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See detailOn-Line Measurement Validation and Performance Monitoring Using Robust Kalman Filtering Techniques
Dewallef, Pierre ULg; Léonard, Olivier ULg

in 5th European Conference on Turbomachinery - Fluid Dynamics and Thermodynamics - Conference Proceedings (2003, March)

In an on-line engine performance monitoring, two tasks must be simultaneously carried out: an on-line engine health parameter estimation and an on-line engine state variables estimation. Estimation of the ... [more ▼]

In an on-line engine performance monitoring, two tasks must be simultaneously carried out: an on-line engine health parameter estimation and an on-line engine state variables estimation. Estimation of the state variables constitutes a general application of the Extended Kalman Filter theory, while the health parameter estimation is a classical recurrent regression problem. Recent advances show that both problems can be solved by two Kalman filters working jointly. Such filters are usually named Dual Kalman Filters. The present contribution aims at using a modified dual Kalman filter to provide robustness. This procedure should be able to cope with as much as 20 to 30% of faulty data. The resulting on-line validation method has been applied to a turbofan model developed in the frame of the OBIDICOTE 1 project. Several tests have been carried out to check the performance monitoring capability and the robustness that can be achieved [less ▲]

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See detailOn-Line Performance Monitoring and Engine Diagnostic Using Robust Kalman Filtering Techniques
Dewallef, Pierre ULg; Léonard, Olivier ULg

in Proceedings of the ASME Turbo Expo 2003 (2003, June)

In this contribution, an on-line engine performance monitoring is carried out through an engine health parameter estimation based on several gas path measurements. This health parameter estimation makes ... [more ▼]

In this contribution, an on-line engine performance monitoring is carried out through an engine health parameter estimation based on several gas path measurements. This health parameter estimation makes use of the analytical redundancy of an engine model and therefore implies the knowledge of the engine state. As the latter is a priori not known the second task is therefore an engine state variable estimation. State variables here designate working conditions such as inlet temperature, pressure, Mach number, rotational speeds, . . . Estimation of the state variables constitutes a general application of the Extended Kalman Filter theory, while the health parameter estimation is a classical recurrent regression problem. Recent advances in stochastic methods [1] show that both problems can be solved by two Kalman filters working jointly. Such filters are usually named Dual Kalman Filters. The present contribution aims at using a dual Kalman filter modified to provide robustness. This procedure should be able to cope with as much as 20 to 30% of faulty data. The resulting online method is applied to a turbofan model developed in the frame of the OBIDICOTE 1 project. Several tests are carried out to check the performance monitoring capability and the robustness that can be achieved. [less ▲]

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See detailOn-line prediction of technological and organoleptic properties of beef by near infrared spectroscopy
Dotreppe, Olivier ULg; Lambotte, Sébastien; Leroy, Bernadette ULg et al

in Proceedings of the 48th International Congress of Meat Science and Technology (2002)

The aim of this study was to investigate the use of the NIR spectroscopy for on-line prediction of technological and organoleptic properties of beef in slaughterhouse. In this work, two different fibre ... [more ▼]

The aim of this study was to investigate the use of the NIR spectroscopy for on-line prediction of technological and organoleptic properties of beef in slaughterhouse. In this work, two different fibre optic probes - transmission and reflection - were compared. It can be concluded from this experiment when applied on-line that when applied on-line the NIR spectroscopy prediction of several meat quality parameters can be at less equal to those obtained directly on meat samples in the laboratory. Nevertheless, the performances varied according to the acquisition mode: the reflection and the transmission showing potentialities for prediction of colour and drip loss respectively. Before direct application on slaughterline for early meat quality prediction, the technique needs further adaptations in order to reduce the time of spectra acquisition and treatment. [less ▲]

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See detailOn-line profiling of Escherichia coli stress response
Brognaux, Alison ULg; Shanshan, Han; Sorensen, Soren et al

in Communications in Agricultural and Applied Biological Sciences (2013)

Detailed reference viewed: 57 (29 ULg)
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See detailOn-Line Rectification of Sport Sequences with Moving Cameras
Hayet, Jean-Bernard; Piater, Justus ULg

in Mexican International Conference on Artificial Intelligence (2007)

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See detailOn-line respiratory mechanic monitoring in newborns: reproducibility and effect of ventilatory mode
Rigo, Vincent ULg; Rigo, Jacques ULg

in Archives of Disease in Childhood (2008, November), 93(suppl II), 483

Objectives: Neonatal ventilator softwares provide information on respiratory mechanics (RM). Integration of those values with clinical variables could improve ventilation management. We investigated ... [more ▼]

Objectives: Neonatal ventilator softwares provide information on respiratory mechanics (RM). Integration of those values with clinical variables could improve ventilation management. We investigated accuracy and reproducibility of those variables in Assist Control (AC) and Synchronised Intermittent Mandatory Ventilation (SIMV) modes. [less ▲]

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See detailOn-line respiratory mechanics in newborns: stability and effect of ventilatory mode.
Rigo, Vincent ULg; Rigo, Jacques ULg

in Berger, Th. (Ed.) 9th EPNV Final Program and Abstracts (2008, April 11)

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See detailOn-Line Sample Preparation for the Measurement of Selected POPs in Food
Focant, Jean-François ULg

Scientific conference (2007, May)

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See detailOn-line Simultaneous Learning and Tracking of Visual Feature Graphs
Declercq, Arnaud ULg; Piater, Justus ULg

in 2007 IEEE Conference on Computer Vision and Pattern Recognition (CVPR07) (2007)

Model learning and tracking are two important topics in computer vision. While there are many applications where one of them is used to support the other, there are currently only few where both aid each ... [more ▼]

Model learning and tracking are two important topics in computer vision. While there are many applications where one of them is used to support the other, there are currently only few where both aid each other simultaneously. In this work, we seek to incrementally learn a graphical model from tracking and to simultaneously use whatever has been learned to improve the tracking in the next frames. The main problem encountered in this situation is that the current intermediate model may be inconsistent with future observations, creating a bias in the tracking results. We propose an uncertain model that explicitly accounts for such uncertainties by representing relations by an appropriately weighted sum of informative (parametric) and uninformative (uniform) components. The method is completely unsupervised and operates in real time. [less ▲]

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See detailOn-line soil mechanical resistance mapping and correlation with soil physical properties for precision agriculture
Sirjacobs, Damien ULg; Hanquet, Bernard; Lebeau, Frédéric ULg et al

in Soil & Tillage Research (2002), 64

Measurement of local soil strength may be used for real time regulation of tillage parameters in precision agriculture. Cartography of soil physical properties will also facilitate the study of their ... [more ▼]

Measurement of local soil strength may be used for real time regulation of tillage parameters in precision agriculture. Cartography of soil physical properties will also facilitate the study of their influence on plant development and yields. The aim of this research was to develop and test in field conditions a sensor measuring on-line soil strength variations. The sensor was constituted of a thin blade pulled in the soil at constant depth and speed and a beam which transferred the soil–blade forces to a transducer fixed on the machine. This transducer measured the draft force (Fx), the vertical force (Fz) and the moment (My). A field experiment was performed in 2 ha field of silt soil (Hesbaye, Belgium). A soil strength map of the field was established by pulling the sensor at 5 m interline separation by a tractor equipped with a DGPS receiver. The relationship between the recorded forces and several soil physical parameters was studied by identifying 10 control plots on the sensor track. In each of them, cone index penetrometry profiles and soil water content were measured. Soil samples were taken in the centre of the plots to determine cohesion and internal friction angle, simple compression resistance, Atterberg limits, granulometry and pF curves. Triaxial tests identified over-consolidated soils in plots situated in the pounds of the field. Based on the parameters measured in the other plots, significant relationships were established between (1) a global penetrometry index and the Fx and My solicitations measured by the sensor; (2) gravimetric water content and the vertical force Fz. Interpolation by inverse distance with a range of 45 m gave the best result for the cartography of the three measured signals (Fx, Fz and My). The confrontation of those maps with pedological and topographic maps together with the statistical relationships and the farmer’s knowledge of the field showed high consistency. The results of this experiment in field conditions are encouraging and show the promising perspective of technological innovations allowing on-line characterisation of soil physical state for precision agriculture. [less ▲]

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See detailOn-line stability and dynamic security assessment of electric power systems
Ribbens-Pavella, Mania; Van Cutsem, Thierry ULg; Rousseaux, Patricia ULg

in Proceedings of the IFAC Symposium on Planning and Operation of Electric Energy Systems (1985)

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See detailOn-Line Transient Engine Diagnostics in a Kalman Filtering Framework
Borguet, Sébastien ULg; Dewallef, Pierre ULg; Léonard, Olivier ULg

in Proceedings of the ASME Turbo Expo 2005 (2005, June)

A common assumption made in the performance assessment of a turbine engine for aircraft propulsion consists in restricting the data processing to steady-state data. This especially holds for on-board ... [more ▼]

A common assumption made in the performance assessment of a turbine engine for aircraft propulsion consists in restricting the data processing to steady-state data. This especially holds for on-board performance monitoring of a commercial aircraft which spends up to 90% of the time in cruise flight where such conditions are satisfied. The present contribution is intended to investigate the ability of a diagnosis method to process unsteady data rather than steady-state data. The aim of this unsteady approach is to strongly reduce the time and the efforts spent to obtain a reliable diagnosis. In order to assess the improvements in terms of diagnosis efficiency and engine operability, the resulting diagnostic method is tested for different degradations that can be expected on commercial turbofans. The results are also compared to those obtained from cruise flight steady-state data in order to balance the two approaches. [less ▲]

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See detailOn-line transient stability constrained ATC calculations
Avilas-Rosales, R.; Ruiz-Vega, Daniel; Ernst, Damien ULg et al

in Proceedings of the IEEE Power Engineering Society Summer Meeting 2000 - Volume 2 (2000)

Transient Stability Assessment, preventive control measures and dynamic A X calculations are addressed for the new deregulated EMS system. The combination of time domain analysis, SIME and Optimal Power ... [more ▼]

Transient Stability Assessment, preventive control measures and dynamic A X calculations are addressed for the new deregulated EMS system. The combination of time domain analysis, SIME and Optimal Power Flow provide a reliable solution for future transaction requirements and the current operating point. [less ▲]

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See detailOn-Line Validation of Measurements on Jet Engines Using Automatic Learning Methods
Dewallef, Pierre ULg; Léonard, Olivier ULg

in Proceedings od the 15th ISABE Conference (2001)

Nowadays, turbine engine tests are processed using an open loop, i.e. the measurements are verified and treated a posteriori, sometimes weeks or months after the end of the test. The purpose of the ... [more ▼]

Nowadays, turbine engine tests are processed using an open loop, i.e. the measurements are verified and treated a posteriori, sometimes weeks or months after the end of the test. The purpose of the present project is to develop a new methodology which enables real time detection of faulty measurements and the suppression of the source of these faults during the test. The validation of the measurements is achieved by a “robust” parameter identification [1]. Such a method is called robust in the sense that it can cope with 20 to 30% of faulty measurements. The robustness is insured by a distribution of the measurement noise, as introduced by Huber [7, 8], that takes into account the possibility of faults. The purpose of a parameter identification is to find the set of parameters which has most likely generated the measurements observed on the process. This leads to an optimisation problem that has to be solved for the parameters. The measurements are linked to the parameters through a non-linear model, leading to a large system of equations for modern jet engines. If no physical model of the process can be made available or if this model is too complex to allow real time validation, automatic learning methods may provide a solution: • either a mathematical representation is generated, directly based on the measurements (online learning), • or a database is first generated, based on the existing (but expensive) physical model, the database being subsequently used to build a statistical model (off-line learning). Neural networks seem to be very suitable for modeling the behavior of turbojets, avoiding the resolution of a time-consuming non-linear system. In this paper neural networks are tested to generate a mathematical representation of a single flow, single spool and variable geometry nozzle turbojet, from a data base of “measurements” generated by a physical model of the engine. Only the off-line learning approach is considered. [less ▲]

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See detailOn-line voltage security assessment
Vournas, Costas; Van Cutsem, Thierry ULg

in Savulescu, Savu (Ed.) Real-time stability in power systems: Techniques for the early detection of the risk of blackout (2006)

This chapter deals with voltage security assessment and its on-line application. Methods for contingency analysis are briefly reviewed. The associated con-cepts of transfer capability, loadability limit ... [more ▼]

This chapter deals with voltage security assessment and its on-line application. Methods for contingency analysis are briefly reviewed. The associated con-cepts of transfer capability, loadability limit, and secure operation margin are explored in some detail. Methods for preventive security control are outlined. An application of on-line VSA in the control center of a real system is then de-scribed and typical results available to operators are presented. [less ▲]

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See detailOn-Line Voltage Security Assessment of the Hellenic Interconnected System
Vournas, Costas; Manos, George; Kabouris, John et al

(2003, June 26)

This paper describes the on-line Voltage Security Assessment environment developed within the framework of the EU-sponsored OMASES project, as well as its application to the Greek Interconnected Power ... [more ▼]

This paper describes the on-line Voltage Security Assessment environment developed within the framework of the EU-sponsored OMASES project, as well as its application to the Greek Interconnected Power System. The heart of all computations is a fast time-domain method. Security is analyzed with respect to power transfers in critical corridors or power consumption in load areas. Results take on the form of either precontingency secure operation limits, or post-contingency loadability limits, together with various diagnosis tips. Typical results obtained during the test phase of the project are reported. [less ▲]

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See detailOn-site follow up of the characterisitics of controlled backfill, using the Time Domain Reflectometry moisture-measurement method.
Gille, A.; Geerts, G.; Mella, J.-P. et al

Conference (2003, June)

Detailed reference viewed: 8 (4 ULg)
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See detailOn-the-fly domain adaptation of binary classifiers
Pierard, Sébastien ULg; Marcos Alvarez, Alejandro ULg; Lejeune, Antoine ULg et al

in 23rd Belgian-Dutch Conference on Machine Learning (BENELEARN) (2014, June 06)

This work considers the on-the-fly domain adaptation of supervised binary classifiers, learned off-line, in order to adapt them to a target context. The probability density functions associated to ... [more ▼]

This work considers the on-the-fly domain adaptation of supervised binary classifiers, learned off-line, in order to adapt them to a target context. The probability density functions associated to negative and positive classes are supposed to be mixtures of the source distributions. Moreover, the mixture weights and the priors are only available at runtime. We present a theoretical solution to this problem, and demonstrate the effectiveness of the proposed approach on a real computer vision application. Our theoretical solution is applicable to any classifier approximating Bayes' classifier. [less ▲]

Detailed reference viewed: 39 (4 ULg)