Showing papers on "Bounding overwatch published in 1997"

Spatial relations, minimum bounding rectangles, and spatial data structures

Abstract: Spatial relations are important in numerous domains, such as Spatial Query Languages, Image and Multimedia Databases, Reasoning and Geographic Applications. This paper is concerned with the retrieval of topological and direction relations using spatial data structures based on Minimum Bounding Rectangles. We describe topological and direction relations between region objects and we study the spatial information that Minimum Bounding Rectangles convey about the actual objects they enclose. Then we apply the results in R-trees and their variations, R-trees and R*-trees, in order to minimize the number of disk accesses for queries involving topological and direction relations. We also investigate queries that express complex conditions in the form of disjunctions and conjunctions, and discuss possible extensions.

An Algorithm for Improving the Bounding Procedure in Solving Process Network Synthesis by a Branch-and-Bound Method

Abstract: Process network synthesis (PNS) has enormous practical impact; however, its mixed integer programming model is tedious to solve because it usually involves a large number of binary variables. A structural model of PNS can be given on the basis of a combinatorial approach. An optimal solution of this model can conveniently be generated by a branch-and-bound method if an effective bounding procedure is available. In the present work, a sharp bounding function is given for solving PNS by a branch-and-bound method.

SR-Tree : An Index Structure for Nearest Neighbor Searching of High-Dimensional Point Data

Abstract: Similarity search methods using feature vectors are employed widely for implementation of content-based retrieval of visual data, and appropriate index structures were explored to accelerate the search. Methods proposed hitherto have used the R*-tree and the SS-tree. This study offers a faster index structure namely, the SR-tree (sphere/rectangle-tree). The main feature of the proposed method is that both bounding spheres and bounding rectangles are used in combination. Bounding spheres and rectangles have been already employed in the SS-tree and the R*-tree, respectively. Experiments carried out as a part of the present study show, however, that as dimensionality grows high, both methods become problematic. Thus, when using bounding rectangles, the difference between the length of the edge of the rectangle and the diagonal becomes too large; with bounding spheres, the volume increases considerably as compared to rectangles. On the other hand, the SR-tree method uses both spheres and triangles, which ensures more efficient partitioning as compared to the SS-tree or R*-tree. Evaluation experiments proved that the proposed method outperforms both SS-tree and R*-tree in terms of CPU time and number of disk accesses. © 1998 Scripta Technica, Syst Comp Jpn, 29(6): 59–73, 1998

Bounding resources in Cooperating Distributed Grammar Systems.

Abstract: A method and device for adjusting camber and caster in a solid axle steerable structure including a yoke, and a steering knuckle rotatably carried in the yoke by a pair of ball joints, by inserting a connecting offset and/or skewed bushing in at least one of the ball joint receiving openings in the yoke and positioning the connecting bushing to accommodate the steering knuckle in the desired, aligned position relative to the yoke.

Simplifying complex CAD geometry with conservative bounding contours

Abstract: Megabytes of data are often required for today's detailed CAD models. Users are often willing to sacrifice some of this detail for efficient rendering, transmission over networks, and robot motion planning. For example, many robotics and automation applications such as collision checking require only the simple bounding envelope of a complex set of nested CAD models. In contrast to approximate graphics rendering, these applications require that the simplified envelope be conservative: that the true CAD model be strictly contained inside it. One conservative bounding envelope is the bounding box. Another is the convex hull. Generally each conservative bounding envelope can be "trimmed" by a conservative bounding contour (CBC) of its 2D projection. This yields a hierarchy of conservative bounding envelopes of the original CAD model. In this paper we describe a method for generating the CBC at different levels of simplification. We give an algorithm that computes the CBC of a given 2D projection of a wireframe model. Since the wireframe requires neither boundary representation (BREP) nor constructive solid geometry (CSG) our method is compatible with almost all existing CAD standards.

Stochastic convergence of optimal bounding ellipsoid algorithms

Abstract: Given appropriate persistency of excitation, the ellipsoidal seta associated with optimal bounding ellipsoid (OBE) algorithms with an interpretable optimization (volume) criterion, converge to a point under the condition that the model disturbance process visit the error bounds infinitely often. The spectral properties of the disturbance are not primary in the convergence behavior of OBE algorithms, rendering these identifiers distinctly different from the structurally similar RLS. Rigorous proof of the sufficiency of the "infinite visitation" property is given for both independent and correlated noise. In the colored noise case, it is shown that a mixing condition on the observations will assure convergence if the OBE algorithm is slightly modified. Examples of simulations are used to illustrate the theoretical developments.

Robust, reduced-order modeling for state-space systems via parameter-dependent bounding functions

Abstract: One of the most important problems in dynamic systems theory is to approximate a higher-order system model with a low-order, relatively simpler model. However, the nominal high-order model is never an exact representation of the true physical system. In this paper the problem of approximating an uncertain high-order system with constant real parameter uncertainty by a robust reduced-order model is considered. A parameter-dependent quadratic bounding function is developed that bounds the effect of uncertain real parameters on the model-reduction error. An auxiliary minimization problem is formulated that minimizes an upper bound for the model-reduction error. The principal result is a necessary condition for solving the auxiliary minimization problem which effectively provides sufficient conditions for characterizing robust reduced-order models.

Automatic bound estimation: a practical development in optimal bounding ellipsoid processing

Abstract: Practical application of optimal bounding ellipsoid identification is made possible by the optimal bounding ellipsoid algorithm with automatic bound estimation (OBE-ABE), which automatically estimates model error bounds. Lack of tenable bounds in many real problems has rendered these interesting new methods impractical. OBE-ABE is consistently convergent under proven conditions, and offers significant computational advantages.

Interval and Bounding Hessians

Abstract: Bounding Hessians are defined and an O(n 2) method of obtaining optimal bounding Hessians from interval Hessians is presented. They are applied to a framework of an adaptive second derivative covering method for global optimization, which is presented here. Also, bounding Hessians can be used for reformulation of very general global optimization problems into several useful forms for which there are existing algorithms.

Bounding method based on generalised real power distribution factors

Abstract: An efficient bounding method for distribution network contingency screening is presented. It is based on the use of generalised real power distribution factors capable of modelling the effects of single and multiple topological contingencies, also including bus splits and bus joins deriving from circuit breaker operation. The proposed bounding method consists in identifying the main reclosing paths for the incremental power change. Power flow limits are evaluated for the branches belonging to an interest area centred around the contingency location. The interest area is expanded until the amount of power reclosing through not yet examined branches (boundary flow) falls under a preselected threshold value. Distribution factors are used both in branch flow limit checking and in the computation of the boundary flow. Validation of the proposed method was achieved by extensive testing on both the IEEE 118-bus network and actual systems of Italian, European and North American origin.