双基STAP雷达杂波非平稳特性消除的新方法

在单基侧视机载或星载雷达系统中,空时自适应处理是一种成熟可行的慢速移动目标检测方法。在双基雷达系统中,由于杂波的非平稳特性,空时自适应处理无法获得理想的性能。为了揭示双基雷达杂波的非平稳特性,文中推导出了方位-多普勒曲线,研究了一种基于AD曲线配准的杂波非平稳特性的消除方法,给出了此种方法的处理步骤和性能分析。通过仿真发现,该方法处理算法不太复杂且性能优良。     

基于多个时间点联合解相关的卷积盲源分离

实际信号的混合均为卷积混合,且信号是非平稳的。盲源分离的目标就是找到一组分离滤波器,使得源信号的估计信号互相统计独立。结合信号的非平稳性,利用二阶解相关原理,文章阐明了一种在频域实现卷积混合的盲源分离算法,并且考虑了噪声对分离性能的影响。为了避免频点排列次序的不确定性,利用了多阶段盲源分离思想。利用该算法,对两路混合的实录水声信号进行盲分离,得到了两路源信号的估计信号,通过对估计信号的分析,利用信噪比提高率这一标准,验证了该算法的有效性。该算法收敛速度快,精度高,可用于浅海环境下实录水声混合信号的盲分离。     

A Deformable Template Model, with Special Reference to Elliptical Templates

This paper suggests a high-level continuous image model for planar star-shaped objects. Under this model, a planar object is a stochastic deformation of a star-shaped template. The residual process, describing the difference between the radius-vector function of the template and the object, is allowed to be non-stationary. Stationarity is obtained by a time change. A parametric model for the residual process is suggested and straightforward parameter estimation techniques are developed. The deformable template model makes it possible to detect pathologies as demonstrated by an analysis of a data set of cell nuclei from a benign and a malignant tumour, using stochastic deformations of ellipses.     

Dynamic infant–parent affect coupling during the face-to-face/still-face.

We examined dynamic infant–parent affect coupling using the Face-to-Face/Still-Face (FFSF). The sample included 20 infants whose older siblings had been diagnosed with Autism Spectrum Disorders (ASD-sibs) and 18 infants with comparison siblings (COMP-sibs). A series of mixed effects bivariate autoregressive models was used to represent the self-regulation and interactive dynamics of infants and parents during the FFSF. Significant bidirectional affective coupling was found between infants and parents, with infant-to-parent coupling being more prominent than parent-to-infant coupling. Further analysis of within-dyad dynamics revealed ongoing changes in concurrent infant–parent linkages both within and between different FFSF episodes. The importance of considering both inter- and intradyad differences is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

非平稳随机扰动对水质预测的影响

本文建立了一个非平稳随机模型，研究了扰动为非平稳随机过程时，对水质预测的影响，并对模型的统计特性进行了分析，最后给出了一个扰动为白噪声时实例。     

A NOTE ON NON-STATIONARITY AND CANONICAL ANALYSIS OF MULTIPLE TIME SERIES MODELS

Abstract. Box and Tiao (1977) established the correspondence between non-stationary roots and canonical correlations of an AR(1) process. In this paper, we give an alternative, more direct, proof of the correspondence and extend a special case of that result to AR( p ) processes. The usefulness of these results for multiple time series modelling is also briefly discussed.     

Examining spatially varying relationships between land use and water quality using geographically weighted regression I: model design and evaluation

Traditional regression techniques such as ordinary least squares (OLS) can hide important local variations in the model parameters, and are not able to deal with spatial autocorrelations existing in the variables. A recently developed technique, geographically weighted regression (GWR), is used to examine the relationships between land use and water quality in eastern Massachusetts, USA. GWR models make great improvements of model performance over OLS models, which is proved by F-test and comparisons of model R² and corrected Akaike Information Criterion (AIC_c) from both GWR and OLS. GWR models also improve the reliabilities of the relationships by reducing spatial autocorrelations. The application of GWR models finds that the relationships between land use and water quality are not constant over space but show great spatial non-stationarity. GWR models are able to reveal the information previously ignored by OLS models on the local causes of water pollution, and so improve the model ability to explain local situation of water quality. The results of this study suggest that GWR technique has the potential to serve as a useful tool for environmental research and management at watershed, regional, national and even global scales.     

土-结构非线性相互作用体系演变随机过程响应分析

在假定结构体系受到非均匀调制的演变随机激励基础上,考虑到地震动强度和频谱非平稳特性,应用等效线性化方法分析了土-结构相互作用体系在演变随机激励下的响应演变谱和时变均方根响应,给出了一种实用计算方法,再通过示例叙述了此方法的实施过程。计算结果表明,地震动频谱非平稳特性对非线性相互作用体系响应有较大的影响。     

气候变化对防洪安全影响研究面临的机遇与挑战

全球气候变化背景下的防洪安全影响是国际国内关注的热点问题。随着气候变暖、城镇化快速发展对地区强降水、洪涝等极端事件的影响,未来我国防洪安全保障将面临新的挑战。本文针对中国面临的严重洪涝灾害问题,阐述了全球到中国气候变化对洪涝灾害影响的事实,综述了国际国内最新的研究进展与前沿问题。最后提出了为应对气候变化减少洪涝灾害的若干对策与建议,为未来中国开展气候变化影响下防洪安全研究提供借鉴。     

完全非平稳多点人工波的模拟方法

在考虑地震动空间变化效应的基础上,提出了模拟完全非平稳多点人工波的思路,并用MATLAB编写了相应的程序。针对Clough-Penzien功率谱密度函数,建议了模拟多点地震动的峰值因子的取值。该方法不仅全面考虑了地震动的空间变化效应,即行波效应、部分相干效应和局部场地效应,而且在考虑地震动强度非平稳特性的同时,还考虑了频率非平稳特性。强度非平稳特性通过传统的包络函数来考虑,频率非平稳特性通过相位差谱来体现。用周期-频度谱验证了人工波的频率非平稳特性,并用不规则指数分析了地震波的不规则程度。分析表明：生成的人工波具有明显的强度和频率非平稳特性,而且能较好的反映硬土场地和中硬土场地上地震动随距离的衰减特性。