37 research outputs found
OTIMIZAÇÃO EM ESPORTES: PROGRAMAÇÃO DE TABELAS E PROBLEMAS DE CLASSIFICAÇÃO
No full textO planejamento e a gestão de atividades esportivas é uma
área promissora e pouco explorada para aplicações de
Pesquisa Operacional. Os problemas nesta área são em geral
de formulação simples e alcançam grande difusão nos meios
de comunicação. Embora sua formulação seja simples, em
geral estes problemas são difíceis de serem resolvidos em
termos computacionais. Os resultados de muitos trabalhos
acadêmicos nesta área têm sido aceitos como soluções para
problemas reais e várias soluções vem sendo implementadas
na prática. Esta tese tem como objetivo principal estudar
dois tipos de problemas que surgem na área de esportes: a
programação de tabelas e os problemas da classificação. A
programação de tabelas para competições esportivas é uma
tarefa difícil, na qual diversas técnicas de otimização
combinatória têm sido aplicadas. Nesta tese, formula-se o
Problema do Torneio com Viagens Espelhado como um problema
de otimização em grafos. O problema é resolvido utilizando-
se algoritmos aproximados. Apresentam-se duas heurísticas
para este problema. A primeira é muito rápida e serve para
fornecer soluções iniciais para a segunda, que é capaz de
obter soluções de boa qualidade em tempos razoáveis. São
deduzidos limites duais para um tipo particular de
instâncias. Estes limites permitem provar a otimalidade
das soluções obtidas heuristicamente para instâncias muito
maiores do que as maiores instâncias resolvidas na
literatura. Por ultimo, é apresentado um modelo de
programação linear inteira para o problema, ao qual são
acrescentadas desigualdades válidas. Os problemas da
classificação visam obter condições, necessárias e
suficientes, para a classificação de uma determinada
equipe para as finais de um campeonato em relação ao
número de pontos a ser obtido. São apresentados modelos de
programação linear inteira que permitem resolver estes
problemas no contexto do Campeonato Brasileiro de Futebol.Sports management is a very attractive and not very
explored area for applications of Operations Research.
Problems in this area use to have simple formulations and
reach a big coveragge by the media. Although their
formulations are simple, in general these problems are
difficult to be solved in computational terms. The results
of many academic works in this area have been accepted as
solutions for real problems and some solutions are being
implemented.
This thesis has the main objective of studying two types
of problems that appear in the sports area: the fixture
creation and the qualification problems.
Fixture creation (also known as sport scheduling) for
sport competitions is a difficult task, in which several
combinatorial optimization techniques has been applied. In
this thesis, the Mirrored Traveling Tournament Problem is
formulated as a graph optmization problem. The problem is
solved using approximation algorithms. Two heuristics are
introduced for this problem. The first one is very fast
and is used to supply initial solutions for the second one
which is able to obtain high quality solutions in
reasonable computation times. Dual limits are deduced for
a particular type of instances. These limits allow to
prove the optimality of the heuristically abtained
solutions for instances that are much bigger than those
soved in the literature. Finally, an integer programming
model is introduced in wich valid inequalities are added.
The qualification problems aim to obtain necessary and
sufficient conditions for the playoffs qualification of a
given team in terms of the number of points to be
obtained. Integer programming models are introduced which
allow solving these problems in the context of the
Brazilian Football Championship
Using the N/C ratio to correct bulk radiocarbon ages from lake sediments : insights from Chilean Patagonia
No full textAuthor Posting. © The Author(s), 2012. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Quaternary Geochronology 12 (2012): 23-29, doi:10.1016/j.quageo.2012.06.003.The offset between AMS radiocarbon ages obtained on bulk lake sediments and the true age of deposition was evaluated at four sites in Northern Chilean Patagonia. Our results show that the bulk radiocarbon ages are systematically older by 300 to 1100 years. In this region free of carbonate and carbonaceous rocks, we argue that this difference results from variable inputs of terrestrial organic carbon from the Holocene soils that cover the lake watersheds. For the four studied lakes, the age offset is clearly related to the fraction of terrestrial carbon preserved in the lake sediments, which was estimated using the N/C ratio of the bulk organic matter. We propose that N/C measurements can be used to significantly improve chronologies based on radiocarbon dating of bulk lake sediments.This research was partly funded by Fondecyt grant #1070508 to R. Urrutia, by FNRS grant R.FNRS.1360 and ULg grant R.CFRA.1060 to N. Fagel, and by an EU FP6 Marie Curie Outgoing Fellowship to S. Bertrand
Improved enumeration of simple topological graphs
No full textA simple topological graph T = (V (T ), E(T )) is a drawing of a graph in the plane where every two edges have at most one common point (an endpoint or a crossing) and no three edges pass through a single crossing. Topological graphs G and H are isomorphic if H can be obtained from G by a homeomorphism of the sphere, and weakly isomorphic if G and H have
the same set of pairs of crossing edges. We generalize results of Pach and Tóth and the author's previous results on counting different drawings of a graph under both notions of isomorphism. We prove that for every graph G with n vertices, m edges and no isolated vertices the number of weak isomorphism classes of simple topological graphs that realize G is at most 2
O(n2log(m/n)), and at most 2O(mn1/2 log n) if m ≤ n 3/2. As a consequence we obtain a new upper bound 2 O(n3/2 log n) on the number of intersection
graphs of n pseudosegments. We improve the upper bound on the number of weak isomorphism classes of simple complete topological graphs with n vertices to 2n2 ·α(n) O(1), using an upper bound on the size of a set of permutations with bounded VC-dimension recently proved by Cibulka and the author. We show that the number of isomorphism classes of simple topological graphs that realize G is at most 2 m2+O(mn) and at least 2
Ω(m2) for graphs with m > (6 + ε)n.Graph Drawings and Representations, EuroGIGA ProjectCentre Interfacultaire Bernoull
On the nonexistence of k-reptile simplices in R3 and R4
No full textA d-dimensional simplex S is called a k-reptile (or a k-reptile simplex) if it can be tiled without overlaps by k simplices with disjoint interiors that are all mutually congruent and similar to S. For d=2, triangular k-reptiles exist for many values of k and they have been completely characterized by Snover, Waiveris, and Williams. On the other hand, the only k-reptile simplices that are known for d≥3, have k=m d, where m is a positive integer. We substantially simplify the proof by Matoušek and the second author that for d=3, k-reptile tetrahedra can exist only for k=m 3. We also prove a weaker analogue of this result for d=4 by showing that four-dimensional k-reptile simplices can exist only for k=m 2.Czech Science FoundationCentre Interfacultaire BernoulliSwiss National Science Foundatio
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Health and well-being in prison design ::a theory of prison systems and a framework for evolution /
No full text"This book establishes a new framework for prison design to promote the health and well-being of all prison users. Based on international research in Europe and America, and drawing on the expertise of key international advisors, this book uniquely reveals the perspectives of both designers and prison authorities concerning well-being in prison architecture. It is the first book to compare perspectives between prison models while providing essential guidance for the design of prison environments to promote the rehabilitation of inmates and their desistance from crime. The promotion of health and well-being of people in prison is vital to enable rehabilitation and traditional prison architecture severely weakens both rehabilitation efforts and opportunities for desistance, but only a handful of prison systems in the world have shown significant changes in their prison designs. Underpinned by Critical Realism and the PERMA theory of well-being, this book reveals significant new insights to inform prison design. The author presents international case-study research with interviews of prison authorities and designers from four countries and the three different prison models, as well as key international United Nations advisors. It contrasts for the first time the visions of prison designers and prison authorities, bringing a new synthesised understanding of the differences and similarities in their approach to the health and well-being of both inmates and staff from which to generate a new framework for design considerations. This book illuminates new directions for prison design and is essential reading for policymakers, academics and students involved in the study and development of criminology, corrections, and penology. It is also an indispensable source of up-to-date knowledge for prison authorities, public health officials, architects and designers involved in the design of prisons and any other type of coercive detention facilities"-
Estudio de la tendencia de caudales mínimos, medios y máximos del rio Patía del departamento de Nariño
No full textEsta investigación tiene el estudio de la tendencia de caudales del rio Patía en el departamento de Nariño, localizada en la región pacifico colombiana. En la primera etapa del estudio se verifico la consistencia de los datos de caudales de las estaciones seleccionadas del rio Patía del departamento de Nariño proporcionadas por el Instituto de Hidrología, Meteorología y Estudios Ambientales de Colombia; posteriormente en la segunda etapa se estableció y analizo la tendencia de caudales máximos, medios y mínimos por medio de graficas de datos mensuales y anuales por estación limnímetrica o limnígrafica . En la tercera fase se establece la tendencia de caudales por medio del método de medias móviles obtenidas por los valores anuales pertinentes de cada estación logrando resultados gráficos. Por último la cuarta fase se relaciona la tendencia de las precipitaciones totales anuales en milímetros de las estaciones cercanas al rio, con la tendencia de caudales analizados. Este estudio es de vital importancia en el área hidrológica, ya que permite dar una posible visión de los niveles de los caudales del rio Patía en sus niveles mínimos, medios y máximos. Para obtener valores verdaderos a mediano plazo se tendrán en cuenta en la presente investigación la afectación de fenómenos climáticos, sin olvidar la importancia de comprender la dinámica de los fluidos en estas cuencas hidrográficas, para mejorar la navegabilidad y poblar algunos sectores que se encuentran sin ser aprovechados
BALANCE OF PAYMENTS CRISES UNDER FIXED EXCHANGE RATE IN COLOMBIA: 1938-1967
No full textBetween 1938 and 1967, including the Bretton Woods period after 1947, Colombia pegged its currency to the dollar. Although the exchange rate was fixed, the peso was devaluated more than 12% on six occasions. The devaluation episodes were complex, traumatic, highly politicized and had costly macroeconomic effects. The Bretton Woods agreement stated that countries could only devalue their exchange rate in the presence of fundamental imbalances driven, for example, by structural terms of trade deterioration. However, this paper states that in Colombia, the imbalance in the money market was a key factor in explaining the exchange rate crises during the period. The paper is organized as follows: first, a simple theoretical model of a small open economy with imperfect capital mobility is described in order to examine the possible causes of nominal devaluations; second, a narrative approach is used to describe the economic circumstances that surrounded each of the devaluation episodes; finally, a set of econometric tests are used in order to identify the key variables behind the macroeconomic imbalances that preceded each exchange rate crisis. The results show that the external imbalances were mainly associated with the imbalances in the money market. Terms of trade deterioration account for just a small part of current account crisesBretton Woods, Devaluation, Fixed Exchange Rate Regime, Monetary Policy
