A quasi random search technique for functional fitting of detector responses

The problem of nonlinear optimization is encountered while fitting the observed response of certain radiation detectors. In this paper the development of an optimizing technique based on quasi random search is described. The performance of this technique is compared with other existing methods of gradient search and linear Taylor differential correction technique in the case of fitting the photopeak responses of Nal(Tl) detectors. Our results are favourable especially when the observed data are associated with poor statistics.     

SETMOS实现多涡卷蔡氏电路的研究

基于细胞神经网络结构,利用具有负微分电阻特性的单电子晶体管与金属氧化物半导体混合结构器件SETMOS实现了多涡卷蔡氏电路.对该电路系统的基本动力学特性(如相图、分岔图、Lyapunov指数、Poincaré映射和功率谱)进行了理论分析和数值仿真,并利用电路仿真实验验证了该三阶四涡卷蔡氏电路设计的正确性和可行性.研究结果表明,SETMOS的负微分电阻特性决定着多涡卷蔡氏电路的复杂动力学行为,而且所设计的电路结构简单易行.     

LAMOST光纤单元定位参数研究

大天区多目标光纤光谱天文望远镜LAMOST是世界上光谱获取量最大的望远镜,4000个双回转光纤单元的精确定位是关键因素之一。根据对星像观测的要求以及单元的定位方式,确立了所需的7个定位参数,研究了在复杂现场环境下获取定位参数的具体流程和可行性算法,包括光重心法、摄像机快速标定算法、基于最小二乘拟合圆算法、空间坐标旋转算法等。通过模拟星像观测仿真测试和现场星像试观测证明,定位参数精度能很好地满足观测需求。目前LAMOST望远镜观测光谱获取率已达到90%以上。     

基于室温脉冲量子级联激光器的NO气体检测中的光谱处理方法研究

报导了采用基于室温脉冲量子级联激光器的脉内光谱检测技术,利用中心波长为1904 cm^-1的量子级联激光器,在实验室对NO气体样品进行检测的研究结果. 针对单线直接吸收光谱反演算法进行了研究,介绍了基线拟合的最小二乘算法以获取其吸光度,根据HITRAN数据库中相应吸收谱线的吸收线强,采用扫描积分实现了气体浓度的反演,避免了标气标定造成的误差及污染;通过拟合残差分析得到了系统的检测限,达到34×10^-6 m.     

Nitrogen bonding in aluminum oxynitride films

Assignment of oxidation states of N_1s in XPS spectra of aluminum oxynitride by curve fitting is difficult. The XPS curve fitting was previously discussed in the paper published in J. Non-Cryst. Solids, 224 (1998) 31, in which O_1s photoelectrons from GeO₂ glass were used to illustrate how to fit the XPS spectra. Three different ways were pointed out to eliminate the ambiguity caused by curve fitting such as comparing the data to data from standard samples, investigating the continuous surface modifications caused by slowly sputtering the surface, and monitoring the continuous surface modifications due to gradual increases in surface species under heating, cooling, or irradiation. Our recent work in aluminum oxynitride films provides another example of how to fit the XPS spectra of N_1s by three different oxidation states of N⁺, N²⁺, and N³⁺, by comparison of the measured data to data from previously published results, and by the gradual changes of spectra as functions of the oxygen contents in the films. Three oxidation states in different nitrogen bonding in the aluminum oxynitride, AlO₂N, Al₂O₅N₂, and AlO₃N, were clearly deduced.     

ON ENERGY CONSERVATION BY TRIGONOMETRIC INTEGRATORS IN THE LINEAR CASE WITH APPLICATION TO WAVE EQUATIONS

Trigonometric integrators for oscillatory linear Hamiltonian differential equations are considered. Under a condition of Hairer & Lubich on the filter functions in the method, a modified energy is derived that is exactly preserved by trigonometric integrators. This implies and extends a known result on all-time near-conservation of energy. The extension can be applied to linear wave equations.     

On finitely generated module whose first nonzero fitting ideal is maximal

Let R be a Noetherian ring and M be a finitely generated R-module. Let I(M) be the first nonzero Fitting ideal of M. The main result of this paper asserts that when I(M) = Q is a regular maximal ideal of R, then M?R∕Q⊕P, for some projective R-module P of constant rank if and only if T(M)?QM. As a consequence, it is shown that if M is an Artinian R-module and I(M) = Q is a regular maximal ideal of R, then M?R∕Q.     

Richards模型参数估计及其模型应用

在非线性模型中,Richards模型是一个含有四参数的增长曲线模型,该模型对数据的拟合有较强的适应性,应用较为广泛.但其参数的估计较为复杂,给出简便易行的三种方法,实例应用表明拟合效果很好.     

Shape analysis of cubic trigonometric Bézier curves with a shape parameter

For the cubic trigonometric polynomial curves with a shape parameter (TB curves, for short), the effects of the shape parameter on the TB curve are made clear, the shape features of the TB curve are analyzed. The necessary and sufficient conditions are derived for these curves having single or double inflection points, a loop or a cusp, or be locally or globally convex. The results are summarized in a shape diagram of TB curves, which is useful when using TB curves for curve and surface modeling. Furthermore the influences of shape parameter on the shape diagram and the ability for adjusting the shape of the curve are shown by graph examples, respectively.