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See detailExperimental Passive Flutter Mitigation Using a Linear Tuned Vibrations Absorber
Verstraelen, Edouard ULg; Habib, Giuseppe ULg; Kerschen, Gaëtan ULg et al

in Proceedings of the IMAC XXXIV Conference (2016)

The current drive for increased efficiency in aeronautic structures such as aircraft, wind turbine blades and helicopter blades often leads to weight reduction. A consequence of this tendency can be ... [more ▼]

The current drive for increased efficiency in aeronautic structures such as aircraft, wind turbine blades and helicopter blades often leads to weight reduction. A consequence of this tendency can be increased flexibility, which in turn can lead to unfavourable aeroelastic phenomena involving large amplitude oscillations and nonlinear effects such as geometric hardening and stall flutter. Vibration mitigation is one of the approaches currently under study for avoiding these phenomena. In the present work, passive vibration mitigation is applied to an experimental aeroelastic system by means of a linear tuned vibration absorber. The aeroelastic apparatus is a pitch and flap wing that features a continuously hardening restoring torque in pitch and a linear one in flap. Extensive analysis of the system with and without absorber at subcritical and supercritical airspeeds showed an improvement in flutter speed around 34%, a suppression of a jump due to stall flutter, and a reduction in LCO amplitude. Mathematical modelling of the experimental system showed that optimal flutter delay can be obtained when two of the system modes flutter simultaneously. However, the absorber quickly loses effectiveness as it is detuned. The wind tunnel measurements showed that the tested absorbers were much slower to lose effectiveness than those of the mathematical predictions. [less ▲]

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See detailExperimental passive flutter suppression using a linear tuned vibration absorber
Verstraelen, Edouard ULg; Habib, Giuseppe ULg; Kerschen, Gaëtan ULg et al

in AIAA Journal (in press)

The current drive for increased efficiency in aeronautic structures such as aircraft, wind turbine blades and helicopter blades often leads to weight reduction. A con- sequence of this tendency can be ... [more ▼]

The current drive for increased efficiency in aeronautic structures such as aircraft, wind turbine blades and helicopter blades often leads to weight reduction. A con- sequence of this tendency can be increased flexibility, which in turn can lead to un- favourable aeroelastic phenomena involving large amplitude oscillations and non- linear effects such as geometric hardening and stall flutter. Vibration mitigation is one of the approaches currently under study for avoiding these phenomena. In the present work, passive vibration mitigation is applied to a nonlinear experimental aeroelastic system by means of a linear tuned vibration absorber. The aeroelastic apparatus is a pitch and flap wing that features a continuously hardening restoring torque in pitch and a linear restoring torque in flap. Extensive analysis of the sys- tem with and without absorber at pre-critical and post-critical airspeeds showed an improvement in flutter speed of around 36%, a suppression of a jump due to stall flutter, and a reduction in LCO amplitude. Mathematical modelling of the exper- imental system is used to demonstrate that optimal flutter delay is achieved when two of the system modes flutter at the same flight condition. Nevertheless, even this optimal absorber quickly loses effectiveness as it is detuned. The wind tunnel mea- surements showed that the tested absorbers were much slower to lose effectiveness than those of the mathematical predictions. [less ▲]

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See detailExperimental performance characterization of a new single room ventilation device with heat recovery
Gendebien, Samuel ULg; Georges, Emeline ULg; Prieels, Luc et al

in Proceedings of the 34th AIVC conference (2013, September)

Nowadays, important efforts are made to reduce the residential building energy consumption. In this context, a growing interest for heat recovery ventilation has been observed during the last decades. The ... [more ▼]

Nowadays, important efforts are made to reduce the residential building energy consumption. In this context, a growing interest for heat recovery ventilation has been observed during the last decades. The present paper focuses on a new single room ventilation with heat recovery. Double flow ventilation is achieved through the integration of the unit into windows ledges. The developed device is particularly suitable compared to traditional centralized heat recovery ventilation units for retrofitted houses due to the absence of air extracting and air pulsing ducts through the house. The first part of the paper consists in describing the characteristics and properties of the developed device (volume, components, flow configuration, advantages and drawbacks). In the second part of the paper, an experimental approach is presented to characterize the unit. The criteria of performance are based on: - Thermal effectiveness of the unit (testing of a recovery heat exchanger), - Hydraulic aspects (flows delivered by the unit vs energy supplied to the unit), - Acoustic aspects. The overall performance of the unit can be established based on the experimental results described here above. Cartography of performance (ratio between the recovered heat and the supply electrical power) can be drawn, depending on the flow rates delivered by the unit and the indoor/outdoor temperature difference. The last part of the paper compares the new system with natural, simple exhaust ventilation and traditional centralized systems in terms of primary energy, consumer price and carbon dioxide emissions. Results show that the presented device seems more competitive than natural and simple exhaust ventilation for the Belgian climate. The single room ventilation investigated in this paper also shows better performance than most of the centralized ventilation systems tested on site. [less ▲]

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See detailExperimental performance of a piston expander in a smallscale organic Rankine cycle
Oudkerk, Jean-François ULg; Dickes, Rémi ULg; Dumont, Olivier ULg et al

in IOP Conf. Series: Materials Science and Engineering 90 (2015) (2015)

Volumetric expanders are suitable for more and more applications in the field of micro- and small-scale power system as waster heat recovery or solar energy. This paper present an experimental study ... [more ▼]

Volumetric expanders are suitable for more and more applications in the field of micro- and small-scale power system as waster heat recovery or solar energy. This paper present an experimental study carried out on a swatch-plate piston expander. The expander was integrated into an ORC test-bench using R245fa. The performances are evaluated in term of isentropic efficiency and filling factor. The maximum efficiency and power reached are respectively 53% and 2 kW. Inside cylinder pressure measurements allow to compute mechanical efficiency and drown P-V diagram. A semi-empirical simulation model is then proposed, calibrated and used to analyse the different sources of losses. [less ▲]

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See detailExperimental procedure and statistical data treatment for the kinetic study of selective hydrodechlorination of 1,2-dichloroethane into ethylene over a Pd-Ag sol–gel catalyst
Pirard, Sophie ULg; Pirard, Jean-Paul ULg; Heyen, Georges ULg et al

in Chemical Engineering Journal (2011), 173(3), 801-812

The kinetics of selective hydrodechlorination of 1,2-dichloroethane into ethylene over a Pd- Ag/SiO2 catalyst was studied using an a priori experimental design with five independent variables—temperature ... [more ▼]

The kinetics of selective hydrodechlorination of 1,2-dichloroethane into ethylene over a Pd- Ag/SiO2 catalyst was studied using an a priori experimental design with five independent variables—temperature and partial pressures of 1,2-dichloroethane, hydrogen, ethylene and hydrogen chloride. A Langmuir–Hinshelwood model including two types of active site and the 1,2-dichloroethane adsorption as the rate-determining step was found to fit correctly with experimental data, according to the analysis of variance and the analysis of pondered residuals. The study allowed for catalytic deactivation. The rigorous experimental and statistical approach followed to carry out such a kinetic study is explained in detail. [less ▲]

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See detailExperimental production of hypocalcemia by EDTA infusion in calves : a critical appraisal assessed from the profile of blood chemicals and enzymes
Desmecht, Daniel ULg; Linden, Annick ULg; Godeau, J. M. et al

in Comparative Biochemistry and Physiology. A : Comparative Physiology (1995), 110A(2), 115-130

Detailed reference viewed: 34 (0 ULg)
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See detailExperimental quantification of the local strains in bone TE scaffolds by the combined use of micro-CT imaging, in-situ loading and local strain mapping
Kerckhofs, Greet ULg; Moesen, Maarten; Loeckx, Dirk et al

in Proc. ECCOMAS - International Conference on Tissue Engineering 2009. . 2009, Bártolo, P. (Eds.) (2009)

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See detailExperimental quantification of Wolff's law in an in vivo loading model
Ruffoni, Davide ULg; Schulte, F. A.; Lambers, F. M. et al

in BONE (2012), 50(1), 125-125

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See detailExperimental reactivation of equine herpesvirus-3 following corticosteroid treatment.
Barrandeguy, M.; Vissani, A.; Olguin, C. et al

in Equine Veterinary Journal (2008), 40(6), 593-5

State of latency, well known for several herpesviruses, has been proposed for equine herpesvirus-3 (EHV-3) and supported by epidemiological observations. No detailed assessment about reactivation ... [more ▼]

State of latency, well known for several herpesviruses, has been proposed for equine herpesvirus-3 (EHV-3) and supported by epidemiological observations. No detailed assessment about reactivation, patterns of excretion and reexcretion has been formally reported. An experimental reactivation study by corticosteroid treatment in previously naturally infected horses was therefore carried out. Two polo mares with clinical and virologically confirmed history of equine coital exanthema were injected with dexamethasone and prednisolone on 3 successive days. Clinical signs, body temperature and clinical samples for virological and serological studies were obtained daily. Mares did not show any systemic clinical signs or hyperthermia. EHV-3 shedding, seroconversion and the presence of a small lesion were observed in one of the mares under study 2 weeks after corticosteroid treatment. The results demonstrate that this virus exhibits a latency-reactivation behaviour similar to that of other alpha herpesviruses. Reactivation of latency may have an important bearing on the appearance of clinical signs in mares and/or stallions during the breeding season without the actual evidence of transfer from mare to stallion or vice versa. [less ▲]

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See detailExperimental replication of Australian grinding stone implements
Hayes, Elspeth; Cnuts, Dries ULg; Fullagar, Richard et al

Poster (2014)

Until recently in Australia, lithic tool-use experiments were dominated by flaked stone with relatively few studies of ground-stone. This poster reports on a workshop, during which tool-use experiments ... [more ▼]

Until recently in Australia, lithic tool-use experiments were dominated by flaked stone with relatively few studies of ground-stone. This poster reports on a workshop, during which tool-use experiments were designed to document the wear traces associated with grinding various materials (n=7), different processing techniques (n=3), and sandstones of different hardness (n=5). The specific variables were selected to build a use-wear and residue reference library applicable to Australian archaeological grinding implements proposed for detailed functional analysis. [less ▲]

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See detailExperimental replication of Australian grinding stone implements
Hayes, Elspeth; Cnuts, Dries ULg; Fullagar, Richard et al

Conference (2014, September 05)

Introduction: Until recently, lithic tool-use experiments in Australia were dominated by flaked stone with relatively few studies of ground-stone. This paper reports on a workshop, during which tool-use ... [more ▼]

Introduction: Until recently, lithic tool-use experiments in Australia were dominated by flaked stone with relatively few studies of ground-stone. This paper reports on a workshop, during which tool-use experiments were designed to document the wear traces associated with grinding various materials, different processing techniques and sandstones of different hardness. The specific variables were selected to build a use-wear and residue reference library applicable to archaeological grinding implements proposed for detailed functional analysis. Materials/Methods: Experimental sandstone grinding implements were used primarily to process organic and inorganic materials, documented ethnographically. Other materials were processed to investigate characteristics of seeds that were unavailable locally. Upper and lower stones were used together to grind seeds and bone; and abrading stones were used to file bone, stone and wood, and to grate haematite. The experimental stones came from five geographic regions in Australia, each associated with the archaeological assemblages proposed for study. Usewear was sampled with polyvinyl siloxane peels, which were examined under a stereomicroscope and a metallographic microscope. Residues were extracted with two solvents (water and a tri-mixture of acetonitrile, ethanol and water), and subsequently mounted on slides and examined under transmitted light microscopy. The slide preparations were stained to highlight constituent plant and animal tissues. Results: The hardness/softness of the sandstone and the degree of grain cementation have a strong influence on the development and appearance of use-wear. On the hard sandstone, the processing time affected polish formation. Use-wear patterns were distinctive of the broad categories of processed material (seed, bone, stone, haematite and wood). Key use-wear features relating to activity and processed material are reflected in the degree of grain rounding and grain levelling, the presence of macroscopic surface striations and the occurrence of micro-fractures, polish and striations observed at high magnification. Residues included collagen and cellulose fibres, starch granules, phytoliths, resins, bone fragments and pigment crystals. As for use-wear, the residues were also distinctive of the broad categories of processed material. Staining was particularly useful to distinguish plant and animal tissues. Conclusions: The experiments provided insights into the wear formation on sandstones of different hardness and degree of cementation. Stained cellular structures provide a reliable basis for distinguishing the investigated plant and animal tissue subjected to mechanical damage, resulting from grinding and pounding. Studies are underway to further test the viability of residue identification on ethnographic specimens of varying ages, and experimental grinding stones greater than 30 years. The residue and usewear experiments build on previous studies and help form the basis of a systematic and collaborative use-wear and residue reference library for ground-stone tools in Australia. Future experiments will focus on the wider range of plant taxa processed by grinding and documented ethnographically. [less ▲]

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See detailExperimental reproduction of bluetongue virus serotype 8 clinical disease in calves.
Dal Pozzo, Fabiana ULg; De Clercq, Kris; Guyot, Hugues ULg et al

in Veterinary Microbiology (2009), 136(3-4), 352-8

Cattle are commonly subclinically infected following natural or experimental infection with bluetongue virus (BTV). The introduction of BTV serotype 8 (BTV-8) in Europe has been characterized by the ... [more ▼]

Cattle are commonly subclinically infected following natural or experimental infection with bluetongue virus (BTV). The introduction of BTV serotype 8 (BTV-8) in Europe has been characterized by the manifestation of clinical signs in infected cattle. In order to study the pathogenesis of BTV-8 in this host, an animal model able to reproduce the clinical manifestations of the disease is required. In this work, two calves were subcutaneously and intravenously injected with a low passage cell-adapted strain of BTV-8. Both calves showed typical bluetongue clinical signs, including pyrexia, ocular discharge, conjunctivitis, oral mucosal congestion, development of ulcers and necrotic lesions on the lips and tongue, submandibular oedema, coronitis and oedema of the coronet and pastern region. A score was assigned depending on the severity of the lesions and a total clinical score was calculated for each animal daily and at the end of the experiment. Both calves became viraemic 24h post-infection and seroconversion occurred between 7 and 11 days P.I. In this study we present the development of a protocol of infection in calves able to reproduce the severity of the lesions observed with BTV-8 in field conditions. [less ▲]

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See detailExperimental research on the determination of the main parameters affecting the behaviour of reinforced concrete columns under fire conditions
Dotreppe, Jean-Claude ULg; Franssen, Jean-Marc ULg; Bruls, Alois et al

in Magazine of Concrete Research (1996), 48(6), 117-127

The design of reinforced concrete columns under fire conditions is generally made on the basis of national and international recommendations. The CEB/FIP recommendations have been used for many years ... [more ▼]

The design of reinforced concrete columns under fire conditions is generally made on the basis of national and international recommendations. The CEB/FIP recommendations have been used for many years. Recently, in the framework of the Eurocodes, the document ENV 1992-1-2 (Eurocode 2-1-2), Structural fire design, has been approved by Commission CEN/TC250/SC2 of the European Committee for Standardization. In the CEB/FIP documents and in Eurocode 2-1-2 the main part is devoted to design from tabulated data containing the dimensions of the cross-sections and values for the concrete cover. The use of simplified calculation methods is not current practice for concrete elements, while they are widely used in the case of steel. The determination of the temperature distribution in the cross-section does not facilitate the development of a simplified method. Furthermore, in columns there is a wide scatter of experimental results. In order to gain additional information, an extensive experimental research programme on the behaviour of reinforced concrete columns under fire conditions, financially supported by the Belgian Funds for Fundamental Collective Research (FRFC-FKFO), has been performed at the Universities of Liege and Ghent. In this article the results of this research are presented and the influence of the main parameters is analysed. [less ▲]

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See detailExperimental results for hydrocarbon refrigerant vaporization in brazed plate heat exchangers at high pressure
Desideri, Adriano ULg; Rhyl Kaern, Martin; Ommen Schmidt, Torben et al

in Proceedings of the 16th International Refrigeration and Air Conditioning Conference at Purdue (2016, July 11)

In recent years the interest in small capacity organic Rankine cycle (ORC) power systems for harvesting low quality waste thermal energy from industrial processes has been steadily growing. Micro ORC ... [more ▼]

In recent years the interest in small capacity organic Rankine cycle (ORC) power systems for harvesting low quality waste thermal energy from industrial processes has been steadily growing. Micro ORC systems are normally equipped with brazed plate heat exchangers which allows for efficient heat transfer with a compact design. An accurate prediction of the heat transfer process characterizing these devices is required from the design phase to the development of model- based control strategies. The current literature is lacking experimental data and validated correlations for vaporization of organic fluids at typical working conditions of ORC systems for low temperature waste heat recovery (WHR) applications. Based on these premises, a novel test-rig has been recently designed and built at the Technical University of Denmark to simulate the evaporating condition occurring in a small capacity ORC power unit. In this contribution the preliminary experimental results obtained from the first experimental campaign carried out on the rig are reported. HFC-134a was selected as working fluid. The experiments were carried out at saturation temperature of 60, 70 and 80 ○C and inlet and outlet qualities ranging between 0.01-0.3 and 0.5-0.95 respectively. The heat flux ranged between 19.4 and 43.1 kWm−2. The results are presented in terms of refrigerant side heat transfer coefficient and pressure drop. The heat transfer coefficient showed significant sensitivity to the saturation temperature and was characterized by a decreasing trend with respect to the mean evaporator quality. The frictional pressure drop showed a linear dependence on the mean quality value and increased as the saturation temperature decreased. The experimental heat transfer coefficients were compared with a well-known correlation for nucleate boiling which is able to predict the results with an accuracy of around 20 %. [less ▲]

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See detailExperimental Results of Flat Fresnel Doublets made of PMMA and PC
Languy, Fabian ULg; Fleury-Frenette, Karl ULg; Lenaerts, Cedric ULg et al

Conference (2012, April)

To reduce the chromatic aberration lots of imaging systems like cameras and telescopes turn to achromatic doublets. On the other hand, to be cheaper, lighter and thinner, more and more systems like ... [more ▼]

To reduce the chromatic aberration lots of imaging systems like cameras and telescopes turn to achromatic doublets. On the other hand, to be cheaper, lighter and thinner, more and more systems like projectors and headlights use Fresnel lenses. To combine high performances and low cost, the use achromatic Fresnel doublets has been investigated. [less ▲]

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See detailExperimental Results of Hybrid and Refractive Achromatic Doublets Made of PC and PMMA
Languy, Fabian ULg; Lenaerts, Cedric ULg; Loicq, Jerôme ULg et al

Conference (2012)

To combine achromatic system with cost-effective technology, we propose the use or hybride (refractive/diffractive) and refractive doublets Fresnel lenses. These two technologies have been compared ... [more ▼]

To combine achromatic system with cost-effective technology, we propose the use or hybride (refractive/diffractive) and refractive doublets Fresnel lenses. These two technologies have been compared experimentally from an optical point of view [less ▲]

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See detailExperimental study and dynamic modeling of a WHR ORC power system with screw expander
Desideri, Adriano ULg; Van Den Broek, Martijn; Gusev, Sergei et al

Conference (2013, October 07)

In recent years, due to the increasing concern over energy shortage and global warming, the interest in low grade heat recovery from industrial processes has grown dramatically. Several studies have ... [more ▼]

In recent years, due to the increasing concern over energy shortage and global warming, the interest in low grade heat recovery from industrial processes has grown dramatically. Several studies have underlined the potential of small-capacity ORC power plants for waste heat recovery (WHR) applications. For such systems accurate dynamic modeling represents an important tool in particular when control issues are considered. This paper presents a dynamic model of an ORC system, validated both in steady-state and transient conditions via experimental data from a 10 kWe waste heat recovery ORC system with a screw expander. [less ▲]

Detailed reference viewed: 136 (8 ULg)