了SiO2/Al,ITO/Al,SiO2/Au和ITO/Au全方位反射镜结构和分布式布拉格反射镜的反射特性.用PECVD和溅射设备制作了Glass/SiO2/Au结构,用LP-MOCVD生长了DBR结构,并测量了其反射特性,实验与模拟结果基本吻合.从模拟和实验的结果得到,SiO2/Au ODR结构在波长为630nm的垂直入射光下反射率很高,达到91%以上.对于不同角度的入射光,SiO2/Au在20°～85°都有很高的反射率,远高于DBR结构的反射率.在实际器件测试中,ODR结构的AlGaInP红光LED比无DBR结构的LED提高了115%,比DBR结构的LED提高了28%.这说明,ODR结构与DBR结构相比可以大幅提高红光LED的出光效率.     

基于3G的地空通信组网仿真

地空通信系统作为军事通信的重要组成部份，在作战中发挥着重要作用．为打赢信息化条件下的局部战争，发挥军事通信作为战场神经网络的作用．文中结合3G技术发展情况提出基于3G的地空通信组网方案，并对组网关键技术进行分析，最后利用OPNET网络仿真软件对组网场景进行仿真，为军事通信现存矛盾的解决开辟了有效途径。     

软件无线电中的数字化快速解调算法

软件无线电中信号的调制与解调是研究的重点问题之一。文章基于希尔伯特变换提出了一种在软件无线电中的数字化快速解调算法，理论分析和仿真结果表明，该解调方案的抗干扰性能有明显改善，与传统解调方法相比，通用性强、简单、计算量小且易于实现，能很好地满足软件无线电中的要求。具有理论意义和实际应用价值．     

飞机电力作动器半实物仿真技术研究

飞机电力作动器是未来飞机电源系统的重要负载，对电源系统的质量和稳定性问题有很大影响，通常要在电力系统全集成之前进行半实物仿真。本文首先介绍该种飞机电力作动器半实物仿真理论实现方法，然后县体通过电力作动器动态功率特性、恒功率特性、电源输入阻抗特性及电磁兼容性几个方面对该疗法的可行性进行了一定程度的论证，最后介绍了该种飞机电力作动器半实物仿真具体的硬件实现方法。     

仿真嵌入实装的技术实现

随着通信对抗装备的复杂性增加和对其形成作战能力的要求不断提出,装备训练的问题日益突出。阐述了把仿真嵌入实装的需求层次和思路,并提出了相应的实现途径和总体框架。     

再入飞行器驻点流光辐射特性的理论建模

本文用直接模拟蒙特卡罗法，对再入体驻点区域的流场、光辐射特性进行了研究．针对头部锥体驻点区（包括激波层），建立了流场中的化学反应模型，中性粒子和等离子体的热运动、粒子间碰撞的理论模型，碰撞激发辐射和化学发光辐射的物理模型．给出了样本粒子运动方向和速率、粒子碰撞对的选择等蒙特卡罗法概率模型和计算方法．     

Evaluating perturbation contributions in SAFT models by comparing to molecular simulation of n-alkanes

SAFT models are generally written as a perturbation series of the Helmholtz energy with reciprocal temperature as the argument. The perturbation coefficients are then functions of density and molecular size. The variation of the perturbation coefficients with molecular size is given primarily by Wertheim's theory [6], [7], [8] and [9], but there may be additional variations as in the PC-SAFT model. In the present work, we compare the characterization of perturbation coefficients inferred from PC-SAFT to those derived from molecular simulations.The molecular simulations are based on Discontinuous Molecular Dynamics (DMD) and second order Thermodynamic Perturbation Theory (TPT). DMD simulation is applied to the repulsive part of the potential model with molecular details like fused hard spheres for the interaction sites and 110° bond angles. The thermodynamic effects of disperse attractions are treated by rigorous application of TPT. The present work re-examines the related work of Elliott and Gray [35] in the low density and critical regions, focusing on n-alkanes with carbon numbers ranging from 3 to 80.We find that SAFT theory overestimates the repulsive contribution (A₀) and underestimates the first order contribution (A₁) of Helmholtz energy relative to simulation. Nevertheless, the correlations are qualitatively reasonable. Significant inconsistencies arise when considering the second order contribution (A₂). For example, the PC-SAFT characterization of A₂ becomes larger than A₁ in the low density, long chain limit, raising concerns about the convergence of the series. Furthermore, fluctuations are underestimated in the critical region and overestimated in the liquid region. In each case, we can suggest improved characterizations. Altogether, these results suggest ways to modify the SAFT formalism to achieve greater consistency between atomistic and coarse-grained models.     

基于Simulink＆DSP Blockset功率谱估计的仿真实现

Matlab／DSP Blockset／Estimation库提供了对输入信号进行功率谱分析的各种模块。在Simulink图形化的交互环境下,用户只需用鼠标拖动Estimation库中的功率谱估计模块,便能迅速地进行信号的功率谱估计的仿真。     

Numerical simulation of 2D lid‐driven cavity flow with CLEARER algorithm on extremely highly skewed grids at high Reynolds numbers

It is crucial to deal with the grid non‐orthogonality effectively in solving the flow in complex geometries, especially at high Reynolds numbers. In this study, the newly proposed Coupled and Linked Equations Algorithm Revised‐ER (CLEARER) algorithm is adopted to solve this problem successfully. In CLEARER algorithm the second relaxation factor is introduced in constructing the contravariant interface velocities, by setting it to a low value. CLEARER algorithm can overcome the severe grid non‐orthogonality and non‐linearity of equations effectively. After the numerical results with CLEARER are validated with the benchmark solutions, this algorithm is used to solve the lid‐driven flow in inclined cavity with inclination angles varying from 10 to 170^°, and Reynolds numbers varying from 5000 to 15 000. The streamlines and the centerline velocity distributions are provided in detail for all cases, which may offer some guidance for the study in this area. Copyright © 2010 John Wiley & Sons, Ltd.     

Dimensions of branched polymers formed in simultaneous long‐chain branching and random scission

In free‐radical olefin polymerizations, the polymer‐transfer reactions could lead to chain scission as well as the formation of long‐chain branches. The Monte Carlo simulation for free‐radical polymerization that involves simultaneous long‐chain branching and random scission is used to investigate detailed branched structure. The relationship between the mean‐square radius of gyration 〈s²〉 and degree of polymerization P as well as that between the branching density and P is the same for both with and without random scission reactions—at least for smaller frequencies of scission reactions. The 〈s²〉 values were larger than those calculated from the Zimm–Stockmayer (Z‐S) equation in which random distribution of branch points is assumed, and therefore, the Z‐S equation may not be applied for low‐density polyethylenes. The elution curves of size exclusion chromatography were also simulated. The molecular weight distribution (MWD) calibrated relative to standard linear polymers is much narrower than the true MWD, and high molecular weight tails are clearly underestimated. A simplified method to estimate the true MWD from the calibrated MWD data is proposed. The MWD obtained with a light scattering photometer in which the absolute weight‐average molecular weight of polymers at each retention volume is determined directly is considered a reasonable estimate of the true MWD. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2960–2968, 2001