Particle Content in Topological Field Theories

By demanding that the path integral measure of topological field theories be metric independent, we can derive powerful constraints on the particle content of a topological field theory as well as on the dimensionality of space-time.Comment: 9p, OUTP-92-30

Point Pair Feature based Object Detection for Random Bin Picking

Point pair features are a popular representation for free form 3D object detection and pose estimation. In this paper, their performance in an industrial random bin picking context is investigated. A new method to generate representative synthetic datasets is proposed. This allows to investigate the influence of a high degree of clutter and the presence of self similar features, which are typical to our application. We provide an overview of solutions proposed in literature and discuss their strengths and weaknesses. A simple heuristic method to drastically reduce the computational complexity is introduced, which results in improved robustness, speed and accuracy compared to the naive approach

Background Fields in 2+1 Topological Gravity

The partition function of 2+1 Chern-Simons Witten topological gravity has an attractive interpretation in terms of the unbroken and broken phases of gravity. We make this physical interpretation manifest using the background field method.Comment: 10 pages, LaTeX, OUTP-93-03

Design of a four-point bend test for ultra-low cycle fatigue of pipelines under inelastic bending

This master thesis is situated in the research domain dealing with the ductile failure of pipelines under extreme loading conditions. It is part of an umbrella research aiming to develop innovative experimental and computational methodologies to simulate fracture of steel structural elements under ultralow cycle fatigue. The focus of this study is on steel pipeline applications. The objective of this thesis is to design a large-scale four-point bend test setup to cyclically bend pipes. The feasibility of instrumentation will be evaluated using small scale test specimens. In this paper some ideas, constraints and opportunities for the design are considered, based on a literature review of several test setups for other applications. The design parameters have been calculated to compose the design windows and an initial overview of the possible instrumentation is given

Quantum Einstein Gravity as a Topological Field Theory

General covariance in quantum gravity is seen once one integrates over all possible metrics. In recent years topological field theories have given us a different route to general covariance without integrating over all possible metrics. Here we argue that Einstein quantum gravity may be viewed as a topological field theory provided a certain constrant from the path integral measure is satisfied.Comment: 10 pages, LaTe

Inefficiencies in regional commuting policy.

This paper discusses investments in transport infrastructure and incentives for commuting taxes in a multiregional setting. We study the horizontal and vertical interactions between governments. We identify incentives for strategic and tax exporting behavior that might lead to underinvestment in transport infrastructure. Furthermore, we show that the intensity of the strategic behavior is affected by geographic firm ownership structure, the number of labor-supplying regions and the revenue-sharing mechanism in the federation. A numerical example applies the insights on commuting in Belgium.

Monitoring and Modelling the Vibrational Effects of Small (<50 kW) Wind Turbines on the Eskdalemuir IMS Station

It is known (Styles et al., 2005) that windfarms generate low frequency vibrations which propagate through the ground and have the potential to adversely affect sensitive installations, most notably seismometer arrays set up to monitor for nuclear tests. Significant work on the effects of large wind turbines has been carried out by Keele University as well as by Schofield (2002) and Fiori et al (2009). For the Eskdalemuir International Monitoring System station in Scotland, a vibration threshold was set, for wind farms within 50 km of Eskdalemuir, at frequencies around the 4 to 5 Hz region. However, with increased development, the threshold is being approached and small wind turbines (less than 50kW), even of the order of 15kW have also been restricted despite the differences in scale and modes of vibration. In order to protect Eskdalemuir a threshold limit was set for any turbine as a holding measure and a programme to try to establish whether they were really problematic has been carried out. Models for two wind turbine types from the manufacturers Proven and Gaia-Wind have been calculated and measurement programmes carried out. It has been possible to demonstrate that in most cases these small turbines do not generate significant energy in the band of concern and that the levels are low enough to be negligible. Small turbines once evaluated and monitored by Keele University and given approval by the UK Ministry of Defence, will receive clearance for deployment around the Eskdalemuir site at distances greater than 10km

Hybrid group recommendations for a travel service

Recommendation techniques have proven their usefulness as a tool to cope with the information overload problem in many classical domains such as movies, books, and music. Additional challenges for recommender systems emerge in the domain of tourism such as acquiring metadata and feedback, the sparsity of the rating matrix, user constraints, and the fact that traveling is often a group activity. This paper proposes a recommender system that offers personalized recommendations for travel destinations to individuals and groups. These recommendations are based on the users' rating profile, personal interests, and specific demands for their next destination. The recommendation algorithm is a hybrid approach combining a content-based, collaborative filtering, and knowledge-based solution. For groups of users, such as families or friends, individual recommendations are aggregated into group recommendations, with an additional opportunity for users to give feedback on these group recommendations. A group of test users evaluated the recommender system using a prototype web application. The results prove the usefulness of individual and group recommendations and show that users prefer the hybrid algorithm over each individual technique. This paper demonstrates the added value of various recommendation algorithms in terms of different quality aspects, compared to an unpersonalized list of the most-popular destinations