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See detailAssessing heat stress effects on production traits of Holsteins in a temperate region
Hammami, Hedi ULg; Bormann, Jeanne; Gengler, Nicolas ULg

Conference (2012)

Heat stress impaired productive, reproductive and animal behaviour. Examination of milk production loss due to heat stress was mainly evaluated in USA and few tropical countries using the temperature ... [more ▼]

Heat stress impaired productive, reproductive and animal behaviour. Examination of milk production loss due to heat stress was mainly evaluated in USA and few tropical countries using the temperature humidity index (THI1) developed in the 1950’s. The main objective of this study was to evaluate the effects of six new environmental stress indices on production traits in a temperate region. These indices include solar radiation and wind speed in addition to the temperature and humidity only defining THI1. For that purpose, 530820 milk, fat, protein, and somatic cell count first-lactation test-day records (TD) collected between 2000 and 2011 in Luxembourg were used. TD records were merged with meteorological data from 14 public weather stations. Each TD was assigned to the average daily thermal index of the 3 days before. Firstly, broken-line regression models were applied to identify the threshold of heat stress (THR) for each of the thermal indices. The decline of daily production of the different traits above THR point was assessed by mixed linear models including regression on unit of each of the thermal index. Estimates of THR were specific to each thermal index and trait. Significant decrease of milk, fat and protein yields above THR was observed for all studied thermal predictors. Whereas, an increase of the somatic cell score was observed above the specific THR point. THR estimates for THI1 and THI6 were of 68 and 80 and 62 and 78 for milk and protein yields respectively. Respective rate of decline per unit were of 0.243 and 0.188 kg and 0.0045 and 0.0051 kg respectively. Results from this phenotypic analysis show that evaluating heat tolerance based on bio-meteorological indicators is promising and phenotypic and genetic implications should be investigated. [less ▲]

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See detailAssessing heat stress effects on production traits of Holsteins in a temperate region
Hammami, Hedi ULg; Bormann, Jeanne; Gengler, Nicolas ULg

in Book of abstracts of the 63rd Annual Meeting of the European Association for Animal Production (2012)

Detailed reference viewed: 29 (7 ULg)
See detailAssessing IT Innovations in US State Governments: a research framework
Markus, M. Lynne; Bui, Quang Neo; Jacobson, Dax D. et al

Poster (2011, August)

Detailed reference viewed: 39 (10 ULg)
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See detailAssessing local Ca2+ concentrations in calcium phosphate scaffolds by computational modelling
Manhas, Varun ULg; Guyot, Yann ULg; Chai, Yoke Chin et al

Poster (2013, October 24)

Detailed reference viewed: 23 (4 ULg)
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See detailAssessing overall heating efficiency of office buildings
Parys, Wout; Bertagnolio, Stéphane ULg; Saelens, Dirk et al

in Lemort, Vincent; Andre, Philippe; Bertagnolio, Stéphane (Eds.) 8th Conference on System Simulation in Buildings (2010, December 13)

The current methodology applied to estimate system efficiencies oversimplifies the complex interaction between the building, the occupants and the system. By detailed modelling of the building and the ... [more ▼]

The current methodology applied to estimate system efficiencies oversimplifies the complex interaction between the building, the occupants and the system. By detailed modelling of the building and the system, it is possible to define system efficiencies at the building level as a function of the system type and the building characteristics. In this study, the performance of a simple heating system in a middle-sized office building is simulated. The monthly average total efficiency, defined at the building level, proves to be very well correlated with the monthly ratio of heat gains over heat losses of the building. At ratios over 0.6, the efficiency falls sharply. This is mainly due to declining control efficiency. This secondary effect can annul partly the targeted increase in energy efficiency of well insulated and airtight buildings. [less ▲]

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

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

To support policy makers combating travel-related externalities, quality data is required for the design and management of transportation systems and policies. To this end, large amounts of money have ... [more ▼]

To support policy makers combating travel-related externalities, quality data is required for the design and management of transportation systems and policies. To this end, large amounts of money have been spent on collecting household and person-based data. The main objective of this paper is to assess the quality of origin-destination matrices derived from household activity/travel surveys. To this purpose, a Monte Carlo experiment is set up to estimate the precision of OD-matrices given different sampling rates. The Belgian 2001 census data, containing work/school-related travel information for all 10,296,350 residents, are used for the experiment. For different sampling rates, 2000 random stratified samples are drawn. For each sample, three origin-destination-matrices are composed: one at municipality level, one at district level, and one at 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 OD-matrices can be directly derived from these surveys. Only when half of the population is queried, an acceptable OD-matrix is obtained at provincial level. Therefore, it is recommended to use additional information to better grasp the behavioral realism underlying destination choices and to collect information about particular origin-destination pairs by means of vehicle intercept surveys. In addition, the results suggest using the MCAPE next to traditional criteria to examine dissimilarities between different OD 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 reactive power reserves with respect to operating constraints and voltage stability
Capitanescu, Florin ULg

in IEEE Transactions on Power Systems (2011), 26(4), 2224-2234

This paper proposes a two-step approach to evaluate reactive power reserves with respect to operating constraints and voltage stability for a set of postulated operating scenarios. The first step ... [more ▼]

This paper proposes a two-step approach to evaluate reactive power reserves with respect to operating constraints and voltage stability for a set of postulated operating scenarios. The first step determines the minimum overall needed reactive power reserves of generators such that the system withstands, from a static viewpoint, any postulated scenario. This problem is formulated as a security constrained optimal power flow (SCOPF) which includes operating constraints relative to all postulated scenarios. Particular attention is paid to the techniques aimed to reduce the large size of the SCOPF problem. The second step determines additional reserves to ensure voltage stability of scenarios for which, when modeling dynamic system behaviour, the reserves obtained by SCOPF are insufficient. These reserves are computed using a heuristic technique which relies on dynamic simulation. Numerical results on four test systems of 60, 118, 618, and 1203 buses support the interest of the approach. [less ▲]

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See detailAssessing Response to Industrial Marketing Strategy
Choffray, Jean-Marie ULg; Lilien, Gary L.

in Journal of Marketing (1978)

An operational structure for use in making new industrial products design and marketing decisions

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See detailAssessing spatio-temporal variability and trends in modelled and measured Greenland Ice Sheet albedo (2000–2013)
Alexander, P.; Tedesco, M.; Fettweis, Xavier ULg et al

in Cryosphere (The) (2014), 8

Accurate measurements and simulations of Greenland Ice Sheet (GrIS) surface albedo are essential, given the role of surface albedo in modulating the amount of absorbed solar radiation and meltwater ... [more ▼]

Accurate measurements and simulations of Greenland Ice Sheet (GrIS) surface albedo are essential, given the role of surface albedo in modulating the amount of absorbed solar radiation and meltwater production. In this study, we assess the spatio-temporal variability of GrIS albedo during June, July, and August (JJA) for the period 2000–2013. We use two remote sensing products derived from data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS), as well as outputs from the Modèle Atmosphérique Régionale (MAR) regional climate model (RCM) and data from in situ automatic weather stations. Our results point to an overall consistency in spatio-temporal variability between remote sensing and RCM albedo, but reveal a difference in mean albedo of up to ~0.08 between the two remote sensing products north of 70° N. At low elevations, albedo values simulated by the RCM are positively biased with respect to remote sensing products by up to ~0.1 and exhibit low variability compared with observations. We infer that these differences are the result of a positive bias in simulated bare ice albedo. MODIS albedo, RCM outputs, and in situ observations consistently indicate a decrease in albedo of −0.03 to −0.06 per decade over the period 2003–2013 for the GrIS ablation area. Nevertheless, satellite products show a decline in JJA albedo of −0.03 to −0.04 per decade for regions within the accumulation area that is not confirmed by either the model or in situ observations. These findings appear to contradict a previous study that found an agreement between in situ and MODIS trends for individual months. The results indicate a need for further evaluation of high elevation albedo trends, a reconciliation of MODIS mean albedo at high latitudes, and the importance of accurately simulating bare ice albedo in RCMs. [less ▲]

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See detailAssessing structure potential in soil and water conservation: monitoring top soil hydrology from micro to field scale.
Kummert, Nora ULg; Beckers, Eléonore ULg; Roisin, Christian et al

in Wollesen de Jonge, Lis; Moldrup, Per; Lindblad Vendelboe, Anders (Eds.) 1st international conference and exploratory workshop on soil architecture and physico-chemical functions "CESAR" (2010)

Soil structure is a key parameter influencing erosion and water transfers. This paper describes an experiment that covers different aspects of soil structure. Three tillage systems are tested: reduced ... [more ▼]

Soil structure is a key parameter influencing erosion and water transfers. This paper describes an experiment that covers different aspects of soil structure. Three tillage systems are tested: reduced tillage, and two ploughing systems. At micro-scale, analyses are tomography which study images to determine porosity characteristics (connectivity, size, number…) and pF curves where total available water and effective porosity are deducted. At field scale, soil losses and runoff are collected and measured after rainfall simulation on plots for the different tillage systems. The comparison of the results for both scales shows the links between phenomenons at those scales. [less ▲]

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See detailAssessing the Accuracy of Simulation Model for Septoria Leaf Blotch Disease Progress on Winter Wheat.
El Jarroudi, Moussa ULg; Delfosse, Philippe; Maraite, Henri et al

in Plant Disease (2009), 93

A mechanistic model, PROCULTURE, for assessing the development of each of the last five leaf layers and the progress of Septoria leaf blotch, caused by Septoria tritici (teleomorph Mycosphaerella ... [more ▼]

A mechanistic model, PROCULTURE, for assessing the development of each of the last five leaf layers and the progress of Septoria leaf blotch, caused by Septoria tritici (teleomorph Mycosphaerella graminicola), has been applied on susceptible and weakly susceptible winter wheat (Triticum aestivum) cultivars in two locations (Everlange and Reuland) in Luxembourg over a 3-year period (2000 to 2002). A double performance assessment of PROCULTURE was conducted in this study. First, the capability of PROCULTURE to correctly simulate S. tritici incidence was checked. Second, the model's ability to accurately estimate disease severity was assessed on the basis of the difference between simulated and observed levels of disease development at each leaf layer. The model accurately predicted disease occurrence in the 2000 and 2002 seasons, on susceptible and semi-susceptible cultivars, with a probability of detection (POD) exceeding 0.90. However, in 2001, even though the POD never fell below 0.90, the false alarm ratio (FAR) was too high to consider the simulations satisfactory. Concerning the evaluation of disease severity modeling, statistical tests revealed accurate simulations performed by PROCULTURE for susceptible cultivars in 2000 and 2002. By contrast, for weakly susceptible cultivars, the model overestimated disease severity, especially for the upper leaves, for the same period. [less ▲]

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See detailAssessing the accuracy of the surface gravity determination in late-type stars with solar-like pulsators
Morel, Thierry ULg; Miglio, Andrea ULg

in Monthly Notices of the Royal Astronomical Society (2012), 419

The frequency of maximum oscillation power measured in dwarfs and giants exhibiting solar-like pulsations provides a precise, and potentially accurate, inference of the stellar surface gravity. An ... [more ▼]

The frequency of maximum oscillation power measured in dwarfs and giants exhibiting solar-like pulsations provides a precise, and potentially accurate, inference of the stellar surface gravity. An extensive comparison for about 40 well-studied pulsating stars with gravities derived using classical methods (ionization balance, pressure-sensitive spectral features or location with respect to evolutionary tracks) supports the validity of this technique and reveals an overall remarkable agreement with mean differences not exceeding 0.05 dex (although with a dispersion of up to ˜0.2 dex). It is argued that interpolation in theoretical isochrones may be the most precise way of estimating the gravity by traditional means in nearby dwarfs. Attention is drawn to the usefulness of seismic targets as benchmarks in the context of large-scale surveys. [less ▲]

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See detailAssessing the causes inducing lengthening of hospital stays by means of the Appropriateness Evaluation Protocol.
Fontaine, Pierre ULg; Jacques, Jessica ULg; Gillain, Daniel ULg et al

in Health Policy (2011)

OBJECTIVES: The objective is to evaluate the use of the Appropriateness Evaluation Protocol (AEP) as a screening tool for determining the causes of the non-justified days to help hospitals to decrease the ... [more ▼]

OBJECTIVES: The objective is to evaluate the use of the Appropriateness Evaluation Protocol (AEP) as a screening tool for determining the causes of the non-justified days to help hospitals to decrease the length of stay while preserving the quality of care. METHODS: Three successive cross-sectional surveys were conducted from 2003 till 2005, in 23 Belgian hospitals. During this period, 10921 days were audited by means of the AEP. This study is focused on adult acute non-intensive care units. The appropriateness of each day of the sample was assessed, and for those considered as inappropriate, the reasons explaining the prolongation of the stay were investigated. RESULTS: The proportion of inappropriate days was 24.61%. There is a high variability across specialties and hospitals. Regarding inappropriate days, the analysis of causes of prolongation, globally, by bed index or by hospital, indicated clearly internal and external factors that lengthen stays. The most frequent reasons are waits for an examination (22%) and the lack of extra-hospital structures (31%). CONCLUSIONS: The use of AEP as a tool of internal audit to measure the proportion of non-justified days and their causes turns out to be possible and the obtained results has provided some accurate and useful information for the participating, and allowed them to take concrete decisions which lead to shrinking of the length of hospital stay. [less ▲]

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See detailAssessing the Effect of Persistent Organic Pollutants on Reproductive Activity in Common Dolphins and Harbour Porpoises
Murphy, S.; Pierce, G.; Law, R. et al

in Journal of Northwest Atlantic Fishery Science (2010), 42

Detailed reference viewed: 29 (9 ULg)