An evolutionary algorithm for online, resource constrained, multi-vehicle sensing mission planning

Mobile robotic platforms are an indispensable tool for various scientific and industrial applications. Robots are used to undertake missions whose execution is constrained by various factors, such as the allocated time or their remaining energy. Existing solutions for resource constrained multi-robot sensing mission planning provide optimal plans at a prohibitive computational complexity for online application [1],[2],[3]. A heuristic approach exists for an online, resource constrained sensing mission planning for a single vehicle [4]. This work proposes a Genetic Algorithm (GA) based heuristic for the Correlated Team Orienteering Problem (CTOP) that is used for planning sensing and monitoring missions for robotic teams that operate under resource constraints. The heuristic is compared against optimal Mixed Integer Quadratic Programming (MIQP) solutions. Results show that the quality of the heuristic solution is at the worst case equal to the 5% optimal solution. The heuristic solution proves to be at least 300 times more time efficient in the worst tested case. The GA heuristic execution required in the worst case less than a second making it suitable for online execution.Comment: 8 pages, 5 figures, accepted for publication in Robotics and Automation Letters (RA-L

Political Institutions and Greenhouse Gas Controls

Research and insights taken from the field of political economy suggest that institutions limit the extent to which efficient policies to reduce greenhouse gas emissions are likely to be adopted. High transaction costs among nations, as well as domestic constraints like voter xenophobia and distrust of markets in the U.S. and ineffective legal and economic institutions in China, discourage international agreement. The U.S. must focus upon limiting economic harm from adopting poorly designed policies and developing strategies for adaptation or technology-driven geoengineering. Most importantly, the lessons of political economy must become central to the study of climate policy, including a healthy exchange of views between political economists and climate modelers.

Extension of bundles of null directions

The geometry of P, the bundle of null directions over an Einstein space-time, is studied. The full set of invariants of the natural G-structure on P is constructed using the Cartan method of equivalence. This leads to an extension of P which is an elliptic fibration over the space-time. Examples are given which show that such an extension, although natural, is not unique. A reinterpretation of the Petrov classification in terms of the fibres of an extension of P is presented.Comment: LaTex file, accepted in CQ

Study of Blood Flow Using Indicator Dilution Techniques

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Jobs, Workers and Changes in Earnings Dispersion

The 'fractal' nature of the rise in earnings dispersion is one of its key features and remains a puzzle. In this paper, we offer a new perspective on the causes of changes in earnings dispersion, focusing on the role of labour reallocation. Once we drop the assumption that all firms pay a given worker the same, the allocation of workers to firms matters for the dispersion of earnings. This perspective highlights two new factors that can affect the dispersion of earnings: rates of job and worker reallocation, and the nature of the process allocating workers to jobs. We set out a framework capturing this idea and quantify the impact of reallocation on earnings dispersion, using a dataset that comprises almost the universe of workers and the universe of employers in Maryland. We show that these factors have potentially large effects in general on earnings dispersion. In the case of Maryland over the period 1985-1994, the changing allocation of workers to jobs played a significant role in explaining movements in the dispersion of earnings.Earnings inequality, labour reallocation, matched worker and firm panels

Finite domination and Novikov rings. Iterative approach

Suppose C is a bounded chain complex of finitely generated free modules over the Laurent polynomial ring L = R[x,1/x]. Then C is R-finitely dominated, ie, homotopy equivalent over R to a bounded chain complex of finitely generated projective R-modules, if and only if the two chain complexes C((x)) and C((1/x)) are acyclic, as has been proved by Ranicki. Here C((x)) is the tensor product over L of C with the Novikov ring R((x)) = R[[x]][1/x] (also known as the ring of formal Laurent series in x); similarly, C((1/x)) is the tensor product over L of C with the Novikov ring R((1/x)) = R[[1/x]][x]. In this paper, we prove a generalisation of this criterion which allows us to detect finite domination of bounded below chain complexes of projective modules over Laurent rings in several indeterminates.Comment: 15 pages; diagrams typeset with Paul Taylor's "diagrams" macro package. Version 2: clarified proof of main theorem, fixed minor typos; Version 3: expanded introduction, now 16 pages; Version 4: corrected mistake on functoriality of mapping tor