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See detailComparison of Machine Learning techniques for atmospheric pollutant monitoring in a Kraft pulp mill
Sainlez, Matthieu UL; Heyen, Georges

Scientific Conference (2011, November)

In this paper, machine learning techniques are compared to predict nitrogen oxide (NOx) pollutant emission from the recovery boiler of a Kraft pulp mill. Starting from a large database of raw process data ... [more ▼]

In this paper, machine learning techniques are compared to predict nitrogen oxide (NOx) pollutant emission from the recovery boiler of a Kraft pulp mill. Starting from a large database of raw process data related to a Kraft recovery boiler, we consider a regression problem in which we are trying to predict the value of a continuous variable. Generalization is done on the worst case configuration possible to make sure the model is adequate: the training period concerns stationary operations while test periods mainly focus on NOx emissions during transient operations. This comparison involves neural network techniques (i.e., static multilayer perceptron and dynamic NARX network), tree-based methods and multiple linear regression. We illustrate the potential of a dynamic neural approach compared to the others in this prediction task. [less ▲]

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See detailA mixed integer linear programming approach to pursuit evasion problems with optional connectivity constraints
Thunberg, Johan UL; Ögren, P.

in Autonomous Robots (2011), 31(4), 333-343

In this paper, we address the multi pursuer version of the pursuit evasion problem in polygonal environments. By discretizing the problem, and applying a Mixed Integer Linear Programming (MILP) framework ... [more ▼]

In this paper, we address the multi pursuer version of the pursuit evasion problem in polygonal environments. By discretizing the problem, and applying a Mixed Integer Linear Programming (MILP) framework, we are able to address problems requiring so-called recontamination and also impose additional constraints, such as connectivity between the pursuers. The proposed MILP formulation is less conservative than solutions based on graph discretizations of the environment, but still somewhat more conservative than the original underlying problem. It is well known that MILPs, as well as multi pursuer pursuit evasion problems, are NP-hard. Therefore we apply an iterative Receding Horizon Control (RHC) scheme where a number of smaller MILPs are solved over shorter planning horizons. The proposed approach is implemented in Matlab/Cplex and illustrated by a number of solved examples. [less ▲]

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See detailDesign and Implementation of a Reliable Distributed Energy Management System
Hoben, Ralf UL

Doctoral thesis (2011)

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See detailEnergieeffizienz neuer Schul-und Bürogebäude in Luxemburg basierend auf Verbrauchsdaten und Simulationen
Thewes, Andreas UL

Doctoral thesis (2011)

In Luxemburg, energy consumption in the building and housing sector has been significantly increasing over the last years. An assessment of the energy saving potential of buildings requires a ... [more ▼]

In Luxemburg, energy consumption in the building and housing sector has been significantly increasing over the last years. An assessment of the energy saving potential of buildings requires a comprehensive data basis with real consumption figures that are not yet available. One focus of this study was to create a priori a detailed energy consumption database for new “School and Administrative Buildings” for Luxembourg. These are both groups cover a major part of the building and housing sector in Luxembourg besides residential buildings. Based on the samples collected, it was able to expand the figures to the entire country using mathematical methods and the medium heat and electricity consumption of these two types of buildings could determined. After collecting some details about each object, it was able to analyze the influence of different parameters, such as building age, size, type, glass fraction etc., on energy consumption using multivariate statistical methods. A posteriori, the results from the database were verified using parameter studies to existing objects and one object still under construction. Based on this, important key parameters relevant for both energy savings and thermal comfort could be found. This knowledge are necessary to understand energy flows within buildings better and, based on this, to be able meeting the nearly zero energy buildings requirements as set out by the EU Directive in the years to come. As conclusion, the central-European climatic zone provides opportunities to design energy-saving office and school buildings (primary energy consumption < 100 kWh/m2a) without mechanical cooling and ventilation systems that still guarantee appropriate degrees of thermal comfort. Unfortunately, the real average primary energy consumption figures of new school (187 kWh/m2a) and office buildings (677 kWh/m2a) in Luxemburg are still significantly higher. [less ▲]

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See detailInfluence of piston position on the scavenging and swirling flow in two-stroke Diesel engines
Obeidat, Anas UL; Haider, S.; Meyer, K.E. et al

in EUROMECH Colloquium 525 - Instabilities and transition in three-dimensional flows with rotation (2011, June 21)

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See detailRobust dynamical network structure reconstruction
Yuan, Ye; Stan, Guy-Bart; Warnick, Stan et al

in Automatica (2011), 47(6),

This paper addresses the problem of network reconstruction from data. Previous work identified necessary and sufficient conditions for network reconstruction of LTI systems, assuming perfect measurements ... [more ▼]

This paper addresses the problem of network reconstruction from data. Previous work identified necessary and sufficient conditions for network reconstruction of LTI systems, assuming perfect measurements (no noise) and perfect system identification. This paper assumes that the conditions for network reconstruction have been met but here we additionally take into account noise and unmodelled dynamics (including nonlinearities). In order to identify the network structure that generated the data, we compute the smallest distances between the measured data and the data that would have been generated by particular network structures. We conclude with biologically inspired network reconstruction examples which include noise and nonlinearities. [less ▲]

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See detailRationalised computational time in fracture simulation: adaptive model reduction and domain decomposition
Goury, Olivier; Kerfriden, Pierre; Margetts, Lee et al

Scientific Conference (2011, June)

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See detailEnriched Element Free Galerkin Method for Gradient Elasticity
Natarajan, S; Kerfriden, P; Bordas, Stéphane UL et al

Scientific Conference (2011, June)

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See detailSimulation of Shear Deformable Plates using Meshless Maximum Entropy Basis Functions
Hale, Jack UL; Baiz, P. M.

Scientific Conference (2011, June)

First-order Shear Deformable Plate Theory (FSDT) is widely used throughout engineering practice to simulate structures with planar dimensions much larger than their thickness. Meshless methods have seen ... [more ▼]

First-order Shear Deformable Plate Theory (FSDT) is widely used throughout engineering practice to simulate structures with planar dimensions much larger than their thickness. Meshless methods have seen use in the literature as a method for discretising the FSDT equations and hold numerous advantages over traditional mesh based techniques. A recent advance in the area of meshless methods are Maximum Entropy approximants (MaxEnt). MaxEnt combines many properties of various prior meshless approximants such as a weak Kronecker-delta property, seamless blending with Delaunay triangulations, high continuity, and convexity. In this work MaxEnt along with other meshless approximants have been implemented in a hybrid object-oriented Python/C++/Fortran computer simulation for the simulation of static deflection, free vibration and linear buckling of FSDT plates. The relative performance and ease of implementation of each of the methods will be discussed. The causes of shear locking along with the merits of various alleviation techniques will be covered, including matching fields method, mixed-variational formulations and construction of higher order polynomial basis via both intrinsic and extrinsic (partition of unity) methods. Convergence results show that MaxEnt provides in most cases similar and in some cases superior behaviour to MLS and RPIM approximants when used to discretise the FSDT equations. [less ▲]

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See detailApproche neuronale dynamique pour la prédiction de polluants atmosphériques: application à l'industrie papetière.
Sainlez, Matthieu UL; Heyen, Georges; Lumen, Philippe

Scientific Conference (2011, May 27)

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See detailDynamic neural network approach for atmospheric pollutant prediction: A pulp mill case study
Sainlez, Matthieu UL

Scientific Conference (2011, May 27)

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See detailGeneric Inference A Unifying Theory for Automated Reasoning
Pouly, Marc UL; Kohlas, Jürg

Book published by John Wiley & Sons (2011)

This book provides a rigorous algebraic study of the most popular inference formalisms with a special focus on their wide application area, showing that all these tasks can be performed by a single ... [more ▼]

This book provides a rigorous algebraic study of the most popular inference formalisms with a special focus on their wide application area, showing that all these tasks can be performed by a single generic inference algorithm. Written by the leading international authority on the topic, it includes an algebraic perspective (study of the valuation algebra framework), an algorithmic perspective (study of the generic inference schemes) and a "practical" perspective (formalisms and applications). Researchers in a number of fields including artificial intelligence, operational research, databases and other areas of computer science; graduate students; and professional programmers of inference methods will benefit from this work. [less ▲]

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See detailDynamic modelling of ground antennas
Breyer, Laurent UL

Doctoral thesis (2011)

Detailed reference viewed: 79 (3 UL)
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See detailNatural frequencies of cracked isotropic & specially orthotropic plates using the extended finite element method
Natarajan, S; Baiz, P; Mahapatra, D Roy et al

Scientific Conference (2011, April)

In this paper, the linear free flexural vibration of cracked isotropic and specially orthotropic plates is studied using the extended finite element method. The mixed interpolation technique of the well ... [more ▼]

In this paper, the linear free flexural vibration of cracked isotropic and specially orthotropic plates is studied using the extended finite element method. The mixed interpolation technique of the well- established MITC4 [1] quadrilateral finite element with 12 standard degrees of freedom per element is used for this study. The natural frequencies of simply supported square plates are computed as a function of crack length and crack location. [less ▲]

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See detailThe circadian oscillator gene GIGANTEA mediates a long-term response of the Arabidopsis thaliana circadian clock to sucrose
Dalchau, Neil; Baek, Seong; Briggs, Helen et al

in PNAS (2011), 108(12), 51045109

Circadian clocks are 24-h timing devices that phase cellular responses; coordinate growth, physiology, and metabolism; and anticipate the day–night cycle. Here we report sensitivity of the Arabidopsis ... [more ▼]

Circadian clocks are 24-h timing devices that phase cellular responses; coordinate growth, physiology, and metabolism; and anticipate the day–night cycle. Here we report sensitivity of the Arabidopsis thaliana circadian oscillator to sucrose, providing evidence that plant metabolism can regulate circadian function. We found that the Arabidopsis circadian system is particularly sensitive to sucrose in the dark. These data suggest that there is a feedback between the molecular components that comprise the circadian oscillator and plant metabolism, with the circadian clock both regulating and being regulated by metabolism. We used also simulations within a three-loop mathematical model of the Arabidopsis circadian oscillator to identify components of the circadian clock sensitive to sucrose. The mathematical studies identified GIGANTEA (GI) as being associatedwith sucrose sensing. Experimental validation of this prediction demonstrated that GI is required for the full response of the circadian clock to sucrose. We demonstrate that GI acts as part of the sucrose-signaling network and propose this role permits metabolic input into circadian timing in Arabidopsis. [less ▲]

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See detailGenetic Algorithm based roadmapping: A method for product innovation
Suzianti, Amalia UL

Doctoral thesis (2011)

Detailed reference viewed: 118 (3 UL)