非对称量子阱中二次极化率的研究

利用密度矩阵的方法研究了一种非对称量子阱的光学非线性,推导出了二次谐波解析表达式,最后利用典型的GaAs/AlGaAs非对称量子阱进行数值计算.数值结果表明,当非对称性增大时,可得到比较大的二次谐波,从而为实验上制作比较大的非线性材料提供一种可行办法.     

核裂变中子发射多重性的蒙特卡罗模拟

本文采用c,h,α参量描述核的形变,建立了含中子发射的朗之万耦合模型,并完成了核裂变前中子发射多重性的蒙特卡罗计算.经过验证,采用蒙特卡罗方法得到的计算结果与实验结果符合较好;另外,本文区分了鞍点前及鞍点后的中子发射,重点考察了裂变核的鞍点振荡,发现鞍点振荡期间的中子发射多重性不可忽略,并且其数量随入射粒子实验室能量及复合核质量数的增加而增大,因此对于热的重核,鞍点振荡期间的中子发射多重性将极大地影响核裂变碎片角分布的计算.     

自适应的over-relaxed快速动态均值漂移算法

为了解决高斯核均值漂移算法收敛速度慢、计算效率不高的问题,提出自适应over-relaxed快速动态更新方法改进高斯核均值漂移算法。首先,在静态均值漂移算法中引入数据集的动态更新机制,每次迭代后将数据集更新到新的数据点,然后,将迭代过程中聚集在一起的数据点用1个收敛点表示,逐步减少参与计算的数据,保证准确性的同时降低计算量。由于非正态分布的数据集动态更新时,主方向上的数据点的收敛速度较慢,采用over-relaxed的策略来提高主方向数据点的迭代步长,并根据数据集直径的变化,自适应地计算步长参数。实验结果表明,改进后的高斯核均值漂移算法以超线性的速度收敛,收敛点的应用降低了收敛过程中的计算量。     

Development and application of flexible substrate sensors in instantaneous heat flux measurement

A new type of sensor with the flexible substrate is introduced. It is applicable in measuring instantaneous heat flux on the model surface in a hypersonic shock tunnel. The working principle, structure and manufacture process of the sensor are presented. The substrate thickness and the dynamic response parameter of the sensor are calculated. Because this sensor was successfully used in measuring the instantaneous heat flux on the surface of a flat plate in a detonation-driven shock tunnel, it may be effective in measuring instantaneous heat flux on the model surface.     

三山五园历史文化景区自助旅游系统APP设计与开发

随着世界范围移动互联网时代的到来,基于位置服务(LBS)的应用成为当前GIS发展的主要趋势之一,建立在LBS基础上的智慧旅游行业发展迅猛,影响和改变了游客的旅游方式和旅游体验。在Android平台,运用百度地图API设计并开发针对北京"三山五园"地区的自助旅游系统APP,该系统能够通过功能集成,实现地图展示、信息检索、线路查询等基本功能,提供"三山五园"地区的历史风貌及文化展示等旅游专题信息,并能提供指南针、实时天气查询等辅助功能。通过免费下载APP,提供更加便捷、高效、全方位的旅游服务系统,使游客自助旅游的愿望得以实现。     

磨料流光整加工性研究

对磨料特性及其加工性进行了系统的研究,实验结果表明：在低速范围内,流动指数较小的磨料加工效果较好。磨料粘度及磨粒含量增加,均能提高加工效果,但流动性变差。磨粒粒度增大也可提高加工效果,其选择应取决于初始表面糙度值。     

斜入射电磁波在大气等离子体层中的衰减

基于WKB近似方法,研究了任意角度入射的电磁波在覆盖金属表面的大气等离子体层中的衰减.讨论了适合等离子体隐身的等离子体密度模型,数值计算了电磁波在大气等离子体层中的衰减与大气等离子体层中的负离子、入射角度以及电子碰撞频率之间的关系,并给出了相关参数的电磁波衰减.     

C-isotope composition and correlation of the Upper Neoproterozoic in Keping area, Xinjiang

C-isotope analysis of the carbonates in the Upper Neoproterozoic in Keping, Xinjiang indicates that the Qigebrak Formation and the Upper Sugaitbrak Formation mainly record positive C-isotope values, and a distinct positive excursion occurs in the lower part of the Qigebrak Formation. There are three negative excursions in the boundary between the Qigebrak Formation and the Cambrian, the uppermost and lowermost Upper Sugaitbrak Formation. These characters resemble those of the Upper Neoproterozoic in the Three-Gorge area, which suggests that the Upper Sugaitbrak Formation and Qigebrak Formation can be correlated with the middle and upper parts of the Doushantuo Formation and Dengying Formation, respectively. The negative excursion at the top of the Upper Sugaitbrak Formation corresponds to that at the top of the Doushantuo Formation, while the negative excursion at the bottom of the Sugaitbrak Formation can be correlated with that at the middle part of the Doushantuo Formation in the Three-Gorge area and that at the top of the Hangelchaok diamictites in the Quruqtagh area.     

Solvent effects on photophysical properties of copper and zinc porphyrins

The photophysics of Zn（tetraphenylporphyrin,TPP）, Zn（tetra-2,4,6-trimethylphenyl porphyrin, TMP）, Zn （tetra-（o-dichlorophenyl） porphyrin, TPPCI8）, Cu（tetraphenylporphyrin,TPP）, Cu（tetra-2,4,6-trimethyl- phenyl porphyrin,TMP）, and Cu（tetra-（o-dichlorophenyl） porphyrin, TPPCIE, TPPCI8） in several solvents have been investigated on steady state and time-resolved spectroscopy. The Cu（TPPCI8 ） is normal and shows no evidence of CT transition in the visible or near UV regions in nonpolar solvent. However, Cu（TPPCI8）shows a blue shift in the absorption spectrum and intramolecular CT bands at absorption spectra in polar solvent, which shows a fluorescence maximum emission at 650 nm and 8.4 ns lifetime. The reason can be attributed to two points. Firstly, the increase of solvent polarity can enlarge outer reorganisational energy, which is favorable to reduce the activation free energy of charger-transfer transition based on Marcus theory of electron transfer. Moreover, the internal heavy-atom effect on Cu（TPPCIE） is encouraging to stabilize the 2T1 state also, which increases the possibility of population to CT band from 2T1 state. This result is in accord with an earlier estimate of a 10 ns lifetime and CT absorption at 640 nm bands for the CT state of Cu （11） octethylporphyrins. Other possible reasons arousing unusual fluorescence like H-bonding, axial ligands, molecular aggregation are excluded.     

多步混沌打靶方法控制混沌

OGY方法是一种有效的混沌控制方法,其利用混沌运动对初值极端敏感及遍历特性,通过系统参数的微小摄动将混沌控制到期望的轨道.在混沌打靶方法的基础上提出了对OGY方法的改进.改进后的方法远优于OGY方法.