Solid-state resonant tunneling thermoelectric refrigeration in the cylindrical double-barrier nanostructure

A solid-state thermoelectric refrigerator with a cylindrical InP/InAs/InP double-barrier heterostructure is proposed.Based on the ballistic electron transport and the asymmetrical transmission, we derive the expressions of the performance parameters of this refrigerator. The cooling rate rather than the coefficient of performance is affected by the area of the inner cylinder. Then through the numerical simulation, a triangular cooling rate region is found with respect to the chemical potential and bias voltage; further, that it is because of the small full width at half maximum of the transmission resonance and the linear relationship between the energy position of resonance and the bias voltage. These tunable results might supply some guide to the cooling in tiny components or devices.     

电光调制晶体半波电压倍频测量方法的讨论

在电光调制晶体的半波电压倍频法测量中,基于晶体电光效应分析了不同偏压下输出信号与调制信号之间的线性与倍频关系,并利用计算机模拟分析了调制信号的调制幅度对倍频信号的影响,分析结果表明倍频信号受高阶谐波分量的干扰产生波形畸变,不利于晶体半波电压的倍频法测量。提出利用李萨如图形的对称性来确定电光调制的倍频位置,克服了调制幅度波形畸变问题的干扰。通过对半波电压不同测量方法的实验测量和对比分析,说明该方法可操作性好,测量精确度也比直接观察倍频信号输出波形要高。     

不良导体导热系数测量实验中两种冷却方式的对比研究

对稳态法测量不良导体导热系数实验中两种冷却方式进行了对比研究,实验结果表明：自然对流冷却方式测量结果很接近理论值,强迫对流冷却方式测量结果偏差较大,分析了偏差产生的原因．     

椭圆偏振光的实验分析与数据处理

利用Jones矩阵解释椭圆偏振光经检偏器的出射光强与检偏器转角不成椭圆分布的原因,并用极坐标系下数据处理的两种物理模型,定量描绘出椭圆偏振光曲线。     

Jones矩阵在偏振光实验中的应用

将Jones矩阵应用于偏振光实验研究,通过偏振光的Jones矢量表示和偏振器件的Jones矩阵,分析了偏振光通过偏振器件后偏振态的变化,准确方便地解释了偏振光实验中的实验现象。     

pH对Eu(Ⅲ)在氧化铝上吸附行为的影响

在N2环境下,离子强度为0.1 mol/L的NaClO4溶液中,考察了不同pH值(3.0~11.0)对Eu(Ⅲ)在氧化铝上吸附行为的影响,用荧光时间衰减光谱法研究了Eu(Ⅲ)在氧化铝表面上的化学形态.结果表明,Eu(Ⅲ)在氧化铝上的吸附随pH值的升高而增强,在较低pH值(<4.0)溶液中,绝大部分Eu以自由的Eu3 存在于溶液中;在较高pH值(>6.9)溶液中,Eu(Ⅲ)在氧化铝上的吸附形态会失去大部分水,形成化学吸附,吸附形态为≡(Al-O)-Eu2 .(H2O)4.     

电光调制不同工作点选择方法下的光偏振态分析

以晶体电光调制实验为基础,分析两种工作点选择方法下光束偏振态的变化及实验中的线性调制、倍频失真等现象,并借助Jones矩阵分析起偏器、检偏器倾斜x、y方向时对实验光强的影响.     

Surface effect of nanocrystals doped with rare earth ions enriched on surface and its application in upconversion luminescence

By employing a certain proportion of hydrogen peroxide, ammonia, ammonium fluoride, and ethylene diamine tetraacetic acid (EDTA) as precipitator, well-crystallized LaOF:Eu3+ and LaOF:Yb3+, Er3+ nanocrystals are synthe- sized by using the chemical co-precipitation method. The structural properties of these samples are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR) spectra. The results show that all the samples have an average size below 70 nm, which decreases gradually with the increase of the EDTA content, and a certain number of EDTA molecules are coupled with doped ions on the surfaces of nanocrystals. Most of the doped ions are proved to be enriched on the surfaces of nanocrystals and surrounded by the high energy vibration groups and bonds in EDTA molecules. The observed differences in upconversion emission spectrum among the different LaOF:Yb3+, Er3+ nanocrystals are explained by the different two-photon upconversion mechanisms. Especially, in the LaOF:Yb3+, Er3+ nanocrystals with EDTA, the two-photon processes that contain several special cross-relaxation processes are introduced to analyse the corresponding upconversion mechanisms.     

一个新的自治混沌系统及其电路实现

在Lü系统的基础上提出了一个新的三维自治混沌系统,并对系统的基本动力学特性进行了深入的分析,利用数值分析软件MATLAB给出了系统的相轨迹图、分岔图、Lyapunov指数谱等.结果研究表明,系统具有丰富的非线性动力学行为.根据非线性电路的基本理论,把新的三维自治混沌系统的数学模型转化为电路方程,构造出符合新混沌系统的非线性电路.利用电路仿真软件Multisim对非线性电路进行了仿真实验,仿真结果证实了该非线性混沌系统电路在物理上的可实现性.