976 research outputs found
Bin Packing and Related Problems: General Arc-flow Formulation with Graph Compression
We present an exact method, based on an arc-flow formulation with side
constraints, for solving bin packing and cutting stock problems --- including
multi-constraint variants --- by simply representing all the patterns in a very
compact graph. Our method includes a graph compression algorithm that usually
reduces the size of the underlying graph substantially without weakening the
model. As opposed to our method, which provides strong models, conventional
models are usually highly symmetric and provide very weak lower bounds.
Our formulation is equivalent to Gilmore and Gomory's, thus providing a very
strong linear relaxation. However, instead of using column-generation in an
iterative process, the method constructs a graph, where paths from the source
to the target node represent every valid packing pattern.
The same method, without any problem-specific parameterization, was used to
solve a large variety of instances from several different cutting and packing
problems. In this paper, we deal with vector packing, graph coloring, bin
packing, cutting stock, cardinality constrained bin packing, cutting stock with
cutting knife limitation, cutting stock with binary patterns, bin packing with
conflicts, and cutting stock with binary patterns and forbidden pairs. We
report computational results obtained with many benchmark test data sets, all
of them showing a large advantage of this formulation with respect to the
traditional ones
Do industrial ao pós-industrial: Transição e diversidade urbana - LX/BCN
Nesta comunicação propomos uma discussão focada na transformação da “cidade industrial” para a “cidade pós-industrial”. Baseando-nos numa leitura interdisciplinar, propomos uma reflexão sobre os períodos de transição, como momentos de construção de identidades e oportunidades futuras. Na problemática actual da cidade, o crescimento da escala metropolitana, as distintas formas de organização espacial, social, económica e cultural e a diversidade dos contextos
urbanos emergentes, não permitem traduzir facilmente, num modelo único, a ideia de “cidade pós-industrial”. A instabilidade das mutações da cidade contemporânea manifestase em contextos de incerteza, que levam a questionar o planeamento e geram maio dificuldade no desenho urbano. A inconstância da transição parece trazer, não só aos profissionais do desenho, mas também aos decisores, agentes, actores e aos próprios habitantes, indeterminações, dificuldades de entendimento, de leitura e de aceitação da transformação. Podemos observar estas questões e tensões, patentes no próprio espaço público: nas intervenções, nos discursos produzidos e nos símbolos criados. Concretamente apoiamos a análise em exemplos de transformação pós-industrial: - Na Margem Sul do Tejo, o território expectante de centralidade e protagonismo na antiga Cintura Industrial da Área Metropolitana de Lisboa;
- Em Barcelona, o projecto 22@Barcelona, operação de transformação de usos e regeneração no bairro industrial do Poblenou. Concluímos com a avaliação da diversidade ou heterogeneidade urbana, como conceito e factor estratégico para manter várias possibilidades e alternativas em aberto, nos momentos indefinidos das mutações da cidade e das identidades colectivas. Avançamos uma hipótese de trabalho: no processo de transição podemos trabalhar com a sobreposição de ciclos de transformação (emergentes e decadentes), resultando o processo, menos da substituição ou da dominância dos modelos, e mais da base da adaptabilidade da cidade.In this communication we discuss the transformation of the “industrial city” to the “post-industrial city.” Based on an interdisciplinary approach, we propose a reflection about transition periods - as times of construction of identities and future opportunities. In the contemporary city, the growth of metropolitan scale, different forms of
spatial, social, economic and cultural organization, and the diversity of emerging urban contexts, do not allow to define the idea of “post-industrial city”, in a single model. The instability of the mutations on the contemporary city is manifested in uncertainty contexts, questioning the action of planning and generating difficultiesin urban design. The fickleness of transition seems to carry – to professional designers, decision-makers, agents, actors and even inhabitants - indeterminacies, difficulties in understanding, in reading and accepting change. We can observe these issues and tensions reflected in the public space: in new projects, in the discourses produced and symbols created. Specifically we support the analysis in examples of post-industrial transformation: - On Margem Sul do Tejo (South Bank of Tagus Estuary), a territory expectant for centrality, in the old Industrial belt of Lisbon’s Metropolitan Area; - In Barcelona, 22@Barcelona project, a operation of uses transformation and regeneration of the industrial neighborhood of Poblenou.
We conclude with an assessment of urban diversity or heterogeneity, as a concept and a strategic factor for maintaining multiple possibilities and options open, in
undefined moments of mutations of the city and its collective identities. We present a working hypothesis: in the transition process, we can work with the overlay of
cycles (emerging and declining), there resulting a process of less replacement of models and more adaptable base of the city.En esta comunicación discutimos la transformación que va de la “ciudad industrial” a la “ciudad posindustrial”. Basándonos en una lectura interdisciplinar, proponemos
una reflexión sobre los periodos de transición, como momentos de construcción de identidades y de oportunidades futuras. En la problemática actual de la ciudad, el crecimiento de la escala metropolitana, las distintas formas de organización espacial, social, económica y la diversidad de los contextos urbanos emergentes, no permiten traducir fácilmente, en un único
modelo, la idea de “ciudad posindustrial”. La inestabilidad de las mutaciones de la ciudad contemporánea se manifiesta en contextos de incertidumbre, que cuestionan el planeamiento y generan una mayor dificultad en el diseño urbano. La inconstancia de la transición parece traer - no solo a los profesionales del diseño, sino también a los gestores, agentes, actores y a los propios habitantes - indeterminaciones, dificultades de entendimiento, de lectura y de aceptación de la transformación. Podemos observar estas cuestiones y tensiones, en el propio espacio público: en las intervenciones, en los discursos y en los símbolos creados.
Concretamente suportamos el análisis en ejemplos de transformación posindustrial: - En la Margem Sul do Tejo (orilla Sur del Estuario del Tajo), un territorio expectante de centralidad e protagonismo, en el antiguo cinturón industrial de la Área Metropolitana de Lisboa; - En Barcelona, el proyecto 22@Barcelona, una operación de transformación de usos y regeneración en el barrio industrial del Poblenou.Concluimos con una evaluación de la diversidad o la heterogeneidad urbana, como concepto y factor estratégico para mantener varias posibilidades y alternativas en abierto, en los momentos indefinidos de las mutaciones de la ciudad y de las identidades colectivas. Avanzamos sobre una hipótesis de trabajo: en el proceso de transición podremos trabajar con la superposición de ciclos de transformación (emergentes y decadentes), resultando el proceso, menos de la substitución o de la supremacía de los modelos y más de la base de la adaptabilidad de la ciudad
Lisbon images and 4 metaphisical dissertations on waterfront urban design: vision, move, ethics, and interdisciplinarity.
Representations of urban utopia, so relevant in recent waterfront projects, challenges us before anything else to understand change - the inevitable mutability of cities. Public art, architecture, landscape design and other urban design disciplines that operate the new kind of postindustrial urban projects, must question themselves about their own actions, in the processes of change. Being obvious that i won´t be able to do these things alone, i purpose myself to start with two lines of thought - that certainly will be returned to in the debates, first about city as image and movement, following the two parts of the sentence: The eyes that see // moving cities. After that, a set of thopics on the theory of interdisciplinarity regarding city questions and on the importance of ethics in it, as it is a fact that ethic values draw a significative role in all design cultures, specially when they are concerned with cities, and life in them. To preface it all, the visual cenario of Lisbon’s waterfront, and some short inspirations
Alan Turing : from the need for computation, the Turing machine to computing
Estudo da importância de Alan Turing na Segunda Guerra Mundial, o papel decisivo no avanço da computação, a sua criação abstrata de inteligência artificial. A forma como foi tratado pelas autoridades britânicas. As teorias do seu principal opositor académico: Gödel.Study of the importance of Alan Turing in World War II, the decisive role in the advancement of computing, his abstract creation of artificial intelligence. The way it was handled by the British authorities. The theories of its main academic opponent: Gödel.info:eu-repo/semantics/publishedVersio
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Abstracting information on body area networks
Healthcare is changing, correction...healthcare is in need of change. The population ageing, the increase in chronic and heart diseases and just the increase in population size will overwhelm the current hospital-centric healthcare.
There is a growing interest by individuals to monitor their own physiology. Not only for sport activities, but also to control their own diseases. They are changing from the passive healthcare receiver to a proactive self-healthcare taker. The focus is shifting from hospital centred treatment to a patient-centric healthcare monitoring.
Continuous, everyday, wearable monitoring and actuating is part of this change. In this setting, sensors that monitor the heart, blood pressure, movement, brain activity, dopamine levels, and actuators that pump insulin, “pump” the heart, deliver drugs to specific organs, stimulate the brain are needed as pervasive components in and on the body. They will tend for people’s need of self-monitoring and facilitate healthcare delivery.
These components around a human body that communicate to sense and act in a coordinated fashion make a Body Area Network (BAN). In most cases, and in our view, a central, more powerful component will act as the coordinator of this network. These networks aim to augment the power to monitor the human body and react to problems discovered with this observation. One key advantage of this system is their overarching view of the whole network. That is, the central component can have an understanding of all the monitored signals and correlate them to better evaluate and react to problems. This is the focus of our thesis.
In this document we argue that this multi-parameter correlation of the heterogeneous sensed information is not being handled in BANs. The current view depends exclusively on the applica- tion that is using the network and its understanding of the parameters. This means that every application will oversee the BAN’s heterogeneous resources managing them directly without taking into consideration other applications, their needs and knowledge.
There are several physiological correlations already known by the medical field. Correlating blood pressure and cross sectional area of blood vessels to calculate blood velocity, estimating oxygen delivery from cardiac output and oxygen saturation, are such examples. This knowledge should be available in a BAN and shared by the several applications that make use of the network. This architecture implies a central component that manages the knowledge and the resources. And this is, in our view, missing in BANs.
Our proposal is a middleware layer that abstracts the underlying BAN’s resources to the applica- tion, providing instead an information model to be queried. The model describes the correlations for producing new information that the middleware knows about. Naturally, the raw sensed data is also part of the model. The middleware hides the specificities of the nodes that constitute the BAN, by making available their sensed production. Applications are able to query for information attaching requirements to these requests. The middleware is then responsible for satisfying the requests while optimising the resource usage of the BAN.
Our architecture proposal is divided in two corresponding layers, one that abstracts the nodes’ hardware (hiding node’s particularities) and the information layer that describes information available and how it is correlated. A prototype implementation of the architecture was done to illustrate the concept.This work was partially supported by PhD scholarship SFRH/BD/28843/2006 from Fundação da Ciência e Tecnologia from Portugal
Cloud Computing: Fundamentals
Abstract
Deepening the concept of Cloud Computing, describing
and analyzing the underlying technologies in this concept’s
technological implementation. The relationship of distributed
computing and virtualization with Cloud Computing. The need
for automation in Cloud Computing
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