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Peer Reviewed
See detailA comparison between harmonic and time techniques to compute electromagnetic resonant structures
Meys, B.; Geuzaine, Christophe ULg; Henrotte, F. et al

in Proceedings of the 4th International Workshop on Electric and Magnetic Fields, EMF 1998 (1998)

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See detailComparison between High Chromium Steel and Semi HSS used in Hot Strip Mill Roughing Stands
Lecomte-Beckers, Jacqueline ULg; Sinnaeve, Mario; Tchuindjang, Jérôme Tchoufack ULg

in Proceedings of the 13th Southern African Roll Users Conference (SARUC 2011) (2011, October)

Two alloys grades for work rolls used in the roughing stand of Hot Strip Mill (HSM) are compared. The first grade known as High Chromium Steel (HCS) is presently the most widely used alloy for such an ... [more ▼]

Two alloys grades for work rolls used in the roughing stand of Hot Strip Mill (HSM) are compared. The first grade known as High Chromium Steel (HCS) is presently the most widely used alloy for such an application, while the second one known as semi-High Speed Steel (semi-HSS) is the new grade developed to improve the overall performance of the work roll in the roughing stands of the HSM. In the present paper, the new semi-HSS grade is studied starting from three chemical compositions closed one to another, the variation in the alloying elements is intended to assess, on one hand the effect of a small increase of the carbon content, and on the other hand the influence of the addition of a strong MC carbide forming element. The comparison of HCS and semi-HSS grades involves many fields. Regarding the metallurgical aspect, such a comparison led to the enhancement of the solidification range, the crystallization behavior and the microstructure in the as-cast condition for both grades. Furthermore, corrosion behavior and performances of the work rolls in service are compared. Various techniques are used in order to characterize both grades, such as Differential Thermal Analysis (to determine phase transformations temperatures, the crystallization behavior and the interval of solidification), hardness measurements, optical microscopy, scanning electron microscopy associated with energy dispersive X ray spectroscopy (to determine the nature and the composition of phases, especially matrix and carbides). Finally micro-macro relations between the nature of the microstructure and the properties of HCS and semi-HSS rolls grades in service conditions could be established. [less ▲]

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See detailComparison between homogeneous and heterogeneous field information for plastic material identification
Lecompte, D.; Sol, H.; Vantomme, J. et al

in Grédiac, Michel; Huntley, Jonathan (Eds.) Proceedings of Photomecanics Conference 2006 (2006)

The accuracy of a Finite Element Simulation for plastic deformation strongly depends on the chosen constitutive laws and the value of the material parameters within these laws. The identification of those ... [more ▼]

The accuracy of a Finite Element Simulation for plastic deformation strongly depends on the chosen constitutive laws and the value of the material parameters within these laws. The identification of those mechanical parameters can be done based on homogeneous stress and strain fields such as those obtained in uniaxial tensile tests and simple shear tests performed in different plane material directions. Another way to identify plastic material parameters is by inverse modeling of an experiment exhibiting a heterogeneous stress and strain field. Experimental forces and strains are in this case compared to the simulated ones and it is tried to reduce the difference in a least-squares sense by optimizing the model parameters. The optimization technique used is this case is gradient based, which means that at every iteration a sensitivity calculation has to be performed in order to indicate the direction in which the parameters are to be identified. The basic principle of the inverse modeling procedure as it is used for parameter identification is the generation of a complex and heterogeneous deformation field that contains as much information as possible about the parameters to be identified. One way of obtaining such a non-homogeneous deformation is by altering the geometry of the specimen for a uniaxial test. Another possibility is to make the loading conditions more complex. In this paper both options are actually combined by using a biaxial tensile test on a perforated cruciform specimen. In the present paper, the work hardening of the material is assumed to be isotropic and it is described by a Swift law. The yield locus is modeled by the anisotropic Hill48 criterion. A comparison is made between the identification of the Hill48 parameters based on the one hand on the Lankford coefficients [1] and on the inverse modeling of a biaxial tensile test on the other hand [less ▲]

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See detailComparison between in situ and satellite surface temperature in the Western Mediterranean Sea
Alvera Azcarate, Aïda ULg; Barth, Alexander ULg; Troupin, Charles ULg et al

Conference (2010, May 06)

A comparison between satellite and in situ sea surface temperature (SST) data in the Western Mediterranean Sea in 1999 is realised. The aim of this study is to better understand the differences between ... [more ▼]

A comparison between satellite and in situ sea surface temperature (SST) data in the Western Mediterranean Sea in 1999 is realised. The aim of this study is to better understand the differences between these two data sets, in order to realise merged maps of SST using satellite and in situ data. When merging temperature from different platforms, it is crucial to take the expected RMS error of the observations into account and to correct for possible biases. Advanced Very High Resolution Radiometer (AVHRR) SST day-time and night-time satellite data are used, and the in situ data have been obtained from various databases (World Ocean Database’05, Coriolis, Medar/Medatlas and ICES). Statistics about the differences due to the hour of the day, the month of the year, the type of sensor/platform used (CTD, XBT, drifter, etc) and the spatial distribution are made using a combination of error measures, diagrams and statistical hypothesis testing. In addition to quantify the errors between different platforms, several assumptions often made when creating gridded analyses will be critically reviewed: unbiased data sets, non-correlated errors of the observations, spatially uniform variance, and Gaussian-distributed data. [less ▲]

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See detailComparison Between Mornigstar Ratings And Traditional Performance Measures Ratings
Bodson, Laurent ULg; Delhalle, Stéphanie ULg; Sougné, Danielle ULg

E-print/Working paper (2012)

In this paper, we compare Morningstar ratings with those obtained using the same methodology of rating attribution with a set of commonly used performance measures. We look at three types of investment ... [more ▼]

In this paper, we compare Morningstar ratings with those obtained using the same methodology of rating attribution with a set of commonly used performance measures. We look at three types of investment horizons: 3-year, 5-year and 10-year ratings. Our analysis focuses on Open-End US Mutual Funds available in Morningstar Direct Database from which we create three sets of 16,617, 13,505 and 7,992 funds corresponding respectively to the three investment horizons analyzed. Our results show that Morningstar ratings are very close (correlation around 80%) to ratings obtained with Sharpe’s alpha, Jensen’s alpha, Four-factor alpha and Excess returns. And less significantly, we also observe that ratings given by the Sortino ratio, Sharpe MVaR, M-squared, Sharpe ratio, One-factor information ratio, Four-factor information ratio, Prospect ratio and Stutzer index are quite similar to Morningstar’s ratings (correlation lying between 70% and 78%). At the other end of the spectrum, however, ratings obtained with Annual return diverge widely from Morningstar ratings. We also analyse which explanatory variables can explain the differences between ratings computed with Morningstar as compared with the alternative performance measures using a probit regression. We find that Load adjustments, tax and risk included by Morningstar in the computation of MRAR are often determining. Expense ratio, Return Skewness and the three factors of the Fama-French model (Beta, Size load and Book-to-market loading) can be significant determinants depending on the performance measure analyzed and on the selected investment horizon. Fund characteristics such as Age, Fund size, Turnover rate and Manager tenure are not statistically significant in determining the differences in ratings. Besides, we analyze differences between ratings (in terms of number of STARs) and we confirm previous results (i.e. the link between Morningstar’s and the alternative performance measures, but also the explanatory capacity of the load for lots of differences between ratings). Finally, we test all possible combinations of our set of performance measures, and observe that Sharpe’s alpha, excess return, Sharpe MVaR, Four-factor alpha and Jensen’s alpha are part of the best combinations. As a conclusion, Morningstar ratings can be replicated using simple and traditional performance measures but the replication is less accurate when tax and loads features are important. Therefore, Morningstar data management and access bring the most of its ratings’ value added. [less ▲]

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See detailComparison Between Morningstar Ratings and Traditional Performance Measures Ratings
Sougné, Danielle ULg; Bodson, Laurent ULg

Scientific conference (2013, July 01)

We compare Morningstar ratings and ratings obtained using the same methodology of rating attribution with a set of commonly used performance measures. We study three types of investment horizons : 3-year ... [more ▼]

We compare Morningstar ratings and ratings obtained using the same methodology of rating attribution with a set of commonly used performance measures. We study three types of investment horizons : 3-year, 5-year and 10-year ratings. Our analysis focuses on Open-End US Mutual Funds available in Morningstar Direct Database from which we create three sets of 16,617, 13,505 and 7,992 funds corresponding respectively to the three investment horizons analyzed. Our results show that Morningstar ratings are very close ( correlation around 80%) to ratings obtained with Sharpe's alpha, Jensen's alpha, Four-factor alpha and Excess returns. [less ▲]

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See detailComparison between new and old excipients
Hubert, Cédric ULg; Ziemons, Eric ULg; Hubert, Philippe ULg

Report (2011)

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See detailComparison between nonsteroidal and steroidal anti-inflammatory treatment in calf pasteurellosis model
Olaerts, J.; Van de Weerdt, M. L.; Lekeux, Pierre ULg

in Pflügers Archiv : European Journal of Physiology (1995), 430

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See detailComparison between Open and Closed Repair for Abdominal Aortic Aneurysms: A Word of Caution
Limet, Raymond ULg; CREEMERS, Etienne ULg

in Acta Chirurgica Belgica (2000), 100(1), 12-5

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See detailComparison between optical pulsed thermography and vibrothermography for the assessment of carbon fibers composite materials
Montrieux, Henri-Michel ULg; Demy, Philippe; Ibarra-Castanedo, Clemente et al

(2013, August 02)

Pulsed thermography and vibrothermography are two active thermography techniques characterized by different heating methods of the specimen. In pulsed phase thermography, a sample is heated by two flash ... [more ▼]

Pulsed thermography and vibrothermography are two active thermography techniques characterized by different heating methods of the specimen. In pulsed phase thermography, a sample is heated by two flash lamps for a short period to inject a Dirac impulse heat in the material. The cooling of the part is monitored with an infrared camera to detect thermal contrast in the image, characteristic of the presence of a defect. In vibrothermography, high frequency vibrations are injected into the sample causing an internal heating observed on surface right above the defect due to diverse phenomena as friction or viscoelastic hysteresis. If pulsed thermography is a well-known technique that has been integrated into the arsenal of industrial NDT methods, vibrothermography is a less common experimental method still subject to theoretical and practical investigations. This article aims to compare the effectiveness of the two methods in the case of different types of composites based on carbon fibers: carbon fiber reinforced plastic (CFRP) plates as well as a completely new material: carbon magnesium composite. [less ▲]

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See detailA Comparison between Optimal Allocations Based on the Modified VaR and on a Utility-Based Risk Measure
Bodson, Laurent ULg; Coën, Alain ULg; Hübner, Georges ULg

in Gregoriou, Greg N. (Ed.) The VaR Modeling Handbook: Practical Applications in Alternative Investing, Banking, Insurance, and Portfolio Management Book (2008)

Many empirical analyses have demonstrated that some financial asset returns like those of hedge funds depart from the normal distribution. From this observation, several new risk measures have been ... [more ▼]

Many empirical analyses have demonstrated that some financial asset returns like those of hedge funds depart from the normal distribution. From this observation, several new risk measures have been created to take into consideration the skewness and the kurtosis of the return distributions. We propose in this chapter to present the impact of higher moments on the optimal portfolio allocation comparing two four-moment risk measures, namely a utility-based risk measure with the preference-free modified VaR (MVaR). [less ▲]

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See detailA comparison between Optimal Allocations Based on the Modified VaR and those based on a Utility-Based Risk Measure
Bodson, Laurent ULg; Coën, Alain; Hübner, Georges ULg

in Gregoriou, Greg (Ed.) The VaR Modeling Handbook (2009)

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See detailComparison between Perkin-Elmer and Chromsytem Vitamin D kit on TQ 5500 from AB SCIEX
LE GOFF, Caroline ULg; PEETERS, Stéphanie ULg; CRINE, Yannick ULg et al

in Biochimica Clinica (2013, May), 37(SS), 471

Background: Twenty-five hydroxy-vitamin D (25(OH) D) determination is now routinely prescribed in the Laboratory. Recently, different new methods have been available for this determination. Among them ... [more ▼]

Background: Twenty-five hydroxy-vitamin D (25(OH) D) determination is now routinely prescribed in the Laboratory. Recently, different new methods have been available for this determination. Among them, LCMS/MS methods have emerged in some laboratories. However these methods are generally “home-brewed” and an important variability between them can be seen on different external quality controls, mainly due to a lack of standardization. Recently, Perkin-Elmer (PE) (Turku, Finland) and Chromsystem (CS) (Grafelfing, Germany) launched a standardised method for 25(OH )D determination on LCMS/MS. The aim of our study was to compare these methods on the AB SCIEX TQ5500 (Framingham, Massachusetts, USA) LCMS/MS to measure 25(OH) D3. Methods All the samples were treated according to our preanalyitical procedure: after sampling, they were spun at +4°c at 3500G, aliquoted and kept frozen at -20°c until determination. A method comparison was assessed with CS and PE for the measurement of the 25(OH)D3. We selected 110 remnant samples with 25(OH)D3 levels ranging from 1.6 to 136.7 ng/ml with the PE method to cover the range of usually values Slope and intercept were calculated using Passing and Bablock linear regression and we compared the methods with the Bland and Altman plots. Results For CS, the method is linear up to 250 µg/L, the LOQ is 3.6 µg/L, the intra-assay CV is < 5% and the inter-assay is < 7%. For PE, the method is linear up to 314 µg/L, the LOQ is 3.4 µg/L, the intra-assay CV is < 7.8% and the inter-assay is < 8.5%. On the whole range of measure (n=110), the regression equation is PE = 0.8521+0.9226 (CS) (95%CI of the intercept: (-0.0048;1.37) and 95% CI of the slope (0.89;0.95). The Bland and Altman plot does not show any bias between the two methods (mean difference CS-PE= -2.5 ng/ml) and the standard deviation of the mean is 3,98 ng/ml Conclusion: The performances of these methods are comparable on our new TQ 5500 from AB SCIEX. For now, there is no consensus on a “reference” method for vitamin D quantification. We notice only that the values obtained by CS are systematically a little bit lower than PE’s values, especially for results below 20 ng/ml. However, we have no clear explanation for such behaviour. [less ▲]

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See detailComparison between platelet-rich plasma (PRP) and vascular endothelial growth factor-111 (VEGF-111) as a therapeutic tool in tendon healing process
Kaux, Jean-François ULg; Drion, Pierre ULg; Libertiaux, Vincent ULg et al

Poster (2010, March 20)

Introduction In spite of the availability of various treatments for tendinopathy, this pathology often becomes chronic. For this reason, it is of interest to develop new treatments. Among them, the ... [more ▼]

Introduction In spite of the availability of various treatments for tendinopathy, this pathology often becomes chronic. For this reason, it is of interest to develop new treatments. Among them, the injection of platelet-rich plasma (PRP) seems to be a promising one. Indeed, several animal models have demonstrated that injection of blood platelets can initiate and stimulate tendon and ligament repair by releasing growth factors (GF) locally. Among all the GF released by activated platelets, the vascular endothelial growth factor-A (VEGF-A) is known to induce positive effects on vascular function and angiogenesis, and could be implicated in the healing process of tendons. Recently, a novel VEGF-A isoform was identified, the VEGF-111, a biologically active and proteolysis-resistant VEGF-A isoform, also known to present beneficial effects on ischemic diseases. This prompted us to evaluate whether VEFF-111 would have a therapeutic interest within the framework of the tendon pathology. Aim of the study: We hypothesized that the healing of ruptured Achilles tendons, which is the last stage of the Blazina’s classification, could be improved by injection of VEGF-111 that was compared to the potential effect of PRP injections using a rat model. Methods: A 5mm defect was surgically induced in rat Achilles tendon after resection of plantaris tendon. Rats were divided into 3 groups: A: control (no injection), B: PRP treatment and C: VEGF-111 treatment. Rats received a local injection of PRP (50µL) or VEGF-111 (100ng) in situ after the surgery and were placed in their cage without immobilization. After 5, 15 and 30 days, the rats were euthanized in each group. The traumatized Achilles tendon of each rat was removed and dissected during the healing process. Immediately after sampling, tendons were submitted to a biomechanical tensile test up to rupture, using a “Cryo-jaw”. Results: Our results show that developed force necessary to induce tendon rupture during biomechanical tensile test was more important for tendons which had received an injection of PRP or VEGF-111. Moreover, the tensile force necessary to break tendons is higher with PRP than with VEGF-111. These results were already noticed from day 5 onwards. Conclusion: This experimentation has shown that both PRP and VEGF-111 injections stimulated tendon healing process as suggested by the increased force needed to break tendons during its healing process. Furthermore, this acceleration of the cicatrisation process was more significant with PRP than with VEGF-111. This could be explained by the release from platelets of a “cocktail” of growth factors acting in synergy on the healing process. Acknowledgement This experimentation was partially financed by “Standard de Liège 2007” and “Lejeune-Lechien 2008” grants. [less ▲]

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See detailComparison between player specialization, anthropometric characteristics and jumping ability in top-level volleybal players
Ciccarone, Guido; Croisier, Jean-Louis ULg; Fontani, G. et al

in Medicina dello Sport : Rivista di Fisiopatologia dello Sport (2008), 61

Aim. Volleyball is an open skill sport with predominant anaerobic alactic acid power. At higher skill levels, performance characteristics are mainly determined by speed and vertical jumping ability. The ... [more ▼]

Aim. Volleyball is an open skill sport with predominant anaerobic alactic acid power. At higher skill levels, performance characteristics are mainly determined by speed and vertical jumping ability. The aim of this study was to compare anthropometric parameters and jumping ability in a group of elite male volleyball players in relation to technical skills required by player position. Methods. The study population included 36 elite male volleyball players (coming from the Italian First and Second Division Championships). Subjects were grouped by playing position on the court: setters (7); blockers (10); hitters (16); liberos (3). Assessment included anthropometric parameters such as height, weight, body mass index (weight in kg/height in m2), indirect calculation of body fat mass by means of the Katch method (%BFM), measurement of reach with one hand (R1) and two hands (R2); and indirect measurement of explosive strength by means of the Bosco method: squat jump, countermovement jump (CMJ), CMJ with arm swing (CMJas), and repeated jumps for 15 s (R15”); measurement of motor coordination and jumping ability by means of the Vertec test combined with specific offense (Vertec attack [VA]) and defense (Vertec block [VB]) skills. Results. Significant differences were observed between player specialization and anthropometric parameters (height, weight, BMI, R1 and R2). Results of the Bosco (SJ, CMJ, CMJas) and Vertec tests (VA and VB) also differed significantly among the player groups. Conclusion. Functional assessment protocols that evaluate anthropometric characteristics and jumping ability by means of two different unrelated methods, confirming that the two measure different aspects of the same performance, provide more complete indications for selecting players, workload planning and monitoring of player development during training. [less ▲]

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See detailComparison between principal component analysis and independent component analysis in EEG modelling
Bugli, Céline; Lambert, Philippe ULg

in Biometrical Journal = Biometrische Zeitschrift (2007), 49

Principal Component Analysis (PCA) is a classical technique in statistical data analysis, feature extraction and data reduction, aiming at explaining observed signals as a linear combination of orthogonal ... [more ▼]

Principal Component Analysis (PCA) is a classical technique in statistical data analysis, feature extraction and data reduction, aiming at explaining observed signals as a linear combination of orthogonal principal components. Independent Component Analysis (ICA) is a technique of array processing and data analysis, aiming at recovering unobserved signals or ‘sources’ from observed mixtures, exploiting only the assumption of mutual independence between the signals. The separation of the sources by ICA has great potential in applications such as the separation of sound signals (like voices mixed in simultaneous multiple records, for example), in telecommunication or in the treatment of medical signals. However, ICA is not yet often used by statisticians. In this paper, we shall present ICA in a statistical framework and compare this method with PCA for electroencephalograms (EEG) analysis.We shall see that ICA provides a more useful data representation than PCA, for instance, for the representation of a particular characteristic of the EEG named event-related potential (ERP). [less ▲]

Detailed reference viewed: 35 (1 ULg)