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 detailThe Calern Asteroid Polarimetric Survey using the Torino Polarimeter: assessment of instrument performances and first scientific results
Devogele, Maxime ULiege; Cellino, Alberto; Bagnulo, Stefano et al

in Monthly Notices of the Royal Astronomical Society (2016)

A new polarimeter based on the Wedged double Wollaston concept has been built at the Torino Observatory and installed on a 1-meter telescope at the Calern observing station of the ``Observatoire de la C ... [more ▼]

A new polarimeter based on the Wedged double Wollaston concept has been built at the Torino Observatory and installed on a 1-meter telescope at the Calern observing station of the ``Observatoire de la C{\^o}te d'Azur''. Its main purpose is to carry out a polarimetric survey of Solar System objects. This survey is called CAPS (Calern Asteroid Polarimetric Survey). In this paper, the new Torino polarimeter (ToPo) and its preliminary validation campaign is described. The first results of the CAPS survey are also presented. A number of standard stars with known polarization states, as well as a number of asteroids for which the polarimetric properties are known, have been observed in order to assess the instrument accuracy. The instrument response over the field of view and also its stability over single nights and longer periods have also been tested. It has been found that the instrument polarization is stable within a few $10^{-4}$ units. The first polarimetric observations of a still limited number of asteroids show an excellent agreement with previously available data and make already some significant contributions by adding new data to a number of objects that had been poorly observed so far. [less ▲]

Detailed reference viewed: 51 (7 ULiège)
Full Text
Peer Reviewed
See detailCalf health: Cholesterol deficiency causing calf illthrift and diarrhoea
Duff, J. P.; Passant, S.; Wessels, M. et al

in The Veterinary record (2016), 178(17), 424-5

Detailed reference viewed: 28 (4 ULiège)
Full Text
See detailA Calibrated Growth Model of Global Imbalances
Artige, Lionel ULiege; Cavenaile, Laurent ULiege

E-print/Working paper (2011)

Detailed reference viewed: 21 (2 ULiège)
Full Text
Peer Reviewed
See detailCalibrating Activity-Based Models with External OD Information: Overview Of Different Possibilities
Cools, Mario ULiege; Moons, Elke; Wets, Geert

in Proceedings of the 89th Annual Meeting of the Transportation Research Board (DVD-ROM) (2010)

Many practitioners question the advantages of activity-based models over conventional four-step models in terms of replication of traffic counts. Therefore, in this paper, a framework is highlighted that ... [more ▼]

Many practitioners question the advantages of activity-based models over conventional four-step models in terms of replication of traffic counts. Therefore, in this paper, a framework is highlighted that actively links travel demand models in general, and activity-based models in particular, with traffic counts. Two approaches are presented that calibrate activity-based models with traffic counts, namely an indirect and a direct approach. The indirect approach tries to incorporate findings, based on the analysis of traffic counts, into the model components of the activity-based models. The direct approach calibrates the parameters of the travel demand model in such a way that the model replicates the observed traffic counts (quasi-)perfectly. A practical example is provided to illustrate the direct approach. The study area for this practical example is Hasselt, a Belgian city of about 70,000 residents, and its surrounding municipalities. The practical examples revealed that there is not a single roadway to success in calibrating activity based models, but that different options exist in fine-tuning the activity-based model. Notwithstanding, it is important to recognize some open issues and avenues for further research. First, it is not always appropriate to assume that traffic counts are completely correct. Setting up some belief-structure might increase the responsiveness of the activity-based model. In addition, the OD-matrix calibration that optimizes the correspondence between estimated and observed screen-line counts could negatively impact the correspondence to other measures such as vehicle miles traveled. To conclude, formulation of a multi-objective calibration method is a key challenge for further research. [less ▲]

Detailed reference viewed: 27 (0 ULiège)
Full Text
Peer Reviewed
See detailCalibrating Activity-Based Models with External Origin-Destination Information: Overview Of Different Possibilities
Cools, Mario ULiege; Moons, Elke; Wets, Geert

in Transportation Research Record: Journal of the Transportation Research Board (2010), 2175

Many practitioners question the advantages of activity-based models over conventional four-step models in regard to replication of traffic counts. This paper highlights a framework that actively links ... [more ▼]

Many practitioners question the advantages of activity-based models over conventional four-step models in regard to replication of traffic counts. This paper highlights a framework that actively links travel demand models in general and activity-based models in particular with traffic counts. Two approaches are presented that calibrate activity-based models with traffic count—an indirect and a direct approach. The indirect approach tries to incorporate findings based on the analysis of traffic counts into the components of the activity-based models. The direct approach calibrates the parameters of the travel demand model in such a way that the model replicates the observed traffic counts (quasi-) perfectly. A practical example is provided to illustrate the direct approach. The study area for this practical example is Hasselt, Belgium, a city of about 70,000 residents, and its surrounding municipalities. The practical examples revealed not a single roadway to success in calibrating activity-based models, but different options exist in fine-tuning the activity-based model. It is important to recognize some open issues and avenues for further research. First, it is not always appropriate to assume that traffic counts are completely correct. Setting up some belief structure might increase the responsiveness of the activity-based model. In addition, the origin-destination matrix calibration that optimizes the correspondence between estimated and observed screen-line counts could negatively affect the correspondence to other measures, such as vehicle miles traveled. To conclude, the formulation of a multiobjective calibration method is a key challenge for further research. [less ▲]

Detailed reference viewed: 39 (6 ULiège)
Full Text
Peer Reviewed
See detailCalibration and precision of serum creatinine and plasma cystatin C measurement: impact on the estimation of glomerular filtration rate
DELANAYE, Pierre ULiege; CAVALIER, Etienne ULiege; Cristol, Jean-Paul et al

in Journal of Nephrology (2014), 27(5), 467-75

Serum creatinine (SCr) is the main variable for estimating glomerular filtration rate (GFR). Due to interassay differences, the prevalence of chronic kidney disease (CKD) varies according to the assay ... [more ▼]

Serum creatinine (SCr) is the main variable for estimating glomerular filtration rate (GFR). Due to interassay differences, the prevalence of chronic kidney disease (CKD) varies according to the assay used, and calibration standardization is necessary. For SCr, isotope dilution mass spectrometry (IDMS) is the gold standard. Systematic differences are observed between Jaffe and enzymatic methods. Manufacturers subtract 0.30 mg/dl from Jaffe results to match enzymatic results (‘compensated Jaffe method’). The analytical performance of enzymatic methods is superior to that of Jaffe methods. In the original Modification of Diet in Renal Disease (MDRD) equation, SCr was measured by a Jaffe Beckman assay, which was later recalibrated. A limitation of this equation was an underestimation of GFR in the high range. The Chronic Kidney Disease Epidemiology (CKD-EPI) consortium proposed an equation using calibrated and IDMS traceable SCr. The gain in performance was due to improving the bias whereas the precision was comparable. The CKD-EPI equation performs better at high GFR levels (GFR[60 ml/ min/1.73 m2). Analytical limitations have led to the recommendation to give a grade ([60 ml/min/1.73 m2) rather than an absolute value with the MDRD equation. By using both enzymatic and calibrated methods, this cutoff-grade could be increased to 90 ml/min/1.73 m2 (with MDRD) and 120 ml/min/1.73 m2 (with CKD-EPI). The superiority of the CKD-EPI equation over MDRD is analytical, but the precision gain is limited. IDMS traceable enzymatic methods have been used in the development of the Lund– Malmo¨ (in CKD populations) and Berlin Initiative Study equations (in the elderly). The analytical errors for cystatin C are grossly comparable to issues found with SCr. Standardization is available since 2011. A reference method for cystatin C is still lacking. Equations based on standardized cystatin C or cystatin C and creatinine have been proposed. The better performance of these equations (especially the combined CKD-EPI equation) has been demonstrated. [less ▲]

Detailed reference viewed: 37 (5 ULiège)
See detailCalibration and quality assessment of water vapor radiometer observations using radiosonde GPS and VLBI
Pottiaux, Eric; Becker, M.; Buerki, B. et al

Conference (2003)

Detailed reference viewed: 12 (0 ULiège)
Full Text
See detailCalibration and reliability of an alluvial aquifer model using inverse modelling and sensitivity analysis
Rentier, Céline; Brouyère, Serge ULiege; Dassargues, Alain ULiege

in Stauffer, F.; Kinzelbach, W.; Kovar, K. (Eds.) et al Calibration and Reliability in Groundwater Modelling Pre-published Proc. of ModelCARE99 (1999)

Detailed reference viewed: 28 (7 ULiège)
Full Text
Peer Reviewed
See detailCalibration and testing of wide-field UV instruments
Frey, Harald; Mende, Stephen; Loicq, Jerôme ULiege et al

in Journal of Geophysical Research. Space Physics (2017), 122

As with all optical systems the calibration of wide-field ultraviolet (UV) systems includes three main areas: sensitivity, imaging quality, and imaging capability. The one thing that makes UV calibrations ... [more ▼]

As with all optical systems the calibration of wide-field ultraviolet (UV) systems includes three main areas: sensitivity, imaging quality, and imaging capability. The one thing that makes UV calibrations difficult is the need for working in vacuum substantially extending the required time and effort compared to visible systems. In theory a ray tracing and characterization of each individual component of the optical system (mirrors, windows, and grating) should provide the transmission efficiency of the combined system. However, potentially unknown effects (contamination, misalignment, and measurement errors) can make the final error too large and unacceptable for most applications. Therefore, it is desirable to test and measure the optical properties of the whole system in vacuum and compare the overall response to the response of a calibrated photon detector. A proper comparison then allows the quantification of individual sources of uncertainty and ensures that the whole instrument performance is within acceptable tolerances or pinpoints which parts fail to meet requirements. Based on the experience with the IMAGE Spectrographic Imager, the Wide-band Imaging Camera, and the ICON Far Ultraviolet instruments, we discuss the steps and procedures for the proper radiometric sensitivity and passband calibration, spot size, imaging distortions, flatfield, and field of view determination. [less ▲]

Detailed reference viewed: 33 (6 ULiège)
Peer Reviewed
See detailCalibration and testing of wide-field UV instruments
Frey, Harald; Mende, Stephen; Loicq, Jerôme ULiege et al

Conference (2015, April)

As with all optical systems the calibration of wide-field ultraviolet systems includes three main areas: sensitivity, imaging quality, and imaging capability. The one thing that makes these calibrations ... [more ▼]

As with all optical systems the calibration of wide-field ultraviolet systems includes three main areas: sensitivity, imaging quality, and imaging capability. The one thing that makes these calibrations difficult is the need for working in vacuum substantially extending the required time and effort compared to visible systems. In theory a ray tracing and characterization of each individual component of the optical system (mirrors, windows, grating) should provide the transmission efficiency of the combined system but potential unknown effects (contamination, misalignment, measurement errors) will make the final error too large for most applications. Therefore it is desirable to test and measure the optical properties of the whole system in vacuum and compare the overall response to the response of a calibrated photon detector. Based on the experience with the IMAGE Spectrographic Imager (SI) and Wide-band Imaging Camera (WIC), and the ICON-FUV instrument we will discuss the steps and procedures for the proper radiometric sensitivity and pass-band calibration, spot size, imaging distortions, flat field and field of view determination. [less ▲]

Detailed reference viewed: 32 (5 ULiège)
Full Text
See detailCalibration et validation du Modèle Pégase :Ajout d’une nouvelle fonctionnalité : Couplage du modèle Pégase avec un modèle sols pour le calcul des apports diffus : Evaluation et étude de faisabilité
Deliège, Jean-François ULiege; Everbecq, Etienne ULiege; Grard, Aline ULiege et al

Report (2008)

Le modèle Pegase (Planification Et Gestion de l’ASsainissement des Eaux) est un modèle intégré bassins hydrographiques/rivières qui permet de calculer de façon déterministe et prévisionnelle la qualité ... [more ▼]

Le modèle Pegase (Planification Et Gestion de l’ASsainissement des Eaux) est un modèle intégré bassins hydrographiques/rivières qui permet de calculer de façon déterministe et prévisionnelle la qualité des eaux des rivières en fonction des rejets et apports de pollution (relation pression-impact). Développé depuis la fin des années 1980 à l’université de Liège, il permet d'orienter les choix des opérateurs publics et privés en matière de gestion des eaux de surface à l'échelle des petits et grands bassins versants. L’Agence de l’eau Adour-Garonne utilise ce modèle depuis 2004 dans le cadre de ses missions liées entre autres à la Directive Cadre sur l’Eau (EC/2000/60). L'Agence a confié à l'Aquapôle une étude visant à améliorer les simulations Pégase en termes d’apports diffus des sols via l’étude de faisabilité du couplage du modèle Pégase avec un modèle « Sols », en vue du calcul déterministe et explicite des apports diffus. [less ▲]

Detailed reference viewed: 10 (2 ULiège)
Peer Reviewed
See detailCalibration of a finite element model for bolted endplate steel connections
Bursi, O.; Jaspart, Jean-Pierre ULiege

in Journal of Constructional Steel Research (1997), 44(No 3), 225-262

Detailed reference viewed: 99 (1 ULiège)
Full Text
Peer Reviewed
See detailCalibration of an Air Entrainment Model for CFD Spillway Applications
Valero Huerta, Daniel ULiege; García-Bartual, Rafael

in Gourbesville, Philippe; Cunge, Jean A.; Caignaert, Guy (Eds.) Advances in Hydroinformatics (2016)

Air entrained has become one of the main variables in the study of large spillways performance since it can help avoiding cavitation. Moreover, high rates of air concentration produce significant bulking ... [more ▼]

Air entrained has become one of the main variables in the study of large spillways performance since it can help avoiding cavitation. Moreover, high rates of air concentration produce significant bulking of the flow as well as a water–solid friction reduction, generating flow acceleration and increasing maximum velocities at the inlet of the energy dissipation structure. Air entrained also affects turbulence inside the flow producing different energy dissipation rates. Aerated spillways physical models are affected by scale effects, with Weber and Reynolds numbers being usually too low to adequately reproduce observed flows. Alternatively, simulation of air–water flows can be carried out by means of Computational Fluid Dynamics techniques in 1:1 scale. However, 3D numerical simulations of spillway flows are time expensive and air–water interfaces need fine resolution meshes which would require extensive computing. Thus, the use of a subgrid scale in air entrainment models can be useful to predict the inception point and the air concentration profile of the flow along the spillway. Computational techniques can handle a more accurate momentum distribution over the spillway sections with affordable costs. In this research, FLOW-3D® routine for turbulent air entrainment is used, coupled with variable density evaluation. VOF and κ-ε RNG turbulence model are also employed. Over 200 spillway flow simulations have been carried out to obtain optimal values of the air-entrainment model parameters, which can be used in future spillway simulations. The calibration of the model is carried out employing prototype data. Interesting conclusions are obtained concerning air entrainment model performance. [less ▲]

Detailed reference viewed: 27 (2 ULiège)
Full Text
Peer Reviewed
See detailCalibration of building energy simulation models based on optimization: A case study
Monetti, V.; Davin, Elisabeth ULiege; Fabrizio, E. et al

in Energy Procedia (2015), 78

This study applies an optimization-based approach for calibrating building energy models using monitored data. The calibration was carried out on a test building coupling the EnergyPlus energy simulation ... [more ▼]

This study applies an optimization-based approach for calibrating building energy models using monitored data. The calibration was carried out on a test building coupling the EnergyPlus energy simulation tool with the GenOpt optimization tool. The objective function was set to minimize the difference between simulated and monitored energy consumption. For evaluating the model accuracy, the Mean Bias Error (MBE) and the Coefficient of Variation of the RMSE (Cv (RMSE)) were calculated and found consistent with ASHRAE guideline 14 limits for a model to be considered calibrated. © 2015 The Authors. [less ▲]

Detailed reference viewed: 24 (2 ULiège)
Full Text
Peer Reviewed
See detailCalibration of Building Simulation Models: Assessment of Current Acceptance Criteria
Ruiz Flores, Roberto ULiege; Lemort, Vincent ULiege

in Proceedings of the 8th International Conference Improving Energy Efficiency in Commercial Buildings (IEECB’14) (2014, September)

In this paper, the most used acceptance criteria in calibration of building simulation models are introduced and tried out by means of a practical exercise. In order to simplify the process of obtaining ... [more ▼]

In this paper, the most used acceptance criteria in calibration of building simulation models are introduced and tried out by means of a practical exercise. In order to simplify the process of obtaining “simulated data” and to avoid carrying out a formal calibration procedure; two yearly testing profiles (hourly time scale) are created from real building electrical metered data (¼ hour profile). Both testing profiles represent two model responses that could possibly be obtained in a common calibration procedure. The objective of this work is to test the capabilities of the method to determine (1) the model adequacy to represent an existing situation; (2) the reliability of the model when predicting a future or different scenario and also (3) the ability of the method to orient the practitioner to upgrade the model when it provides a non-satisfactory response. To do this, the real accuracy of both testing profiles is verified by means of a complementary statistical bin analysis. This crosschecking analysis allows highlighting the strengths and weakness of the current criteria and determining whether they need to be revised, modified or complemented. At the end of the analysis, it is concluded that the capabilities of the current acceptance criteria are limited because don’t provide any satisfactory answer, indication or clue for none of the three points aforementioned and some other complementary tests (such as bin analysis) must be implemented and performed in order to properly declare a model as calibrated. [less ▲]

Detailed reference viewed: 369 (27 ULiège)
Peer Reviewed
See detailCalibration of comprehension : An underconfidence effect
Broonen, Jean-Paul ULiege

Poster (1995, May 19)

Detailed reference viewed: 14 (2 ULiège)
Full Text
Peer Reviewed
See detailCalibration of force actuators on an adaptive secondary prototype
Ricci, Davide ULiege; Riccardi, Armando; Zanotti, Daniela

in Applied Optics (2008), 47

In the context of the Large Binocular Telescope project, we present the results of force actuator calibrations performed on an adaptive secondary prototype called P45, a thin deformable glass with magnets ... [more ▼]

In the context of the Large Binocular Telescope project, we present the results of force actuator calibrations performed on an adaptive secondary prototype called P45, a thin deformable glass with magnets glued onto its back. Electromagnetic actuators, controlled in a closed loop with a system of internal metrology based on capacitive sensors, continuously deform its shape to correct the distortions of the wavefront. Calibrations of the force actuators are needed because of the differences between driven forces and measured forces. We describe the calibration procedures and the results, obtained with errors of less than 1.5%. [less ▲]

Detailed reference viewed: 52 (5 ULiège)
Full Text
See detailCalibration of Gauges for Dynamic Strain Measurements on Compressor Bladed Disks
Beckers, Rémy; Nyssen, Florence ULiege; Benabou, Hicham et al

Poster (2014, June)

Detailed reference viewed: 42 (8 ULiège)
Full Text
Peer Reviewed
See detailCalibration of ion effective temperatures achieved by resonant activation in a quadrupole ion trap
Gabelica, Valérie ULiege; Karas, Michael; De Pauw, Edwin ULiege

in Analytical Chemistry (2003), 75(19), 5152-5159

The present paper describes a calibration of the ion effective temperatures as a function of the resonant activation amplitude in a quadrupole ion trap mass spectrometer. MS/MS experiments are performed ... [more ▼]

The present paper describes a calibration of the ion effective temperatures as a function of the resonant activation amplitude in a quadrupole ion trap mass spectrometer. MS/MS experiments are performed on leucine enkephalin (M + H)(+), bradykinin (M + H)(+), (M + 2H)(2+), and (M + 3H)(3+), and ubiquitin (M + 11H)(11+). For each amplitude, the effective temperature is calculated as the temperature that would give the same dissociation rate constant as the one observed and is calculated using published Arrhenius parameters. The effective temperature is found to be linearly dependent on the activation amplitude on the range investigated. The dependence of the slope and of the intercept of the T-eff = f (amplitude) functions on the parent ion m/z is examined and an equation is derived to calibrate the ion effective temperature between 365 and 600 K Below 365 K, a deviation from linearity is expected. Above 600 1 the validity of the equation will depend on whether the rapid energy exchange limit is still reached. Calculating backward, the Arrhenius parameters from the measured dissociation rates using this calibration show excellent agreement with the published values. The calibration can therefore be used to determine Arrhenius activation parameters from dissociation kinetics under resonant activation in quadrupole ion trap mass spectrometers. [less ▲]

Detailed reference viewed: 49 (1 ULiège)
Full Text
Peer Reviewed
See detailCalibration of MATSim in the context of natural hazards in Liège (Belgium): Preliminary results
Saadi, Ismaïl ULiege; El Saeid Mustafa, Ahmed Mohamed ULiege; Teller, Jacques ULiege et al

in Proceedings of the 12th Conference on Transport Engineering (2016)

In Belgium, river floods are among the most frequent natural disasters and they may cause important changes on travel demand. In this regard, we propose to set up a large scale scenario using MATSim for ... [more ▼]

In Belgium, river floods are among the most frequent natural disasters and they may cause important changes on travel demand. In this regard, we propose to set up a large scale scenario using MATSim for guarantying an accurate assessment of the river floods impact on the transportation systems. In terms of inputs, agent-based models require a base year population. In this context, a synthetic population with a respective set of attributes is generated as a key input. Afterwards, agents are assigned activity chains through an activity-based generation process. Finally, the synthetic population and the transportation network are integrated into the dynamic traffic assignment simulator, i.e. MATSim. With respect to data, households travel surveys are the main inputs for synthesizing the populations. Besides, a steady-state inundation map is integrated within MATSim for simulating river floods. To our knowledge, very few studies have focused on how river floods affect transportation systems. In this regard, this research will undoubtedly provide new insights in term of methodology and traffic pattern analysis under disruptions, especially with regard to spatial scale effects. The results indicate that at the municipality level, it is possible to capture the effects of disruptions on travel behavior. In this context, further disaggregation is needed in future studies for identifying to what extent results are sensitive to disaggregation. In addition, results also suggest that the target sub-population exposed to flood risk should be isolated from the rest of the travel demand to reach have more sensitive effects. [less ▲]

Detailed reference viewed: 53 (6 ULiège)