检索结果-内蒙古大学图书馆

Specification and implementation of directional operators in a 3D spatial query language for building information models

引用

ADVANCED ENGINEERING INFORMATICS 2009年第1期23卷 32-44页

作者： Borrmann, Andre Rank, Ernst Tech Univ Munich D-80290 Munich Germany

A spatial query language enables the spatial analysis of building information models and the extraction of partial models that fulfill certain spatial constraints. Among other features, the developed spatial query language includes directional operators, i.e., operators that reflect the directional relationships between 3D spatial objects, such as northOf, southOf, eastOf, westOf, above and below. The paper presents in-depth definitions of the semantics of two new directional models for extended 3D objects, the projection-based and the halfspace-based model, by using point-set theory notation. It further describes the possible implementation of directional operators using a newly developed space-partitioning data structure called slot-tree, which is derived from the objects' octree representation. The slot-tree allows for the application of recursive algorithms that successively increase the discrete resolution of the spatial objects employed and thereby enables the user to trade-off between computational effort and the required accuracy. The article also introduces detailed investigations on the runtime performance of the developed algorithms. (C) 2008 Elsevier Ltd. All rights reserved.

关键词： BUILDING information modeling QUERY languages (computer science) SPATIAL analysis (Statistics) THREE-dimensional imaging OPERATOR theory computer algorithms

来源：评论

学校读者我要写书评

暂无评论

An improved harmony search algorithm for synchronization of discrete-time chaotic systems

引用

CHAOS SOLITONS & FRACTALS 2009年第5期41卷 2526-2532页

作者： Coelho, Leandro dos Santos de Andrade Bernert, Diego Luis Pontif Catholic Univ Parana PUCPR LAS PPGEPS Ind & Syst Engn Grad Program BR-80215901 Curitiba Parana Brazil

The harmony search (HS) algorithm is a recently developed meta-heuristic algorithm, and has been very successful in a wide variety of optimization problems. HS was conceptualized using an analogy with music improvisation process where music players improvise the pitches of their instruments to obtain better harmony. The HS algorithm does not require initial values and uses a random search instead of a gradient search, so derivative information is unnecessary. Furthermore. the HS algorithm is simple in concept, few in parameters, easy in implementation, imposes fewer mathematical requirements, and does not require initial value settings of the decision variables. In recent years, the investigation of synchronization and control problem for discrete chaotic systems has attracted much attention, and many possible applications. The tuning of a proportional-integral-derivative (PID) controller based on an improved HS (IHS) algorithm for synchronization of two identical discrete chaotic systems subject the different initial conditions is investigated in this paper. Simulation results of the IHS to determine the PID parameters to synchronization of two Henon chaotic systems are compared with other HS approaches including classical HS and global-best HS. Numerical results reveal that the proposed IHS method is a powerful search and controller design optimization tool for synchronization of chaotic systems. (C) 2008 Elsevier Ltd. All rights reserved.

关键词： computer algorithms DISCRETE-time systems CHAOS theory SYNCHRONIZATION MATHEMATICAL optimization VARIABLES (Mathematics) PID controllers NUMERICAL analysis

来源：评论

学校读者我要写书评

暂无评论

Stability and Neimark-Sacker bifurcation of numerical discretization of delay differential equations

引用

CHAOS SOLITONS & FRACTALS 2009年第4期41卷 2010-2017页

作者： He, Zhimin Lai, Xin Hou, Aiyu Cent S Univ Dept Appl Math Changsha 410083 Hunan Peoples R China

A kind of a discrete delay model obtained by Euler method is investigated. Firstly, the linear stability of the model is studied. It is found that there exist Neimark-Sacker bifurcations when the delay passes a sequence of critical values. Then the explicit algorithm for determining the direction and stability of the Neimark-Sacker bifurcations are derived by using the normal form theory and center manifold theorem. Finally, computer simulations are provided to illustrate the analytical results found. (C) 2008 Elsevier Ltd. All rights reserved.

关键词： DELAY differential equations BIFURCATION theory LYAPUNOV stability computer science -- Mathematics EULER method SEQUENCES (Mathematics) computer algorithms computer simulation

来源：评论

学校读者我要写书评

暂无评论

Exact computation of the null distribution of a test for multiple outliers in an exponential sample

引用

COMPUTATIONAL STATISTICS & DATA ANALYSIS 2009年第9期53卷 3281-3290页

作者： Lin, Chien-Tai Balakrishnan, N. Tamkang Univ Dept Math Tamsui 251 Taiwan McMaster Univ Dept Math & Stat Hamilton ON Canada

Through a systematic application of the recursion of Huffer [Huffer, F., 1988. Divided differences and the joint distribution of linear combinations of spacings. journal of Applied Probability 25,346-354], we present an algorithm for evaluating the exact null distribution of the test statistic proposed by Kimber [Kimber, A.C., 1982. Tests for many outliers in an exponential sample. Applied Statistics 31, 263-271] for the testing of up to k upper outliers for discordancy in exponential samples. This method presents another way of obtaining the exact null distribution of the test statistic without first obtaining their joint density. The advantage of this approach is in its generality and also in its ease of use. In addition, it can provide critical values for the test statistic that are accurate to any required degree of precision. Similar results for the sequential testing of up to k lower outliers for discordancy are also presented. (C) 2009 Elsevier B.V. All rights reserved.

关键词： DISTRIBUTION (Probability theory) STATISTICAL hypothesis testing OUTLIERS (Statistics) EXPONENTIAL functions COMBINATIONS (Mathematics) SAMPLING (Statistics) computer algorithms SEQUENCES (Mathematics)

来源：评论

学校读者我要写书评

暂无评论

Robust PDF control with guaranteed stability for non-linear stochastic systems under modelling errors

引用

IET CONTROL THEORY AND APPLICATIONS 2009年第5期3卷 575-582页

作者： Guo, L. Yin, L. Southeast Univ Sch Automat Nanjing 210096 Peoples R China Beihang Univ Sch Instrument Sci & Optoelect Beijing 100083 Peoples R China

The authors consider the robust probability density function (PDF) control problem for non-linear stochastic systems. The controlled systems are described by using non-Gaussian non-linear difference equations with the un-modelled uncertainty and modelling error, as well as time delays. The non-linear multi-step-ahead predictive cost function is adopted and the relationship between the PDFs of the input and output via the uncertain mapping is established. With these formulations, the cost function can be bounded by a non-linear functional of the control input and the known bounds of the errors. Design algorithms are presented for the robust sub-optimal controller and further for the stabilisation controllers. Simulations are given to demonstrate the effectiveness of the proposed control algorithm.

关键词： Modeling Cost functions line stochastic system Controllers stochastic systems control input computer algorithms Difference equation

来源：评论

学校读者我要写书评

暂无评论

New delay-dependent global robust stability conditions for interval neural networks with time-varying delays

引用

CHAOS SOLITONS & FRACTALS 2009年第5期42卷 2954-2964页

作者： Zong, Guangdeng Liu, Jia Qufu Normal Univ Res Inst Automat Qufu 273165 Shandong Peoples R China

This paper deals with the problem of delay-dependent global robust stability analysis for interval neural networks with time-varying delays. By introducing an equivalent transformation of interval systems and the free-weighting matrix technique, a new delay-dependent condition on global robust stability is established. This condition is presented in terms of a linear matrix inequality (LMI), which can be easily checked by using recently developed algorithms in solving LMIs. A numerical example is provided to demonstrate the effectiveness of the proposed method. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.

关键词： NEURAL networks (computer science) LYAPUNOV stability TIME delay systems ROBUST statistics MATRIX inequalities computer algorithms NUMERICAL analysis computer science -- Mathematics

来源：评论

学校读者我要写书评

暂无评论

A meta-level evolutionary strategy for many-criteria design: Application to improving tracking filters

引用

ADVANCED ENGINEERING INFORMATICS 2009年第3期23卷 243-252页

作者： Dotu, I. J. Garcia, J. Berlanga, A. Molina, J. M. Univ Carlos III Madrid Dept Comp Sci Appl Artificial Intelligence Grp Madrid 28270 Spain

We present a novel meta-level heuristic algorithm for multi-criteria search. It focuses on dynamically adapting the optimization criteria through the set of active objectives instead of using the evolutionary strategy (ES) parameters as other meta-level approaches do. The meta-level ES dynamically searches for the subset of objectives that achieves the best global performance. It assumes that the active subset can represent the real structure of the trade-off surface and consider all objectives at the same time as a pure multi-objective evolutionary approach (MOEA) would do. We have successfully applied this heuristic to improve the efficiency of tracking filters design, a real-world problem requiring effective and fast optimization techniques. Our approach yields competitive results and drastically reduces the computational cost. The results show an important advantage in efficiency with respect to previous conventional approaches for applying evolutionary algorithms (EA) to the same design problem. The proposed technique can be applied to real-world problems with a high number of active dependent objectives, a frequent occurrence in engineering design. (C) 2008 Elsevier Ltd. All rights reserved.

关键词： EVOLUTIONARY computation ENGINEERING design HEURISTIC programming INDUSTRIAL efficiency PERFORMANCE evaluation computer algorithms DIGITAL filters (Mathematics) MATHEMATICAL optimization

来源：评论

学校读者我要写书评

暂无评论

Optimistic Parallelism Requires Abstractions

引用

COMMUNICATIONS OF THE ACM 2009年第9期52卷 89-97页

作者： Kulkarni, Milind Pingali, Keshav Walter, Bruce Ramanarayanan, Ganesh Bala, Kavita Chew, L. Paul Univ Texas Austin Austin TX 78712 USA Cornell Univ Ithaca NY USA

The problem of writing software for multicore processors is greatly simplified if we could automatically parallelize sequential programs. Although auto-parallelization has been studied for many decades, it has succeeded only in a few application areas such as dense matrix computations. In particular, auto-parallelization of irregular programs, which are organized around large, pointer-based data structures like graphs, has seemed intractable. The Galois project is taking a fresh look at auto-parallelization. Rather than attempt to parallelize all programs no matter how obscurely they are written, we are designing programming abstractions that permit programmers to highlight opportunities for exploiting parallelism in sequential programs, and building a runtime system that uses these hints to execute the program in parallel. In this paper, we describe the design and implementation of a system based on these ideas. Experimental results for two real-world irregular applications, a Delaunay mesh refinement application and a graphics application that performs agglomerative clustering, demonstrate that this approach is promising.

关键词： Data structures (computer science) computer algorithms Data mining Parallel logic programming Abstract thought Microprocessors computer logic Software architecture Sequential processing (computer science) Program transformation (computer programming) computer graphics software Abstract data types (computer science) Java (computer program language) Data parsing

来源：评论

学校读者我要写书评

暂无评论

Optimal Design of Clinical Tests for the Identification of Physiological Models of Type 1 Diabetes Mellitus

引用

INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH 2009年第4期48卷 1989-2002页

作者： Galvanin, Federico Barolo, Massimiliano Macchietto, Sandro Bezzo, Fabrizio Univ Padua Dipartimento Principi & Impianti Ingn Chim I-35131 Padua Italy Univ London Imperial Coll Sci Technol & Med Dept Chem Engn London SW7 2AZ England

Type 1 diabetes mellitus is a disease affecting millions of people worldwide and causing the expenditure of millions of euros every year for health care. One of the most promising therapies derives from the use of an artificial pancreas, based on a control system able to maintain the normoglycaemia in the subject affected by diabetes. A dynamic simulation model of the glucose-insulin system can be useful in several circumstances for diabetes care, including testing of glucose sensors, insulin infusion algorithms, and decision support systems for diabetes. This paper considers the problem of the identification of single individual parameters in detailed dynamic models of glucose homeostasis. Optimal model-based design of experiment techniques are used to design a set of clinical tests that allow the model parameters to be estimated in a statistically sound way, while meeting constraints related to safety of the subject and ease of implementation. The model with the estimated set of parameters represents a specific subject and can thus be used for customized diabetes care solutions. Simulated results demonstrate how such an approach can improve the effectiveness of clinical tests and serve as a tool to devise safer and more efficient clinical protocols, thus providing a contribution to the development of an artificial pancreas.

关键词： DIABETES -- Treatment OPTIMAL designs (Statistics) CLINICAL trials ARTIFICIAL pancreases INSULIN pumps SIMULATION methods & models HOMEOSTASIS computer algorithms

来源：评论

学校读者我要写书评

暂无评论

Method for calculating the current-voltage characteristics of thermionic electricity-generating channels with complex geometry

引用

ATOMIC ENERGY 2009年第5期106卷 326-333页

作者： Vinogradov, E. G. Linnik, V. A. Lazarenko, D. G. Yarygin, V. I. State Sci Ctr Russian Federat Leipunskii Inst Phys & Power Engn GNTs RF FEI Obninsk Russia

A method for performing numerical calculations of the thermo-electro-physical characteristics of an electricity generating channel with a complex geometry using the experimental databases developed at the Leipunskii Institute for Physics and Power Engineering is described. The current-voltage characteristic of the electricity-generating channel is calculated in order to predict the electro-thermo-physical characteristics of new-generation space-craft thermionic nuclear power facilities. An analytical relation for determining the current-voltage characteristic of an electricity-generating element on the basis of the average temperature of the electrodes is derived;this relation can be used to compare the output characteristics of advanced thermionic nuclear power facilities. An iterative algorithm for calculating the parameters of the electricity-generating elements and the entire channel by the grid method is developed.

关键词： NUCLEAR power plants NUMERICAL calculations ELECTRIC resistors THERMIONIC emission ITERATIVE methods (Mathematics) computer algorithms TEMPERATURE effect

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：