381 research outputs found
Knuthian Drawings of Series-Parallel Flowcharts
Inspired by a classic paper by Knuth, we revisit the problem of drawing
flowcharts of loop-free algorithms, that is, degree-three series-parallel
digraphs. Our drawing algorithms show that it is possible to produce Knuthian
drawings of degree-three series-parallel digraphs with good aspect ratios and
small numbers of edge bends.Comment: Full versio
Continuous global optimization for protein structure analysis
Optimization methods are a powerful tool in protein structure analysis. In this paper we show that they can be profitably used to solve relevant problems in drug design such as the comparison and recognition of protein binding
sites and the protein-peptide docking. Binding sites recognition is generally based on geometry often combined with physico-chemical properties of the site whereas the search for correct protein-peptide docking is often based on the minimization of an interaction energy model. We show that continuous global optimization methods can be used to solve the above problems and show some computational results
Upward Planar Morphs
We prove that, given two topologically-equivalent upward planar straight-line
drawings of an -vertex directed graph , there always exists a morph
between them such that all the intermediate drawings of the morph are upward
planar and straight-line. Such a morph consists of morphing steps if
is a reduced planar -graph, morphing steps if is a planar
-graph, morphing steps if is a reduced upward planar graph, and
morphing steps if is a general upward planar graph. Further, we
show that morphing steps might be necessary for an upward planar
morph between two topologically-equivalent upward planar straight-line drawings
of an -vertex path.Comment: Appears in the Proceedings of the 26th International Symposium on
Graph Drawing and Network Visualization (GD 2018) The current version is the
extended on
Development of a CFD Procedure for the Axial Thrust Evaluation in Multistage Centrifugal Pumps
One of the most challenging aspects in horizontal pumps design is represented by the evaluation of the axial thrust acting on the rotating shaft. The thrust is affected by pump
characteristics, working conditions and internal pressure fields. Solving this problem is simple for single stage pumps while several complications arise for multistage pumps even in
partially self-balancing opposite impeller configuration. Therefore a systematic approach to the axial thrust evaluation for a multistage horizontal centrifugal pump has been assessed and
validated. The method consists in CFD simulation of each single pump component to obtain correlations which express the axial thrust as a function of the working conditions. The global
axial thrust is finally calculated as balance of the forces acting on each stage. The numerical procedure will be explained and its main results shown and discussed in the present paper
Extending Upward Planar Graph Drawings
In this paper we study the computational complexity of the Upward Planarity
Extension problem, which takes in input an upward planar drawing of
a subgraph of a directed graph and asks whether can be
extended to an upward planar drawing of . Our study fits into the line of
research on the extensibility of partial representations, which has recently
become a mainstream in Graph Drawing.
We show the following results.
First, we prove that the Upward Planarity Extension problem is NP-complete,
even if has a prescribed upward embedding, the vertex set of coincides
with the one of , and contains no edge.
Second, we show that the Upward Planarity Extension problem can be solved in
time if is an -vertex upward planar -graph. This
result improves upon a known -time algorithm, which however applies to
all -vertex single-source upward planar graphs.
Finally, we show how to solve in polynomial time a surprisingly difficult
version of the Upward Planarity Extension problem, in which is a directed
path or cycle with a prescribed upward embedding, contains no edges, and no
two vertices share the same -coordinate in
Finite volume scheme based on cell-vertex reconstructions for anisotropic diffusion problems with discontinuous coefficients
We propose a new second-order finite volume scheme for non-homogeneous and anisotropic diffusion problems based on cell to vertex reconstructions involving minimization of functionals to provide the coefficients of the cell to vertex mapping.
The method handles complex situations such as large preconditioning number diffusion matrices and very distorted meshes.
Numerical examples are provided to show the effectiveness of the method
Artificial co-drivers as a universal enabling technology for future intelligent vehicles and transportation systems
This position paper introduces the concept of artificial “co-drivers” as an enabling technology for future intelligent transportation systems. In Sections I and II, the design principles of co-drivers are introduced and framed within general human–robot interactions. Several contributing theories and technologies are reviewed, specifically those relating to relevant cognitive architectures, human-like sensory-motor strategies, and the emulation theory of cognition. In Sections III and IV, we present the co-driver developed for the EU project interactIVe as an example instantiation of this notion, demonstrating how it conforms to the given guidelines. We also present substantive experimental results and clarify the limitations and performance of the current implementation. In Sections IV and V, we analyze the impact of the co-driver technology. In particular, we identify a range of application fields, showing how it constitutes a universal enabling technology for both smart vehicles and cooperative systems, and naturally sets out a program for future research
Algorithms for Visualizing Phylogenetic Networks
We study the problem of visualizing phylogenetic networks, which are
extensions of the Tree of Life in biology. We use a space filling visualization
method, called DAGmaps, in order to obtain clear visualizations using limited
space. In this paper, we restrict our attention to galled trees and galled
networks and present linear time algorithms for visualizing them as DAGmaps.Comment: Appears in the Proceedings of the 24th International Symposium on
Graph Drawing and Network Visualization (GD 2016
Advances on Testing C-Planarity of Embedded Flat Clustered Graphs
We show a polynomial-time algorithm for testing c-planarity of embedded flat
clustered graphs with at most two vertices per cluster on each face.Comment: Accepted at GD '1
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