2,293 research outputs found

    Honk if you love book reviews! Looking back at 10 years of book reviews in The Goose

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    This editorial looks back at 10 years of book reviews in The Goose to consider how book reviews have helped to shape the landscape of Canadian ecocriticism. It also looks forward to suggest how book reviews will continue to be an integral part of The Goose

    The Environmental Humanities in a Post-Truth World

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    Editorial introduction to The Goose Volume 15, Issue 2 (2017)

    Responding to a Racist Climate: An Editorial

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    Editorial introduction to The Goose Volume 16, Issue 1 (2017)

    Editor\u27s Notebook

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    Editorial introduction to The Goose Volume 15, Issue 1 (2016)

    Planar L-Drawings of Directed Graphs

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    We study planar drawings of directed graphs in the L-drawing standard. We provide necessary conditions for the existence of these drawings and show that testing for the existence of a planar L-drawing is an NP-complete problem. Motivated by this result, we focus on upward-planar L-drawings. We show that directed st-graphs admitting an upward- (resp. upward-rightward-) planar L-drawing are exactly those admitting a bitonic (resp. monotonically increasing) st-ordering. We give a linear-time algorithm that computes a bitonic (resp. monotonically increasing) st-ordering of a planar st-graph or reports that there exists none.Comment: Appears in the Proceedings of the 25th International Symposium on Graph Drawing and Network Visualization (GD 2017

    The Partial Visibility Representation Extension Problem

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    For a graph GG, a function ψ\psi is called a \emph{bar visibility representation} of GG when for each vertex vV(G)v \in V(G), ψ(v)\psi(v) is a horizontal line segment (\emph{bar}) and uvE(G)uv \in E(G) iff there is an unobstructed, vertical, ε\varepsilon-wide line of sight between ψ(u)\psi(u) and ψ(v)\psi(v). Graphs admitting such representations are well understood (via simple characterizations) and recognizable in linear time. For a directed graph GG, a bar visibility representation ψ\psi of GG, additionally, puts the bar ψ(u)\psi(u) strictly below the bar ψ(v)\psi(v) for each directed edge (u,v)(u,v) of GG. We study a generalization of the recognition problem where a function ψ\psi' defined on a subset VV' of V(G)V(G) is given and the question is whether there is a bar visibility representation ψ\psi of GG with ψ(v)=ψ(v)\psi(v) = \psi'(v) for every vVv \in V'. We show that for undirected graphs this problem together with closely related problems are \NP-complete, but for certain cases involving directed graphs it is solvable in polynomial time.Comment: Appears in the Proceedings of the 24th International Symposium on Graph Drawing and Network Visualization (GD 2016

    Weather, Weathering, Weathered: Editors\u27 Notebook

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    Editorial introduction to The Goose Volume 17, Issue 1 (2018)

    Editors\u27 Notebook

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    Editorial introduction to The Goose Volume 16, Issue 2 (2018)

    Experimental and Numerical Dynamic Investigation of an ORC System for Waste Heat Recovery Applications in Transportation Sector

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    ORC power units represent a promising technology for the recovery of waste heat in Internal Combustion Engines (ICEs), allowing to reduce emissions while keeping ICE performance close to expectations. However, the intrinsic transient nature of exhaust gases represents a challenge since it leads ORCs to often work in off-design conditions. It then becomes relevant to study their transient response to optimize performance and prevent main components from operating at inadequate conditions. To assess this aspect, an experimental dynamic analysis was carried out on an ORC-based power unit bottomed to a 3 L Diesel ICE. The adoption of a scroll expander and the control of the pump revolution speed allow a wide operability of the ORC. Indeed, the refrigerant mass flow rate can be adapted according to the exhaust gas thermal power availability in order to increase thermal power recovery from exhaust gases. The experimental data confirmed that when the expander speed is not regulated, it is possible to control the cycle maximum pressure by acting on the refrigerant flow rate. The experimental data have also been used to validate a model developed to extend the analysis beyond the experimental operating limits. It was seen that a 30% mass flow rate increase allowed to raise the plant power from 750 W to 830 W

    Monotone Grid Drawings of Planar Graphs

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    A monotone drawing of a planar graph GG is a planar straight-line drawing of GG where a monotone path exists between every pair of vertices of GG in some direction. Recently monotone drawings of planar graphs have been proposed as a new standard for visualizing graphs. A monotone drawing of a planar graph is a monotone grid drawing if every vertex in the drawing is drawn on a grid point. In this paper we study monotone grid drawings of planar graphs in a variable embedding setting. We show that every connected planar graph of nn vertices has a monotone grid drawing on a grid of size O(n)×O(n2)O(n)\times O(n^2), and such a drawing can be found in O(n) time
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