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See detailEvaluation of adaptive facades: The case study of Al Bahr Towers in the UAE
Attia, Shady ULiege

in Shaping Qatar’s Sustainable Built Environment (2017), 2(6), 1-13

The assessment of adaptive facades presents a barrier as there is no established assessment technique. Many of the available facade performance evaluation systems or frameworks have limited applicability ... [more ▼]

The assessment of adaptive facades presents a barrier as there is no established assessment technique. Many of the available facade performance evaluation systems or frameworks have limited applicability for such advanced building facades. The complexity of adaptive or dynamic facades’ evaluation is related to the performance evaluation of facade elements, systems, and overall building performance coupled with occupant behavior and occupant satisfaction. In this context, this paper presents a case study of an adaptive sunscreen facade and evaluation of its performance and occupant behavior. The evaluation mainly focuses on pre- and post-construction phases of adaptive facades: the design assist phase (including the durability test, visual mockup, onsite mashrabiya mounting, and weather stripping), the commissioning phase (field verification and performance testing), and the monitoring phase. The selected project is a 150-meter-high twin tower that stands with a honeycombinspired structure and automated dynamic solar screen that responds to the sun’s movement. These solar screens respond dynamically and automatically to the angle of the sun, which improves the control over energy consumption, solar radiation, and glare with the ability to allow natural light into the building. This paper is part of the research activities of working group 3 of the European COST Action 1403 on “Adaptive Facades”. Different methods were used for evaluation and these include the following: interviews with the architect, facade engineer, technical control specialist and occupants, reviews of standards and codes, review of energy models, and a systematic design process mapping. A documentation of the case study describing the post-construction occupant comfort and facade operation was prepared. This paper’s audience comprises mainly project managers, architects, and building facade engineers together with facility managers who are concerned with the process of design, construction, and operation of adaptive sunscreens facades. The outcome of this study identifies quantifiable performance indicators and effective strategies for the design and performance evaluation of optimal adaptive facades. [less ▲]

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See detailExperimental and theoretical analysis of shear bolted connections for tubular structures
D'Antimo, Marina ULiege; Demonceau, Jean-François ULiege; Jaspart, Jean-Pierre ULiege et al

in Journal of Constructional Steel Research (2017), 138

In this paper, numerical and experimental investigations devoted to the evaluation of the bearing resistance of tubular members with gusset plates and through-all long bolts are presented. Unlike lap ... [more ▼]

In this paper, numerical and experimental investigations devoted to the evaluation of the bearing resistance of tubular members with gusset plates and through-all long bolts are presented. Unlike lap shear joints, the analysed connection evidences a reduced confinement of the bearing area associated to the use of long bolts and the presence of a gap in the member, which can lead, consequently, to a reduction of the bearing resistance. In order to investigate the behaviour of shear connections made up of thin and thick SHS (Square Hollow Section) profiles and long bolts, an experimental test campaign including 24 specimens and FE simulations have been conducted. Both experimental and FE results have confirmed the influence of local instability on the hole in bearing resistance of thin profiles and the poor accuracy of the available standards for this particular joint typology. In particular, the performed comparisons have shown that, for thin profiles, EC3 model is likely to overestimate the resistance, while for higher thickness of the SHS conservative predictions are obtained. The present paper presents the conducted experimental and numerical investigations, highlighting at the end the need for a proper formulation able to account for the local instability effect on the bearing resistance. [less ▲]

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See detailAn incremental-secant mean-field homogenization method with second statistical moments for elasto-visco-plastic composite materials
Wu, Ling ULiege; Adam, Laurent; Doghri, Issam et al

in Mechanics of Materials (2017), 114

This paper presents an extension of the recently developed incremental-secant mean-field homogenization (MFH) procedure in the context of elasto-plasticity to elasto-visco-plastic composite materials ... [more ▼]

This paper presents an extension of the recently developed incremental-secant mean-field homogenization (MFH) procedure in the context of elasto-plasticity to elasto-visco-plastic composite materials while accounting for second statistical moments. In the incrementalsecant formulation, a virtual elastic unloading is performed at the composite level in order to evaluate the residual stress and strain states in the different phases, from which a secant MFH formulation is applied. When applying the secant MFH process, the Linear-Comparison-Composite is built from the piece-wise heterogeneous residual strain-stress state using naturally isotropic secant tensors defined using either first or second statistical moment values. As a result non-proportional and non-radial loading conditions can be considered because of the incremental-secant formulation, and accurate predictions can be obtained as no isotropization step is required. The limitation of the incremental-secant formulation previously developed was the requirement in case of hard inclusions to cancel the residual stress in the matrix phase, resulting from the composite material unloading, to avoid over-stiff predictions. It is shown in this paper that in the case of hard inclusions by defining a proper second statistical moment estimate of the von Mises stress, the residual stress can be kept in the different composite phases. Moreover it is shown that the method can be extended to visco-plastic behaviors without modifying the homogenization process as the incremental-secant formulation only requires the definition of the secant operator of the different phase material models. Finally, it is shown that although it is also possible to define a proper second statistical moment estimate of the von Mises stress in the case of soft inclusions, this does not improve the accuracy as compared to the increment-secant method with first order statistical moment estimates. [less ▲]

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See detailRecommandation pour le dépistage du mésusage d'alcool et de l'intervention brève subséquente par les médecins du travail
Godderis, Lode; Lambrechts, Marie-Claire; Vanmeerbeek, Marc ULiege et al

Report (2017)

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See detailBIGMOMAL - Big Data Analytics for Mobile Malware Detection
Wassermann, Sarah ULiege; Casas, Pedro

Poster (2017, November)

Mobile malware is on the rise. Due to their popularity, smartphones represent an attractive target for cybercriminals, especially regarding unauthorized access to private user data; smartphones ... [more ▼]

Mobile malware is on the rise. Due to their popularity, smartphones represent an attractive target for cybercriminals, especially regarding unauthorized access to private user data; smartphones incorporate a lot of sensitive information about users, even more than a personal computer. Indeed, besides personal information such as documents, accounts, passwords, contacts, etc., smartphone sensors centralize other sensitive data such as user location, physical activities, etc. In this paper, we study the problem of malware detection in smartphones, using supervised machine learning models and big data analytics frameworks. Using a publicly available dataset for smartphone data analysis (the SherLock data collection, see http://bigdata.ise.bgu.ac.il/sherlock/), we train and benchmark different supervised machine learning models to detect malware apps activity.The Sherlock data collection is a crowdsourcing-based smartphone dataset in which hundreds of features from many different "sensors" or vantage points within the device are monitored, using a tailored smartphone agent. The collection is done during a long-term - 2 years (2015/16), field trial on 50 smartphones used as primary device for 50 different participants. The monitoring agent collects a wide variety of network, software and sensor data at a high sample rate (as low as 5 seconds); in addition, participant devices include a sandbox-like smartphone agent which runs controlled malware apps, perpetrating attacks on the user's device (such as contacts theft, spyware, phishing, etc.), while creating labels for the SherLock dataset. The complete labeled dataset contains more than 10 billion data records, with a total of about 4 TB of data. We additionally complement the labels for malicious apps which might have been installed by participants by analyzing the installed apps' hashes in Virus Total (https://www.virustotal.com), a well-known multi antivirus online scanning system. From the complete dataset, we keep two specific feature categories: all those features related to the network traffic generated by the apps, and all those features corresponding to the footprint of the app on the CPU and internal running processes (e.g., statistics on CPUs, memory usage, linux-level processes information, etc.). The rationale is that some malware activity would be more visible at the network traffic level, whereas some others would be better identified at the local processes level. Using this dataset, we train different machine learning models (e.g., decision trees, neural networks, SVMs, etc.) and verify their accuracy to automatically spot out malicious apps running on the users’ devices. We also apply feature selection strategies to improve results and reduce computational times. Given the size of the dataset, we rely on big data platforms (such as Spark) to perform the analysis, complementing the machine learning based analysis with scikit-learn like pipelines. We evaluate three different concepts, including (i) overall model performance (using multi-fold cross validation on the complete dataset), (ii) generalization of the learned models across different users (train in N-1 users, and test in the remaining user), and (iii) detection accuracy drift along time (train during first month, test the resulting model in the subsequent months). Initial results are very promising, especially regarding overall model performance for decision tree based models. [less ▲]

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See detailMeasuring brain synaptic vesicle protein 2A with positron emission tomography and [18F]UCB-H.
Bahri, Mohamed Ali ULiege; Plenevaux, Alain ULiege; Aerts, Joël ULiege et al

in Alzheimer’s & Dementia: Translational Research & Clinical Interventions (2017), 4(4), 481-486

Introduction: Brain distribution of synaptic vesicle protein 2Awas measured with fluorine-18 UCBH ([18F]UCB-H) and positron emission tomography (PET). Methods: Images of synaptic density were acquired in ... [more ▼]

Introduction: Brain distribution of synaptic vesicle protein 2Awas measured with fluorine-18 UCBH ([18F]UCB-H) and positron emission tomography (PET). Methods: Images of synaptic density were acquired in healthy volunteers (two young participants and two seniors). Input function was measured by arterial blood sampling (arterial input function) and derived from PET images using carotid activity (image-derived input function). Logan graphical analysis was used to estimate regional synaptic vesicle protein 2A distribution volume. Results: [18F]UCB-H uptake was ubiquitous in cortical and subcortical gray matter. Arterial input function and image-derived input function provided regional distribution volume with a high linear relationship. Discussion: The cerebral distribution of [18F]UCB-H is similar to that recently observed with carbon-11 UCB-J ([11C]UCB-J). An accurate [18F]UCB-H quantification can be performed without invasive arterial blood sampling when no suitable reference region is available, using dynamic PET carotid activity. Brain synaptic density can be studied in vivo in normal and pathological aging. [less ▲]

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See detailCrowdsourcing for agricultural applications: A review of uses and opportunities for a farmsourcing approach
Minet, Julien ULiege; Curnel, Yannick; Gobin, Anne et al

in Computers & Electronics in Agriculture (2017), 142, Part A

Abstract Crowdsourcing, understood as outsourcing tasks or data collection by a large group of non-professionals, is increasingly used in scientific research and operational applications. In this paper ... [more ▼]

Abstract Crowdsourcing, understood as outsourcing tasks or data collection by a large group of non-professionals, is increasingly used in scientific research and operational applications. In this paper, we reviewed crowdsourcing initiatives in agricultural science and farming activities and further discussed the particular characteristics of this approach in the field of agriculture. On-going crowdsourcing initiatives in agriculture were analysed and categorised according to their crowdsourcing component. We identified eight types of agricultural data and information that can be generated from crowdsourcing initiatives. Subsequently we described existing methods of quality control of the crowdsourced data. We analysed the profiles of potential contributors in crowdsourcing initiatives in agriculture, suggested ways for increasing farmers’ participation, and discussed the on-going initiatives in the light of their target beneficiaries. While crowdsourcing is reported to be an efficient way of collecting observations relevant to environmental monitoring and contributing to science in general, we pointed out that crowdsourcing applications in agriculture may be hampered by privacy issues and other barriers to participation. Close connections with the farming sector, including extension services and farm advisory companies, could leverage the potential of crowdsourcing for both agricultural research and farming applications. This paper coins the term of farmsourcing as a professional crowdsourcing strategy in farming activities and provides a source of recommendations and inspirations for future collaborative actions in agricultural crowdsourcing. [less ▲]

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See detailThrough the Wormhole: Tracking Invisible MPLS Tunnels
Vanaubel, Yves ULiege; Mérindol, Pascal; Pansiot, Jean-Jacques et al

in ACM Internet Measurement Conference (2017, November)

For years, Internet topology research has been conducted through active measurement. For instance, CAIDA builds router level topologies on top of IP level traces obtained with traceroute. The resulting ... [more ▼]

For years, Internet topology research has been conducted through active measurement. For instance, CAIDA builds router level topologies on top of IP level traces obtained with traceroute. The resulting graphs contain a significant amount of nodes with a very large degree, often exceeding the actual number of interfaces of a router. Although this property may result from inaccurate alias resolution, we believe that opaque MPLS clouds made of invisible tunnels are the main cause. Using Layer-2 technologies such as MPLS, routers can be configured to hide internal IP hops from traceroute. Consequently, an entry point of an MPLS network appears as the neighbor of all exit points and the whole Layer-3 network turns into a dense mesh of high degree nodes. This paper tackles three problems: the revelation of IP hops hidden by MPLS tunnels, the MPLS deployment underestimation, and the overestimation of high degree nodes. We develop new measurement techniques able to reveal the presence and content of invisible MPLS tunnels. We assess them through emulation and cross-validation and perform a large-scale measurement campaign targeting suspicious networks on which we apply statistical analysis. Finally, based on our dataset, we look at basic graph properties impacted by invisible tunnels. [less ▲]

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See detailImproving QoE Prediction in Mobile Video through Machine Learning
Casas, Pedro; Wassermann, Sarah ULiege

in Proc. 8th International Conference on Network of the Future (2017, November)

Despite the massive adoption of HTTP adaptive streaming technology, buffering is still the most harmful event for QoE in video streaming. Previous studies have shown that buffering is not only detrimental ... [more ▼]

Despite the massive adoption of HTTP adaptive streaming technology, buffering is still the most harmful event for QoE in video streaming. Previous studies have shown that buffering is not only detrimental for the overall user experience, but is also highly correlated to viewer engagement. The occurrence of buffering is particularly critical in cellular networks and mobile video deployments, as network conditions are less stable and network resources more limited. In this context, monitoring and properly predicting the QoE of video streaming services becomes paramount to cellular network operators, who need to offer high quality levels to reduce the risks of customers churning for quality dissatisfaction. In this paper, we present a novel approach to multi-dimensional QoE prediction in mobile video using machine learning models. Contrary to previous models for QoE prediction in video streaming, which are generally uni- or low-dimensional and model the impact of single video descriptors independently, we use a high-dimensional input space to model the impact of buffering and initial delay on QoE.We train and test the proposed models on a publicly available mobile video dataset, generated from subjective QoE tests with real viewers. Besides improving prediction performance, the proposed models show that there is a clear influence of other buffering pattern descriptors generally neglected in previous models - in particular those linked to the occurrence of the last stalling event, shedding light on new KPIs to monitor for better QoE assessment in video streaming. [less ▲]

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See detailAssessment of damage and residual load bearing capacity of a concrete slab after fire: Applied reliability-based methodology
Molkens, Tom; Van Coile, Ruben; Gernay, Thomas ULiege

in Engineering Structures (2017), 150

For most fires occurring in buildings with a concrete structural frame, the structural elements do not collapse during fire exposure, and further use of the building after fire may be possible. Fire can ... [more ▼]

For most fires occurring in buildings with a concrete structural frame, the structural elements do not collapse during fire exposure, and further use of the building after fire may be possible. Fire can nevertheless result in a permanent loss of strength and thus a post-fire evaluation of the residual load bearing capacity has to be made to inform decisions on continued use and the need for structural repairs. This evaluation is however particularly difficult due to the many uncertainties associated with both the fire exposure and the characteristics of the structural elements. These uncertainties cannot be neglected when determining the residual capacity since adequate safety is a major societal concern as indicated by the predominance of safety in current design standards and guidance documents. In this paper a comprehensive methodology is presented for the assessment of the residual capacity of concrete structures after exposure to fire. The methodology is introduced through application to a real-life case study of an apartment fire with a focus on the end-span of the affected continuous concrete slab. It results in a reliability-based evaluation of the maximum allowable characteristic value for the imposed load on the slab. The presented methodology is useful to make informed decision about continued use of structures after a fire event. [less ▲]

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See detailCHAPTER 10 Measures of Wage Moderation in Times of Crisis: The Example of Belgium
Kéfer, Fabienne ULiege

in Laulom, Sylvaine (Ed.) Collective Bargaining Developments in Times of Crisis (2017)

The influence of the crisis on state interventionism in Belgian collective bargaining can be observed in various fields. Wage moderation lends itself particularly well to the demonstration, since a ... [more ▼]

The influence of the crisis on state interventionism in Belgian collective bargaining can be observed in various fields. Wage moderation lends itself particularly well to the demonstration, since a government intervention mechanism set up in 1996 was only activated from – and due to – the economic crisis and has been continuously in use between 2010 and 2016. The mesures of moderating wages are negociated by de representative organisations. The crosssectoral agreement concluded on 22 December 2008 only emerged after very difficult negotiations. It was not been possible to conclude any other agreement of this kind during the eight following years. Since 2010, interventions of public authority in the evolution of wages were subsidiary but reccurrent. [less ▲]

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See detailAnycast on the Move - A First Look at Mobile Anycast Performance
Wassermann, Sarah ULiege; Rula, John P.; Bustamante, Fabian

Poster (2017, November)

Service providers rely on replication to improve service performance and reliability, placing instances in multiple locations and redirecting clients to nearby copies. Anycast is a common mechanism used ... [more ▼]

Service providers rely on replication to improve service performance and reliability, placing instances in multiple locations and redirecting clients to nearby copies. Anycast is a common mechanism used for redirecting clients in a variety of domains from naming to CDNs and video streaming. IP anycast offers a method for making a service IP address available to a routing system from several locations at once, and clients' requests are directed based on BGP routing policies. For operators, IP anycast offers an economic, scalable, and simple approach to replicated services; BGP provides considerable robustness, adapting to changes in service and network availability. For clients, however, the mapping can be suboptimal, unstable, and seemingly chaotic, as routing policies have not only technical motivations, and routing changes can silently shift traffic from one site to another with a consequent loss of shared state and potential performance impact. Given its wide deployment and interesting tradeoffs, IP anycast has been the focus of much recent measurement work. All prior studies have, nevertheless, focused on wired networks despite the growing dominance of mobile Internet. Today, the number of mobile subscriptions is over 7.4 billion, and users spend over 2x times more hours browsing on their smartphones than on any other device, with the corresponding increase on cellular traffic. We present early results on the first study of anycast performance for mobile users. Our evaluation focuses on two distinct anycast services, K-and F-Root, each providing part the DNS Root zone. Both services are widely replicated with publicly available site locations and unicast IP addresses that allow us to evaluate the relative performance of anycast routing to its "optimal" (in terms of unicast) site location. We collected active measurements from geographically distributed clients on both cellular and WiFi networks from September 2016 until April 2017, using the Aqualab’s ALICE engine [1]. In each experiment clients launched ping and traceroute measurements towards the root servers’ anycast addresses, as well as to five chosen unicast addresses determined to be the closest to the client in terms of geographic distance, at an hourly rate. Clients also recorded their geographic location, anonymized to a 10 km² area. Our findings show that mobile clients are routed to suboptimal replicas in terms of geographical distance, more frequently while on a cellular connection than on WiFi, with a significant impact on perceived service performance. The phenomenon seems to be more pronounced for K-Root than for F-Root. A possible explanation for the long distances would be that our cellular clients are simply far away from all the available replicas. However, our investigations demonstrate that this is not necessarily the case. Finally, we start to explore the root causes for anycast anomalies in cellular networks. We reveal three classes of anomalies: distant client packet gateways, poor anycast routing within Tier-1 networks, and improper routing out of cellular networks. [1] http://aqualab.cs.northwestern.edu/projects/261-alice [less ▲]

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See detailEffets de la fertilisation NP et de l'irrigation à des périodes critiques sur le rendement et la qualité des fruits du figuier de Barbarie (Opuntia ficus-indica (L.) Mill.)
Arba, Mohamed ULiege

Doctoral thesis (2017)

Selon la classification révisée récemment, les cactus appartiennent à la famille des Opuntiaceae Desv. (Synon. Cactaceae Juss.), dont le genre-type Opuntia Mill. est économiquement le plus important car ... [more ▼]

Selon la classification révisée récemment, les cactus appartiennent à la famille des Opuntiaceae Desv. (Synon. Cactaceae Juss.), dont le genre-type Opuntia Mill. est économiquement le plus important car il comprend un ensemble de variétés qui participent à la plupart des systèmes agricoles des régions arides et semi-arides. Récemment, dans le Maghreb, la culture de plusieurs espèces et variétés s'est développée à de fins de production fruitière commercialisable, c’est-à-dire répondant à des critères de qualité de plus en plus sévères et exigeant des technologies culturales précises. La partie expérimentale de notre étude s'est déroulée pendant deux années dans le Sud du Maroc, région d'Agadir, sur trois variétés représentatives. Les essais ont été réalisés à la ferme expérimentale de l'Institut Agronomique et Vétérinaire Hassan II, Complexe Horticole d'Agadir (30°36' Nord, 9°36' Est; altitude: 32 m). Le site est caractérisé par des températures moyennes mensuelles qui varient de 8°C en janvier à 31°C en juillet, la température journalière maximale pouvant atteindre 45°C en juillet-aout. La pluviométrie annuelle varie de 100 à 200 mm. La durée moyenne d'ensoleillement est de 8 heures par jour. Un premier objectif de notre étude a été de préciser les réponses quantitatives (rendement en fruits) et qualitatives à des apports modérés d'eau d'irrigation. Un deuxième objectif consistait à évaluer les effets d'apports limités de fertilisation minérale azotée et phosphatée, ces deux éléments majeurs étant les plus susceptibles de se trouver déficitaires dans le contexte pédoclimatique propre à la région. Un troisième objectif a été de préciser la phénologie des trois variétés - surtout les phases de développement floral et fruitier - afin de mettre en évidence d'éventuels impacts des interventions culturales sur la phénologie et de mieux situer les moments de ces interventions en les reliant de manière plus objective à la physiologie du développement. Dans l'étude sur l'irrigation, les variétés utilisées ont été les inermes 'Aissa' et 'Moussa' d'Opuntia ficus-indica (L.) Mill. et l'épineuse 'Achefri’ d’O. megacantha Salm Dyck. En première année, caractérisée par un printemps pluvieux, les traitements d'irrigation ont été: (T1) 0 mm, (T2) 30 mm à la floraison et 30 mm au grossissement des fruits et (T3) 30 mm seulement au grossissement des fruits; les irrigations ont été appliquées entre la mi-avril et la mi-juin. Les irrigations T2 et T3 ont eu un effet négatif sur le rendement en fruits des variétés inermes 'Aissa' et 'Moussa' (-2,8 kg/plant) et T2 a eu un effet positif hautement significatif (p <0,01) sur la variété épineuse 'Achefri’ (+ 2,7 kg/plant ou +18 %). La qualité des fruits n'a pas été affectée par l'irrigation. En deuxième année, caractérisée par un printemps sec, les traitements d’irrigation ont été: (T1) 0 mm, (T2) 60 mm à la floraison et 60 mm au grossissement des fruits et (T3) 60 mm seulement au grossissement des fruits; les irrigations ont été apportées entre février et mai. Toutes les variétés ont répondu positivement à l'irrigation, les augmentations de rendement très significatives (p <0,01) ont varié entre 30% pour 'Moussa' avec T2 et 63 % pour 'Achefri' avec T3 par rapport au témoin non irrigué. Toutes les irrigations ont augmenté le nombre et la taille des fruits et ont provoqué une légère diminution de la teneur en sucres totaux et de l'acidité titrable. Les irrigations n'ont eu aucun effet significatif sur les autres paramètres physiques, chimiques et organoleptiques participant à la définition de la qualité. L'essai sur la fertilisation minérale azotée-phosphorique sur le cultivar ‘Moussa’, mettait en comparaison cinq traitements: 0N-0P; 0N-80P; 40N-40P; 60N-0P et 60N-80P (en kg N ha-1- kg P2O5 ha-1). En première année, l'application de N et/ou de P n'a eu aucun effet sur le rendement en fruits. En deuxième année, les apports de 60 unités de N ou de 80 unités de P2O5 ont augmenté (p <0,01) le rendement de resp. 3,0 et 6,1 kg par plante (+ 18% et + 36%), par rapport au témoin. L'apport simultané des deux éléments N et P (60N-80P2O5) a conduit à une augmentation très significative (p <0,01) de 14,9 kg/plante (+ 90%) mettant en évidence une interaction positive très significative (p <0,01) entre ces deux éléments. Les apports de N et de P ont eu des effets positifs sur le nombre de fruits et leurs poids moyens mais ils n'ont pas modifié le contenu de la pulpe, la teneur en jus, l'épaisseur de l’écorce, la matière sèche du jus, le pH, l’acidité titrable, les sucres totaux, ni le °Brix. L'étude portant sur la phénologie et le développement a été effectuée simultanément dans un essai spécifique reprenant les trois variétés et dans chacun des essais d'irrigation et de fertilisation. Elle a d'une part permis de préciser la variabilité du déroulement des phénologies comme résultant des conditions de milieu (climat), de la génétique, des techniques culturales (fumure et irrigation), et de certaines de leurs interactions. Notre attention s'est portée prioritairement sur les effets des techniques culturales maîtrisables. En première année, les essais ont montré que l'émission de bourgeons est plus élevée (p<0,05) chez la variété épineuse que chez les inermes (plus de 6 bourgeons émis/cladode contre moins de 4,5 chez les variétés inermes). En 2ème année, l'irrigation a augmenté (p <0,05) l'émission de bourgeons chez les trois variétés (plus de 7 bourgeons émis/cladode pour chacun des traitements T2 et T3 vs pas plus que 5 pour T1). L'irrigation a aussi allongé la durée de la phase de floraison de ces variétés. La fertilisation a montré des effets allant dans le même sens. Cependant, ni l'irrigation, ni la fertilisation minérale n'ont modifié significativement la durée de la réalisation du stade maturité du fruit, ne permettant pas ainsi d'allonger la saison de récolte. [less ▲]

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See detailCaractérisations phénotypiques des populations de pintades (Numida meleagris) locales élevées au Bénin
Houndonougbo, Pascal ULiege

Doctoral thesis (2017)

La pintade (Numida meleagris) est une volaille d’origine africaine. Son élevage est répandu en Afrique subsaharienne dans un système traditionnel où plusieurs variétés sont élevées en liberté. Ces ... [more ▼]

La pintade (Numida meleagris) est une volaille d’origine africaine. Son élevage est répandu en Afrique subsaharienne dans un système traditionnel où plusieurs variétés sont élevées en liberté. Ces variétés qui diffèrent par le coloris de leur plumage sont très peu caractérisées. Au nord Bénin, l’élevage avicole moderne est peu rencontré et la pintade constitue la pondeuse d’œufs de table dans cette région. Mais, la mortalité élevée, la faible productivité de la pintade locale limitent fortement le développement de son élevage. Il est alors nécessaire de caractériser les variétés de pintades élevées pour mieux les valoriser dans un système amélioré. L’objectif de cette thèse est de caractériser phénotypiquement la population de pintade locale élevée au Bénin afin de mieux valoriser l’espèce dans des programmes d’amélioration et de développement du secteur avicole national. Une revue bibliographique (Article de synthèse) a permis de réaliser l’état des lieux de l’élevage de pintade au Bénin et de mieux orienter nos travaux pour une bonne caractérisation des variétés élevées. L’existence de plusieurs variétés dans les élevages a été soulignée dans la revue bibliographique et nous a amené à des enquêtes et un suivi des élevages de pintades en milieu villageois. Ces enquêtes et suivi nous ont permis de caractériser les pintades locales dans leur milieu d’élevage selon les dire des éleveurs. Ils nous ont aussi permis de dégager selon les éleveurs, les objectifs de production, l’importance socio-économique et culturelle des variétés élevées. L’influence de l’alimentation sur les performances technico-économiques des pintades locales a été soulignée dans l’Article de synthèse et l’Article I. Cette influence a été abordée en évaluant l’influence de l’alimentation sur le potentiel de croissance de la pintade locale en station (Article II). Enfin, des travaux ont été réalisés en station pour mieux caractériser les variétés de pintades rencontrées dans les élevages sur le plan morphologique, performances de croissance et de reproduction (Articles III, IV et V). Ces différents travaux nous ont permis de recenser les différentes variétés de pintades locales élevées au Bénin, les objectifs d’élevage des éleveurs ainsi que quelques difficultés liées au développement de cet élevage. Ces travaux nous ont surtout permis de mieux caractériser les variétés rencontrées. Cette caractérisation pourrait être valorisée pour améliorer la productivité des variétés par sélection. [less ▲]

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See detailAnalyse comparée des chaines de valeur du riz dans la plaine de la Ruzizi de la Communauté Economique des pays des Grands Lacs (CEPGL)
Furaha Mirindi, Germaine ULiege

Doctoral thesis (2017)

This thesis aims at carrying out a comparative study of three rice value chains in the Ruzizi plain shared between three countries of the Economic Community of the Great Lakes Countries (CEPGL) namely ... [more ▼]

This thesis aims at carrying out a comparative study of three rice value chains in the Ruzizi plain shared between three countries of the Economic Community of the Great Lakes Countries (CEPGL) namely Burundi, the Democratic Republic of Congo and Rwanda. These include the Burundi rice value chain (Imbo Plain), the Congolese rice value chain (Ruzizi Plain) and the Rwandan rice value chain (Bugarama Plain). The diagnostic analysis was about analyzing the rice-farming environment (ie policies and support services accessed by actors along the value chain), analyzing economic performance of these three value chains and to identify the factors that may foster the development of a value chain with a regional potential. For this purpose, the study adopted the field approach, which allowed carrying out investigations during three years (2013 to 2015). The data collection process involved a sample of 228 actors distributed equitably among the three countries. It combined several techniques, namely, direct stakeholder surveys (producers, processors, collectors, wholesalers and retailers), interviews with various support structures and state services, focus group discussions with producer groups and representatives of their organizations. The analysis of these three value chains driving conditions linked the policies implemented in each country and the access by the actors to certain production factors and services such as land, water, credit and the use of inputs. It also highlighted the issue of wage labor and its different roles in the sector. The analysis shows that land policy in Bugarama plain in Rwanda has reduced the cost of land to more than half compared to land costs in Burundi and the DRC. Moreover, this policy is accused by the producers of Bugarama of limiting their entrepreneurial innovations since they can not enlarge their farms (the cultivated area is 0.23 ha). Despite the high cost of water access and management, all rice plots access irrigation water in Rwanda, while the lack of organization and good water management is one of the factors behind low yields in Burundi and the DRC, where 25% and 40% of the rice plots have difficulties in accessing water. Regarding access to agricultural credit, the results reveal that the value chain of rice in the three countries experiences the lack of funding in spite of improvements observed in Rwanda. The rate of access to credit is 17.5% (in Burundi), 16% (in DRC) and 52.8% (in Rwanda), and among them rice farmers with access to formal credits account for only 8% (in Burundi), 10% (in the DRC) and 37.5% (in Rwanda). Analysis of the wage labour force shows that labor is not as widely available as was thought in the study area. Indeed, the DRC is the zone of deficit in wage labor due to the rural exodus and the diversity of economic activities. In the DRC, 60% of the rice workforce used is foreign, including 46% from Burundi and 14% from Rwanda. This mobility of the workforce leads to technology transfers, the supply of inputs at lower cost, but also to consolidate the social cohesion in a post-conflict context. The economic analysis of these three value chains reveals that production costs in the study area remain very high, varying between 292 and 388USD per ton. The highest costs are observed in the DRC where paradoxically there is a better financial performance in terms of profit and added value. The statistical tests carried out on certain parameters identified by the financial analysis undermines the policies regarding the inputs subsidies, agricultural financing and fixing sales prices. Indeed, there are no significant differences between the means of rice farmers who benefit from these policies and those who do not. Paradoxically, statistical analyzes reveal that rice farmers not affected by the pricing policy (they are not price takers) have a good financial performance in terms of income. The three studied areas are complementary in terms of the development potentials of a regional value chain. Indeed, Rwanda has modern underutilization peeling plants that are capable of responding almost entirely to the needs of the whole plain. In addition, Burundi and the DRC should develop land and water potentials to increase production. Several other regional structures in favor of the regional value chain have to be relaunched or strengthened in logic of rice development in the Ruzizi plain. These include the benefits of economic integration of the CEPGL countries. [less ▲]

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See detailVigne guida Confedilizia alla giornata di Varsavia
Gagliani Caputo, Giovanni; Grandjean, Geoffrey ULiege

Article for general public (2017)

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See detailUpscaling winter wheat above-ground biomass measurements using multispectral imagery and 3D data from unmanned aerial vehicle
Michez, Adrien ULiege; Bauwens, Sébastien ULiege; Heinesch, Bernard ULiege et al

Poster (2017, October 20)

Field measurements in the ICOS program are spatially limited whereas the monitored gas fluxes may have a large footprint. Aerial remote sensing has the advantage to monitor large areas. The main goal of ... [more ▼]

Field measurements in the ICOS program are spatially limited whereas the monitored gas fluxes may have a large footprint. Aerial remote sensing has the advantage to monitor large areas. The main goal of our research was to test the potential of unmanned aerial vehicles (UAV) to upscale parameters monitored through the ICOS program. In this study, we specifically focus on above-ground biomass (AGB) monitoring in a winter wheat crop. We used a octocopter drone (X frame type) to acquire a time series over the crop growing season (8 flights from the 14th of February 2017 to the 7th of July 2017) of multispectral imagery covering the ICOS candidate station of Lonzée (Wallonia, Belgium) and the surrounding field crop areas (ca. 0.25 km² per flight). The multispectral camera provides spectral information on the green (550 +/- 50 nm), red (660 +/- 50 nm), near infrared (735 +/- 50 nm) and red-edge (790 +/- 10 nm) wavelengths bands. The UAV also brought an off-the-shelf high resolution (20 Mpx) RGB camera to derive accurate 3D data. We performed a photogrammetric 3D reconstruction of the acquired imagery for every flight survey. The images provided by the RGB sensor (Sony RX100) were used to produce a high spatial resolution Digital Surface Model (0.05 m) and the images acquired by the multispectral sensor were used to derive reflectance maps (0.1 m) in the four wavelengths bands. The four reflectance layers were combined to produce two straight-forward vegetation indices (Normalized Difference Vegetation Index and Green NDVI). The photogrammetric DSM’s were combined to a LiDAR Digital Terrain Model (public database, survey in winter 2013) to produce Crop Height Models (CHM) of the study area. We used multiple linear regressions modelling in order to predict the AGB of the field crop monitored by the ICOS station of Lonzée with UAV imagery. AGB=a+b*GNDVI+c*NDVI+d *CHM The field crop data were provided by the ICOS program and by field research conducted in experimental field crops close to the flux tower. The field sampling consisted in destructive samples of the crop which were weighted after drying. For each field sample, an associated area was computed based on the outdistance sowing and the number of sampled crops in order to compute an AGB per area unit (t / Ha). Each AGB field estimation was associated to the closest flight date to build a multi date model presenting good performances (r² = 0.85, RMSE = 2.3 t/Ha). We used the same modelling approach to adjust a single date model to derive a predicted AGB map for the 7th of July. The performance of the single date model is lower but still highlights the biomass variation within the crop (r² = 0.71, RMSE = 1.9 t/Ha). The predicted AGB map displays a high spatial heterogeneity with some spatial patterns. Locally low AGB values are found along two old pedestrian whereas higher AGB values can be associated to areas which were sprayed twice (in-between two tractor tracks). Our results highlight the potential of UAV multispectral imagery to monitor the AGB variation within the footprint of the flux tower and highlight the need for repeated field sampling with a precise geolocation to improve the matching between the flight and the field surveys. [less ▲]

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See detailSun-Earth Interaction
Grodent, Denis ULiege

Learning material (2017)

Sun-Earth Interaction

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See detailRadiative Transfer
Grodent, Denis ULiege

Learning material (2017)

Radiative Transfer

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