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See detailAssessing the Probability of Training Image-Based Geological Scenarios Using Geophysical Data
Hermans, Thomas ULg; Caers, Jef; Nguyen, Frédéric ULg

in Pardo-Iguzquiza, Eulogio; Guardiola-Albert, Carolina; Heredia, Javier (Eds.) et al Mathematics of Planet Earth - Proceedings of the 15th Annual Conference of the International Association for Mathematical Geosciences (2013, September)

In multiple-point statistics (MPS), the construction of training im-ages (TIs) is one of the most critical steps. Reliable geological studies may not always be available to depict with certainty what ... [more ▼]

In multiple-point statistics (MPS), the construction of training im-ages (TIs) is one of the most critical steps. Reliable geological studies may not always be available to depict with certainty what geological patterns or heterogeneity are present. In this context, geophysical techniques may provide additional information to reduce the possible large uncertainty in the understanding of prior geological scenarios. To overcome this problem, we developed a methodology to verify the consistency of geophysical data with independently-built TIs representing different plausible geological scenarios. If a TI is deemed consistent with the field geophysical survey, then in a sec-ond step we calculate a likelihood probability for each consistent TI. Our methodology starts by creating subsurface models with each TI. From these models we create synthetic geophysical data and from this synthetic data, synthetic inverted models. These models are now compared with a single inverted model obtained from the field sur-vey, allowing for our definition of what is “consistent”. To that ex-tent, we calculate the Euclidean distance between any two inverted models as well as field data and visualize the results in a 2D or 3D space using multidimensional scaling (MDS). With this technique, it is possible to verify if field cases fall in the distribution represented by synthetic cases, and thus are consistent with them. In a second step, we present a cluster analysis on the MDS-map to highlight which parameters are the most sensitive for the construction of TI. Based on this analysis, a probability of each geological scenario is computed through kernel smoothing of the densities in reduced pro-jected metric space. This approach was tested using electrical resistivity tomography as geophysical data to analyze TI scenarios for the Meuse alluvial aqui-fer (Belgium), where the lack of reliable sedimentological data lead to the definition of a multitude of geological scenarios, hence TIs. [less ▲]

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See detailAssessing the Proximity of Time Evolutions through Dynamic Time Warping
Fabozzi, Davide ULg; Van Cutsem, Thierry ULg

in IET Generation, Transmission & Distribution (2011), 5(12), 1268-1276

Comparing time-series is a frequent task in many scientific fields. In power systems, in particular, it may be of interest to compare the outputs of a simplified and a detailed model, or to validate the ... [more ▼]

Comparing time-series is a frequent task in many scientific fields. In power systems, in particular, it may be of interest to compare the outputs of a simplified and a detailed model, or to validate the output of a model with respect to a measured time response. The classical Euclidean distance, involving pairs of points of the two data series aligned in time, is not suited to the practical time evolutions met in power systems, which often involve variable time delays and jumps at discrete times. In this paper, an alternative measure of proximity, stemming from other scientific fields, is proposed for power system applications. It consists in warping the time axis to guarantee the best match between the two time-series, i.e. it maps points on two curves that are not aligned in time so as to minimize the sum of squared differences of their ordinates. Modifications and adaptations of the classical algorithm to better fit power system problems are discussed. The method is illustrated through three representative curve comparison problems. A multi-dimensional extension allowing system-wide measures of similarity is also proposed. [less ▲]

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See detailAssessing the Quality of Origin-Destination Matrices Derived from Activity Travel Surveys: Results from a Monte Carlo Experiment
Cools, Mario ULg; Moons, Elke; Wets, Geert

in Transportation Research Record: Journal of the Transportation Research Board (2010), 2183

To support policy makers combating travel-related externalities, quality data are required for the design and management of transportation systems and policies. To this end, much money has been spent on ... [more ▼]

To support policy makers combating travel-related externalities, quality data are required for the design and management of transportation systems and policies. To this end, much money has been spent on collecting household- and person-based data. The main objective of this paper is to assess the quality of origin-destination (O-D) matrices derived from household activity travel surveys. To this purpose, a Monte Carlo experiment is set up to estimate the precision of O-D matrices given different sampling rates. The Belgian 2001 census data, containing work- and school-related travel information for all 10,296,350 residents, are used for the experiment. For different sampling rates, 2,000 random stratified samples are drawn. For each sample, three O-D matrices are composed: one at the municipality level, one at the district level, and one at the provincial level. The correspondence between the samples and the population is assessed by using the mean absolute percentage error (MAPE) and a censored version of the MAPE (MCAPE). The results show that no accurate O-D matrices can be derived directly from these surveys. Only when half of the population is queried is an acceptable O-D matrix obtained at the provincial level. Therefore, use of additional information to grasp better the behavioral realism underlying destination choices and collection of information about particular O-D pairs by means of vehicle intercept surveys are recommended. In addition, results suggest using the MCAPE next to traditional criteria to examine dissimilarities between different O-D matrices. An important avenue for further research is the investigation of the effect of sampling proportions on travel demand model outcomes. [less ▲]

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See detailAssessing the role of pore structure and porosity in composite electrodes through model thin film electrode studies
Krins, Natacha ULg; Shukla, Alpesh K.; Milliron, Delia J. et al

Poster (2012)

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See detailAssessing the role of porosity in composite electrodes through model thin film electrode studies
Krins, Natacha ULg; Shukla, Alpesh K.; Milliron, Delia J. et al

Poster (2012)

Detailed reference viewed: 4 (0 ULg)
See detailAssessing the role of porosity in composite electrodes through model thin film electrode studies
Krins, Natacha ULg; Shukla, Alpesh K.; Milliron, Delia J. et al

Poster (2012)

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Peer Reviewed
See detailAssessing the Service Provided by a Connection-less Protocol
Leduc, Guy ULg

in Diaz, Michel (Ed.) Protocol Specification, Testing and Verification (1985, June)

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See detailAssessing the stimulant and sedative effects of alcohol with explicit and implicit measures in a balanced placebo design
Kreusch, Fanny ULg; Vilenne, Aurélie ULg; Quertemont, Etienne ULg

in Journal of Studies on Alcohol and Drugs (2013), 74(6), 923-930

Objective: Alcohol consumption is characterized by biphasic stimulant and sedative effects. In previous studies, various tools were used to assess these effects, including expectancy questionnaires ... [more ▼]

Objective: Alcohol consumption is characterized by biphasic stimulant and sedative effects. In previous studies, various tools were used to assess these effects, including expectancy questionnaires, implicit association tests, and self-report scales. The present study was aimed at clarifying the relationships between these measures. Method: Three different measures were used to directly or indirectly assess the stimulant and sedative effects of alcohol in 61 undergraduate students. The participants completed the Alcohol Expectancy Questionnaire (AEQ) and performed two unipolar Implicit Association Tasks to assess implicit associations between alcohol and the concepts of “stimulation” and “sedation.” The levels of alcohol consumption also were recorded by means of the Alcohol Use Disorders Identifi cation Test. An alcohol (0.4 g/kg) or placebo challenge was then administered using a balanced placebo design. After alcohol/placebo administration, the participants completed the Biphasic Alcohol Effects Scale (BAES). Results: Alcohol consumption signifi cantly correlated with AEQ alcohol explicit expectancies of arousal and relaxation, whereas no signifi cant correlations were obtained with the implicit associations. There were positive correlations between AEQ and BAES subscales, especially for the arousal subscale of the AEQ. Self-reported sedation recorded with the BAES was signifi cantly affected by what the participants believed that they had drunk but not by the actual consumption of alcohol. Conclusions: These fi ndings indicate that alcohol explicit expectancies of arousal measured with the AEQ best predict current alcohol consumption. Regarding explicit measures of alcohol-induced stimulation and sedation, BAES subscales seem to be more affected by alcohol drinking expectations than by actual alcohol consumption. [less ▲]

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See detailAssessing the success of river restoration projects through Geomorphology
Peeters, Alexandre ULg; Verniers, Gisèle; De le Court, Bernard et al

Conference (2013, August 30)

In the context of the Water Framework Directive’s goal of attaining “good ecological status”, a LIFE+ project (called Walphy), co-funded by the European Union and the Service Public de Wallonie, was ... [more ▼]

In the context of the Water Framework Directive’s goal of attaining “good ecological status”, a LIFE+ project (called Walphy), co-funded by the European Union and the Service Public de Wallonie, was launched in 2009. It aims to undertake experimental river restoration projects and to assess their success on the basis of ecological and geomorphological monitoring. Geomorphological monitoring differs depending on the type of restoration project: improvement of longitudinal continuity or transversal continuity. Restoration projects involving longitudinal continuity concern courses where obstacles impede the free movement of fish and sediment. In the Bocq basin, many of these obstacles (old weirs between 1 and 3 m high) have been removed. The release of sediment was studied using traced pebbles (PIT tags), which enable the recovery of bedload transport to be highlighted. Additional monitoring is based on the comparison of topographic surveys and cross-sections carried out pre- and post-removal. This can show a recovery of the natural transport of sediment when stream bed aggradation is observed downstream from the removed dam. Restoration projects involving transversal continuity concern straightened courses with artificial banks and therefore poor stream-floodplain connectivity. These works consist of enhancing river channels and restoring meanders or banks. Geomorphological monitoring is also based on surveys conducted pre- and post-restoration work. Some reaches have been improved by the reintroduction of spawning gravel. Several methods were used to characterize the clogging of this gravel reintroduction (hydraulic conductivity, wooden stakes). In addition, the mobility of this gravel was monitored using traced pebbles (PIT tags). Finally, restoration works and their stability and resistance to erosion are considered in relation to flood characteristics (discharge, recurrence, specific stream power and shear stress). [less ▲]

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See detailAssessing the Thermal Performance of Bedouin Tents in Hot Climates
Attia, Shady ULg

in Proceedings of the 1st International Conference on Energy & Indoor Environment for Hot Climates (2014, February 24)

The aims of this study it to improve conditions inside Bedouin tents shelters and to develop tools to assess shelter quality and comfort. A prototype tent was tested in hot conditions with an internal ... [more ▼]

The aims of this study it to improve conditions inside Bedouin tents shelters and to develop tools to assess shelter quality and comfort. A prototype tent was tested in hot conditions with an internal vapor load. Temperature, humidity measurements and air speed were taken inside the shelter while the external temperature was maintained at 40°C (104°F). Building performance simulation was conducted to produce a simulation model. A model of a tent was constructed using the EnergyPlus simulation software and were calibrated with the test data. The shelter models were simulated in Wadi Rum, Jordan using real data from. The feasibility of heating the tent using only the casual gains from occupants and solar radiation was investigated, although it was found that a tent heated in this way would only be appropriate in spring and autumn. Design issues included coping with stratification of air temperature inside the tent, improving thermal comfort without compromising fabricating the materials cheaply and simply. The validity of the results is limited by the lack of measured data for rates of air infiltration. [less ▲]

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See detailAssessing the World Ocean ventilation timescales with simple analogs - the leaky funnel model
Mouchet, Anne ULg; Deleersnijder, Eric

Poster (2011, May)

Detailed reference viewed: 11 (0 ULg)
See detailAssessing the World Ocean ventilation timescales with simple analogs - the leaky funnel model
Mouchet, Anne ULg; Deleersnijder, Eric

Conference (2009, February)

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See detailAssessing urbanisation effects on rainfall-runoff using a remote sensing supported modelling strategy
Verbeiren, Boud; Van de Voorde, Tim; Canters, Frank et al

in International Journal of Applied Earth Observation and Geoinformation (2013), 21

This paper aims at developing a methodology for assessing urban dynamics in urban catchments and the related impact on hydrology. Using a multi-temporal remote sensing supported hydrological modelling ... [more ▼]

This paper aims at developing a methodology for assessing urban dynamics in urban catchments and the related impact on hydrology. Using a multi-temporal remote sensing supported hydrological modelling approach an improved simulation of runoff for urban areas is targeted. A time-series of five medium resolution urban masks and corresponding sub-pixel sealed surface proportions maps was generated from Landsat and SPOT imagery. The consistency of the urban mask and sealed surface proportion timeseries was imposed through an urban change trajectory analysis. The physically based rainfall-runoff model WetSpa was successfully adapted for integration of remote sensing derived information of detailed urban land use and sealed surface characteristics. A first scenario compares the original land-use class based approach for hydrological parameterisation with a remote sensing sub-pixel based approach. A second scenario assesses the impact of urban growth on hydrology. Study area is the Tolka River basin in Dublin, Ireland. The grid-based approach of WetSpa enables an optimal use of the spatially distributed properties of remote sensing derived input. Though change trajectory analysis remains little used in urban studies it is shown to be of utmost importance in case of time series analysis. The analysis enabled to assign a rational trajectory to 99% of all pixels. The study showed that consistent remote sensing derived land-use maps are preferred over alternative sources (such as CORINE) to avoid over-estimation errors, interpretation inconsistencies and assure enough spatial detail for urban studies. Scenario 1 reveals that both the class and remote sensing sub-pixel based approaches are able to simulate discharges at the catchment outlet in an equally satisfactory way, but the sub-pixel approach yields considerably higher peak discharges. The result confirms the importance of detailed information on the sealed surface proportion for hydrological simulations in urbanised catchments. In addition a major advantage with respect to hydrological parameterisation using remote sensing is the fact that it is site- and period-specific. Regarding the assessment of the impact of urbanisation (scenario 2) the hydrological simulations revealed that the steady urban growth in the Tolka basin between 1988 and 2006 had a considerable impact on peak discharges. Additionally, the hydrological response is quicker as a result of urbanisation. Spatially distributed surface runoff maps identify the zones with high runoff production. It is evident that this type of information is important for urban water management and decision makers. The results of the remote sensing supported modelling approach do not only indicate increased volumes due to urbanisation, but also identifies the locations where the most relevant impacts took place. [less ▲]

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See detailAssessing wind comfort in urban planning
Reiter, Sigrid ULg

in Environment & Planning B : Planning & Design (2010), 37(5), 857-873

There are increasing concerns regarding the quality of urban public spaces. Wind is one important environmental factor that influences pedestrians’ comfort and safety. In modern cities, there are more and ... [more ▼]

There are increasing concerns regarding the quality of urban public spaces. Wind is one important environmental factor that influences pedestrians’ comfort and safety. In modern cities, there are more and more high constructions and complex forms which can involve significant problems of wind discomfort around these buildings. Today, architects and town planners need guidelines and simple design tools to take account of wind in their projects. This paper addresses the progress made towards computational fluid dynamics (CFD) simulations for assessing wind comfort in urban planning. We validated Fluent software for wind studies in urban environments by comparing our simulations results with wind tunnel tests. This validation shows that wind mean velocities around buildings can be simulated numerically with a very high degree of accuracy. Based on the results of a great number of CFD simulations, we developed a methodology and simple graphical tools to quantify critical wind speeds around buildings. This article should thus help in practice architects and town planners to design our built environment. Moreover, this paper shows how numerical modeling is now a high-performance tool to work out useful guidelines and simple design tools for urban planners. [less ▲]

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See detailAssessment and detection of pain in noncommunicative severely brain-injured patients.
Schnakers, Caroline ULg; Chatelle, Camille ULg; Majerus, Steve ULg et al

in Expert Review of Neurotherapeutics (2010), 10(11), 1725-31

Detecting pain in severely brain-injured patients recovering from coma represents a real challenge. Patients with disorders of consciousness are unable to consistently or reliably communicate their ... [more ▼]

Detecting pain in severely brain-injured patients recovering from coma represents a real challenge. Patients with disorders of consciousness are unable to consistently or reliably communicate their feelings and potential perception of pain. However, recent studies suggest that patients in a minimally conscious state can experience pain to some extent. Pain monitoring in these patients is hence of medical and ethical importance. In this article, we will focus on the possible use of behavioral scales for the assessment and detection of pain in noncommunicative patients. [less ▲]

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See detailAssessment and management of aortic stenosis [Evaluation et traitement de la sténose aortique]
Pirlet, C.; Magne, Julien ULg; Lancellotti, Patrizio ULg et al

in Revue Medicale Suisse (2011), 7(306), 1606-1611

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See detailAssessment and mechanism of variations in pubertal timing in internationally adopted children: a developmental hypothesis
Domine, Françoise ULg; Parent, Anne-Simone ULg; Rasier, Gregory et al

in European Journal of Endocrinology (2006), 155(Suppl. 1), 17-25

During the past decades, children migrating for international adoption have increased in number, creating an original condition of dramatic environmental change during development. In several countries ... [more ▼]

During the past decades, children migrating for international adoption have increased in number, creating an original condition of dramatic environmental change during development. In several countries, cohorts of these subjects have been shown to experience a global advancement in age at the onset of puberty, and sexual precocity is seen more frequently than in other conditions. Such early or precocious development has been assessed in relatively small cohorts or individual patients using well-defined physical indicators in comparison with updated references in the foster country. Family and adolescent evaluation of pubertal timing could allow for the study of large series of internationally adopted subjects. Also, this type of assessment integrates the physical changes of puberty with the adolescent changes in psychological and social functioning. The pathophysiological mechanisms leading to advancement of puberty in migrating children are still unclear and possibly involve several factors. In the present paper, we hypothesize that the sexual precocity in children migrating for international adoption could represent a developmentally programmed disorder resulting from cumulative anomalies in early remodeling of the central nervous system by communicational, social, nutritional, and hormonal inputs. There is some evidence that the deviations in those inputs can result in altered brain structure, particularly in the limbic system. We discuss the possible association with further disorders of developmental functions, such as cognitive, psychosocial, and sexual maturation. Along this hypothesis, some forms of idiopathic sexual precocity could result from dysfunction of one or several of the environmental programming factors, while other forms may involve predominantly genetic or familial factors. [less ▲]

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See detailAssessment and monitoring of forest-game balance: an exclosure experiment
Lehaire, François ULg; Licoppe, Alain ULg; Lejeune, Philippe ULg

Poster (2013, August)

During the last decades, populations of large ungulates have largely increased, strengthening the pressure exerted by these species on forest vegetation. Therefore, monitoring this pressure has become ... [more ▼]

During the last decades, populations of large ungulates have largely increased, strengthening the pressure exerted by these species on forest vegetation. Therefore, monitoring this pressure has become unavoidable for sustainable forest management. Such monitoring requires a rigorous approach in order to evaluate objectively the balance between game population and forestry. The use of exclosure experiment offers an interesting solution to observe the effects of game populations on forest ecosystem. When objectives expected from forest management are clearly defined, exclosure experiments can effectively be used as a monitoring tool, to allow detecting unbalanced situations, for example, herbivore pressure threatening forest regeneration. The monitoring tool combines on one side an exclosure, defined as "the real environment", fully accessible to herbivores and, on the other side an enclosure, which is the "control treatment", fenced and therefore unavailable to any large ungulates. Our main aim was to compute a set of indicators characterizing the ecological changes due to large herbivores pressure on forest ecosystems. We identified 2 categories of ecological indicators: the short-term and the medium-term indicators. Short-term indicators require only two-year of monitoring to correctly quantify herbivore pressure whereas medium-term indicators require at least 4 years of monitoring. The study site is located in Southern Belgium (Wallonia), in mixed beech and oak forests. The predominant vegetation type is the "Luzulo-Fagetum", typically found in acidophileous beech forests. The ungulate species of interest are red deer, roe deer, wild boar and mouflon. In 2006, enclosures and exclosures (4 x 4 m) were installed in 17 sites scattered in two zones with contrasted deer densities to assess indicators efficiency. Between 2006 and 2012, we performed floristic surveys and we recorded the height, density and cover of the understory vegetation of every plot. [less ▲]

Detailed reference viewed: 33 (10 ULg)