基于遗传算法构建巴耳末公式

基于遗传算法构建了巴耳末公式．通过建立合适的拟合数学模型，用计算机对数学模型进行优化，使之尽可能反映氢原子实际谱线分布，并求出经验常量和拟合公式，最后分析了所得结果．     

Theoretical analysis of the onset of liquid entrainment for slots of finite width

The onset of liquid entrainment during discharge from large reservoirs containing a stratified mixture of two immiscible fluids through a side slot of a finite width is considered theoretically. A previously reported analysis in which the slot was approximated as a two-dimensional line sink has been extended to account for the finite width of the slot. The model resulting from the present analysis is expressed in terms of two simple algebraic equations suitable for hand calculations. According to the present results, the ratio of the critical height to the slot width is dependent only on the Froude number. Numerical results show that the present model approaches the correct physical limits at low Froude numbers and it converges to the predictions of the previously reported simple model at high Froude numbers.     

A statistical study of the analysis of congested spectra by total spectrum fitting

Heavily overlapped, or congested spectra often display much structure but few individual “lines.” Methods have been devised for analyzing such spectra through nonlinear least-squares fitting of the intensity as a function of wavelength or wavenumber. Such total spectrum fitting (TSF) methods are examined statistically for a simple diatomic model and compared with the standard “measure-assign-fit” (MAF) approach in use since the dawn of spectroscopy. Monte Carlo computations on typically 1000 synthetic spectra at a time verify that the predictions of the variance-covariance matrix are reliable under many circumstances. However in regions where the P and R branches double up, the predicted standard errors in the key spectroscopic constants rise sharply and greatly exceed estimates from the Monte Carlo ensemble statistics. In the same regions, the MAF method actually gives better precision. However, for imperfectly overlapped R and P branches, the MAF standard errors are typically three times larger than the TSF values; moreover, the MAF statistical errors are dwarfed by bias. The TSF approach, while clearly superior in these tests, has a practical drawback: it, too, can give significant bias if the spectra are analyzed with an incorrect model, as illustrated here through calculations employing the wrong function to describe the spectral lineshape.     

弱光波前传感器质心计算的新方法

研究了Shack Hartmann波前传感器质心计算的新方法,即最小二乘高斯拟合方法。分析了Shack-Hartmann波前传感器采用一阶矩质心计算位置方法对光斑强度的敏感性,与最小二乘高斯拟合方法进行了比较,并对Shack Hartmann波前传感器的子孔径波前斜率探测的正确性进行了分析。最后的计算结果表明最小二乘高斯拟合法计算子孔径光斑的质心位置可以减小质心探测的误差。     

菲佐测风激光雷达及风速反演算法

 研制了基于菲佐干涉仪的测风激光雷达系统,并使用高斯拟合法和最大似然法反演风速,对两种风速反演方法进行了分析,结果表明：风速较小时,两种方法具有相似的风速反演精度,但高斯拟合法收敛快、受条纹信噪比影响较小;风速较大时,高斯拟合法会由于条纹移出而产生较大误差,而最大似然法在处理风速较大情况时具有优势。实际风速测量时,应根据风速估计值的大小,采用两种方法分别处理大风速和小风速时的情况。最后,使用研制的测风激光雷达系统和风速反演算法,得到了1.5 km以内的大气风速廓线。     

Least Squares Convex-Concave Data Smoothing

We consider n noisy measurements of a smooth (unknown) function, which suggest that the graph of the function consists of one convex and one concave section. Due to the noise the sequence of the second divided differences of the data exhibits more sign changes than those expected in the second derivative of the underlying function. We address the problem of smoothing the data so as to minimize the sum of squares of residuals subject to the condition that the sequence of successive second divided differences of the smoothed values changes sign at most once. It is a nonlinear problem, since the position of the sign change is also an unknown of the optimization process. We state a characterization theorem, which shows that the smoothed values can be derived by at most 2n – 2 quadratic programming calculations to subranges of data. Then, we develop an algorithm that solves the problem in about O(n ²) computer operations by employing several techniques, including B-splines, the use of active sets, quadratic programming and updating methods. A Fortran program has been written and some of its numerical results are presented. Applications of the smoothing technique may be found in scientific, economic and engineering calculations, when a potential shape for the underlying function is an S-curve. Generally, the smoothing calculation may arise from processes that show initially increasing and then decreasing rates of change.     

The convergence of three spline methods for scattered data interpolation and fitting

The convergences of three L₁ spline methods for scattered data interpolation and fitting using bivariate spline spaces are studied in this paper. That is, L₁ interpolatory splines, splines of least absolute deviation, and L₁ smoothing splines are shown to converge to the given data function under some conditions and hence, the surfaces from these three methods will resemble the given data values.     

中温沥青超声萃取物的热解特性与分子结构间关联性的FTIR解析

沥青分子结构和沥青热转化行为的调控是制备高品质沥青基炭材料的关键.为进一步明晰沥青热解行为与沥青分子结构间的关联性,选用8种有机溶剂对中温沥青(AGM P)在常温下进行超声萃取处理得到8种萃取物.利用PeakFit v4.12软件对各种萃取物的红外光谱吸收峰700～900,1000～1800,2800～3000和300...     

结构可靠性仿真方法研究简

可靠性仿真是对复杂结构系统进行可靠性分析计算最为有效的方法,引起了研究者越来越广泛的关注. 综合目前结构可靠性仿真方法研究现状,介绍了蒙特卡罗（Monte-Carlo,MC）法、极限状态方程重构法、随机有限元法（stochastic finite element method,SFEM）进行结构可靠性仿真计算的特点及发展现状,归纳了固体火箭发动机（solid rocket motor,SRM）结构可靠性的特点及当前进行仿真的方法;并在此基础上分析了目前结构可靠性仿真方法及对SRM 结构可靠性进行仿真分析计算时存在的不足及需要进一步研究的内容.     

一种视频图像规则圆目标的超分辨率位置测量方法

介绍了一种用于视频图像规则圆目标的超分辨率位置测量方法。分析了超分辨率测量的原理 ,并提出和完成了测量方案 ,取得了满意的结果。首先在目标静止时 ,连续采集多帧视频图像 ,通过叠加平均进行降噪 ;其次通过罗伯特微分算子进行边界探测 ,求出目标的大致位置 ;最后通过边界重心拟合法、边界圆拟合法和最小二乘法拟合求出目标的精确位置。理论分析和实验表明 ,完整圆目标时 ,测量精度可达 1/4像素 ;而当目标图像有缺陷时 ,边界圆拟合法和最小二乘法拟合测量误差增加较少 ,边界重心法的测量误差增加较多。在具体情况下 ,算法及参数应该作相应的调整