Minimal representations of implicit linear systems

Definitions of external behaviour, equivalence and minimality are given for a class of implicit non-oriented linear dynamical systems of particular interest in computer-aided analysis and design. Conditions for minimality are stated in terms of the rank properties of submatrices in the singular-pencil realization, and a geometric analysis is used in the proof. A stable, library-quality numerical algorithm for minimization is included.     

On state representations of nonlinear implicit systems

The parameter identification problem in systems governed by partial differential equations is investigated. Stochastic approximation algorithms are applied for identifying a class of distributed systems driven by random inputs and observed through noisy measurements. No restrictions about the probability distributions are imposed. These algorithms converge with probability one, and are suitable for on-line applications. The proposed identification method assumes that a previous system classification has been performed, such that the model to be identified is known up to a set of space-varying parameters, where extraneous terms may be included. The very real case of noisy measurements taken at a limited number of discrete points Located in the spatial domain is considered.     

Implementation techniques for geometric branch-and-bound matching methods

Algorithms for geometric matching and feature extraction that work by recursively subdividing transformation space and bounding the quality of match have been proposed in a number of different contexts and become increasingly popular over the last few years. This paper describes matchlist-based branch-and-bound techniques and presents a number of new applications of branch-and-bound methods, among them, a method for globally optimal partial line segment matching under bounded or Gaussian error, point matching under a Gaussian error model with subpixel accuracy and precise orientation models, and a simple and robust technique for finding multiple distinct object instances. It also contains extensive reference information for the implementation of such matching methods under a wide variety of error bounds and transformations. In addition, the paper contains a number of benchmarks and evaluations that provide new information about the runtime behavior of branch-and-bound matching algorithms in general, and that help choose among different implementation strategies, such as the use of point location data structures and space/time tradeoffs involving depth-first search.     

A geometric index reduction method for implicit systems of differential algebraic equations

This paper deals with the index reduction problem for the class of quasi-regular DAE systems. It is shown that any of these systems can be transformed to a generically equivalent first order DAE system consisting of a single purely algebraic (polynomial) equation plus an under-determined ODE (a differential Kronecker representation) in as many variables as the order of the input system. This can be done by means of a Kronecker-type algorithm with bounded complexity.     

Free-form geometric modeling by integrating parametric and implicit PDEs

Parametric PDE techniques, which use partial differential equations (PDEs) defined over a 2D or 3D parametric domain to model graphical objects and processes, can unify geometric attributes and functional constraints of the models. PDEs can also model implicit shapes defined by level sets of scalar intensity fields. In this paper, we present an approach that integrates parametric and implicit trivariate PDEs to define geometric solid models containing both geometric information and intensity distribution subject to flexible boundary conditions. The integrated formulation of second-order or fourth-order elliptic PDEs permits designers to manipulate PDE objects of complex geometry and/or arbitrary topology through direct sculpting and free-form modeling. We developed a PDE-based geometric modeling system for shape design and manipulation of PDE objects. The integration of implicit PDEs with parametric geometry offers more general and arbitrary shape blending and free-form modeling for objects with intensity attributes than pure geometric models     

A topology preserving level set method for geometric deformable models

Active contour and surface models, also known as deformable models, are powerful image segmentation techniques. Geometric deformable models implemented using level set methods have advantages over parametric models due to their intrinsic behavior, parameterization independence, and ease of implementation. However, a long claimed advantage of geometric deformable models-the ability to automatically handle topology changes-turns out to be a liability in applications where the object to be segmented has a known topology that must be preserved. We present a new class of geometric deformable models designed using a novel topology-preserving level set method, which achieves topology preservation by applying the simple point concept from digital topology. These new models maintain the other advantages of standard geometric deformable models including subpixel accuracy and production of nonintersecting curves or surfaces. Moreover, since the topology-preserving constraint is enforced efficiently through local computations, the resulting algorithm incurs only nominal computational overhead over standard geometric deformable models. Several experiments on simulated and real data are provided to demonstrate the performance of this new deformable model algorithm.     

指令集仿真器的关键技术

为适应嵌入式系统开发中对指令集仿真器仿真速度的要求,提出一种改进的指令集仿真技术.该技术在现有的静态多核仿真器基础上引入指令预处理、动态译码缓存、多线程C函数生成和动态调度运行等技术,以实现对仿真器性能的优化.该技术已成功应用于中国科学院微电子所自主研发的IME-Diamond DSP处理器的多核指令集仿真器OPT-ISS中.实际应用程序测试结果表明,该技术在仿真速度提升方面有明显效果.     

6DoF haptic rendering using distance maps over implicit representations

This paper presents a haptic rendering scheme based on distance maps over implicit surfaces. Using the successful concept of support planes and mappings, a support plane mapping formulation is used so as to generate a convex representation and efficiently perform collision detection. The proposed scheme enables, under specific assumptions, the analytical reconstruction of the rigid 3D object’s surface, using the equations of the support planes and their respective distance map. As a direct consequence, the problem of calculating the force feedback can be analytically solved using only information about the 3D object’s spatial transformation and position of the haptic interaction point. Moreover, several haptic effects are derived by the proposed mesh-free haptic rendering formulation. Experimental evaluation and computational complexity analysis demonstrates that the proposed approach can reduce significantly the computational cost when compared to existing methods.     

Maximal independent set graph partitions for representations of body-centered cubic lattices

A maximal independent set graph data structure for a body-centered cubic lattice is presented. Refinement and coarsening operations are defined in terms of set-operations resulting in robust and easy implementation compared to a quad-tree-based implementation. The graph only stores information corresponding to the leaves of a quad-tree thus has a smaller memory foot-print. The adjacency information in the graph relieves one from going up and down the quad-tree when searching for neighbors. This results in constant time complexities for refinement and coarsening operations.     

A survey of constraint satisfaction techniques for geometric modeling

In geometric modeling, a model is built by specifying relations between geometric entities, which are to be maintained by the modeling system. Many relations can be specified declaratively as geometric constraints on these entities. Constraint satisfaction techniques are used for validation of the geometric model. This article presents an overview of general constraint satisfaction techniques, both for finite domain and infinite domain constraint satisfaction problems. Specific satisfaction techniques for geometric constraints get special attention. Furthermore, the article presents concepts from constraint programming, concerning the integration of constraint specification and programming languages.     

Graph-based representations and techniques for image processing and image analysis

In this paper we will discuss the use of some graph-based representations and techniques for image processing and analysis. Instead of making an extensive review of the graph techniques in this field, we will explain how we are using these techniques in an active vision system for an autonomous mobile robot developed in the Institut de Robòtica i Informàtica Industrial within the project “Active Vision System with Automatic Learning Capacity for Industrial Applications (CICYT TAP98-0473)”. Specifically we will discuss the use of graph-based representations and techniques for image segmentation, image perceptual grouping and object recognition. We first present a generalisation of a graph partitioning greedy algorithm for colour image segmentation. Next we describe a novel fusion of colour-based segmentation and depth from stereo that yields a graph representing every object in the scene. Finally we describe a new representation of a set of attributed graphs (AGs), denominated function-described graphs (FDGs), a distance measure for matching AGs with FDGs and some applications for robot vision.     

Some techniques for solving linear equation systems with guarantee

Methods are described for solving a system of linear equations with error bounds. Rectangular and spherical intervals ofR ⁿ are used combined. The objective is to get guaranteed accuracy with a minimal effort of computing time.     

基于几何方法的约束线性系统控制快速算法

针对存在状态量和控制量约束的线性系统控制问题, 提出了新快速算法. 已有的处理上述约束系统控制问题的多面体方法和椭球方法在实际应用过程中分别存在计算繁琐和计算保守的问题. 在数学分析的基础上, 通过对上述算法的水平集计算过程的优化, 提出了一种计算简单的约束控制算法. 仿真结果表明, 这种算法计算简单, 且可以满足系统控制的要求.