14,946 research outputs found

    Towards a sustainable economy? Socio-technical transitions in the green building sector

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    Making the transition to a green economy is a major policy driver in the UK and other countries. Entrepreneurs are suggested as being at the forefront of this transition and as a driving force for sustainability. These “green entrepreneurs” may represent a new type of entrepreneurial behaviour combining economic, environmental and social aims. In this paper, we present empirical work conducted with green entrepreneurs in the UK green building sector. Buildings have significant impacts on the environment, both in terms of materials and post-construction energy demands. Drawing on sustainability transitions theory, we examine the role of green entrepreneurs in affecting change and suggest that green building niches are less consensual than previously theorised. In theorising green entrepreneurs, we also point to the need to consider them within wider networks of activity rather than as lone actors and the implications this has for policy

    Anisotropic imbibition on surfaces patterned with polygonal posts

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    We present and interpret lattice Boltzmann simulations of thick films spreading on surfaces patterned with polygonal posts. We show that the mechanism of pinning and depinning differs with the direction of advance, and demonstrate that this leads to anisotropic spreading within a certain range of material contact angles.Comment: DSFD Proceedings 201

    The Lebesgue Universal Covering Problem

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    In 1914 Lebesgue defined a "universal covering" to be a convex subset of the plane that contains an isometric copy of any subset of diameter 1. His challenge of finding a universal covering with the least possible area has been addressed by various mathematicians: Pal, Sprague and Hansen have each created a smaller universal covering by removing regions from those known before. However, Hansen's last reduction was microsopic: he claimed to remove an area of 610186 \cdot 10^{-18}, but we show that he actually removed an area of just 810218 \cdot 10^{-21}. In the following, with the help of Greg Egan, we find a new, smaller universal covering with area less than 0.84411530.8441153. This reduces the area of the previous best universal covering by a whopping 2.21052.2 \cdot 10^{-5}.Comment: 11 pages, 5 jpeg figures, numerical errors correcte

    Critical teaching in classrooms of healing: Struggles and testimonios

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    Using testimonio methodology, this article describes the testimonio and struggle of two Chicanx activist social studies teachers teaching in a large urban high school serving socio-economically poor Latinx students. Both teach critically working to develop their students’ understanding of how their ethnic and community histories contrast with larger historical narratives. Both teach the racism, misogyny, and homophobia rampant in American history by connecting it to the present. They also engage a culturally sustaining pedagogy to give students strength from their cultural inheritance. Each approached this differently, one developing an ethnic studies course, and the second developing a circulo de hombres, and embedding a youth participation action research. Each teacher tackled critical teaching and healing simultaneously from different perspectives yielding a variety of accompanying struggles

    Covariance analysis of the airborne laser ranging system

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    The requirements and limitations of employing an airborne laser ranging system for detecting crustal shifts of the Earth within centimeters over a region of approximately 200 by 400 km are presented. The system consists of an aircraft which flies over a grid of ground deployed retroreflectors, making six passes over the grid at two different altitudes. The retroreflector baseline errors are assumed to result from measurement noise, a priori errors on the aircraft and retroreflector positions, tropospheric refraction, and sensor biases

    Estimation of Kalman filter model parameters from an ensemble of tests

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    A methodology for estimating initial mean and covariance parameters in a Kalman filter model from an ensemble of nonidentical tests is presented. In addition, the problem of estimating time constants and process noise levels is addressed. Practical problems such as developing and validating inertial instrument error models from laboratory test data or developing error models of individual phases of a test are generally considered
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