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Documents authored by Wong, Prudence W. H.

Document
DOI: 10.4230/LIPIcs.SEA.2017.32
The Impact of Landscape Sparsification on Modelling and Analysis of the Invasion Process

Authors: Daniyah A. Aloqalaa, Jenny A. Hodgson, and Prudence W. H. Wong

Published in: LIPIcs, Volume 75, 16th International Symposium on Experimental Algorithms (SEA 2017)

Abstract
Climate change is a major threat to species, unless their populations are able to invade and colonise new landscapes of more suitable environment. In this paper, we propose a new model of the invasion process using a tool of landscape network sparsification to efficiently estimate a duration of the process. More specifically, we aim to simplify the structure of large landscapes using the concept of sparsification in order to substantially decrease the time required to compute a good estimate of the invasion time in these landscapes. For this purpose, two different simulation methods have been compared: full and R-local simulations, which are based on the concept of dense and sparse networks, respectively. These two methods are applied to real heterogeneous landscapes in the United Kingdom to compute the total estimated time to invade landscapes. We examine how the duration of the invasion process is affected by different factors, such as dispersal coefficient, landscape quality and landscape size. Extensive evaluations have been carried out, showing that the R-local method approximates the duration of the invasion process to high accuracy using a substantially reduced computation time.
Cite as

Daniyah A. Aloqalaa, Jenny A. Hodgson, and Prudence W. H. Wong. The Impact of Landscape Sparsification on Modelling and Analysis of the Invasion Process. In 16th International Symposium on Experimental Algorithms (SEA 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 75, pp. 32:1-32:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)

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@InProceedings{aloqalaa_et_al:LIPIcs.SEA.2017.32,
  author =	{Aloqalaa, Daniyah A. and Hodgson, Jenny A. and Wong, Prudence W. H.},
  title =	{{The Impact of Landscape Sparsification on Modelling and Analysis of the Invasion Process}},
  booktitle =	{16th International Symposium on Experimental Algorithms (SEA 2017)},
  pages =	{32:1--32:16},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-036-1},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{75},
  editor =	{Iliopoulos, Costas S. and Pissis, Solon P. and Puglisi, Simon J. and Raman, Rajeev},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2017.32},
  URN =		{urn:nbn:de:0030-drops-76160},
  doi =		{10.4230/LIPIcs.SEA.2017.32},
  annote =	{Keywords: Landscape sparsification, invasion process, network sparsification, dense and sparse networks}
}
Document
DOI: 10.4230/LIPIcs.ISAAC.2016.53
Optimal Nonpreemptive Scheduling in a Smart Grid Model

Authors: Fu-Hong Liu, Hsiang-Hsuan Liu, and Prudence W. H. Wong

Published in: LIPIcs, Volume 64, 27th International Symposium on Algorithms and Computation (ISAAC 2016)

Abstract
We study a scheduling problem arising in demand response management in smart grid. Consumers send in power requests with a flexible feasible time interval during which their requests can be served. The grid controller, upon receiving power requests, schedules each request within the specified interval. The electricity cost is measured by a convex function of the load in each timeslot. The objective is to schedule all requests with the minimum total electricity cost. Previous work has studied cases where jobs have unit power requirement and unit duration. We extend the study to arbitrary power requirement and duration, which has been shown to be NP-hard. We give the first online algorithm for the general problem, and prove that the worst case competitive ratio is asymptotically optimal. We also prove that the problem is fixed parameter tractable. Due to space limit, the missing proofs are presented in the full paper.
Cite as

Fu-Hong Liu, Hsiang-Hsuan Liu, and Prudence W. H. Wong. Optimal Nonpreemptive Scheduling in a Smart Grid Model. In 27th International Symposium on Algorithms and Computation (ISAAC 2016). Leibniz International Proceedings in Informatics (LIPIcs), Volume 64, pp. 53:1-53:13, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2016)

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@InProceedings{liu_et_al:LIPIcs.ISAAC.2016.53,
  author =	{Liu, Fu-Hong and Liu, Hsiang-Hsuan and Wong, Prudence W. H.},
  title =	{{Optimal Nonpreemptive Scheduling in a Smart Grid Model}},
  booktitle =	{27th International Symposium on Algorithms and Computation (ISAAC 2016)},
  pages =	{53:1--53:13},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-026-2},
  ISSN =	{1868-8969},
  year =	{2016},
  volume =	{64},
  editor =	{Hong, Seok-Hee},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ISAAC.2016.53},
  URN =		{urn:nbn:de:0030-drops-68252},
  doi =		{10.4230/LIPIcs.ISAAC.2016.53},
  annote =	{Keywords: Scheduling, Smart Grid, Convex function cost, Fixed parameter tractable, Online algorithms, Non-preemptive}
}
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