InP基多周期InAs/InAlGaAs量子点阵列的结构和光学性质

在InP（001）衬底上使用分子束外延技术自组织生长了多周期InAs/InAlGaAs量子点阵列结构。根据对透射电镜和光致发光谱结果的分析，认为引入与InP衬底晶格匹配的InAlGaAs缓冲层可以获得较大的InAs量子点结构，而InAlGaAs层的表面特性对InAs量子点的结构及光学性质有很大影响。对InP基InAlGaAs缓冲层上自组织量子点的形核和演化机制进行了探讨，提出量子点的演化过程表现为量子点的合并长大并伴随着自身的徙动，以获得能量最优的分布状态。     

GaAs基量子级联激光器材料结构设计的进展

GaAs基量子级联激光器的出现,在器件的设计制作和处理工艺上开辟了有意义的前景。本文概述了近年来GaAs基量子级联激光器在波导核心层、波导以及光学谐振腔方面设计的原理、进展,并介绍了一些新颖的结构。     

利用光纤马赫曾德干涉仪对金属腐蚀速率进行测量

为了提高对金属腐蚀过程的监测精度,缩短腐蚀过程的实验时间,本文利用所设计的光纤马赫曾德干涉仪(MZ)的高灵敏度,对0.5wt%的NaCl溶液在腐蚀不锈钢材料过程中等效折射率的变化进行分析,得到2 mL 0.5wt%的NaCl溶液,检测到条纹移动的最快速率为-9.32×10^-2 nm/s,产生的光谱峰值变化为-3.93×10^-2 dB/s,腐蚀速率呈现先增加后减小的趋势.由于采用电化学方法加速腐蚀过程,可在一分钟内对腐蚀过程进行监测,并可推广至其他金属材料.本实验可以作为金属线胀系数实验的延伸实验或创新设计实验.     

Exploring the Critical Sensitivity in Small-World Networks

Catastrophic phenomena such as earthquakes, avalanches, and critical points in the stock market are hard to predict. Recently, Xia et al. [Pure Appl. Geophys. 159 (2002)2491] showed that a geometrical system near catastrophic rupture presents a general critical sensitivity: the system becomes significantly sensitive near the catastrophe transition. Here we report that the phenomenon of critical sensitivity also exists in small-world network systems. With the increase of the small-world rewiring probability p, from the regular network p=0 to the random one p=1, the system performs more sensitively before the critical point while remaining in better organization through the evolutional progress, and the prediction threshold P8 performs more in advance. The concept of critical sensitivity can be applied to other complex network systems.     

液体定压比热容的理论推算

液体定压比热容的理论推算赵小明，刘志刚，王文，陈钟颀（西安交通大学能源与动力工程学院西安７１００４９）关键词聚集理论，循环，比热容１前言物质的比热容不仅是其重要的热物性参数之一，而且是与物质结构密切相关的特征数据，它对物理学和化学的理论研究及许多化工...     

基于改进粒子滤波的RFID室内目标定位算法

针对于LANDMARC算法的RFID室内定位精度受传输路径影响严重,直接采用粒子滤波自适应性差的问题,提出一种基于改进粒子滤波的RFID室内定位算法。该算法首先利用极限学习机(ELM)拟合阅读器接收信号强度与标签距离之间的非线性关系,构建信号传输模型,筛选邻近标签集;然后采用自适应学习因子优化粒子滤波过程,提高粒子全局寻优能力和收敛速度。仿真实验结果表明,该算法能够有效实现待测标签的RFID室内定位,且定位精度较高,收敛速度较快。     

遭遇乐富豪SUNFIRE I

不久前,一好友欲组建一套纯音乐系统,跟在下商议应该如何“配菜”?笔者当时想起乐富豪将有一些中价本土产的Hi-Fi器材9月份从广州开始向内地巾场推广,问他愿不愿意等等看,好友说怎么会有这样的好事呢?那就等等吧。我们到产品发布会的试听现场,先欣赏了一下这批新品音响陈列室摆了两排,最抢眼的是一对“身材” 极     

Pattern Formation in the Turing-Hopf Codimension-2 Phase Space in a Reaction-Diffusion System

We systematicaily investigate the behaviour of pattern formation in a reaction-diffusion system when the system is located near the Turing-Hopf codimension-2 point in phase space. The chloride-iodide-malonic acid （CIMA） reaction is used in this study. A phase diagram is obtained using the concentration of polyvinyl alcohol （PVA ） and malonic acid （MA） as control parameters. It is found that the Turing-Hopf mixed state appears only in a small vicinity near the codimension-2 point, and has the form of hexagonal pattern overlapped with anti-target wave; the boundary line separating the Taring state and the wave state is independent of the concentration of MA, only relies on the concentration of PVA. The corresponding numerical simulation using the Lengyel-Epstein （LE） model gives a similar phase diagram as the experiment; it reproduces most patterns observed in the experiment. However, the mixed state we obtain in simulation only appears in the anti-wave tip area, implying that the 3-D effect in the experiments may change the pattern forming behaviour in the codimension-2 regime.