36003188
Online Searching with an Autonomous Robot
8840780
Searching with an autonomous robot
We demonstrate how one of the classical areas of computationalgeometry has reached practical application, which in turngives rise to new, fascinating geometric problems.In particular, we discuss the problem of developing a goodonline strategy for anautonomous mobile robot to locate an object that is hidden behinda corner or door.
696
Online searching with an autonomous robot
We discuss online strategies for visibility-based searching for an object hidden behind a corner, using Kurt3D, a real autonomous mobile robot. This task is closely related to a number of well-studied problems. Our robot uses a three-dimensional laser scanner in a stop, scan, plan, go fashion for building a virtual three-dimensional environment. Besides planning trajectories and avoiding obstacles, Kurt3D is capable of identifying objects like a chair. We derive a practically useful and asymptotically optimal strategy that guarantees a competitive ratio of 2, which differs remarkably from the well-studied scenario without the need of stopping for surveying the environment. Our strategy is used by Kurt3D, documented in a separate video.
1585010
Exact and Approximation Algorithms for Computing the Dilation Spectrum of Paths, Trees, and Cycles
Let G be a graph embedded in Euclidean space. For any two vertices of G their dilation denotes the length of a shortest connecting path in G, divided by their Euclidean distance. In this paper we study the spectrum of the dilation, over all pairs of vertices of G. For paths, trees, and cycles in 2D we present O(n3/2+e) randomized algorithms that compute, for a given value κ ≥ 1, the exact number of vertex pairs of dilation > κ. Then we present deterministic algorithms that approximate the number of vertex pairs of dilation > κ up to an 1+η factor. They run in time O(n log2n) for chains and cycles, and in time O(n log3n) for trees, in any constant dimension.
30580193
A PTAS for minimum vertex dilation triangulation of a simple polygon with a constant number of sources of dilation
We design a fully polynomial-time approximation scheme for the problem of finding a triangulation of a simple polygon with a constant number of sources of dilation that achieves the minimum vertex dilation.
1743128
Embedding Point Sets into Plane Graphs of Small Dilation
Let S be a set of points in the plane. What is the minimum possible dilation of all plane graphs that contain S? Even for a set S as simple as five points evenly placed on the circle, this question seems hard to answer; it is not even clear if there exists a lower bound >1. In this paper we provide the first upper and lower bounds for the embedding problem. 
 
Each finite point set can be embedded into the vertex set of a finite triangulation of dilation ≤ 1.1247. 
 
Each embedding of a closed convex curve has dilation ≥ 1.00157. 
 
Let P be the plane graph that results from intersecting n infinite families of equidistant, parallel lines in general position. Then the vertex set of P has dilation $\geq 2/\sqrt{3} \approx 1.1547$.
11060886
Visual Inspection Methods for Quality Control in Automotive Engineering
The automotive industry demands visual support for the verification of the quality of their products from the design phase to the manufacturing phase. This implies the need of tools for measurement planning, programming measuring devices, managing measurement data, and the visual exploration of the measurement results. To improve the quality control throughout the whole process chain an integration of such tools in a platform independent framework is crucial. We present eMMA (enhanced Measure Management Application), a client/server system integrating measurement planning, data management, and straightforward as well as sophisticated visual exploration tools in a single framework.
18735413
Service and commodity based electronic intermediaries: a comparative analysis
The theoretical literature concerning supply chain intermediation is surveyed to develop a framework of five intermediary states. Data collected on 134 electronic intermediaries are employed to explore correlations between intermediation states, growth strategies and firm profitability, in a sample representing both service based and commodity based intermediaries. The study finds a positive relationship between more capital intensive states of intermediation and profitability. In addition, we find a higher use of acquisitions as growth mechanisms in service based intermediaries, and a greater use of joint ventures as growth mechanisms within commodity based portals.
3012905
The density of iterated crossing points and a gap result for triangulations of finite point sets
Consider a plane graph <i>G</i>, drawn with straight lines. For every pair <i>a,b</i> of vertices of <i>G</i>, we compare the shortest-path distance between <i>a</i> and <i>b</i> in <i>G</i> (with Euclidean edge lengths) to their actual distance in the plane. The worst-case ratio of these two values, for all pairs of points, is called the <i>dilation</i> of <i>G</i>. All finite plane graphs of dilation 1 have been classified. They are closely related to the following iterative procedure. For a given point set <i>P</i> ⊆ <i>R</i><sup>2</sup>, we connect every pair of points in <i>P</i> by a line segment and then add to <i>P</i> all those points where two such line segments cross. Repeating this process infinitely often, yields a limit point set <i>P</i><sup>∞</sup>⊇<i>P</i>. This limit set <i>P</i><sup>∞</sup> is finite if and only if <i>P</i> is contained in the vertex set of a triangulation of dilation 1.The main result of this paper is the following gap theorem: For any finite point set <i>P</i> in the plane for which <i>P</i><sup>∞</sup> is infinite, there exists a threshold λ > 1 such that <i>P</i> is not contained in the vertex set of any finite plane graph of dilation at most λ. As a first ingredient to our proof, we show that such an infinite <i>P</i><sup>∞</sup> must lie dense in a certain region of the plane. In the second, more difficult part, we then construct a concrete point set <i>P</i><sub>0</sub> such that any planar graph that contains this set amongst its vertices must have a dilation larger than 1.0000047.
2107176
A Hybrid Web-Based Toolkit for Human Modeling
Modern web-based Scientific Visualization applications try to overcome common limitations imposed by limited internet bandwidth, server bottlenecks or network latency. A further aspect is the desire to gain platform independence by solely using instruments which are platform independent by conception: the programming language Java, the Virtual Reality Modeling Language (VRML), or the 3D API Java3D.We present a prototype of a hybrid web-based Scientific Visualization system which makes use of the increasing computational power of modern desktop workstations and personal computers on the client side, and the superior performance provided by a powerful machine on the server side. In order to achieve high interaction rates and to balance computational load the user can dynamically assign selected tasks to his client or to the server.Within the scientific field of human modeling we have implemented a hybrid web-based toolkit for the modeling of human muscles and skin. Our application allows the on-line generation and manipulation of three-dimensional implicit muscle models in a heterogeneous network and it offers various parameters to adjust computation and response time versus rendering quality.