Ba(1S)+N2O反应的化学发光偏振研究

The variation of ehemiluminescent polarization for reaction Ba(~1S)+N_2O with respect to the Ba beam temperature or the average collision energy E_(rtr) was studied under the single collision condition on beam-gas apparatus. If E_(rtr)<0.06 eV, the distribution of rotational angular momentum for product BaO, i.e. -, increased with the impact energy; while E_(rtr)>0.06 eV, - decreased with the E_(rtr). It is plausible to point out the corresponding relationship between the characteristics of the reaction potential surface and the conformation of the intermediate complexes.     

纤锌矿相GaN空穴输运特性的Monte Carlo模拟研究

用全带多粒子Monte Carlo方法模拟纤锌矿相(Wurtzite)GaN空穴输运特性的结果. 用经验赝势法计算得到能带结构数据. 模拟包含了声学声子散射，光学声子散射，极性光学声子散射，压电散射，电离杂质散射及带间散射等散射机理. 计算得到了空穴沿3个主要对称方向上的空穴平均漂移速度和平均能量与电场强度的关系曲线，室温下漂移速度呈现饱和特性. 在所研究的电场范围内，最大平均漂移速度约为6×10⁶cm s^-1，最大空穴平均能量约为0.12eV, 这些值均比电子的相应参数低很多. 还给出了空穴的扩散迁移率与杂质浓度关系的模拟结果. 关键词： 蒙特卡罗 氮化镓 输运特性 能带结构     

Ba(~1S)+N_2O反应的化学发光偏振研究

当原子或分子之间经历反应碰撞后,产物分子的转动角动量矢量相对于初始相对速度矢量具有较明显的取向。达一信息可从测量反应生成的激发态产物分子的化学发光偏振度P得到。Zare等首先研究了反应Ba(~1S)+N_2O产物的化学发光偏振;近期Jalink等利用六极电场将反应物分子取向,研究了反应Ba(~1S)+N_2O的化学发光偏振与不同碰撞方位的关系。本文研究了化学发光偏振度随Ba(~1S)束速度(即反应物相对平动能)的变化,根据产物转动角动量分布对反应物相对平动能的依赖关系得到了Ba(~1S)+N_2O反应的反应机理及势能面的新图象。     

层状复合氢氧化物的药物控释动力学机制

以层状复合氢氧化物(LDH)为载体组装乙酰苯甲酸(ASP)的插层复合物LDH-ASP,以pH2.48~6.89的磷酸盐溶液为介质进行药物释放动力学实验,通过对不同时间药物释放度的测定及释放药物后载体结构变化分析研究了LDH对层间药物的控制释放机制。结果表明粉末状LDH-ASP能在较宽的pH范围表现明显缓控释作用,药物释放度积分方程与Higchi方程、Ritger-Peppas方程、Bhaskar方程及一级动力学方程等经验模型吻合。复合物与溶出介质的反应机制研究表明,药物释放速率及释放度大小取决于交换配比n(ASP)/n[HnPO4(3-n)-]所决定的LDH层间通道畅阻情况。     

MICROSTRUCTURES AND SEQUENCE DISTRIBUTIONS IN POLYDIENES

The sequence distribution of polydienes is studied both theoretically and experimentally. The expressions for sequence length distribution, the probability functions for monads and dyads are derived from solving a set of kinetic differential equations on the condition of constant monomer concentration [M]. The microstructure data of polybutadiene generated by anion and Ziegler-Natta catalyst at low conversion or in the case of constant [M] show that our theory mentioned above is correct, i. e. as in the case of batch reactor, there is also an unsteady stage during the initial period of polymerization for the system of constant [M] when the sequence structures of the product vary with reaction time; then the polymerization arrives at the steady stage when the microstructures become unchanging.     

聚双烯烃的近程结构

本文首先求解单体浓度恒定条件下的动力学微分方程组,得到各种不同结构的序列分布函数的表达式,从而给出一元组和二元组的概率函数。当低转化率时或单体浓度不变时,由阴离子方法和稀土催化合成的聚丁二烯的实验数据表明:上述理论是正确的,即在恒定单体浓度的双烯烃聚合反应的初期,和变浓体系一样,存在着一个非稳态阶段,这时产物的结构随反应时间而变化;然后才逐渐进入聚合反应的稳态阶段,此时产物的微观结构趋于恒定。     

基于因子分析的简支梁桥损伤识别

为了降低测量噪声对桥梁损伤检测结果的影响,提高检测方法在实际工程中的实用性,提出了一种基于因子分析的简支梁桥损伤识别方法。首先,对采集的位移信号进行因子分析,得到信号的公共因子和特殊因子,通过去除公共因子达到降噪目的。然后,采用统计方法和D-S证据理论对特殊因子进行处理并构造损伤指标。通过一个简支梁桥有限元模型的算例进行数值分析,讨论了噪声、车辆移动速度及质量对损伤识别产生的影响。结果表明：车速在30～80 km/h范围内时,所提方法可以准确定位较小程度的结构损伤;此外,噪声和载质量对识别结果影响较小,满足实际工况需求,说明所提方法具有很强的抗噪能力和实用价值。     

Retrieval of high-order susceptibilities of nonlinear metamaterials

Active metamaterials embedded with nonlinear elements are able to exhibit strong nonlinearity in microwave regime.However, existing S-parameter based parameter retrieval approaches developed for linear metamaterials do not apply in nonlinear cases. In this paper, a retrieval algorithm of high-order susceptibilities for nonlinear metamaterials is derived.Experimental demonstration shows that, by measuring the power level of each harmonic while sweeping the incident power,high-order susceptibilities of a thin-layer nonlinear metamaterial can be effectively retrieved. The proposed approach can be widely used in the research of active metamaterials.