16,372 research outputs found

    Upward Three-Dimensional Grid Drawings of Graphs

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    A \emph{three-dimensional grid drawing} of a graph is a placement of the vertices at distinct points with integer coordinates, such that the straight line segments representing the edges do not cross. Our aim is to produce three-dimensional grid drawings with small bounding box volume. We prove that every nn-vertex graph with bounded degeneracy has a three-dimensional grid drawing with O(n3/2)O(n^{3/2}) volume. This is the broadest class of graphs admiting such drawings. A three-dimensional grid drawing of a directed graph is \emph{upward} if every arc points up in the z-direction. We prove that every directed acyclic graph has an upward three-dimensional grid drawing with (n3)(n^3) volume, which is tight for the complete dag. The previous best upper bound was O(n4)O(n^4). Our main result is that every cc-colourable directed acyclic graph (cc constant) has an upward three-dimensional grid drawing with O(n2)O(n^2) volume. This result matches the bound in the undirected case, and improves the best known bound from O(n3)O(n^3) for many classes of directed acyclic graphs, including planar, series parallel, and outerplanar

    The high temperature erosion-corrosion behaviour of industrial thermal sprayed coatings

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    Describes the high temperature erosion-corrosion behaviour of industrial thermal sprayed coatings

    Hybrid bounds for twisted L-functions

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    The aim of this paper is to derive bounds on the critical line Rs 1/2 for L- functions attached to twists f circle times chi of a primitive cusp form f of level N and a primitive character modulo q that break convexity simultaneously in the s and q aspects. If f has trivial nebentypus, it is shown that L(f circle times chi, s) << (N vertical bar s vertical bar q)(epsilon) N-4/5(vertical bar s vertical bar q)(1/2-1/40), where the implied constant depends only on epsilon > 0 and the archimedean parameter of f. To this end, two independent methods are employed to show L(f circle times chi, s) << (N vertical bar s vertical bar q)(epsilon) N-1/2 vertical bar S vertical bar(1/2)q(3/8) and L(g,s) << D-2/3 vertical bar S vertical bar(5/12) for any primitive cusp form g of level D and arbitrary nebentypus (not necessarily a twist f circle times chi of level D vertical bar Nq(2))

    Observer-based offset-free internal model control

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    A linear feedback control structure is proposed that allows internal model control design principles to be applied to unstable and marginally stable plants. The control structure comprises an observer using an augmented plant model, state estimate feedback and disturbance estimate feedback. Conditions are given for both nominal internal stability and offset-free action even in the case of plant-model mismatch. The Youla parameterization is recovered as a limiting case with reduced order observers. The simple design methodology is illustrated for a marginally stable plant with delay

    The erosion of functionally graded coatings under fluidized bed conditions

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    Details the erosion of functionally graded coatings under fluidized bed conditions

    Wetland Management Strategies that Maximize Marsh Bird Use in the Midwest Annual Performance Report Period: 1 July 2015 – 30 June 2016

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    We determined marsh bird use across a wide range of wetland types (e.g., emergent, non-vegetated, riparian), hydrologic regimes (e.g., temporary, seasonal, semi-permanent), management practices (e.g., active, passive, unmanaged), and past disturbance regimes (e.g., natural and restored, impounded and unimpounded) in Illinois during late spring and early summer 2016. Our objectives were to 1) compare marsh bird use of wetland impoundments managed for waterfowl across a continuum of management 3 intensities and strategies to predict how these actions can increase use by both groups, 2) compare marsh bird use of restored and natural wetlands, and 3) determine characteristics of wetlands and the surrounding landscape that influence marsh bird use of restored wetlands. Additionally, we surveyed marsh birds using the standard protocols on wetlands concurrently surveyed within the Illinois Critical Trends Assessment Program (CTAP) for comparison of methodologies.United States Fish and Wildlife Service Contract Number: F14AP00485unpublishednot peer reviewedOpe

    Minimal Brownian Ratchet: An Exactly Solvable Model

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    We develop an exactly-solvable three-state discrete-time minimal Brownian ratchet (MBR), where the transition probabilities between states are asymmetric. By solving the master equations we obtain the steady-state probabilities. Generally the steady-state solution does not display detailed balance, giving rise to an induced directional motion in the MBR. For a reduced two-dimensional parameter space we find the null-curve on which the net current vanishes and detailed balance holds. A system on this curve is said to be balanced. On the null-curve, an additional source of external random noise is introduced to show that a directional motion can be induced under the zero overall driving force. We also indicate the off-balance behavior with biased random noise.Comment: 4 pages, 4 figures, RevTex source, General solution added. To be appeared in Phys. Rev. Let

    Tunable dipolar magnetism in high-spin molecular clusters

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    We report on the Fe17 high-spin molecular cluster and show that this system is an exemplification of nanostructured dipolar magnetism. Each Fe17 molecule, with spin S=35/2 and axial anisotropy as small as D=-0.02K, is the magnetic unit that can be chemically arranged in different packing crystals whilst preserving both spin ground-state and anisotropy. For every configuration, molecular spins are correlated only by dipolar interactions. The ensuing interplay between dipolar energy and anisotropy gives rise to macroscopic behaviors ranging from superparamagnetism to long-range magnetic order at temperatures below 1K.Comment: Replaced with version accepted for publication in Physical Review Letter