堆泵浦^3He—Ar—Xe体系的激光原理性实验

介绍了在ＣＦＢＲ－Ⅱ脉冲堆上进行的￣３Ｈｅ─Ａｒ─Ｘｅ体系的激光演示实验。当热中子注量率６×１０￣（１４）／ｃｍ￣２·ｓ，气体组配￣３Ｈｅ：Ａｒ：Ｘｅ＝３４．７：３４．７：０．２６７（ｋＰａ）时，获得波长λ＝１．７３μｍ、脉宽（ＦＷＨＭ）平均值７３８μｓ、峰值功率为毫瓦级的激光输出。同时对测得的光信号及其特性进行了分析。     

堆泵浦~3He－Ar－Xe体系的激光原理性实验

介绍了在ＣＦＢＲ－Ⅱ脉冲堆上进行的￣３Ｈｅ─Ａｒ─Ｘｅ体系的激光演示实验。当热中子注量率６×１０￣（１４）／ｃｍ￣２·ｓ，气体组配￣３Ｈｅ：Ａｒ：Ｘｅ＝３４．７：３４．７：０．２６７（ｋＰａ）时，获得波长λ＝１．７３μｍ、脉宽（ＦＷＨＭ）平均值７３８μｓ、峰值功率为毫瓦级的激光输出。同时对测得的光信号及其特性进行了分析。     

电子束泵浦KrF激光放大器增益与吸收的测量

为研制百焦耳级ＫｒＦ激光放大器，发展ＭＯＰＡ系统，我们用自探测法在百焦耳级电子束泵浦ＫｒＦ激光装置上进行了激光放大器的增益与吸收的测量。泵浦率约为０．６７ＭＷ／ｃｍ￣２，激光介质为８９．６％Ａｒ：１０％Ｋｒ：０．４％Ｆ＿２的混合气体，总气压０．２５ＭＰａ，实验测得激光放大器的小信号增益系数ｇ＿０＝６．６％ｃｍ￣（－１）、非饱和吸收系数α＿ｎ＝０．９３％ｃｍ￣（－１）、饱和光强Ｉ＿ｓ＝２．５ＭＷ／ｃｍ￣２。     

电子束泵浦KrF激光放大器增益与吸收的测量

为研制百焦耳级ＫｒＦ激光放大器，发展ＭＯＰＡ系统，我们用自探测法在百焦耳级电子束泵浦ＫｒＦ激光装置上进行了激光放大器的增益与吸收的测量。泵浦率约为０．６７ＭＷ／ｃｍ￣２，激光介质为８９．６％Ａｒ：１０％Ｋｒ：０．４％Ｆ＿２的混合气体，总气压０．２５ＭＰａ，实验测得激光放大器的小信号增益系数ｇ＿０＝６．６％ｃｍ￣（－１）、非饱和吸收系数α＿ｎ＝０．９３％ｃｍ￣（－１）、饱和光强Ｉ＿ｓ＝２．５ＭＷ／ｃｍ￣２。     

氙灯泵浦新型晶体Nd：S—FAP的激光特性

测量了新型晶体Ｎｄ：Ｓ－ＦＡＰ，（Ｎｄ；Ｓｒ５（ＰＯ４）３Ｆ）的非偏振光吸收光谱，它具有宽的有效吸收带，在５７５ｎｍ和８０４．５ｎｍ处有二个强的吸收峰，采用微型氙灯泵浦实现了自由运转和染料片调Ｑ运转。激光输出波长为１．０５９μｍ，自由运转的阈值能量仅为１５０ｍＪ，斜效率为１．２５％，调Ｑ输出的峰值功率密度为１０ＭＷ／ｃｍ＾２，测量了发射光谱及不同腔长，不同染料片小信号透射率情况下的输出能量，脉冲宽     

HT—6B的Zeff监测及RHF对杂质约束的影响

本文通过测量ＨＴ－６Ｂ等离子体中ＯⅥ的线辐射强度随放电参数的变化，利用杂质输运分析的数值结果，给出了在等离子体参数很大的变化范围内［ｎｅ＝（０．２－２．０）×１０＾１３ｃｍ＾－３，ｑａ＝３－８．５］Ｚｅｆｆ及杂质相对浓度随放电参数的变化规律。在外加共振螺旋磁场（ＲＨＦ）抑制外撕裂模的实验中，ＯⅢ、ＣⅢ的线辐射测量表明ＲＨＦ具有改善杂质约束的迹象，此时光谱信号中反映出的相应频率的粒子扰动也被ＲＨＦ所     

酞菁钴/铁纳米填充母粒的制备及其稳定性

采用有机／无机原位复合技术，将酞菁钴（ＣｏＰｃ）的ＤＭＦ溶液与Ｆｅ（ＣＯ）５混合、加热回流制备出稳定的、规则球形的、平均粒径为１．４μｍ的酞菁钴／铁纳米填充母料。其内部为１０￣１５ｎｍ的α－Ｆｅ填充，外部为厚５０￣１５０的酞菁钴层包覆。纳米填充母粒的填３实密度为３．６６４ｇ／ｃｍ＾３，比饱和磁化强度为７６．３Ａｍ＾２／ｋｇ，矫顽力为４．１５ｋＡ／ｍ，纳米填充母粒的热稳定性高于１５０℃，与甲基硅油组     

超短超强激光与稀薄等离子体相互作用的数值研究

用一维粒子模拟方法（Ｐａｒｔｉｃｌｅ－ｉｎ－Ｃｅｌｌ）数值研究了超短超强激光（Ｉλ＾２〉１０＾１８Ｗ．μｍ＾２／ｃｍ＾２）与稀薄等离子体的相互作用过程，结果表明，超短超强激光与稀薄等相互作用后，在等离子体中激发起尾波和拉曼（Ｒａｍａｎ）波，它们的波长和频率的值与解析解符合得很好；同时在尾波的作用下，等离子体的部分电子被加速的很高的速度，甚至接近光速。     

CW／COIL照射LF 6M铝合金板热耦合效应研究

用热电偶计和热象仪探测靶升温，积分球－光电转换放大测量反射率，金相显微图象数据处理和电子天平称量获得激光照射质量和熔融质量等诊断技术，对连续波（波长１．３１５μｍ）氧碘化学激光（ＣＷ／ＣＯＩＬ），与ＬＦ６Ｍ板相互作用的有效热耦合系数α＿（ｅｆｆ）和热耦合率α＿ａ，进行了实验测量。当照射靶面激光强度Ｉ≈（０．６０～１．１３）ｋＷ／ｃｍ￣２和发生熔融时，α＿（ｅｆｆ）≈０．１６～０．１８和α＿ａ≈０．２０～０．２５（工业商品铝表面）；α＿（ｅｆｆ）≈０．１１和α＿ａ≈０．１２～０．１４（表面加工粗糙度１６μｍ）。当Ｉ≈０．０７～０．１１ｋｗ／ｃｍ￣２和表面不发生熔融时，α＿ａ≈０．０９～０．１０（工业商品铝表面），α＿ａ≈０．０２～０．０３（表面加工粗糙度１．６μｍ）。     

聚乙二醇-钍试剂-硫酸钠体系中非有机溶剂萃取光度法测定铁

本文研究了铁（Ⅲ）－ＰＥＧ（聚乙二醇－２０００）－钍试剂－Ｎａ２ＳＯ４体系的析相光度法并应用于测定Ｆｅ（Ⅲ），最适酸度为４．６（ＮａＡｃ－ＨＡｃ）缓冲溶液，其络合物的最大吸收位于５６６ｎｍ，表观摩尔吸光系数为８．０６×１０３Ｌ·ｍｏｌ－１·ｃｍ－１。Ｆｅ（Ⅲ）浓度在０—３０μｇ·ｍＬ－１范围内服从比耳定律，该方法用于发样中铁的测定，获得了满意结果     

Fractal Character of Dynamic Light Scattering of Particles

Dynamic light scattering signals from particles, exhibit fractal characteristics. This feature can be used to determine the particle size. The use of the fractal dimension, as a quantitative method to analyze the properties of dynamic light scattering signals from submicron particles, is presented. The analysis is performed directly on the time‐resolved scattered intensity, and the Box Dimensions of light scattering signals of particles with diameters 100, 200, 500 and 1000 nm. The experimental results show that the fractal dimensions of light scattering signals correlate well with particle size. In the submicron size range, the smaller the particles, the larger their fractal dimensions. Compared with the PCS technique, only several hundreds of samples are required in the fractal method. Therefore, the data processing is easily accomplished. However, this method only provides the mean particle size, but not the particle size distribution.     

The Use of Small Angle Light Scattering to Study Structure of Flocs

In this paper, a new approach using small angle light scattering to study the structure of large micron sized flocs is described. The flocs were made up from uniformly sized, approximately spherical hematite particles, induced to aggregate using 250 mM KCl to ensure that growth was governed by diffusion limited aggregation alone. The fractal dimensions of the hematite aggregates changed from 1.73 to 2.23 ± 0.05 as the aggregation proceeded, indicating that restructuring occurred during aggregation. The fractal dimensions obtained from the small angle light scattering technique are compared with those obtained from the combination of volume fraction and floc size measurement. The steady state fractal dimensions (2.23 ± 0.05) obtained by small angle light scattering are comparable to the fractal dimensions obtained from determining the slope of the relationship between floc volume fraction and floc size (2.09 and 2.14 ± 0.05). The discrepancy between the fractal dimensions obtained by these techniques during the initial stages of aggregation is due to the fact that the latter method measures the average fractal dimensions, whilst the former method measures the fractal dimensions at any particular instant.     

调制无线电信号的分形特征研究

调制方式的不同以及信号受到功率放大器的非线性变换决定了调制无线电信号的形状存在着差异,提取这些差异特征是信号识别的基础. 基于分形理论提取信号特征是一种新的方法,本文模拟了在不同信噪比条件下,通过计算调制无线电信号的方差分形维以及Mandelbrot奇异分形维谱,将信号的调制特征以及非线性变换特征投射到分形特征空间. 数值仿真结果表明,不同调制方式、非线性变换对应了分形特征空间中的不同位置. 这些结果表明分形理论能够有效提取无线电信号的调制特征以及功率放大器的特征,对信号的调制方式以及个体特征识别具有一定 关键词： 无线电 信号 分形特征 识别     

The Fractal Characteristic of Particles in Granular Material Flows and Its Effect on Effective Thermal Conductivity

According to the fact that many pulverized particles possess fractal characteristic, a fractal model for studying fine particles in granular material flows is first proposed. An expression of particles' fractal distribution is derived to describe the relationship between the particle fractal dimensions and particle velocity distribution function. In accordance with this model, the theoretical particle effective thermal conductivity is derived. The analytical results show that for the small Biot-Fourier number, the effective thermal conductivity increases with the square root of the granular temperature. For very large Biot-Fourier number, the effective thermal conductivity linearly increases with the granular temperature. Numerically calculated results show that the thermal conductivity increases with the particle size fractal dimensions and decreases with the particle surface fractal dimensions.     

Influence of fractal surface dimension on the dissolution process of sparingly soluble CaCO<Subscript>3</Subscript> microparticles

The dissolution process of sparingly soluble CaCO₃ microparticles and how the fractal surface dimension of the particles changes during dissolution is analyzed. The particles and the dissolution process are studied using scanning electron microscopy, X-ray diffraction, nitrogen adsorption, laser diffraction and conductance measurements. Ball milling of the particles is shown to maintain the particle crystallinity, and to introduce an increased fractal surface dimension in the 1–10 μm size range. Dissolution is found to increase the surface dimension of initially smooth particles and to maintain the fractal surface roughness of milled particles. The dissolution process increases the relative number of small particles (50 nm–1 μm) whereas the larger ones decrease in size. The solubility of the milled fractal particles was ∼1.8 times higher than that for the initially smooth ones. The presented findings show that developing methods for increasing the fractal surface roughness of particles should be of interest for improving the solubility of poorly soluble drug candidates.     

随机分布烟尘团簇粒子辐射特性研究

基于分形理论,采用蒙特卡罗方法对随机分布的烟尘团簇粒子结构进行了仿真模拟,利用离散偶极子近似(discrete dipole approximation, DDA)方法研究了随机分布的烟尘团簇粒子的辐射特性,分析讨论了分形维数、原始微粒粒径和数量以及复折射率对随机分布烟尘团簇粒子辐射特性的影响.研究表明,在给定分形维数的情况下,烟尘团簇粒子的辐射特性取决于原始微粒粒径、数量及复折射率;原始微粒较小的团簇粒子,当分形维数较小时,吸收截面变化不明显,但当分形维数大于2时,吸收截面骤然增大,然而,对于具有比较大的原始微粒粒径、数量及复折射率的烟尘团簇粒子,吸收截面随着分形维数的增大而单调递减;随着分形维数的增大,团簇粒子的散射截面、消光截面及单次散射反照率均单调递增;从整体上来讲,团簇粒子的辐射特性与等效球形粒子的辐射特性存在着比较大的差别,并且这种差别随着分形维数的增大而减小.该工作对研究气溶胶粒子的辐射及气候效应具有重要的科学价值. 关键词： 烟尘团簇粒子 辐射特性 离散偶极子近似方法     

Fractal dimensions of speech sounds: computation and application to automatic speech recognition

The dynamics of airflow during speech production may often result in some small or large degree of turbulence. In this paper, the geometry of speech turbulence as reflected in the fragmentation of the time signal is quantified by using fractal models. An efficient algorithm for estimating the short-time fractal dimension of speech signals based on multiscale morphological filtering is described, and its potential for speech segmentation and phonetic classification discussed. Also reported are experimental results on using the short-time fractal dimension of speech signals at multiple scales as additional features in an automatic speech-recognition system using hidden Markov models, which provide a modest improvement in speech-recognition performance.     

Small angle neutron scattering and small angle X-ray scattering studies of platinum-loaded carbon foams

The morphology of carbon nanofoam samples comprising platinum nanoparticles dispersed in the matrix was characterized by small angle neutron scattering (SANS) and small angle X-ray scattering (SAXS) techniques. Results show that the structure of pores of carbon matrix exhibits a mass (pore) fractal nature and the average radius of the platinum particles is about 2.5 nm. The fractal dimension as well as the size distribution parameters of platinum particles varies markedly with the platinum content and annealing temperature. Transmission electron micrographs of the samples corroborate the SANS and SAXS results.      

高速铁路轮轨滚动噪声的分形描述及分形维估计

提出基于分形分析的轮轨滚动噪声研究方法,研究了不同尺度下轮轨滚动噪声增量的统计特性,证明轮轨滚动噪声具有分形特性,可由分形布朗运动描述。在此基础上,利用分形布朗运动的小波系数方差与分形维的幂律关系估计了轮轨滚动噪声的分形维,并估计了以裂纹扩展为代表的钢轨伤损声发射信号的分形维,对比研究发现:轮轨滚动噪声分形维本身具有随机性,不同车速下的轮轨滚动噪声分形维估计以1.5666为均值随机分布在小于2的小区间内;分形维是轮轨滚动噪声的固有特征,与车速无关,不同车速的轮轨滚动噪声可由统一的分形布朗运动模型描述;裂纹扩展信号与轮轨滚动噪声不同,其分形维估计大于2,不满足分形布朗运动模型的要求,但分形维可作为二者的区别特征。研究提取了轮轨滚动噪声的分形维作为固有特征,为高速轮轨滚动噪声描述及轮轨伤损检测提供了有效的分析方法。      

Finite size effect of harmonic measure estimation in a DLA model: Variable size of probe particles

A finite size effect in the probing of the harmonic measure in simulation of diffusion-limited aggregation (DLA) growth is investigated. We introduce a variable size of probe particles, to estimate harmonic measure and extract the fractal dimension of DLA clusters taking two limits, of vanishingly small probe particle size and of infinitely large size of a DLA cluster. We generate 1000 DLA clusters consisting of 50 million particles each, using an off-lattice killing-free algorithm developed in the early work. The introduced method leads to unprecedented accuracy in the estimation of the fractal dimension. We discuss the variation of the probability distribution function with the size of probing particles.