Approximation Error and Error Accumulation for the Landen Transform

In this note we derive explicit a priori error bounds for the approximation error and error accumulation of the descending Landen transform. Our results apply to incomplete elliptic integral of the first kind and give the framework to calculate error bounds in the representation of Jacobi's Zeta- and Theta-function.     

Monte Carlo planning for active object classification

Classifying objects in complex unknown environments is a challenging problem in robotics and is fundamental in many applications. Modern sensors and sophisticated perception algorithms extract rich 3D textured information, but are limited to the data that are collected from a given location or path. We are interested in closing the loop around perception and planning, in particular to plan paths for better perceptual data, and focus on the problem of planning scanning sequences to improve object classification from range data. We formulate a novel time-constrained active classification problem and propose solution algorithms that employ a variation of Monte Carlo tree search to plan non-myopically. Our algorithms use a particle filter combined with Gaussian process regression to estimate joint distributions of object class and pose. This estimator is used in planning to generate a probabilistic belief about the state of objects in a scene, and also to generate beliefs for predicted sensor observations from future viewpoints. These predictions consider occlusions arising from predicted object positions and shapes. We evaluate our algorithms in simulation, in comparison to passive and greedy strategies. We also describe similar experiments where the algorithms are implemented online, using a mobile ground robot in a farm environment. Results indicate that our non-myopic approach outperforms both passive and myopic strategies, and clearly show the benefit of active perception for outdoor object classification.     

Unification in datastructure multisets

In a recent paper A. Herold and J. Siekmann generalize pure AC unification to terms containing additional function symbols. Generalized AC unification thus attains practical relevance for a broad range of applications. Pure AC unification is used as a basic mechanism and it is this key role that has motivated our research. We have improved upon earlier approaches by basing (pure) AC unification on a firm theoretical basis and presenting algorithms which fully exploit the properties of the underlying mathematical structure. In particular, the high degree of parallelism for AC unification will become apparent. Our algorithms have been designed for parallel hardware but still yield significant improvements over earlier algorithms when used in the sequential mode.     

A New Method for the Study of Adhesion: Application of Inelastic Electron Tunneling Spectroscopy

Inelastic electron tunneling spectroscopy provides an incredibly sensitive and versatile method of detecting and identifying molecular species adsorbed on the surface of a metal oxide. IETS spectra have been measured on the components of the commercial adhesive, Hercules 3501. This epoxy system consists of two molecular components; diamino diphenyl sulfone (DPS) and tetraglycidycl 4,4' diamino diphenyl methane (DPM). IETS spectra of the individual components and of the epoxy mixture adsorbed on aluminum oxide have been obtained and the vibrational modes and frequencies assigned by comparison with computer calculations and existing infrared optical spectra.

IETS is a useful tool for the study of molecular adhesion to an oxide. It is one of the most important methods available for determining the interface physics and chemistry of adhesive bondlines. Its usefulness is greatly enhanced by the fact that in situ studies can be made.

Spectra have been obtained on the components and mixture of the high performance, two component epoxy Hercules 3501. The vibrational modes were identified by comparison with infrared and Raman data, and with computer calculations using force constant information. Evidence for an aging effect was found in the DPS component.

It is suggested that initial studies using IETS should be applied to adhesives of simple molecular structure before proceeding to more complex systems.     

Large scale graph-based SLAM using aerial images as prior information

The problem of learning a map with a mobile robot has been intensively studied in the past and is usually referred to as the simultaneous localization and mapping (SLAM) problem. However, most existing solutions to the SLAM problem learn the maps from scratch and have no means for incorporating prior information. In this paper, we present a novel SLAM approach that achieves global consistency by utilizing publicly accessible aerial photographs as prior information. It inserts correspondences found between stereo and three-dimensional range data and the aerial images as constraints into a graph-based formulation of the SLAM problem. We evaluate our algorithm based on large real-world datasets acquired even in mixed in- and outdoor environments by comparing the global accuracy with state-of-the-art SLAM approaches and GPS. The experimental results demonstrate that the maps acquired with our method show increased global consistency.     

An Accurate Distance-Calculation Algorithm for Convex Polyhedra

The paper describes an efficient and accurate algorithm to calculate the distance between convex polyhedra. The closest points between two objects can be calculated by simple projections and can be followed continuously in time. The polyhedra are given by the vertices. Interval data are supported. The accuracy of the calculation is explored.     

Numerische Simulation des Knickverhaltens von Mauerwerk

Numerical simulation of the buckling behaviour of masonry. The paper presents a numerical approach for the simulation and analysis of the buckling behaviour of masonry. The assumed parabolic stress‐strain function allows a realistic modelling of the composite material behaviour in compression and bending. The equilibrium is formulated in the deformed state and takes into consideration the effect of the deflections on the bearing capacity. Due to the physical nonlinearity, the stress limitations and the system modification when cracking in tension occurs, the bending stiffness becomes under loading a function of the stress state, thus leading to variable coefficients of the governing differential equation. The system solution is obtained within the frame of an iterative numeric procedure in terms of the transfer matrix method, based on the discretization of the structure into finite segments and the piecewise linearization of its parameters.