A Framework for Decision-based Consistencies

International audienceConsistencies are properties of constraint networks that can be enforced by appropriate algorithms to reduce the size of the search space to be explored. Recently, many consistencies built upon taking decisions (most often, variable assignments) and stronger than (general- ized) arc consistency have been introduced. In this paper, our ambition is to present a clear picture of decision-based consistencies. We identify four general classes (or levels) of decision-based consistencies, denoted by S∆φ, E∆φ, B∆φ and D∆φ, study their relationships, and show that known consistencies are particular cases of these classes. Interestingly, this gen- eral framework provides us with a better insight into decision-based con- sistencies, and allows us to derive many new consistencies that can be directly integrated and compared with other ones

Upwelling events, coastal offshore exchange, links to biogeochemical processes - Highlights from the Baltic Sea Sciences Congress at Rostock University, Germany, 19-22 March 2007

The Baltic Sea Science Congress was held at Rostock University, Germany, from 19 to 22 March 2007. In the session entitled"Upwelling events, coastal offshore exchange, links to biogeochemical processes" 20 presentations were given,including 7 talks and 13 posters related to the theme of the session.This paper summarises new findings of the upwelling-related studies reported in the session. It deals with investigationsbased on the use of in situ and remote sensing measurements as well as numerical modelling tools. The biogeochemicalimplications of upwelling are also discussed.Our knowledge of the fine structure and dynamic considerations of upwelling has increased in recent decades with the advent ofhigh-resolution modern measurement techniques and modelling studies. The forcing and the overall structure, duration and intensity ofupwelling events are understood quite well. However, the quantification of related transports and the contribution to the overall mixingof upwelling requires further research. Furthermore, our knowledge of the links between upwelling and biogeochemical processes is stillincomplete. Numerical modelling has advanced to the extent that horizontal resolutions of c. 0.5 nautical miles can now be applied,which allows the complete spectrum of meso-scale features to be described. Even the development of filaments can be describedrealistically in comparison with high-resolution satellite data.But the effect of upwelling at a basin scale and possible changes under changing climatic conditions remain open questions

Multi-objective optimization of regenerator placement using Constraint Programming

In translucent optical networks, connections bypass most intermediate nodes transparently. However, their signal quality is affected by the traveled distance and/or the bypass operations. Hence, they might require optical-electrical-optical conversions at some intermediate nodes, in order to regenerate the carried signal. In this paper, we evaluate several approaches to deal with connection routing and regenerator placement within a translucent network. We present our Constraint Programming based multi-objective optimization model which accepts three criteria: total routing cost, total number of regeneration operations, and number of nodes performing regeneration. Our results show that this approach provides solutions in a reasonable running time for problem instances of practical interest. We discuss our method in the context of the state-of-the-art and show that optimization based on one criterion only misses the possibility to improve the solution in respect to the other aspects. © 2011 IFIP

Compass gait mechanics account for top walking speeds in ducks and humans

The constraints to maximum walking speed and the underlying cause of the walk-run transition remains controversial. However, the motions of the body and legs can be reduced to a few mechanical principles, which, if valid, impose simple physics-based limits to walking speed. Bipedal walking may be viewed as a vaulting gait, with the centre of mass (CoM) passing over a stiff stance leg (an 'inverted pendulum'), while the swing leg swings forward (as a pendulum). At its simplest, this forms a. compass gait' walker, which has a maximum walking speed constrained by simple mechanics: walk too fast, or with too high a step length, and gravity fails to keep the stance foot attached to the floor. But how useful is such an extremely reductionist model? In the present study, we report measurements on a range of duck breeds as example unspecialized, non-planar, crouch-limbed walkers and contrast these findings with previous measurements on humans, using the theoretical framework of compass gait walking. Ducks walked as inverted pendulums with near-passive swing legs up to relative velocities around 0.5, remarkably consistent with the theoretical model. By contrast, top walking speeds in humans cannot be achieved with passive swing legs: humans, while still constrained by compass gait mechanics, extend their envelope of walking speeds by using relatively high step frequencies. Therefore, the capacity to drive the swing leg forward by walking humans may be a specialization for walking, allowing near-passive vaulting of the CoM at walking speeds 4/3 that possible with a passive (duck-like) swing leg

Barred galaxies : Stars and Bars

‘The definitive version is available at www.blackwell-synergy.com '. Copyright Blackwell Publishing. DOI: 10.1111/j.1468-4004.2005.46628.x [Full text of this article is not available in the UHRA]Bars are prominent features that occur in most disc galaxies and have important dynamical effects on their hosts. This paper describes some of the known properties of bars, illustrating the discussion with images that show the beauty of the galaxies under consideration. The focus of this article is on the evolution of bars and on their influence on the redistribution of matter within galaxies. In this way, bars drive the internal, or secular, evolution of galaxies.Peer reviewe

On the Application of Modified Active Sorbents to Dry Flue Gas Desulphurization (FGD)

The study reported involvedlaboratory tests and full - scale investigations into some modified sorbents,which had been prepared on the basis of fly ash from pulverized- fuel boilers (combined with a dry FGD system)and fluidized-bed boilers.The processesline for the production of such sorbents is described.The utilization of fly ash for such purpose has two major advantages-it yields a high-efficiency sorbent and, at the same time,enables of a troublesome boiler waste containing eluable calcium compounds(CaO and CaSO4)ateluate concentrations which exceed th

The scope and conditions of using coal-water suspensions

W  ostatnich latach rośnie zainteresowanie produkcją i  stosowaniem suspensji węglowo-wodnej do opalania kotłów i pieców, jako zamiennika olejów opałowych i  gazu ziemnego oraz węgla. Działania te mają na celu obniżenie kosztów wytwarzania energii, a  w  przypadku zastępowania węgla obniżenie emisji zanieczyszczeń do środowiska. Przedstawiony materiał omawia wyniki badań i  prób nad opracowaniem przemysłowej technologii produkcji suspensji wę- glowo-wodnej. Opracowana technologia, w  porównaniu do powszechnie stosowanych, charakteryzuje się niższymi kosztami wytwarzania suspensji i  prostszym procesem. Właściwości otrzymywanych suspensji zależą od wielu czynników w tym, od jakości zastosowanego węgla, zawartości i stopnia mikronizacji węgla, sposobu mikronizacji i  homogenizacji oraz warunków ich magazynowania. Dla oceny jakości suspensji węglowo-wodnych jako paliwa, najważniejszymi parametrami są: zawartości zmikronizowanego węgla, lepkość, wartość opa- łowa, zapopielenie i  zawartości siarki oraz stabilność zawiesiny. Następnym etapem, prowadzącym do wdrożenia suspensji do opalania kotłów i pieców jest przeprowadzenie prób spalania na wytypowanych obiektach dla ustalenie zakresu ich adaptacji do nowego paliwa oraz weryfikacji zakładanych efektów ekonomicznych i ekologicznych.In recent years, there can be observed a growing interest in production and application of the coal-water suspensions for combustion in furnaces and boilers as the substitutes for fuel oil, natural gas and coal. These activities aim at reducing cost of energy generation and in case of substitution of coal – also at reducing the emissions of the pollutants to the environment. The paper presents the results of tests and trials on the development of the industrial technology for production of the coal-water suspension. This technology, in comparison with the commonly used ones, is characterized by lower costs of suspension production and a simpler process flow. The properties of the obtained suspensions depend on many factors such as quality of the used coal, the content and level of coal micronization, the method of micronization and homogenization and the conditions of suspension storage. For evaluating the quality of a coal-water suspension as a fuel the most important parameters are: coal content, viscosity, calorific value, ash and sulfur content, slurry stability. The next phase leading to the application of the slurries for combustion in furnaces and boilers is conducting combustion trials at selected sites what will help in determining the possibilities of their adaptation to the new fuel, as well as in verifying the assumed economic and environmental effects