Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Full Text
Peer Reviewed
See detailInvestigating relationships between Landsat ETM+ data and LAI in a semi-arid grassland of northwest China
Lu, L; Li, X; Ma, M G et al

in Geoscience and Remote Sensing Symposium, 2004. Proceedings IGARSS '04. (2004)

Detailed reference viewed: 12 (0 ULg)
Full Text
See detailInvestigating rock-slope failures in the Tien Shan: State-of-the-art and perspectives of international cooperation (M111).
Strom, A.; Korup, O.; Abdrakhmatov, K. et al

Scientific conference (2005)

Detailed reference viewed: 26 (3 ULg)
Full Text
Peer Reviewed
See detailInvestigating State Reconstruction from Scarce Synchronized Phasor Measurements
Glavic, Mevludin; Van Cutsem, Thierry ULg

in Proceedings of the IEEE Trondheim Power Tech 2011 conference (2011, June)

Synchronized phasor measurements can potentially track the system dynamics between two classical state estimations. However, in the PMU configurations available nowadays and in the near future, those ... [more ▼]

Synchronized phasor measurements can potentially track the system dynamics between two classical state estimations. However, in the PMU configurations available nowadays and in the near future, those measurements are too scarce for the whole system state to be estimated. Therefore, we investigate the possibility to reconstruct coherent, time-synchronized system states from the available PMU data. State reconstruction is formulated as an optimization problem. The objective is to minimize, in the space of bus powers, the distance between the reconstructed state and the last state estimate provided by a standard state estimator. PMU data are imposed as equality constraints. Furthermore, the placement of PMUs near generators is advocated for higher accuracy of state reconstruction. The performance and potential benefits of the approach are illustrated by processing snapshots obtained from detailed time simulation of a test system subject to a disturbance and corrective actions. [less ▲]

Detailed reference viewed: 55 (5 ULg)
Full Text
See detailInvestigating the Effects of Training and Techno-Pedagogical Support
Lecomte, Béatrice ULg; Van de Poël, Jean-François ULg; Verpoorten, Dominique ULg et al

Conference (2013, December)

This communication presents a quantitative-qualitative research conducted among 225 teachers and teaching assistants who have benefited from the education technologies training program provided by our ... [more ▼]

This communication presents a quantitative-qualitative research conducted among 225 teachers and teaching assistants who have benefited from the education technologies training program provided by our eCampus department at IFRES (University of Liege, Belgium) since 2011. The data collected are used to a) describe and characterize the public who attended these training sessions, b) identify the types of training programs chosen by the attendees, and c) to explore the influence of those sessions on the techno-pedagogical development of teachers. That effect is manifested by a change of mental representations or by "acting out" in terms of integrating technology into teaching practices. [less ▲]

Detailed reference viewed: 97 (2 ULg)
Full Text
Peer Reviewed
See detailInvestigating the factors for fermentative biohydrogen improvement: original bioreactors design and hydrogen partial pressure effect
Beckers, Laurent ULg; Hiligsmann, Serge ULg; Hamilton, Christopher ULg et al

in WHEC 2012, Toronto June 3rd - 7th (2012, June 05)

The anaerobic production of hydrogen from biomass offers the potential production of usable biogas from a variety of renewable resources. However, in order to produce hydrogen at high yields and ... [more ▼]

The anaerobic production of hydrogen from biomass offers the potential production of usable biogas from a variety of renewable resources. However, in order to produce hydrogen at high yields and production rates the biotechnological process needs to be further optimized and efficient bioreactors must be designed [1]. At the CWBI, a continuous horizontal rotating cylinder bioreactor has been designed and investigated to produce biohydrogen from glucose by the strain Clostridium butyricum [2] at good yields (1,9molH2•molglucose-1) and production rates (48,6mmolH2•Lmilieu-1.molhexose-1•h-1). This reactor has an internal volume of 2.3L and a small working volume (300ml) (fig.1). It enhances the hydrogen production rates (by about three times more than a completely stirred bioreactor) by partially immobilizing the bacteria on the porous support. Moreover, the rotating cylinder design enables efficient H2 gas transfer from the liquid phase increasing hydrogen yields by about 25% compared to a completely stirred bioreactor [3-4]. Other original bioreactors, such as a trickle bed, have been built with the same aim of lowering the hydrogen partial pressure and led to similar results. Our work shows the importance of a good liquid to gas transfers in the biohydrogen-producing reactors to reach higher performances. [less ▲]

Detailed reference viewed: 49 (16 ULg)
Peer Reviewed
See detailInvestigating the Impact of Different Thermal Comfort Models for Zero Energy Buildings in Hot Climates
Attia, Shady ULg; Hensen, JLM

in Proceeding of: Conference on Energy and Indoor Environment for Hot Climates (2014, February 24)

The selection of a thermal comfort model has a major impact on energy consumption of Net Zero Energy Buildings (NZEBs) in hot climates. The objective of this paper is to compare the influence of using ... [more ▼]

The selection of a thermal comfort model has a major impact on energy consumption of Net Zero Energy Buildings (NZEBs) in hot climates. The objective of this paper is to compare the influence of using different comfort models for zero energy buildings in hot climates. The paper compares the impact of applying Givoni’s model, ASHRAE 55 adaptive comfort standard, EN 15251 adaptive comfort standard and EN ISO 7730 on energy consumption and comfort. Using ZEBO and EnergyPlus for energy simulation, an existing prototype of a residential apartment module will be used to evaluate energy performance and thermal comfort in two parametric series. The first one is the result of coupling natural ventilation and mechanical cooling and the second one is guided coupling natural ventilation, mechanical cooling and ceiling fans. Results show a significant difference of cooling loads and total energy generation for the compared comfort models. However, the study remains theoretical and requires post occupancy evaluation for a better reliability of the results. [less ▲]

Detailed reference viewed: 58 (3 ULg)
Full Text
Peer Reviewed
See detailInvestigating the intraspecific biodiversity of the threatened rodent Leopoldamys neilli in Southeast Asia
Latinne, Alice ULg; Waengsothorn, Surachit; Herbreteau, Vincent et al

Conference (2010, September 23)

We study the phylogeography of Leopoldamys neilli, a threatened murine rodent species endemic to limestone karsts of Thailand, in order to assess the influence of its endemicity to karstic habitat on its ... [more ▼]

We study the phylogeography of Leopoldamys neilli, a threatened murine rodent species endemic to limestone karsts of Thailand, in order to assess the influence of its endemicity to karstic habitat on its intraspecific biodiversity and phylogeographic pattern. Samples of L. neilli were collected in limestone karsts from 20 localities in seven provinces of Thailand. Two mitochondrial markers, the cytochrome b gene (cytb) and the cytochrome c oxydase subunit I gene (COI), were sequenced for 115 L. neilli individuals. A nuclear fragment, the β-fibrinogen intron 7 (bfibr), was amplified in a subset of 65 samples. Phylogenetic reconstructions and median joining networks were used to explore relationships between haplotypes of the studied populations. Haplotype and nucleotide diversities of the main lineages were estimated for each locus. Divergence times of the main lineages of L. neilli were estimated using Bayesian inference. The demographic histories of the main lineages of L.neilli were also examined. Our study gave evidence of a strong geographic structure of the genetic diversity for L. neilli. Six highly differentiated genetic lineages were observed in the phylogenetic and phylogeographic analyses. These lineages are allopatric and correspond to particular regions of Thailand. They exhibit very high degree of genetic divergence and gene flows between them are extremely low. Within each lineage, the levels of haplotype and nucleotide diversities are very low for each gene. These results suggest a severe fragmentation of L. neilli’s populations, correlated to the fragmented distribution of its habitat and highlight its high endemicity to limestone karsts. The strong phylogeographic pattern of L. neilli and the very ancient separation of some lineages could be explained by the geological history of Thailand during Tertiary and Quaternary era. In conclusion, this study revealed an unexpectedly high level of intraspecific biodiversity within the species L. neilli. These results consolidate the importance to strengthen the protection of limestone habitats and to preserve not only their huge interspecific but also intraspecific biodiversity. [less ▲]

Detailed reference viewed: 17 (3 ULg)
Full Text
Peer Reviewed
See detailInvestigating the morphology/rheology interrelationships in immiscible polymer blends
Martin, P. P.; Carreau, P. J.; Favis, B. D. et al

in Journal of Rheology (2000), 44(3), 569-583

Morphological changes in immiscible polymer blends have been studied in shear flow using an original method based on quenching following deformation of molten samples Relaxation effects wete expected to ... [more ▼]

Morphological changes in immiscible polymer blends have been studied in shear flow using an original method based on quenching following deformation of molten samples Relaxation effects wete expected to be negligible during cooling and, hence, the real shear-induced blend microstructure could be analyzed The method has been successfully applied to follow morphological changes of immiscible blends composed of polystyrene and relatively high amounts of high-density polyethylene during creep experiments. The final steady-state morphology appeared to be intimately related to the applied shear stress and total deformation. Coalescence as well as large deformation and orientation of the dispersed phase panicles have been observed depending on the flow conditions The variations with time of the blend rheological properties and morphological observations are in qualitative agreement. [less ▲]

Detailed reference viewed: 85 (4 ULg)
Full Text
See detailInvestigating the performance of model order reduction techniques for nonlinear radiative heat transfer problems
Hickey, D.; Masset, Luc ULg; Kerschen, Gaëtan ULg et al

in Proceedings of the International Conference on Advanced Computational Methods in Engineering (2011)

The problem of nonlinear radiative heat transfer is one of great importance to the aerospace industry. However, analysing large-scale, nonlinear, multiphysical, dynamical structures, by using mathematical ... [more ▼]

The problem of nonlinear radiative heat transfer is one of great importance to the aerospace industry. However, analysing large-scale, nonlinear, multiphysical, dynamical structures, by using mathematical modelling and simulation, e.g. Finite Element Modelling (FEM), can be computationally expensive. This provides motivation for the development of Model-Order Reduction (MOR) techniques capable of reducing simulation times without the loss of important information. The objective is to demonstrate the method of Proper Orthogonal Decompostition (POD) as a technique for nonlinear MOR. The nonlinear radiative exchanges between a linear benchmark beam within an external box (Figure 1) are analysed and a reduction procedure for this fully coupled, nonlinear, multiphysical, thermomechanical system is established. The solution to the strongly coupled, thermomechanical equations of motion is found by making use of an extended version of the implicit generalized-alpha scheme. In the reduced model, the residual of the unreduced system of equations need to be evaluated at each Newton iteration of each time step. In order to optimise the efficiency of the reduction method it is shown that the internal forces can be split into their linear and nonlinear counterparts. Only the nonlinear terms change at each time step, thus only these terms need to remain in the iterative loop significantly reducing the number of parameters that are to be computed at each step. These efficiency improvements to the method are discussed and the results are given. [less ▲]

Detailed reference viewed: 32 (6 ULg)
Full Text
Peer Reviewed
See detailInvestigating the relationship between ground-measured LAI and vegetation indices in an alpine meadow, north-west China.
Lu, L; Li, X; Huang, C L et al

in International Journal of Remote Sensing (2005), 26(20), 4471-4484

Detailed reference viewed: 5 (1 ULg)
Peer Reviewed
See detailInvestigating the role of myostatin in the determinism of double muscling characterizing Belgian Texel sheep
Marcq, Fabienne ULg; El Barkouki, S.; Elsen, J.-M. et al

(1998)

Detailed reference viewed: 147 (5 ULg)
Full Text
Peer Reviewed
See detailInvestigating the tinnitus brain using resting-state fMRI
Maudoux, Audrey ULg; Vanneste, Sven; De Ridder, Dirk et al

Conference (2012, June)

Detailed reference viewed: 24 (2 ULg)
Full Text
Peer Reviewed
See detailInvestigating the Variability in Daily Traffic Counts Trough the Use of ARIMAX and SARIMAX Models: Assessing the Effect of Holidays on two diverse site locations
Cools, Mario ULg; Moons, Elke; Wets, Geert

in Proceedings of the 88th Annual Meeting of the Transportation Research Board (DVD-ROM) (2009)

In this paper, daily traffic counts are explained and forecasted by different modeling philosophies, namely the ARIMAX and SARIMA(X) modeling approaches. Special emphasis is put on the investigation of ... [more ▼]

In this paper, daily traffic counts are explained and forecasted by different modeling philosophies, namely the ARIMAX and SARIMA(X) modeling approaches. Special emphasis is put on the investigation of the seasonality in the daily traffic data and on the identification and comparison of holiday effects at different site locations. To get prior insight in the cyclic patterns present in the daily traffic counts, spectral analysis provides the required framework to highlight periodicities in the data. Data originating from single inductive loop detectors, collected in 2003, 2004 and 2005, are used for the analyses. Four traffic count locations are investigated in this study, an upstream and downstream traffic count location on a highway that is excessively used by commuters and an upstream and downstream traffic count location on a highway that is typified by leisure traffic. The different modeling techniques pointed out that weekly cycles appear to determine the variation in daily traffic counts. The comparison between seasonal effects and holiday effects at different site locations revealed that both the ARIMAX and SARIMAX modeling approach are valid frameworks for the identification and quantification of possible influencing effects. The technique yielded the insight that holiday effects play a noticeable role on highways that are excessively used by commuters, while holiday effects have a more ambiguous effect on highways typified for their leisure traffic. Modeling of daily traffic counts on secondary roads, and simultaneous modeling of both the underlying reasons of travel and revealed traffic patterns, certainly are challenges for further research. [less ▲]

Detailed reference viewed: 23 (0 ULg)
Full Text
Peer Reviewed
See detailInvestigating the Variability in Daily Traffic Counts Trough Use of ARIMAX and SARIMAX Models: Assessing the Effect of Holidays on Two Site Locations
Cools, Mario ULg; Moons, Elke; Wets, Geert

in Transportation Research Record: Journal of the Transportation Research Board (2009), 2136

In this paper, daily traffic counts are explained and forecast by different modeling philosophies: an approach using autoregressive integrated moving average (ARIMA) models with explanatory variables (i.e ... [more ▼]

In this paper, daily traffic counts are explained and forecast by different modeling philosophies: an approach using autoregressive integrated moving average (ARIMA) models with explanatory variables (i.e., the ARIMAX model) and approaches using a seasonal autoregressive integrated moving average (SARIMA) model as well as a SARIMA model with explanatory variables (i.e., the SARIMAX model). Special emphasis is placed on the investigation of seasonality in daily traffic data and on the identification and comparison of holiday effects at different sites. To get insight into prior cyclic patterns in the daily traffic counts, spectral analysis provides the required framework to highlight periodicities in the data. The analyses use data from single inductive loop detectors, which were collected in 2003, 2004, and 2005. Four traffic count locations are investigated in this study: an upstream and a downstream traffic count site on a highway used extensively by commuters, and an upstream and a downstream traffic count site on a highway typically used for leisure travel. The different modeling techniques show that weekly cycles appear to determine the variation in daily traffic counts. The comparison between seasonal and holiday effects at different site locations reveals that both the ARIMAX and the SARIMAX modeling approaches are valid frameworks for identifying and quantifying possible influencing effects. The techniques yield the insight that holidays have a noticeable impact on highways extensively used by commuters, while having a more ambiguous impact on highways typically used for leisure travel. Future research challenges are the modeling of daily traffic counts on secondary roads and the simultaneous modeling of underlying reasons for travel and revealed traffic patterns. [less ▲]

Detailed reference viewed: 20 (0 ULg)
Full Text
Peer Reviewed
See detailInvestigating the X-ray emission from the massive WR+O binary WR 22 using 3D hydrodynamical models
Parkin, E. R.; Gosset, Eric ULg

in Astronomy and Astrophysics (2011), 530

<BR /> Aims: We examine the dependence of the wind-wind collision and subsequent X-ray emission from the massive WR+O star binary WR 22 on the acceleration of the stellar winds, radiative cooling, and ... [more ▼]

<BR /> Aims: We examine the dependence of the wind-wind collision and subsequent X-ray emission from the massive WR+O star binary WR 22 on the acceleration of the stellar winds, radiative cooling, and orbital motion. <BR /> Methods: Three dimensional (3D) adaptive-mesh refinement (AMR) simulations are presented that include radiative driving, gravity, optically-thin radiative cooling, and orbital motion. Simulations were performed with instantaneously accelerated and radiatively driven stellar winds. Radiative transfer calculations were performed on the simulation output to generate synthetic X-ray data, which are used to conduct a detailed comparison against observations. <BR /> Results: When instantaneously accelerated stellar winds are adopted in the simulation, a stable wind-wind collision region (WCR) is established at all orbital phases. In contrast, when the stellar winds are radiatively driven, and thus the acceleration regions of the winds are accounted for, the WCR is far more unstable. As the stars approach periastron, the ram pressure of the WR's wind overwhelms the O star's and, following a significant disruption of the shocks by non-linear thin-shell instabilities (NTSIs), the WCR collapses onto the O star. X-ray calculations reveal that when a stable WCR exists the models over-predict the observed X-ray flux by more than two orders of magnitude. The collapse of the WCR onto the O star substantially reduces the discrepancy in the 2-10keV flux to a factor of ≃ 6 at φ = 0.994. However, the observed spectrum is not well matched by the models. <BR /> Conclusions: We conclude that the agreement between the models and observations could be improved by increasing the ratio of the mass-loss rates in favour of the WR star to the extent that a normal wind ram pressure balance does not occur at any orbital phase, potentially leading to a sustained collapse of the WCR onto the O star. Radiative braking may then play a significant rôle for the WCR dynamics and resulting X-ray emission. [less ▲]

Detailed reference viewed: 17 (6 ULg)
Peer Reviewed
See detailInvestigating trickle flow in packed columns by X-ray tomography
Toye, Dominique ULg; Marchot, Pierre ULg; Crine, Michel ULg et al

Conference (1997, October)

Detailed reference viewed: 10 (2 ULg)