Isometric actions of simple Lie groups on pseudoRiemannian manifolds

Let M be a connected compact pseudoRiemannian manifold acted upon topologically transitively and isometrically by a connected noncompact simple Lie group G. If m_0, n_0 are the dimensions of the maximal lightlike subspaces tangent to M and G, respectively, where G carries any bi-invariant metric, then we have n_0 \leq m_0. We study G-actions that satisfy the condition n_0 = m_0. With no rank restrictions on G, we prove that M has a finite covering \hat{M} to which the G-action lifts so that \hat{M} is G-equivariantly diffeomorphic to an action on a double coset K\backslash L/\Gamma, as considered in Zimmer's program, with G normal in L (Theorem A). If G has finite center and \rank_\R(G)\geq 2, then we prove that we can choose \hat{M} for which L is semisimple and \Gamma is an irreducible lattice (Theorem B). We also prove that our condition n_0 = m_0 completely characterizes, up to a finite covering, such double coset G-actions (Theorem C). This describes a large family of double coset G-actions and provides a partial positive answer to the conjecture proposed in Zimmer's program.Comment: 29 pages, published versio

A Framework for Estimating U.S. WTO Domestic Support to 2015

The framework allows comprehensive and consistent measurement and classification of U.S. domestic support to 2015 under different assumptions. Projections of future U.S. domestic support patterns are made with estimates published in the USDA Agricultural Baseline Projections. We also use information from the OECD, FAPRI, NASS, and our own estimates. We present key elements and an overview of our analytical framework, assumptions of a baseline scenario, and some analytical results and observations arising from our analysis. The baseline scenario extends the classification of programs in WTO notifications to 2015. The framework consists of 65 spreadsheets, which are grouped into 4 analytical stages: calculation of program estimates by commodity; calculation of product-specific aggregate measurement of support by commodity; estimates of major U.S. agricultural programs; and estimates for WTO boxes and the overall value of production. The main results of the baseline scenario suggest that the United States would be able to maintain its Uruguay Round commitments under relatively optimistic USDA Baseline assumptions. Because the U.S. overall value of production is projected to increase by almost 40% from 2002 to 2015, de minimis allowances will rise to US$26 billion by 2015. The framework allows us to calculate possible U.S. domestic support expenditures under alternative assumptions about rules and commitments resulting from the Doha negotiations, such as reductions in de minimis percentages, commitments on Total AMS and overall support. This enables us to better understand implications for WTO negotiations.agriculture, AMS, de minimis, domestic support, WTO, framework, International Relations/Trade, F1, Q1, Q17, Q18, F13,

Temperature robust PCA based stress monitoring approach

In this paper, a guided wave temperature robust PCA-based stress monitoring methodology is proposed. It is based on the analysis of the longitudinal guided wave propagating along the path under stress. Slight changes in the wave are detected by means of PCA via statistical T2 and Q indices. Experimental and numerical simulations of the guided wave propagating in material under different temperatures have shown significant variations in the amplitude and the velocity of the wave. This condition can jeopardize the discrimination of the different stress scenarios detected by the PCA indices. Thus, it is proposed a methodology based on an extended knowledge base, composed by a PCA statistical model for different discrete temperatures to produce a robust classification of stress states under variable environmental conditions. Experimental results have shown a good agreement between the predicted scenarios and the real onesPostprint (author's final draft

Flow estimation in a steel pipe using guided waves

In this investigation, a flow rate estimation guided wave based scheme in pipes is proposed. The effect of the fluid over the propagation of longitudinal waves has been experimentally studied by using several laminar flows of water transported by a steel pipe. Results have shown a decrease of the guided wave pattern repeatability and the signal energy as the flow rate increase as a result of the energy leakage from the pipe to the fluid. A Matlab® script is used to excite the PZT actuator via picoscope 2208 of Picotech®, the captured signal is acquired also by the picoscope and the data is processed in Matlab. The test bench utilized is composed by a 1” sch 40 A-106 pipe, a needle valve and a centrifugal pump provides the flow energy. A couple of PZTs are used in a picth-catch configuration to produce and capture the longitudinal waves along the cross section of the pipe.Postprint (author's final draft