教育测量数据的多元自建模模型分析     

尚钢 《武汉大学学报(信息科学版)》1998,(3)

将关于形状不变的自建模回归模型推广到多元自变量,解决了计算问题,并结合教育测量数据给出了实例。该模型既可以反映多条曲线走势的共性,又可以反映每条曲线之间的相互关系及其个性。  相似文献   

Point Cumulative Semivariogram for Identification of Heterogeneities in Regional Seismicity of Turkey     

Zekai en 《Mathematical Geology》1998,30(7):767-787

Geological events are neither isotropic nor homogeneous in their occurrences. These two properties present difficulties for spatial modeling of regionalized variables. This paper presents a point cumulative semivariogram (PCSV) technique for quantifying the heterogeneity characteristics of the phenomenon concerned. The basis of the methodology is to obtain experimental PCSVs for each measurement point which led to estimation of radius of influence around each site. In addition, the experimental PCSVs provide basic information about the heterogeneity of the geological variable in the region, and furthermore many useful interpretations can be made concerning the regional variability of the variable. It provides the measure of cumulative similarity of a regional variable around any measurement site. Because PCSV is a means of measuring total similarity, maps at fixed similarity levels are provided in order to document the regional heterogeneity. Identification of heterogeneities depends on the comparison of fixed PCSV values at a multitude of irregularly scattered sites. The PCSV methodology has been applied to the regional seismic data of Turkey.  相似文献   

利用变参数回归方法反演泥质岩裂缝密度     

赖生华  刘文碧  李德发  周文  彭军 《沉积与特提斯地质》1998,18(3):50-54

本文利用变参数回归分析建立了多口井的泥质岩储层裂缝密度模型。该模型的平均相对误差为１３．５％,较常系数回归分析、ＢＰ网络模型进行裂缝预测的精度高（平均相对误差分别为３８．７％、１７．９％）。通过实际资料处理认为该油田在纵向上随时代变老,深度加深,裂缝密度降低。即从Ｎ２２、Ｎ１２到Ｎ１,平均裂缝密度从０．７８条／ｍ、０．５条／ｍ降低到０．３条／ｍ。在平面上,沿构造轴部裂缝最发育,平均裂缝密度Ｎ２２、Ｎ１２、Ｎ１层分别为０．５８条／ｍ、０．６条／ｍ、０．３条／ｍ。  相似文献   

北京天文台的WET三通道高速光度计     

姜晓军  胡景耀 《天文学报》1998,39(4):438-443

对北京天文台新近改造成的三通道高速光度计的结构和性能进行介绍,并给出了在兴隆站85公分望远镜的一些实测结果.  相似文献   

9711号台风的移动路径和影响山东的特大暴雨分析   总被引：5，自引：2，他引：3  

陈秀杰  顾润源  耿勃  杨晓霞 《气象》1998,24(4):46-49

对９７１１号台风的移动路径及其造成的暴雨进行了分析。分析表明,副高外围环流在台风移动过程中有明显的引导作用;台风的移动路径和暴雨落区与正涡度轴线及高能轴线都有较好的对应关系;对流层中层变能场的分布对台风移动路径有明显的预报指示意义。  相似文献   

大气动力学方程组的定性理论及其应用   总被引：9，自引：2，他引：7  

李建平  丑纪范 《大气科学》1998,22(4):443-453

基于完整的湿大气动力学方程组,利用无穷维动力系统的新理论和新方法,系统讨论了强迫耗散的非线性大气系统的定性理论及其应用。将完整的强迫耗散非线性湿大气动力学方程组化为Hilbert空间中一个等价的算子方程,研究了算子的性质及其物理意义,在此基础上得到湿大气系统全局吸引子的存在性定理,揭示出系统向外源的非线性适应特征,并把结果推广到有地形动力作用和非定常外源强迫的情形。同时探讨了大气方程组惯性流形的存在,大气多平衡态产生的根源以及强迫、耗散和非线性对系统解的渐近行为的影响。在理论结果的基础上,提出强迫耗散的非线性动力系统中存在三类时间边界层、方程组简化准则、分解算法的算子约束原则以及支撑吸引子基底的少数自由度的构造方法,探讨了理论在非线性发展方程差分格式的设计和计算稳定性分析、多平衡态的数值分析、数值模式延伸预报的改进、短期气候预测以及一类中尺度系统分析与预测中的应用,指出描述长期过程动力学模式的必备条件,给出初值与模式相协调的合理解释。最后,对今后的研究方向作了展望。  相似文献   

Bayesian analysis of stage–fall–discharge models for gauging stations affected by variable backwater     

Asgeir Petersen‐Øverleir  Trond Reitan 《水文研究》2009,23(21):3057-3074

Parsimonious stage–fall–discharge rating curve models for gauging stations subject to backwater complications are developed from simple hydraulic theory. The rating curve models are compounded in order to allow for possible shifts in the hydraulics when variable backwater becomes effective. The models provide a prior scientific understanding through the relationship between the rating curve parameters and the hydraulic properties of the channel section under study. This characteristic enables prior distributions for the rating curve parameters to be easily elicited according to site‐specific information and the magnitude of well‐known hydraulic quantities. Posterior results from three Norwegian and one American twin‐gauge stations affected by variable backwater are obtained using Markov chain Monte Carlo simulation techniques. The case studies demonstrate that the proposed Bayesian rating curve assessment is appropriate for developing rating procedures for gauging stations that are subject to variable backwater. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

A complex variable solution for stress and displacement field around a lined circular tunnel at great depth     

Ming‐Bin Wang  Shu‐Cai Li 《国际地质力学数值与分析法杂志》2009,33(7):939-951

By applying the series expansion technique in the complex variable method established by Muskhelishvili, the plane elasticity problem for the stress and displacement field around a lined circular tunnel in conjunction with the consideration of misfit and interaction between the liner and the surrounding geomaterial is dealt with. The tunnel is assumed to be driven in a homogeneous and isotropic geomaterial. The coefficients in the Laurent series expansion of the stress functions are determined. The complex potentials in the liner and the surrounding geomaterial are explicitly derived, respectively. As an example, the case of a lined circular tunnel located in an isotropic initial stress field but subjected to uniform internal pressure is numerically considered. Numerical results indicate that the installation of tunnel liner can reduce the influences of the tunnel excavation on the in situ displacement and stress fields. However, the relative thickness and rigidity of the liner should be in an appropriate range. In addition, the effect of the tunnel excavation upon the displacement field is more significant than that upon the stress field. As far as the stress field in the surrounding geomaterial is concerned, when the ratio between the cover depth of tunnel and the tunnel radius is larger than 5, the results for the stress field in the paper are applicable. When the ratio between the tunnel depth and the tunnel radius is larger than 20, the results are applicable for the displacement field. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Hydrodynamic processes in young binaries as a source of cyclic variations in circumstellar extinction     

N. Ya. Sotnikova  V. P. Grinin 《Astronomy Letters》2007,33(9):594-603

Hydrodynamic models of a young binary accreting matter from the remnants of a protostellar cloud have been calculated by the SPH method. Periodic variations in column density in projection onto the primary component are shown to take place at low inclinations of the binary plane to the line of sight. These can result in periodic extinction variations accompanied by brightness variations in the primary. Generally, there can be three periodic components. The first component has a period equal to the orbital one and is attributable to the streams of matter penetrating into the inner regions of the binary. The second component has a period that is a factor of 5–8 longer than the orbital one and is related to the density waves generated in a circumbinary (CB) disk. Finally, the third, longest period is attributable to the precession of the inner CB disk regions. The relationship between the amplitudes of these cycles depends on the model parameters as well as on the inclination and orientation of the binary in space. We show that at a dust-togas ratio of 1: 100 and amass extinction coefficient of 250 cm² g^?1, the amplitude of the V-band brightness variations in the primary component can reach 1 ^m at a mass accretion rate onto the binary components of 10.8^?8 M _⊙ yr^?1 and a 10° inclination of the binary plane to the line of sight. We discuss possible applications of the model to young, pre-main-sequence stars.  相似文献   

Synchronous <Emphasis Type="Italic">UBVR</Emphasis> photometry and spectroscopy of DI Cephei     

N. Z. Ismailov  K. N. Grankin 《Astronomy Letters》2007,33(2):113-120

We present our synchronous spectroscopy and photometry of DI Cep, a classical T Tauri star. The equivalent widths and radial velocities of the individual components and Hα, Hβ, D1 and D2 Na I, and HeI λ5876 Å emission line profiles exhibit variability. We have found a clear positive correlation between the brightness and equivalent width for the Hα and Hβ emission lines. The photometric and spectroscopic data are satisfactorily described in phases of a 9-day period. The expected magnetic field of the star has been estimated using existing magnetospheric models to be 655–1000 G. The star is suspected to be a binary.  相似文献