成都地区天空光光谱的测量与分析

本文报道成都地区天空光光谱的测量与分析。测量了不同方位不同倾角的天空光谱,测量结果表明,同一天中天空光光谱分布基本保持不变,不同时段,不同方位和不同倾角的天空光光谱强度不同。与天顶角为零的天空光谱(天顶光谱)比较,不同方位和不同倾角的天空光谱中包含了大气吸收的有用信息,可用于大气污染状况的研究与分析。     

基于夫琅禾费衍射的星芒现象探究

对拍摄光源时产生的星芒现象做出了理论解释和实验探究。基于夫琅禾费衍射理论,推导了光线通过正多边形孔后的复振幅分布,并用MATLAB对光场做傅里叶变换,得到了不同频率的光通过不同形状,不同大小的小孔后的衍射图样。并且开展了对应的实验,给出了不同频率的光线通过不同形状和大小的光圈后产生星芒的条件和规律,验证了理论分析的正确性。     

基于离散算法的双包层Er~(3+)/Yb~(3+)共掺光纤激光器动态特性研究

采用基于速率方程的离散算法,对双包层Er3+/Yb3+共掺光纤激光器增益介质在不同位置的动态特性进行了分析。研究了增益介质在不同位置上的能级粒子数、激光功率随时间的变化。结果表明:增益介质在不同位置振荡达到稳态前上能级粒子数随时间的变化是不同的,并呈现出了不同的变化特点;不同位置处振荡开始时的最大峰值功率与达到稳态时的功率也不同;不同位置开始振荡的时间相同,达到稳态的时间也基本相同。对这一算法的稳态结果同简化速率方程的稳态分析值进行了对比,显示了泵浦功率较大且光纤长度较长时两者所具有的差异。     

Altera SRAM型FPGA器件总剂量辐射损伤及退火效应

为了考核FPGA器件空间使用时的抗辐射能力,对Altera SRAM型FPGA器件60Coγ辐照后的总剂量辐射损伤效应及退火效应进行了研究。通过不同模块实现相同的分频功能,比较了不同模块输出波形随总剂量、退火时间的变化关系;通过实现不同源程序所需的模块不同,比较了不同模块、不同源程序功耗电流随总剂量、退火时间的变化关系。分析了功耗电流在不同退火温度下恢复的原因,讨论了不同退火温度下功耗电流恢复幅度的差异。测量了输出端口的高低电平,分析了高低电平随总剂量、退火时间的变化关系。实验结果表明:氧化物正电荷的退火导致了不同退火温度下的功耗电流的恢复,并且浅能级亚稳态的氧化物正电荷的数量多于深能级氧化物正电荷的数量;随着退火时间的增加,功能恢复为突变过程,而功耗电流的恢复为渐变过程。     

基于激光雷达探测的气溶胶分类方法研究

提出了利用激光雷达区分不同类型气溶胶的新方法。建立了包含背景气溶胶和云两种不同类型气溶胶光学参数(后向散射系数、消光系数)的两个激光雷达方程,并推导计算其解的表达式。反演出两种不同类别气溶胶的光学参数,以此区分背景气溶胶和云。根据两种不同气溶胶的光学参数与两种不同消光后向散射比(Saer1,Saer2)模拟激光雷达回波信号,并用该新方法反演得到两不同类别气溶胶的光学参数。反演结果与不同类型气溶胶的模拟参数一致。用该方法区分激光雷达同时探测到的大气背景气溶胶和云。模拟和测量结果都证实了该方法对不同类型气溶胶进行分类的可行性。     

利用FTIR指纹图谱研究中药材黄芪

为了寻求简便快速鉴别黄芪不同生长年限和不同产地的新方法,该文采用分辨率高、准确度好,简便快捷、无污染的FTIR光谱法,研究了山西不同产地同一生长年限黄芪FTIR的光谱特征,并与内蒙和甘肃的黄芪作了比较;同时考察了山西同一产地不同生长年限黄芪的FTIR光谱特征。结果表明：22批样品的黄芪共有峰为9处,可用于鉴别黄芪的真伪;差异峰有5处,其峰的数目、形状及相对强度可用于区分黄芪的不同产地和不同生长年限。因此, 可以利用FTIR指纹图谱方便快捷地区分不同生长年限和不同产地的黄芪。     

傅里叶变换红外光谱法分析复印纸的研究

建立了一种利用傅里叶变换红外光谱技术快速检验复印纸的新方法。采用傅里叶变换红外光谱技术对复印纸中填料种类和纤维素的结晶度进行了分析,并研究了复印纸热老化和紫外光老化的规律。以1 429与893 cm-1的吸光度比值表示纤维素的结晶度,测定不同纸张样品的结晶度的标准偏差为0.010 7～0.016 0,同一包纸样的平均标准偏差为0.014 8。不同厂家不同牌号、相同厂家不同牌号、相同厂家相同牌号不同生产时间复印纸中添加的填料种类和纤维素的结晶度不同,热老化和紫外光老化规律不同, 实现了对复印纸的鉴别,为纸张的相同性比对和同一认定提供了一种实用的检验方法。     

交流电沉积法制备金属氧化物纳米材料及形貌控制

以不同种类的金属丝为电极,采用交流电沉积的方法在液相水溶液中制备了多种金属氧化物纳米材料,并对其形貌进行了控制。由XRD和TEM分析结果表明,在相同的NaCI电解质水溶液中,不同的金属电极对应的不同金属氧化物纳米产物具有明显不同的形貌。     

不同种类燃料火焰的辐射光谱测量

利用CCD光纤光谱仪测量不同燃料的火焰辐射光谱,得到了不同种类燃料燃烧时火焰光谱的不同特征。分析这些特征可以对燃料进行判别,也可以对不同火焰进行监测和诊断。     

初始状态对自组织演化过程的影响

从实验上系统研究了在强电场下处于介质中的大量金属小球从不同初始状态通过自组织演化为分形的过程;用Sandbox方法定量分析了最终形成的稳定树枝状分形的维数。结果表明:不同初始状态形成分形的过程完全不同,但最终的树枝状分形的维数基本相同。分析认为,小球之间的相互作用存在临界作用距离,不同初始状态相邻小球之间的平均间距不同,因而演化过程不同;而维数相同正是系统耗散相同的体现。     

Dual-band frequency selective surface with quasi-elliptic bandpass response

Based on the substrate integrated waveguide technology,we present a dual-band frequency selective surface(FSS) with a quasi-elliptic bandpass response.The characteristics of the quasi-elliptic bandpass response are realized by shunting two substrate integrated waveguide cavities of different sizes,with the same slots on both sides of the metal surfaces.Four cavities of different sizes and two slots of different sizes are used to design the novel FSS.Every bandpass response with sharp sidebands is induced by two transmission nulls that are generated by the coupling between the slot aperture resonance and the cavity resonance.The simulation results show that such dual-band FSS has the advantages of high selectivity and stable performance at different oblique incident angles.Moreover,it is easy to fabricate.     

Dislocation and diffusion deformation mechanisms in ultrafine grained materials and free volume role

The effect of average grain size on the mechanisms of polycrystal deformation are considered in the range of grain sizes from 1nm to 1cm. Critical grain sizes are selected. The activity of dislocation and diffusion mechanisms is analyzed. The deformation distribution in grains of different sizes is considered for a polycrystal as a whole within the grain size distribution.     

Structure of gold island films

Structure of island gold films on carbon and glass substrates is investigated in the present work. The films were deposited by means of vacuum evaporation at constant pressure, temperature and deposition rate. Shapes, diameters, number densities and statistical distributions of island sizes are investigated in the region of the proper growth of island films. Experimental values are compared with the latest considerations on the coalescence theory. In the region of thicknesses where the number density of islands increases, their sizes do not change and the islands have the circular symmetry. In the region with the decreasing number density the island sizes increase, they have approximately the elliptical symmetry and the shapes of the statistical distributions of island sizes are different. It follows from the above facts that the mechanism of the origin of the two types of islands is different.     

Study on localization of plane elastic waves in disordered periodic 2-2 piezoelectric composite structures

Considering the effect of mechanic-electric coupling, the propagation and localization of plane elastic waves in disordered periodic layered piezoelectric composite structures are studied. The transfer matrix between two consecutive unit cells is obtained by means of the continuity conditions and the expression of the localization factors in disordered periodic structures is presented by regarding the variables of mechanical and electrical fields as the elements of state vectors. As examples, numerical results of localization factors are presented and discussed. It can be seen from the results that ordered periodic structures possess the properties of frequency passbands and stopbands and the phenomenon of wave localization in disordered periodic structures is observed, and the larger the coefficient of variation is, the larger the localization factor or the stronger the degree of wave localization is. The characters of wave propagation and localization are very different for different sorts of piezocomposites or different structural sizes, and even for same sorts of piezocomposites and same structural sizes the characters of wave propagation and localization are also very different for different non-dimensional wavenumbers. We may design different piezocomposites or adjust the structural sizes to control the characters of wave propagation and localization.     

气泡对旋光实验的影响

在旋光实验中 ,不同大小的气泡对实验的影响 ,详细分析了各种影响的起因。     

The microwave response of MgB2 /Al2O3 superconducting thin films

Microwave characteristics of MgB2/Al2O3 superconducting thin films were investigated by coplanar resonator technique. The thin films studied have different grain sizes resulting from different growth techniques. The experimental results can be described very well by a grain-size model which combines coplanar resonator theory and Josephson junction network model. It was found that the penetration depth and surface resistance of thin films with smaller grain sizes are larger than those of thin films with larger grain sizes.     

X-ray diffraction on solid solutions with atoms of different sizes

The formula for intensity of diffraction of X-rays on random binary solid solution is derived using the linear model of rigid atoms of different sizes in close-packed arrangement. The shape and position of the peaks of diffuse scattering resulting as the main diffraction effect are influenced by different sizes of atoms. On the other hand, the integrated intensity of the diffuse peaks is practically unaffected by the size effect.     

Optimization of wide band mesa-type enhanced terahertz photoconductive antenna at 1550 nm

A mesa-type enhanced InGaAs/InAlAs multilayer heterostructure(MLHS) terahertz photoconductive antenna(PCA)at 1550 nm is demonstrated on an InP substrate. The InGaAs/InAlAs superlattice multilayer heterostructures are grown and studied with different temperatures and thickness ratios of InGaAs/InAlAs. The PCAs with different gap sizes and pad sizes are fabricated and characterized. The PCAs are evaluated as THz emitters in a THz time domain spectrometer and we measure the optimized THz bandwidth in excess of 2 THz.     

A model of pair interactions in the theory of optical properties of fractal clusters

In the context of a binary model, the optical properties of a cluster consisting of metal nanoparticles of different sizes are considered. It is shown that the occurrence of different sizes of particles leads to a doubling of the number of resonances in the polarizability of a pair, which entails fundamentally new inferences about the absorption spectrum, polarization properties, and nonlinear effects in real metal nanocomposites.     

Size Measurement of Small Magnetic Particles

Many different methods for size measurement are known and since they differ in their physical principles, different results are also obtained. In the recent past, there were rapid developments in new measurement techniques and one can now quickly and routinely determine particle sizes in the very fine range. Smaller particle sizes, on the other hand, tend to increase the probability of agglomeration. The measurement of the particle sizes for magnetic materials is not well understood and this paper reports results regarding the size determination of very fine magnetic materials. Because of their dipole moment, these particles tend to agglomerate even more, which in turn causes certain difficulties during the measurements. Wet and dry laser measurement systems were compared and also magnetic materials with different permeabilities in order to establish the influence of individual factors on the measurement process and on the accuracy of the results obtained.