检索结果-内蒙古大学图书馆

STATISTICS AND COMPUTING 1995年第1期5卷 43-57页

作者： OLKEN, F ROTEM, D UNIV CALIF BERKELEY LAWRENCE BERKELEY LABDIV INFORMAT & COMP SCIBERKELEYCA 94720 SAN JOSE STATE UNIV SCH BUSINESSDEPT MANAGEMENT INFORMAT SYSTSAN JOSECA 95192

This paper deals with techniques for obtaining random point samples from spatial databases. We seek random points from a continuous domain (usually R(2)) which satisfy a spatial predicate that is represented in the database as a collection of polygons. Several applications of spatial sampling (e.g. environmental monitoring, agronomy, forestry, etc) are described. Sampling problems are characterized in terms of two key parameters: coverage (selectivity), and expected slabbing number (overlap). We discuss two fundamental approaches to sampling with spatial predicates, depending on whether we sample first or evaluate the predicate first. The approaches are described in the context of both quadtrees and R-trees, detailing the sample first, acceptance/rejection tree, and partial area tree algorithms. A sequential algorithm, the one-pass spatial reservoir algorithm is also described. The relative performance of the various sampling algorithms is compared and choice of preferred algorithms is suggested. We conclude with a short discussion of possible extensions.

关键词： GEOGRAPHIC INFORMATION SYSTEMS GIS QUADTREES QUERY PROCESSING QUERY OPTIMIZATION R-TREES RANDOM SAMPLING RELATIONAL dataBASES RESERVOIR SAMPLING SAMPLING ALGORITHMS SIMPLE RANDOM SAMPLING SEQUENTIAL SAMPLING spatial data structures spatial dataBASES

来源：评论

学校读者我要写书评

暂无评论

Trajectories of Moving Objects on a Network: Detection of Similarities, Visualization of Relations, and Classification of Trajectories

引用

TRANSACTIONS IN GIS 2013年第1期17卷 18-40页

作者： Sadahiro, Yukio Lay, Raymond Kobayashi, Tetsuo Univ Tokyo Dept Urban Engn Tokyo 1138656 Japan Florida State Univ Dept Geog Tallahassee FL 32306 USA

Development in techniques of spatial data acquisition enables us to easily record the trajectories of moving objects. Movement of human beings, animals, and birds can be captured by GPS loggers. The obtained data are analyzed by visualization, clustering, and classification to detect patterns frequently or rarely found in trajectories. To extract a wider variety of patterns in analysis, this article proposes a new method for analyzing trajectories on a network space. The method first extracts primary routes as subparts of trajectories. The topological relations among primary routes and trajectories are visualized as both a map and a graph-based diagram. They permit us to understand the spatial and topological relations among the primary routes and trajectories at both global and local scales. The graph-based diagram also permits us to classify trajectories. The representativeness of primary routes is evaluated by two numerical measures. The method is applied to the analysis of daily travel behavior of one of the authors. Technical soundness of the method is discussed as well as empirical findings.

关键词： data analysis TRAJECTORIES (Mechanics) spatial data structures ACQUISITION of data GLOBAL Positioning System TOPOLOGY

来源：评论

学校读者我要写书评

暂无评论

Employing Internet GIS Surveys to Characterize Recreational Boating Travel Patterns

引用

TRANSACTIONS IN GIS 2015年第1期19卷 42-62页

作者： Cui, Yue Mahoney, Edward Michigan State Univ E Lansing MI 48824 USA

spatial factors are fundamental features of the tourism and recreation phenomenon. In terms of recreational boating, scholars are interested both in boaters' spatial distribution and movement patterns and in the factors associated with their movements, e.g. travel costs, environmental impacts, and social impacts of the movements. spatial factors are also key to policymakers' decisions about where to establish new boating facilities, how protected areas are used by boaters and in crafting policy that minimizes conflict between recreational boating and other waterway uses. However, systematic studies regarding the recreationist movement are scant, especially at the fine geographic level. One reason for the lack of research is that gathering spatial data presents significant practical problems. In the Florida Saltwater Fishing Study, we integrated Google Map APIs into the online survey instrument to collect spatially-referenced data regarding boaters' movement on water. Results appear to be accurate, highly cost effective, and easily integrated with other survey information such as angler catch, effort, expenditures and attitudes.

关键词： GEOGRAPHIC information systems BOATS & boating TOURISM TRAVEL costs spatial data structures

来源：评论

学校读者我要写书评

暂无评论

Chain-Based Representations for Solid and Physical Modeling

引用

IEEE TRANSACTIONS ON AUTOMATION SCIENCE AND ENGINEERING 2009年第3期6卷 454-467页

作者： DiCarlo, Antonio Milicchio, Franco Paoluzzi, Alberto Shapiro, Vadim Univ Roma Tre I-00146 Rome Italy Univ Wisconsin Dept Mech Engn & Comp Sci Madison WI 53706 USA

In this paper, we show that the (co)chain complex associated with a decomposition of the computational domain, commonly called a mesh in computational science and engineering, can be represented by a block-bidiagonal matrix that we call the Hasse matrix. Moreover, we show that topology-preserving mesh refinements, produced by the action of (the simplest) Euler operators, can be reduced to multilinear transformations of the Hasse matrix representing the complex. Our main result is a new representation of the (co)chain complex underlying field computations, a representation that provides new insights into the transformations induced by local mesh refinements. Our approach is based on first principles and is general in that it applies to most representational domains that can be characterized as cell complexes, without any restrictions on their type, dimension, codimension, orientability, manifoldness, and connectedness. Note to Practitioners-This paper is a further contribution towards bridging the subject of computer representations for solid and physical modeling-which flourished borderline between computer graphics, engineering mechanics and computer science with its own methods and data structures-under the general cover of linear algebra and algebraic topology. The main advantage of such an approach is that topology, geometry and physics may coexist in one and the same formalized framework, concurring together to define, represent and simulate the behavior of the model. Last but not least, our tensor-based approach is a significant step forward in achieving close integration of geometrical representations and physics-based simulations, i.e., in the concurrent modeling of shape and behavior. Contrary to what might appear at first sight, the theoretical complexity of the present approach is not greater than that of current methods, provided that sparse-matrix techniques with double element access (by rows and by columns) are exploited.

关键词： Algorithms computational geometry finite-element methods geometric modeling mesh generation sparse matrices spatial data structures topology

来源：评论

学校读者我要写书评

暂无评论

A compact improved quadtree representation with image manipulations

引用

IMAGE AND VISION COMPUTING 2000年第3期18卷 223-231页

作者： Yang, YH Chung, KL Tsai, YH Natl Taiwan Univ Sci & Technol Dept Informat Management Taipei 10672 Taiwan Natl Taiwan Univ Sci & Technol Inst Informat Engn Taipei 10672 Taiwan

In this paper, a new and compact improved quadtree (compact-IQ) representation is presented for representing binary images. Then, efficient set operations on compact-IQs are also presented. Some experimentations are carried out to demonstrate the memory-efficiency and computational advantages of the proposed method. The experimental results reveal that the proposed image representation has 11.04-18.80% compression improvement and 24.39-36.94% computation-time improvement for set operations when compared to the recently published method on the constant bit-length linear quadtrees (CBLQ) (T.W. Lin, Set operations on constant bit-length linear quadtrees, Pattern Recognition 30(7) (1997) 1239-1249). In addition, geometric operations (area and centroid) on the compact-Iq and the performance comparison with JBIG are also investigated. (C) 2000 Elsevier Science Publishers B.V. All rights reserved.

关键词： constant bit-length linear quadtree entropy coding geometric operations JBIG quadtree set operations spatial data structures

来源：评论

学校读者我要写书评

暂无评论

How many conidia are contained in one pycnidium? Volumetric characteristics of pycnidium and conidial counts estimated for Lichenoconium pyxidatae

引用

LICHENOLOGIST 2018年第1期50卷 147-151页

作者： Osyczka, Piotr Jagiellonian Univ Inst Bot Kopernika 27 PL-31501 Krakow Poland

The variables H, W and WT were determined for 30 mature pycnidia and photographed using light microscopy. Since the top parts of the pycnidia were usually densely covered with masses of conidia and the openings were not easily visible, the width of the opening was measured for eight pycnidia captured from the top by means of SEM (Fig. 2B) after being sputter-coated with a thin layer of gold (Hitachi S-4700 and Noran Vantage). [...]variable thickness of walls and accompanying conidiogenous tissue could cause conidium production to vary enormously even in species with similar-sized pycnidia. [...]due to its structural simplicity, the pycnidium of L. pyxidatae was the most suitable natural design on which to base an attempt to create a universal model. Since we routinely work with flat cross-sectional images, the spatial aspect of the pycnidium structure might escape our attention or our perception of it might be misleading. [...]the function, in this case conidium production, cannot easily be inferred from the simple structural characteristics that usually accompany taxonomic descriptions.

关键词： CONIDIA FUNGAL spores spatial data structures ELASTIC cross sections FUSED deposition modeling

来源：评论

学校读者我要写书评

暂无评论

A modified image representation for bincodes and its manipulations

引用

INTERNATIONAL JOURNAL OF PATTERN RECOGNITION AND ARTIFICIAL INTELLIGENCE 2000年第3期14卷 389-406页

作者： Wu, JG Chung, KL Natl Taiwan Normal Univ Dept Informat & Comp Educ Taipei 10610 Taiwan Natl Taiwan Univ Sci & Technol Inst Informat Engn Taipei 10672 Taiwan Natl Taiwan Univ Sci & Technol Dept Informat Management Taipei 10672 Taiwan

It has been shown that using bincodes (BCs) to represent binary images is storage-saving and easy to be manipulated. Given a set of BCs, this paper presents improved codes, namely, the modified BCs (MBCs) to represent binary images. We first transform the given BCs into a set of logical expressions, then an improved encoding scheme is employed to reduce the storage space required for representing these logical expressions, thus obtaining the MBCs. Given twenty different types of real images, experimental results show that the proposed MBCs has 25% to 28% improvement when compared to BCs. By adopting the level-compact scheme on MBCs, storage space can be reduced further. It is shown that in some cases the storage-saving improvement is more than 50%. Some image manipulations, such as computing geometrical properties and set operations, on the MBCs are also investigated.

关键词： bintrees bincodes image compression image manipulations logical bincodes spatial data structures

来源：评论

学校读者我要写书评

暂无评论

Merging the temporal and spatial aspects of data and information for improved power system monitoring applications

引用

PROCEEDINGS OF THE IEEE 2005年第11期93卷 1909-1919页

作者： Kezunovic, M Abur, A Texas A&M Univ Dept Elect Engn College Stn TX 77843 USA

Many power systems applications, particularly those related to monitoring, control, and protection, depend on the use of field data recorded by, intelligent electronic devices (IEDs) in substations. With the introduction of IEDs in the last 20 years, the amount and type of data collected in substations have dramatically increased. This paper explores the benefits of data integration and information extraction achieved by merging temporal and spatial considerations. In the new approach, time and space issues are treated consistently across all IEDs, and as a result new applications with improved performance characteristics can be defined. As an illustration. two new monitoring functions are discussed in detail: 1) automated fault analysis and 2) hierarchical state and topology estimation. Discussion ends with a description of an implementation framework that will allow development of other functions that will benefit from the merger of time and space considerations.

关键词： communication protocols fault diagnosis spatial data structures state estimation time measurement

来源：评论

学校读者我要写书评

暂无评论

Versatile document image content extraction

Versatile document image content extraction

引用

Conference on Document Recognition and Retrieval XIII

作者： Baird, Henry S. Moll, Michael A. Nonnemaker, Jean Casey, Matthew R. Delorenzo, Don L. Lehigh Univ Dept Comp Sci & Engn 19 Mem Dr West Bethlehem PA 18017 USA

ISBN: (纸本)0819461075

We offer a preliminary, report on a research pro-ram to investigate versatile algorithms for document image content extraction. that is locating re-ions containing handwriting, machine-print text, graphics, line-art, logos, photographs, noise, etc. To solve this problem in its full generality requires coping with a vast diversity of document and image types. Automatically trainable methods are highly desirable, as well as extremely high speed in order to process large collections. Significant obstacles include the expense of preparing correctly labeled ("ground-truthed") samples, unresolved methodological questions in specifying the domain (e.g. what is a representative collection of document images?), and a lack of consensus among researchers on how to evaluate content-extraction performance. Our research strategy emphasizes versatility first: that is, we concentrate at the outset on designing methods that promise to work across the broadest possible range of cases. This strategy, has several important implications: the classifiers must be trainable in reasonable time on vast data sets: and expensive ground-truthed data sets must be complemented by amplification using generative models. These and other design and architectural issues are discussed. We propose a trainable classification methodology that marries k-d trees and hash-driven table lookup and describe preliminary experiments.

关键词： Bayes decision theory classification k Nearest Neighbors k-d trees CART spatial data structures computational geometry hashing

来源：评论

学校读者我要写书评

暂无评论

Chain-Based Representations for Solid and Physical Modeling

Chain-Based Representations for Solid and Physical Modeling

引用

ACM Solid and Physical Modeling Symposium (ACM SPM 07)

作者： DiCarlo, Antonio Milicchio, Franco Paoluzzi, Alberto Shapiro, Vadim Univ Roma Tre I-00146 Rome Italy Univ Wisconsin Dept Mech Engn & Comp Sci Madison WI 53706 USA

关键词： Algorithms computational geometry finite-element methods geometric modeling mesh generation sparse matrices spatial data structures topology

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：