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See detailAssessing the passage of obstacles by fish. Concepts, design and application
Baudoin, Jean-Marc; Burgun, Vincent; Chanseau, Matthieu et al

Book published by Onema - Editeur: Véronique Barre (2015)

The fragmentation of habitats has been acknowledged for 30 years as one of the five main factors of biodiversity loss, in conjunction with pollution, overuse of natural resources, invasive species and ... [more ▼]

The fragmentation of habitats has been acknowledged for 30 years as one of the five main factors of biodiversity loss, in conjunction with pollution, overuse of natural resources, invasive species and climate change. Since then, public environmental policies have strived to restore the connectivity of natural habitats. That is particularly the case for water policy, which has made the ecological continuity of rivers a central element in policy planning, a quality element for monitoring programmes and one of the basic guidelines for river-basin management plans (RBMP). The time has thus come for decisions, with the resulting controversy given that any attempt to modify existing discontinuities impacts our perception of landscapes and various uses of aquatic environments. Given that there is, on average, at least one obstacle for every five kilometres of river in continental France, this issue concerns the entire country, its population and all water managers. That explains why it was necessary to have a single set of standardised procedures for selecting the work to be done on the basis of objective and comparable data. For the ecological continuity of fish, we now have the ICE method presented in this book, which describes obstacles in rivers and assesses the capacity of fish to overcome those obstacles during their upstream migration. The design, development and national deployment of this method required five years of intense, collective effort on the part of numerous scientists and the Onema local and regional offices. The method is the result of an outstanding multi-disciplinary approach involving both hydraulics and ecology, two disciplines that some people might see as irreconcilable, but that must work together synergistically in the effort to restore environments. The publication of this book in the Knowledge for action series marks the transition from the team that developed the method to the people who will use it to acquire better understanding of ecological continuity in rivers and as an operational tool in implementing water policy and enhancing biodiversity. [less ▲]

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See detailAssessing the potential of an algorithm based on mean climatic data to predict wheat yield
Dumont, Benjamin ULg; Leemans, Vincent ULg; Ferrandis, Salvador et al

in Precision Agriculture (2014), 15(3)

The real-time non-invasive determination of crop biomass and yield prediction is one of the major challenges in agriculture. An interesting approach lies in using process-based crop yield models in ... [more ▼]

The real-time non-invasive determination of crop biomass and yield prediction is one of the major challenges in agriculture. An interesting approach lies in using process-based crop yield models in combination with real-time monitoring of the input climatic data of these models, but unknown future weather remains the main obstacle to reliable yield prediction. Since accurate weather forecasts can be made only a short time in advance, much information can be derived from analyzing past weather data. This paper presents a methodology that addresses the problem of unknown future weather by using a daily mean climatic database, based exclusively on available past measurements. It involves building climate matrix ensembles, combining different time ranges of projected mean climate data and real measured weather data originating from the historical database or from real-time measurements performed in the field. Used as an input for the STICS crop model, the datasets thus computed were used to perform statistical within-season biomass and yield prediction. This work demonstrated that a reliable predictive delay of 3-4 weeks could be obtained. In combination with a local micrometeorological station that monitors climate data in real-time, the approach also enabled us to (i) predict potential yield at the local level, (ii) detect stress occurrence and (iii) quantify yield loss (or gain) drawing on real monitored climatic conditions of the previous few days. [less ▲]

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See detailAssessing the potential of an algorithm based on mean climatic data to predict wheat yield.
Dumont, Benjamin ULg; Leemans, Vincent ULg; Ferrandis Vallterra, Salvador ULg et al

in Proceedings of the 11th International Conference on Precision Agriculture (2012, July)

Real-time non-invasive determination of crop biomass and yield prediction are maybe among the major challenges in agriculture. But unknown future weather remains the key point of accurate yield forecast ... [more ▼]

Real-time non-invasive determination of crop biomass and yield prediction are maybe among the major challenges in agriculture. But unknown future weather remains the key point of accurate yield forecast. This paper presents the results of a preliminary study that aims to supply the unknown future by daily mean climatic data. The results show that under the Belgian weather, this approach is relevant. Furthermore, the developed methodology appears to be a powerful diagnosis tool of the remaining yield potential under ongoing weather. [less ▲]

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See detailAssessing the potential of calcium-based artificial ocean alkalinization to mitigate rising atmospheric CO2 and ocean acidification
Ilyina, Tatiana; Wolf-Gladrow, Dieter; Munhoven, Guy ULg et al

in Geophysical Research Letters (2013), 40(22), 5909-5914

Enhancement of ocean alkalinity using calcium compounds, e.g., lime has been proposed to mitigate further increase of atmospheric CO2 and ocean acidification due to anthropogenic CO2 emissions. Using a ... [more ▼]

Enhancement of ocean alkalinity using calcium compounds, e.g., lime has been proposed to mitigate further increase of atmospheric CO2 and ocean acidification due to anthropogenic CO2 emissions. Using a global model, we show that such alkalinization has the potential to preserve pH and the saturation state of carbonate minerals at close to today's values. Effects of alkalinization persist after termination: Atmospheric CO2 and pH do not return to unmitigated levels. Only scenarios in which large amounts of alkalinity (i.e., in a ratio of 2:1 with respect to emitted CO2) are added over large ocean areas can boost oceanic CO2 uptake sufficiently to avoid further ocean acidification on the global scale, thereby elevating some key biogeochemical parameters, e.g., pH significantly above preindustrial levels. Smaller-scale alkalinization could counteract ocean acidification on a subregional or even local scale, e.g., in upwelling systems. The decrease of atmospheric CO2 would then be a small side effect. [less ▲]

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See detailAssessing the Potential of Zwitterionic NHC•CS2 Adducts for Probing the Stereoelectronic Parameters of N-Heterocyclic Carbenes
Delaude, Lionel ULg; Demonceau, Albert ULg; Wouters, Johan

in European Journal Of Inorganic Chemistry (2009), (13), 1882-1891

Five imidazol(in)ium-2-dithiocarboxylates bearing cyclohexyl, mesityl, or 2,6-diisopropylphenyl substituents on their nitrogen atoms were prepared from the corresponding N-heterocyclic carbenes (NHCs) by ... [more ▼]

Five imidazol(in)ium-2-dithiocarboxylates bearing cyclohexyl, mesityl, or 2,6-diisopropylphenyl substituents on their nitrogen atoms were prepared from the corresponding N-heterocyclic carbenes (NHCs) by reaction with carbon disulfide. They were characterized by IR, UV/Vis, and NMR spectroscopy, and by thermogravimetric analysis. Their molecular structures were determined by X-ray diffraction. For the sake of comparison, tricyclohexylphosphonium dithiocarboxylate was also examined. The data acquired were scrutinized to evaluate their usefulness for assessing the steric and electronic properties of NHC ligands. Because of their outstanding ability to crystallize, the five NHC center dot CS2 betaines were found to be highly suitable for probing the steric influence of nitrogen atom substituents on imidazolylidene-based ligand precursors via XRD analysis, while the corresponding NHC center dot CO2 adducts were deemed more appropriate for evaluating the sigma-donating properties of carbene ligands. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [less ▲]

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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 (2014)

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 Experimental Data with Gaussian Processes: Example with an Injection Scroll Compressor
Quoilin, Sylvain ULg; Schrouff, Jessica ULg

in Proceedings of the 2014 Purdue Conferences (2014)

This paper describes an experimental study carried out on a refrigeration scroll compressor with and without vapour injection. The test rig designed for that purposed allows evaluating the performance ... [more ▼]

This paper describes an experimental study carried out on a refrigeration scroll compressor with and without vapour injection. The test rig designed for that purposed allows evaluating the performance over a wide range of operating conditions, by varying the supply pressure, the injection pressure, the discharge pressure, the supply superheating and the injection superheating. 97 Steady-state points are measured, with a maximum isentropic efficiency of 64.1% and a maximum consumed electrical power of 13.1 kW. A critical analysis of the experimental results is then carried out to evaluate the quality of the data using a machine learning method. This method based on Gaussian Processes regression, is used to build a statistical operating map of the compressor as a function of the different inputs. This statistical operating map can then be compared to the experimental data points to evaluate their accuracy. [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 Risk of Ecosystem Disruption in Europe using a Dynamic Vegetation Model driven by CMIP5 Regional Climatic Projections from EURO-CORDEX
Dury, Marie ULg; Hambuckers, Alain ULg; Henrot, Alexandra-Jane ULg et al

Conference (2015, December 18)

While the combination of warmer and drier mean climatic conditions can have severe impacts on ecosystems, extreme events like droughts or heat waves that break the gradual climate change can have more ... [more ▼]

While the combination of warmer and drier mean climatic conditions can have severe impacts on ecosystems, extreme events like droughts or heat waves that break the gradual climate change can have more long-term consequences on ecosystem composition, functioning and carbon storage. Hence, it is essential to assess the changes in climatic variability and the changes in frequency of extreme events projected for the future. Ecosystems could not be in a condition to adapt to these new conditions and might be disrupted. Here, the process-based dynamic vegetation model CARAIB DVM was used to evaluate and analyze how future climate and extreme events will affect European ecosystems. To quantify the uncertainties in the climatic projections and in their potential impacts on ecosystems, the vegetation model was driven with the outputs of different regional climatic models (RCMs), nested in CMIP5 GCM projections for the EURO-CORDEX project. We used the ALADIN version 5.3 (Météo-France/CNRM) and other EURO-CORDEX RCMs. These climatic projections are at a high spatial resolution (0.11-degree, ~12 km). CARAIB simulations were performed across Europe over the historical period 1951-2005 and the future period 2006-2100 under RCP4.5 and RCP8.5 emission scenarios. We simulated a set of 99 individual species (47 herbs, 12 shrubs and 40 trees) representing the major European ecosystem flora. First, we analyzed the climatic variability simulated by the climatic models over the historical period and compared it with the observed climatic variability. None of these climatic models can reproduce accurately the present natural climatic variability. Then, to assess the risk of ecosystem disruption in the future and to identify the vulnerable areas in Europe, we created an index combining several CARAIB outputs: runoff, mean NPP, soil turnover, burned area, appearance and disappearance of species. We evaluated the severity of change projected for these variables (period 2071-2100) relative to their current variability (period 1961-1990). Mean changes were considered severe if they exceed observed variability. The highest values of the index were found in southern Europe, indicating that the amplitude of the expected ecosystem changes largely exceeds current interannual variability in this area. [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)

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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)

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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 ASHRAE 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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