Context-aware environments: from specification to implementation

Abstract: This paper deals with the problem of implementing a context model for a smart environment. The problem has already been addressed several times using many different data- or problem-driven methods. In order to separate the modelling phase from implementation, we first represent the context model by a network of situations. Then, different implementations can be automatically generated from this context model depending on user needs and underlying perceptual components. Two different implementations are proposed in this paper: a deterministic one based on Petri nets and a probabilistic one based on hidden Markov models. Both implementations are illustrated and applied to real-world problems.     

Investigations of Flow Conditions and Solidification in Continuous Casting Moulds by Advanced Simulation Techniques

Concerning further improvement of product quality in continuous casting, advanced simulation techniques are successfully used to investigate and optimise the complex flow and temperature conditions and the physical phenomena related to them. The work presented here focuses on the mould and discusses the corresponding application of selected mathematical and physical simulation techniques. Transient numerical simulations considering multiphase flow conditions and solidification with mould oscillation provide detailed information on the so‐called solidified hook formation directly below the meniscus. Concerning mould powder performance, the numerical simulation approach is carried out considering the flux flow in the meniscus region in order to obtain information e.g. on the mould powder consumption. With physical model investigations performing simultaneous and time dependent measurements of flow field and mould level behaviour, an optimised SEN design for the thin slab casting could be developed, which allows significantly higher casting velocities and yield, respectively. Operational plant trials confirm these results.     

Hierarchical Protection Tree Scheme for Failure Recovery in Mesh Networks

This paper presents a novel technique for link protection in mesh networks based on the use of hierarchical trees. The hierarchical protection tree (or p-tree) provides hierarchical layering of the network. The straddling links that are not located in the tree are protected through tree branches to higher-layer Parent nodes. The links in the tree are protected by links to backup parent nodes. This scheme offers several advantages such as scalability, failure impact restriction, and distributed processing. We provide a mathematical analysis to compute performance measures for our link protection scheme, and perform restorability analysis for several real and arbitrary long haul networks to compare our scheme to other link protection proposals. Our results demonstrate the applicability of hierarchical p-tree link protection schemes in real long-haul networks.     

100美元，将决定电子书兴衰两重天

作为国内较早接触电子书阅读器的一个用户．从索尼Pocket Edition PRS-300开始，我前后接触的专业电子书产品不下七款。曾经有不少身边的朋友对我随身携带的电子书表示了浓厚的兴趣．但在知道它们最少也要1700元人民币的时候．无一例外地打了退堂鼓。到现在，这些喜欢看书的朋友手中浏览电子书文件的利器基本上多是手机、PDA，NDS和PSP．却没有一个人愿意买下专业的电子书阅读器。深入人心的性价比观念，第一次让我哭笑不得。     

Vulnerability analysis of large concrete dams using the continuum strong discontinuity approach and neural networks

Probabilistic analysis is an emerging field of structural engineering which is very significant in structures of great importance like dams, nuclear reactors etc. In this work a Neural Networks (NN) based Monte Carlo Simulation (MCS) procedure is proposed for the vulnerability analysis of large concrete dams, in conjunction with a non-linear finite element analysis for the prediction of the bearing capacity of the Dam using the Continuum Strong Discontinuity Approach. The use of NN was motivated by the approximate concepts inherent in vulnerability analysis and the time consuming repeated analyses required for MCS. The Rprop algorithm is implemented for training the NN utilizing available information generated from selected non-linear analyses. The trained NN is then used in the context of a MCS procedure to compute the peak load of the structure due to different sets of basic random variables leading to close prediction of the probability of failure. This way it is made possible to obtain rigorous estimates of the probability of failure and the fragility curves for the Scalere (Italy) dam for various predefined damage levels and various flood scenarios. The uncertain properties (modeled as random variables) considered, for both test examples, are the Young’s modulus, the Poisson’s ratio, the tensile strength and the specific fracture energy of the concrete.     

A broad and narrow approach to interactive evolutionary design—An aircraft design example

While interactive evolutionary computation (IEC) is starting to penetrate a larger scientific community, only few researchers have applied IEC to the design of complicated artifacts like machines or transportation systems. The present paper introduces a specific approach to interactive evolutionary computation that breaches the two historical categories of user-defined fitness and selection in each generation (narrow) and occasional user-intervention of an automated evolutionary process to correct the fitness function used for (multi-objective) optimization (broad). To highlight the approach, a real world aircraft design problem is employed that demonstrates the relevance and importance of both features for an effective design process.     

The effects of drying and re‐flooding on nutrient availability in ephemeral deflation basin lakes in western New South Wales,Australia

We examined the response of nutrient concentrations to the drying and re‐flooding of ephemeral deflation basin lakes (EDBL) in western New South Wales, Australia. As lakes dried total nitrogen (TN) and total phosphorus (TP) concentrations increased. TN concentrations increased more quickly and TP concentrations increased more slowly than could be attributed to evaporation alone. This suggested that additional nitrogen was being sequestered from the atmosphere or sediments and that some phosphorus loss to the sediments was occurring. Concentrations of nitrogen oxides (NOx) and filterable reactive phosphorus (FRP), however, declined as lakes dried, suggesting a tighter coupling of nutrient release and uptake mechanisms. Inorganic nutrient concentrations rose sharply in response to re‐flooding in all lakes. Evidence is provided to suggest that post‐flood nutrient pulses are the net result of both riverine inputs and sediment releases and that the relative significance of either may be influenced by regulation. Copyright © 2002 John Wiley & Sons, Ltd.     

Deep- and shallow-water slamming at small and zero deadrise angles

This paper reviews and extends theories for two classes of slamming flows resulting from the violent impact of bodies on half-spaces of inviscid fluid. The two configurations described are the impact of smooth convex bodies, and of non-smooth but flat-bottomed bodies, respectively. In each case, theories are presented first for small penetration depths in finite- or infinite-depth fluids (which we call Wagner flows), and secondly when the penetration is comparable to the fluid depth (which we call Korobkin flows). We also discuss the transition from Wagner flow to Korobkin flow.