佛克脱光谱线型干涉图的理论及其应用研究

在一般压强的条件下,佛克脱光谱线型(高斯光谱线型和洛伦兹光谱线型的卷积)是最接近实际的光谱线型,但由于其没有具体的表达式,所以在实际应用中常采用各种近似来表示佛克脱光谱线型。文章未采用任何近似,计算了佛克脱光谱线型干涉图的具体表达式,表明虽然佛克脱光谱线型没有具体表达式,但其干涉图是可以严格求解的。而且其变换结果为一实函数,与高斯光谱线型和洛伦兹光谱线型的变换结果的表达式非常相似,因而可以进行谱线综合展宽的各种计算,而不是像有的文献所预言的有实部和虚部两部分,给计算带来困难。计算结果与实验结果一致。作为应用的一个实例,作者指出了其在大气风场测量中的重要应用。此计算对气体展宽在傅里叶变换光谱仪中的应用方面具有非常重要的意义。     

On controlling the surface curvature of diffraction components

The possibility of interactively controlling the surface curvature of a single-crystal Si(100) plate used as a diffraction element is investigated. The initial component-surface profile is specified by the substrate shape, parameters of the adhesive, and the temperature of its adhesion to the substrate. The results of calculating the changes in surface profile and its curvature radius are presented.     

Voigt线型函数及其最大值的研究

研究了多普勒和洛伦兹线型函数卷积形式的Voigt线型函数, 给出了它的最大值.结果表明, Voigt线型函数是关于中心频率的对称函数, Voigt线型函数的最大值由多普勒和洛伦兹线型函数的半宽度决定, 与中心频率无关, 且比洛伦兹和多普勒线型函数的最大值都小.提出了利用Voigt线型函数最大值和半宽度获得多普勒线型函数和洛伦兹线型函数的方法, 并利用Monte Carlo方法进行了验证. 关键词： Voigt线型函数 半宽度 最大值 傅里叶变换     

脉冲星脉冲轮廓累积的最小熵方法

获取脉冲星辐射信号累积轮廓的传统方法是先识别信号周期,再按周期对信号进行折叠累加,这种方法依赖于周期识别的准确性,对累积轮廓质量也无评价标准.本文分析了脉冲星累积轮廓和周期的强相关性,提出了周期未知时直接进行轮廓累积的最小熵方法,并对其进行证明,在此基础上,讨论了该方法在周期识别中的作用.利用仿真数据和RXTE卫星的实测数据实验验证了该方法的有效性. 关键词： 脉冲星 最小熵 累积轮廓 周期识别     

合肥光源储存环束流截面测量系统改造和软件升级

 存储环束流截面及发射度是同步辐射加速器重要的基本参数。从束流截面大小的变化和束斑位置的移动规律，可以进行环上的束流不稳定性的研究。介绍了合肥光源，储存环束流截面测量系统局部改造和它的软件升级并且着重介绍西欧核子中心(CERN)的软件框架ROOT在数据处理和显示方面的应用。     

Reversed current structure in a Z-pinch plasma

The current profile of a Z-pinch plasma is investigated using a one-dimensional magnetohydrodynamic code. Simulation results reveal the formation of a reversed current profile, its propagation, and an ejection of plasma at boundary region, which have been observed in previous experiments. A new physical mechanism is proposed to account for such phenomena. The physical mechanism involves the propagation of a shock wave. It is found that a reversed current profile appears when a shock wave reflected at axis expands in a compressing plasma column.     

A generalization of optimal estimation for the retrieval of atmospheric vertical profiles

The optimal estimation method for the retrieval of atmospheric vertical profiles uses a priori information made of a profile and its covariance matrix. The underlying assumption is that the a priori profile has an averaging kernel matrix equal to the identity. The method is herewith generalized to the case that the a priori profile has a different averaging kernel matrix. The averaging kernel matrix of the a priori profile is properly taken into account in the cost function and a rigorous and more general solution for the optimal estimation method is derived.     

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利用MEC和LSC耦合的程序研究了EAST天线不同的相位差 对功率谱的影响及对功率沉积位置和电流分布的影响。通过计算发现,随着 的增大,功率谱的结构发生了改变,当 >200°后功率沉积和电流密度分布由原先的向外层移动变为向内层移动; =200°时形成一个离轴最远的驱动电流, =120°、 =260°时分别得到电流强度最小和最大的驱动电流。因此可以通过选取合适的天线相位差 ,实现对低杂波功率沉积和驱动电流剖面的控制。     

Ray delay in gradient waveguides with asymmetric transverse refractive index profiles

Former investigations of symmetric refractive index profiles in gradient waveguides are extended to include also asymmetric profile curves. The generalized delay expression is derived and illustrated by means of various examples. Possibilities of compensating symmetric by asymmetric components of the refractive index in the delay formula lead to a number of optimum profiles for low-dispersion transmission.The pulse broadening in a waveguide with a gradient profile being distributed in a ring-shaped form over its cross section, which is to serve as an example of a guide with an asymmetric profile, is assessed.     

Formation of cross-sectional profile of a clad bead in coaxial laser cladding

In order to determine a cross-sectional profile of a clad bead in coaxial laser cladding, its formation mechanism is investigated theoretically and experimentally. In laser cladding, every point at the back edge of a melt pool is contributed to a cross-sectional profile of the clad bead to be formed, and points at the same pool edge but on different cross sections are located at different cross-sectional profiles of the clad bead. A cross-sectional profile of a clad bead is composed of points of intersection between the cross section and a series of pool edges. Model of the cross-sectional clad profile in single-pass coaxial laser cladding is developed. A 500 W CO₂ laser is used in the experiment. The experimental result agrees well with the calculated cross-sectional clad profile.     

Approximate solutions to fractional subdiffusion equations

The work presents integral solutions of the fractional subdiffusion equation by an integral method, as an alternative approach to the solutions employing hypergeometric functions. The integral solution suggests a preliminary defined profile with unknown coefficients and the concept of penetration (boundary layer). The prescribed profile satisfies the boundary conditions imposed by the boundary layer that allows its coefficients to be expressed through its depth as unique parameter. The integral approach to the fractional subdiffusion equation suggests a replacement of the real distribution function by the approximate profile. The solution was performed with Riemann-Liouville time-fractional derivative since the integral approach avoids the definition of the initial value of the time-derivative required by the Laplace transformed equations and leading to a transition to Caputo derivatives. The method is demonstrated by solutions to two simple fractional subdiffusion equations (Dirichlet problems): 1) Time-Fractional Diffusion Equation, and 2) Time-Fractional Drift Equation, both of them having fundamental solutions expressed through the M-Wright function. The solutions demonstrate some basic issues of the suggested integral approach, among them: a) Choice of the profile, b) Integration problem emerging when the distribution (profile) is replaced by a prescribed one with unknown coefficients; c) Optimization of the profile in view to minimize the average error of approximations; d) Numerical results allowing comparisons to the known solutions expressed to the M-Wright function and error estimations.     

厚胶光刻非线性畸变的校正

利用厚胶光刻技术制作大深度微结构元件是一种有效的途径,但厚胶光刻过程中的非线性畸变对光刻面形质量的严重影响限制了该技术的应用,基于此,提出了一种对掩模透射率函数进行校正的方法。分析空间像形成及其在光刻胶内传递、曝光、显影等过程中非线性因素的影响,利用模拟退火算法对掩模透射率函数进行校正,以提高光刻面形质量,并以凹面柱透镜为例,给出了校正前后的显影轮廓模拟结果,其校正后浮雕面形的体积偏差仅为2.63%。该方法在有效改善面形质量的同时,并没有引起掩模的设计、制作难度及费用增加,这对于设计、制作高质量的微结构元件有重要意义。     

Recovery of Graded Index Profile of Planar Waveguide by Cubic Spline Function

A method is proposed to recover the refractive index profile of graded waveguide from the effective indices by a cubic spline interpolation function. Numerical analysis of several typical index distributions show that the refractive index profile can be reconstructed closely to its exact profile by the presented interpolation model.     

Determination of the Radial Potential Profile in the Modified Penning Discharge with a Heavy Ion Beam Probe

A heavy ion beam probe is used to examine the radial electrostatic potential profile in the Modified Penning Discharge. The plasma potential in the discharge violates the usual constraint on the ion beam energy in that the primary probing beam energy undergoes large changes in its energy while passing through the plasma. In order to determine the radial potential profile, the primary beam trajectories are calculated to agree with measured trajectories by parametric variation of a potential model in the trajectory calculating program. This iteration calculation provides a first approximation to the profile. This profile can be used to predict observation of secondary ions, and observation of such ions provides a confirmation and cross check on the potential profile model found by the primary beam.     

层状GRIN板折射率分布的自动测量

采用溶液 凝胶扩散共聚法成功地合成了二元体系的甲基烯酸苄酯 甲基烯酸甲酯 (BZMA MMA)层状梯度折射率板 ,折射率分布是其主要性能指标。给出了一种测量该制品折射率分布的简便实验装置和自动实现方法。该测量方法基于激光干涉的原理 ,由计算机自动跟踪干涉条纹的移动来计算梯度折射率材料的折射率分布。实验表明 ,该方法简单易行 ,具有较高的折射率测量精度 ,为科学评价自研制梯度折射率材料的性能提供了保证     

Spectral analysis of a laser beam

The formulas of the dependence of the spectral laser power distribution and its spectral half-width on the physical parameters of its laser active medium are derived. In addition it is found that, if the gain line profile has a Lorentzian or Gaussian distribution, the spectral laser power distribution is of a Lorentzian profile. The spectral halfwidth of the laser beam in both cases are slightly different form each other. For a general gain line profile, the spectral laser power distribution behaves as a differential form like that of the gain line profile.The spectral halfwidth of He/Ne laser beam having powers (0·5 mW, 1·0 mW, 3·0 mW and 50 mW) and that of their longitudinal modes, the laser gain factor and the difference between the population atomic densities of the upper and lower energy levels for the laser line transition are experimentally determined.     

振荡射流提高翼型升力的机理研究

本文数值模拟了施加振荡射流以及相应定常吸气条件下的翼型分离流动。对振荡射流改善翼型升力的机理进行了研究。结果表明,翼型表面施加的振荡射流能够控制流动分离的形态,提高分离区流体的湍流度,增强分离区内部流体,以及与主流的动量和能量交换,增强近壁区流体的动能,降低翼型吸力面压力,而对压力面无显著影响,因而翼型的升力得到提高。     

特形脉冲的设计与计算机模拟

根据LiouvillevonNeumann方程从理论上对特形脉冲做了全面的描述,提出了一种具体的调幅特形脉冲设计方案:首先将待设计的脉冲展成一个有限Fourier级数,然后根据Bloch方程的解析解准确计算出各阶正弦、余弦波的频谱,再将这些频谱组合后与该脉冲的理想频谱进行比较构成误差函数,最后运用鲍威尔-模拟退火组合优化算法计算出全局最优Fourier系数,即可得到所需脉冲的表达式.应用此设计方案,得到了体系处于热平衡态时的特形激励脉冲和反转脉冲的具体表达式.计算机模拟表明,所得脉冲的频谱具有较好的选择性 关键词： 核磁共振 特形脉冲 Bloch方程 鲍威尔模拟退火组合优化算法     

High resolution quantitative SIMS analysis of shallow boron implants in silicon using a bevel and image approach

Secondary ion mass spectrometry (SIMS) is frequently used as the preferred tool for dopant profiling due to its sensitivity and depth resolution. However, as dopant profiles become shallower most, if not all of the implant profile lies in the pre-equilibrium or transient region of an SIMS depth profile. In this region sputter yield and ionisation rate vary making accurate quantification of the implant profile very difficult. These problems can be reduced through the use of much lower beam energies or oxygen flooding of the sample. However, most SIMS instruments do not have these capabilities. In this paper an alternative technique for producing an accurate depth profile of a shallow implant, using existing SIMS technology is presented.Through the fabrication of bevels with very small slope angles on a shallow boron implanted silicon via a chemical etch, SIMS ion imaging is performed on the exposed surface. Ion image data is then summed, and in conjunction with accurate measurement of the bevel morphology, a shallow boron implant profile produced. The ‘bevel-image’ profile compares very well with a profile obtained using a 1 keV oxygen beam. To ensure a good dynamic range on the ‘bevel-image’ profile it is important to clean the bevel with a HF etch, prior to imaging.     

Temporal Profile Based Small Moving Target Detection Algorithm in Infrared Image Sequences

A new algorithm is presented which deals with the problem of detecting small moving targets in infrared image sequences that also contain drifting and evolving clutter. Through development of models of the temporal behavior of the static background, target and cloud edge on a single pixel basis, the new algorithm employing the connecting line of the stagnation points (CLSP) of the temporal profile as the baseline is created and tested. The deviation of the temporal profile and its CLSP is analyzed and it is determined that the distribution of the residual temporal profile obtained by subtracting the baseline from the temporal profile can be modeled by a Gaussian distribution. The occurrences of the targets have intensity values significantly different to the distribution of the residual temporal profile. Unlike the conventional 3-D method, this new algorithm operates on the temporal profile in 1-D space, not in 3-D space, thus having a higher computational efficiency. Experiments with real IR image sequences have proved the validity of the new approach. This work was supported by National Natural Science Fund of China (No. 60277005).