PATTERN RECOGNITION VIA ROBUST SMOOTHING WITH APPLICATION TO LASER DATA

Nowadays airborne laser scanning is used in many territorial studies, providing point data which may contain strong discontinuities. Motivated by the need to interpolate such data and preserve their edges, this paper considers robust nonparametric smoothers. These estimators, when implemented with bounded loss functions, have suitable jump‐preserving properties. Iterative algorithms are developed here, and are equivalent to nonlinear M‐smoothers, but have the advantage of resembling the linear Kernel regression. The selection of their coefficients is carried out by combining cross‐validation and robust‐tuning techniques. Two real case studies and a simulation experiment confirm the validity of the method; in particular, the performance in building recognition is excellent.     

Orientation relationship in finite dimensional space

In the present article, we discuss the regression of a point on the surface of a unit sphere in d dimensions given a point on the surface of a unit sphere in p dimensions, where p may not be equal to d. Point projection is added to the rotation and linear transformation for regression link function. The identifiability of the model is proved. Then, parameter estimation in this set up is discussed. Simulation studies and data analyses are done to illustrate the model.     

Estimation of geodesic tortuosity and constrictivity in stationary random closed sets

We investigate the problem of estimating geodesic tortuosity and constrictivity as two structural characteristics of stationary random closed sets. They are of central importance for the analysis of effective transport properties in porous or composite materials. Loosely speaking, geodesic tortuosity measures the windedness of paths, whereas the notion of constrictivity captures the appearance of bottlenecks resulting from narrow passages within a given materials phase. We first provide mathematically precise definitions of these quantities and introduce appropriate estimators. Then, we show strong consistency of these estimators for unboundedly growing sampling windows. In order to apply our estimators to real data sets, the extent of edge effects needs to be controlled. This is illustrated using a model for a multiphase material that is incorporated in solid oxide fuel cells.     

de Sitter空间S_1~(n+1)(c)中标准数量曲率为c的类空超曲面

得到deSitter空间s_1~(n+1)(c)中标准数量曲率为常数c的类空超曲面的一个定理:设M~n是de Sitter空间s_1~(n+1)(c)中标准数量曲率r与s_1~(n+1)(c)的截面曲率c相等的n维(n>2)紧致的类空超曲面,则M~n是全测地超曲面.     

Rank-order tests for the parallelism of several regression surfaces

For testing the hypothesis that several (s?2) linear regression surfaces X_ki=α_k+β_kc_ki+Z_ki (k=1,…,s) are parallel to one another, i.e., β₁=?=β_s, a class of rank-order tests are considered. The tests are shown to be asymptotically distribution-free, and their asymptotic efficiency relative to the general likelihood ratio test is derived. Asymptotic optimality in the sense of Wald is also discussed.     

基于行政记录人口普查方法的国际比较

开展基于行政记录的人口普查被视为有效破解传统人口普查难题的途径之一,亦是顺应大数据时代充分挖掘人口行政记录资源的必然之选。本文较系统地阐述了基于行政记录人口普查方法的基本框架,尝试对“完全模式”人口普查和“组合模式”人口普查的实施步骤进行解析。基于此,本文选择芬兰、奥地利、瑞士、荷兰四个国家,分普查基本情况、行政记录类型选择和基本记录库形成、已存在统计记录系统基本结构、专门组织的抽样调查设计、不同系统间的链接途径、新人口统计信息质量评估方法等六个维度,对实施基于行政记录的人口普查方法进行了国家比较。     

Examination and visualisation of the simplifying assumption for vine copulas in three dimensions

Vine copulas are a highly flexible class of dependence models, which are based on the decomposition of the density into bivariate building blocks. For applications one usually makes the simplifying assumption that copulas of conditional distributions are independent of the variables on which they are conditioned. However this assumption has been criticised for being too restrictive. We examine both simplified and non‐simplified vine copulas in three dimensions and investigate conceptual differences. We show and compare contour surfaces of three‐dimensional vine copula models, which prove to be much more informative than the contour lines of the bivariate marginals. Our investigation shows that non‐simplified vine copulas can exhibit arbitrarily irregular shapes, whereas simplified vine copulas appear to be smooth extrapolations of their bivariate margins to three dimensions. In addition to a variety of constructed examples, we also investigate a three‐dimensional subset of the well‐known uranium data set and visually detect the fact that a non‐simplified vine copula is necessary to capture its complex dependence structure.     

Methods for Uncertainty Analysis: A Comparative Survey

This paper presents a survey and comparative evaluation of methods which have been developed for the determination of uncertainties in accident consequences and probabilities, for use in probabilistic risk assessment. The methods considered are: analytic techniques, Monte Carlo simulation, response surface approaches, differential sensitivity techniques, and evaluation of classical statistical confidence bounds. It is concluded that only the response surface and differential sensitivity approaches are sufficiently general and flexible for use as overall methods of uncertainty analysis in probabilistic risk assessment. The other methods considered, however, are very useful in particular problems.     

基于场所理论的春熙路商业步行街设计分析

罗格·特兰西克的场所理论认为,构成场所实体形态的三个主要要素是空间形态、建筑立面以及 街道铺装和家具,这些要素如果都能在建筑中得到正确体现,将会营造出良好的场所精神。改造后的春熙路商业 步行街虽然取得了一定经济效益,但在营造独特的场所精神方面却是失败的。     

Effects of urbanization and land use on fish communities in Valley Creek watershed, Chester County, Pennsylvania

Valley Creek watershed, located in southeastern Pennsylvania, is a small, fourth-order stream that empties into the Schuylkill River at Valley Forge National Historic Park, thirty-five kilometers northwest of Philadelphia. The 64 km² watershed has been under extreme urbanization pressure over the past 30 years, resulting in rapidly increasing impervious surface cover and decreasing open space. The purpose of this study was to document some of the effects of urbanization on fish assemblages by quantifying the fish communities at fifteen sites throughout the watershed. Long-term effects of continued urbanization were identified, as data from the present study were compared to similar work completed nearly ten years earlier. There has been a shift in species composition from intolerant, coldwater species to more tolerant, eurythermal species. Currently, Valley Creek is supporting a naturally reproducing population of brown trout, but there has been a marked decline in relative abundance and range since 1993. Increased stream temperature from urban run-off is one of the primary issues in Valley Creek. Species composition was unique at each of the 15 stations owing to the effect of local land use in each station’;s drainage area. Fish assemblages revealed a patchy, non-continuous pattern of fish distribution.