High-temperature ultrafast polariton parametric amplification in semiconductor microcavities.

Cavity polaritons, the elementary optical excitations of semiconductor microcavities, may be understood as a superposition of excitons and cavity photons. Owing to their composite nature, these bosonic particles have a distinct optical response, at the same time very fast and highly nonlinear. Very efficient light amplification due to polariton-polariton parametric scattering has recently been reported in semiconductor microcavities at liquid-helium temperatures. Here we demonstrate polariton parametric amplification up to 120 K in GaAlAs-based microcavities and up to 220 K in CdTe-based microcavities. We show that the cut-off temperature for the amplification is ultimately determined by the binding energy of the exciton. A 5-micrometer-thick planar microcavity can amplify a weak light pulse more than 5,000 times. The effective gain coefficient of an equivalent homogeneous medium would be 107 cm-1. The subpicosecond duration and high efficiency of the amplification could be exploited for high-repetition all-optical microscopic switches and amplifiers. 105 polaritons occupy the same quantum state during the amplification, realizing a dynamical condensate of strongly interacting bosons which can be studied at high temperature.     

含叠氮硝胺的低特征信号推进剂的热分解研究

应用高压ＤＳＣ（差示扫描量热法）、ＴＧ（热重法）和ＤＴＧ（差示热重法）了ＤＡＴＨ（１,７－二叠氮－２,４,６－三硝基氮杂庚烷）、ＲＤＸ（黑索金）单组分以脑ＲＤＸ－ＣＭＤＢ（复合改性双基推进剂）和ＣＤＡＴＨ－ＲＤＸ－ＣＭＤＢ推进剂样品的热分解,温度达２００℃时,首先暗ＤＡＴＨ中３个－ＮＯ２从主链上断裂分解,接着是一Ｎ３和其他残余分子在较短的时间剧烈地分解并释放出大量的热,在多组分体系中,ＤＡＴＨ与（     

基于Volterra基函数网络的自适应逆控制方法

提出了一种基于Ｖｏｌｔｅｒｒａ基函数（ＶＰＢＦ）网络的非线性系统自适应逆控制方法。对象和逆控制器各用一个ＶＰＢＦ网络表示,应用正交最小二乘算法进行离线网络结构确定和权值初始化,构造了一种动态归一化非线性最小均方（ＤＮＮＬＭＳ）权值更新算法,以进行网络权值的在线学习。仿真结果表明,该方法具有算法简单、学习速度快、鲁棒性能好等优点。     

分层遗传算法在DC/DC变换器中的应用

DC／DC变换器为强非线性、时变及不确定系统．由于其自身的特点,使得DC／DC变换器的控制研究工作比较困难．文中提出一种用遗传算法优化的模糊控制器,控制DC／DC变换器．对传统的遗传算法进行改进．使之优化能力更好．由仿真和实际试验证明,经过改进的遗传算法优化的模糊控制器,对DC／DC变换器的控制效果更显著,动态特性和静态特性都得到进一步改善．同时说明所介绍的自适应遗传算法的寻优能力更好,收敛速度也更快．     

计算机多点温度实用检测系统的设计

设计一种以89C52为核心的实用新型计算机温度采集系统．它采用J类热电偶作为测温元件,利用集成电流的温度传感器AD590,实现热电偶冷端温度的有效补偿,从而提高系统的精度、稳定性和抗干扰性能．该系统主要从工程实际出发,对元件选择、电路设计等方面进行研究．在给出核心硬件电路的同时,提出可对多路数据作采集、处理并实现报警功能的可拓展电路．实现了低成本、远距离传输温度巡回检测。     

轮胎垂直方向刚性环模型

为研究轮胎在中等频率时的垂向力学特性,建立了垂直方向上的刚性环模型,对1/4车模型进行了振型分析,说明刚性环模型能反映中频时的振动。简单介绍了模型输入和轮胎动态特性试验,并将模型和试验结果进行了对比,表明垂直方向刚性环模型能较好反映轮胎在典型短波长不平路面上垂直方向上的力学特性。     

Improved unequal interval grey model and its applications

A new method to improve prediction precision of GM(1,1) model with unequal time interval is presented.The grey derivative is multiplied by a parameter to guarantee the time response function satisfying approximately exponential function distribution.To simplify the process of parametric estimation,an approximate value is taken for the multiplied parameter.Then the estimators of coefficient of development and grey action quantity can be derived.At the same time,the principle of the new information priority is also considered.We take the last item of the first-order accumulated generation operator(1-AGO) on raw data sequence as the initial condition in the time response function.Then the new information can be taken full advantage of through the improved initial condition.Some properties of this new model are also discussed.The presented method is actually a combination of improvement of grey derivative and improvement of the initial condition.The results of an example indicate that the proposed method can improve prediction precision prominently.     

耦合三角函数的灰色GM(1,1,T)模型及其应用

针对小样本序列的周期性波动特征,将三角函数引入灰色预测模型,提出了耦合结构的灰色GM(1,1,T)模型,该模型适用于既存在周期性又具有趋势性的复合型序列.基于最小二乘思想,探讨了模型参数估计的非线性优化问题,利用Levenberg-Marquardt算法进行求解,并给出了初始点选取的经验方法;通过数值实验验证了模型的适用性和参数估计方法的可行性;最后将该模型应用于河南省获嘉县、禹州市、偃师市的农业干旱预测,结果表明2016-2017年河南省土壤含水量呈现出区域性差异,与实际干旱情势比较吻合.     

高分辨率的飞秒激光自动测试系统及其应用

报导了ＩＢＭ计算机控制下的高时间分辨率的飞秒激光自动测试系统．其时间分辨率小于１ｆｓ（光程分辨率０．０８４μｍ），信号测量相对灵敏度达１０－６，采用集成多功能程序控制，重复性和稳定性高，适用于飞秒激光脉宽的自相关测量和飞秒泵浦探测实验．     

多媒体仿真建模方法和仿真策略

本文首先介绍了多媒体仿真的概念，然后提出“自治的仿真媒体对象”建模概念框架。在此基础上，讨论了多媒体仿真方法中有关多媒体对象建模方法，面向对象的多媒体仿真的消息扫描策略，以及分布式仿真等问题。