Spatial statistical techniques for aggregating point objects extracted from high spatial resolution remotely sensed imagery

 Using a local maximum filter, individual trees were extracted from a 1 m spatial resolution IKONOS image and represented as points. The spatial pattern of individual trees was determined to represent forest age (a surrogate for forest structure). Point attributes, based on the spatial pattern of trees, were generated via nearest neighbour statistics and used as the basis for aggregating points into forest structure units. The forest structure units allowed for the mapping of a forested area into one of three age categories: young (1–20 years), intermediate (21–120 years), and mature (>120 years). This research indicates a new approach to image processing, where objects generated from the processing of image data (rather than pixels or spectral values) are subjected to spatial statistical analysis to estimate an attribute relating an aspect of forest structure. Received: 22 April 2002 / Accepted: 23 November 2002     

Automatic Surface Reconstruction Based on the Fusion of Fuzzy Logic and Robust Estimation Techniques

Automatic surface reconstruction by means of digital image matching essentially involves computation in both image and object spaces. In image space, image matching is performed according to certain radiometric and geometric similarity criteria for conjugate point determination. The matching operations may therefore be regarded as decision–making processes. In practice, however, the similarity criteria for conjugate point determination demonstrate non–deterministic behaviour. Thus, the nature of these decision–making processes is more compatible with fuzzy reasoning concepts. In object space, on the other hand, surface reconstruction procedures, which operate on the basis of previously determined conjugate points, are essentially deterministic in nature and hence demand rigorous geometric modelling. In this paper, a new approach for automatic surface modelling is proposed, based on two different mathematical treatments: a fuzzy logic reasoning method for the conjugate point determination in image space; and a robust finite elements approach for the surface modelling in object space. Tests carried out on real data demonstrate the high potential of the strategy proposed.     

GIS图上地理区域空间不确定性的分析

区域是GIS空间分析的基本单元。它是环境科学、土壤科学等领域中广泛存在的一类地理实体。这类实体抽象概括为GIS中空间目标时不可避免地带有模糊性。利用模糊集这个强有力的数学工具，首先基于场模型提出了表达GIS中模糊区域目标的方法，分析了其空间不确定性。继而，建立了模糊区域的形态描述模式，即模糊区域边界、内部和外部，并指出了Cohn给出的定义中的不足。在此基础上，对Egenhofer提出的九元组进行了扩展，构建了适合于描述确定和模糊区域目标间拓扑空间关系的模型。     

改进的模糊模式识别方法在测井曲线分层中的应用

应用改进的基于数域上的模糊模式识别方法，综合多条测井曲线进行自动分层。首先，找出各条曲线总的上升沿（或下降沿），然后，在对上升沿（或下降沿）中各采样点构造模糊集时采用测井曲线的斜率，而不是采用测井曲线值。在求取各点隶属度时，采用各条曲线中的最大斜率值，反映了地层分层点在测井曲线拐点这一客观规律。最后，应用贴近度准则分层。该方法给出了更合理的分层点。     

涡激振动下管桥段的模糊动力可靠性研究

本文首先给出了管道在流体作用下的力学模型，并对风力作用下管道产生涡激振动的机理进行了分析，从而建立了管桥在风力作用下的力学模型和相应的振动微分方程，同时给出了管桥的固有特性和动力响应分析结果，然后，在此基础上，提出了首超模糊失效、模糊疲劳失效和混合失效等三类模糊失效准则，并依据这些准则分析给出了动力可靠性的计算公式，最后，给出了具体的算例。     

屋盖MR智能隔震系统对升船结构顶部厂房地震鞭梢效应的模糊控制

基于抑制升船结构顶部厂房地震鞭梢效应的目的，本文提出了升船结构顶部厂房屋盖MR智能隔震模糊控制的思想。文中，在建立屋盖智能隔震升船结构计算力学模型的基础上，建立了屋盖MR智能隔震系统对升船结构顶部厂房地震反应模糊控制的设计计算方法。文中并以中国某大坝巨型升船结构为背景，设计了屋盖MR智能隔震系统对升船结构顶部厂房地震反应模糊控制的控制系统。仿真分析和对MR阻尼器的参数研究表明，安装合适的屋盖MR智能隔震系统并采用模糊控制策略能有效地抑制具有不确定参数升船结构顶部厂房地震反应的鞭梢效应，且模糊控制器能保持较好的稳定性能。     

Intelligent technology-based control of motion and vibration using MR dampers

Due to their intrinsically nonlinear characteristics, development of control strategies that are implementable and can fully utilize the capabilities of semiactive control devices is an important and challenging task. In this study, two control strategies are proposed for protecting buildings against dynamic hazards, such as severe earthquakes and strong winds, using one of the most promising semiactive control devices, the magnetorheological (MR) damper. The first control strategy is implemented by introducing an inverse neural network (NN) model of the MR damper. These NN models provide direct estimation of the voltage that is required to produce a target control force calculated from some optimal control algorithms. The major objective of this research is to provide an effective means for implementation of the MR damper with existing control algorithms. The second control strategy involves the design of a fuzzy controller and an adaptation law. The control objective is to minimize the difference between some desirable responses and the response of the combined system by adaptively adjusting the MR damper. The use of the adaptation law eliminates the need to acquire characteristics of the combined system in advance. Because the control strategy based on the combination of the fuzzy controller and the adaptation law doesn’t require a prior knowledge of the combined building-damper system, this approach provides a robust control strategy that can be used to protect nonlinear or uncertain structures subjected to random loads. Supported by: Hong Kong Research Grant Council Competitive Earmarked Research Grant HKUST 6218 / 99E and by the National Science Foundation under grant CMS 99-00234.     

Linear combinations of order statistics to estimate the position and scale parameters of the Generalized Pareto distribution

 Ad hoc techniques for estimating the position and the scale parameters of the Generalized Pareto distribution are introduced. The estimators proposed are simple linear combinations of the order statistics: they provide valuable estimates of the parameters of interest, both when the shape parameter is known and when it is unknown (this latter case being of great relevance in practical applications), and show a good performance as well when the sample size is small. The procedures are tested on simulated data, and comparisons with other techniques are shown.     

九寨沟地质灾害预测的空间分析模型

九寨沟是世界自然遗产,由于其活跃的新构造背景条件,因此是地质灾害的高发区。此次研究,应用了地理信息系统的空间分析工具,提取模型因子,采用模糊综合评价方法,建立九寨沟地区的地质灾害预测空间分析模型,划分地质灾害等级,对九寨沟地区的灾害进行预测,取得较好的效果。     

大连市近岸海域环境的模糊模式识别及动态分析

21世纪是人类开发利用、保护海洋的新世纪。海洋是大连的最大优势，大连的建置和发展得益于海，海洋生态环境保护是大连城市经济与社会可持续发展的前提。首次采用模糊模式识别模型对大连市近岸海域水质环境进行动态分析，结果表明，模糊模式识别模型能够全面反映水质环境的真实状态，大连湾近岸海域水质较差，大连南部海域水质逐渐变好，大窑湾海域水质较好。文章最好提出了海洋环境保护的措施。