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Application of a k-ε Model to Heat Transfer in Impinging Flows

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Journal of Thermal Science 2004年第1期13卷 62-66页

作者： Bart Merci Chris De Langhe koen Lodefier Erik Dick Ghent University Dept.of FlowHeat and Combustion MechanicsSint-Pietersnieuwstraat 41B-9000 GentBelgiumGhent UniversityDept.of FlowHeat and Combustion MechanicsSint-Pietersnieuwstraat 41B-9000 GentBelgiumGhent UniversityDept.of FlowHeat and Combustion MechanicsSint-Pietersnieuwstraat 41B-9000 GentBelgiumGhent UniversityDept.of FlowHeat and Combustion MechanicsSint-Pietersnieuwstraat 41B-9000 GentBelgium

Local heat transfer is predicted in turbulent axisymmetric jets, impinging onto a flat plate. A non-linear k-e model is used, in which both the constitutive law for the turbulent stresses and the transport equation for the turbulent dissipation rate e have an important contribution in the improved heat transfer predictions. The shape of the Nusselt number profiles, expressing dimensionless heat transfer, as well as the stagnation point value, are well predicted for different distances between the nozzle exit and the plate. Accurate flow field predictions are the basis for good heat transfer predictions. For a fixed Reynolds number, the influence of the nozzle-plate distance is well captured. For a fixed distance, the influence of the Reynolds number is correctly reproduced. Comparisons are made to a low-Reynolds standard k-e model and the v2-f model. A thorough discussion is found in [4]. Only a summary of those results is discussed here, while some new results are also presented.

关键词： local heat transfer impinging jets non-linear k-ε model.

Modelling overall particle motion in fluidised beds for top-spray coating processes

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Particuology 2013年第5期11卷 490-505页

作者： Mike Vanderroost Frederik Ronsse koen Dewettinck Jan G.Pietersa Department of Biosystems Engineering Ghent UniversityCoupure links 6539000 GhentBelgium Laboratory of Food Technology and Engineering Ghent UniversityCoupure links 6539000 GhentBelgium

A mathematical model predicting the overall particle motion in liquid-sprayed gas-solid fluidised beds has been developed. The proposed model is a superposition of bubble-induced particle motion and particle random walk. The model was validated using experimental particle residence times from literature. Good agreement between experimental and model-predicted residence times was obtained for those cases where atomisation air was absent and on the condition of the inclusion of a so-called ＂dead zone＂. The ＂dead zone＂, being a region of stagnant particles in the annular bottom part of the bed, has also been previously reported in literature. In case atomisation air was present, a less favourable agreement was seen between the model and the experiment. As the atomisatinn air has been shown to significantly alter the ejection distance of particles in the freeboard, recalibration of the ejection height parameter has been demonstrated to obtain an acceptable agreement between model-predicted and experimental data.

关键词： Fluidized bed coatingParticLe residence timeMathematical modelSimulationParticle motion

Mesomorphism of Lanthanide(Ⅲ) 4-Hexyloxybenzoates

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Journal of Rare Earths 2004年第2期22卷 193-196页

作者： Liesbet Jongen Bart Goderis Igor P Dolbnya koen Binnemans Katholieke Universiteit Leuven Department of Chemistry Celestijnenlaan 200F B-3001 Leuven BelgiumKatholieke Universiteit Leuven Department of Chemistry Celestijnenlaan 200F B-3001 Leuven BelgiumDUBBLE-CRG/ESRF Rue des Martyrs 156 B.P. 220 F-38043 Grenoble Cedex FranceKatholieke Universiteit Leuven Department of Chemistry Celestijnenlaan 200F B-3001 Leuven Belgium

The 4-alkoxybenzoic acids are well-known liquid crystals showing several mesophases (nematic, smectic C phase or both) depending on the alkoxy chain length and whereby the rigid core of the mesogen is formed by intermolecular hydrogen bonds. In this paper it is shown that the thermal behaviour of lanthanide salts of 4-hexyloxybenzoic acids depends on the lanthanide ion (Ln=La, Pr, Nd, Sm, Eu). The lanthanum(Ⅲ) and praseodymium(Ⅲ) 4-hexyloxybenzoates exhibit a smectic A mesophase. No mesophase is found for the corresponding compounds of heavier lanthanides. The thermal properties of the lanthanide(Ⅲ) 4-hexyloxybenzoates were investigated by differential scanning calorimetry (DSC), polarising thermo-optical microscopy and synchrotron X-ray radiation.

关键词： lanthanides 4-alkoxybenzoates thermal behaviour synchrotron measurements metallomesogens rare earths

Mechanochemical-Assisted Leaching of Lamp Phosphors： A Green Engineering Approach for Rare-Earth Recovery

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Engineering 2018年第3期4卷 398-405页

作者： Steff Van Loy koen Binnemans Tom Van Gerven Department of Chemical Engineering KU Leuven Heverlee B-3001 Belgium Department of Chemistry KU Leuven Heverlee B-3001 Belgium

稀土元素(REE)是设计和开发可持续能源应用的重要金属。从富含稀土元素的废物流中回收这些元素对实现独立、可持续的未来能源供应至关重要。本文比较了从绿灯荧光体LaPO_4:Ce^(3+),Tb^(3+)回收稀土元素的两种机制:在湿法冶金酸浸工艺前... 详细信息

稀土元素(REE)是设计和开发可持续能源应用的重要金属。从富含稀土元素的废物流中回收这些元素对实现独立、可持续的未来能源供应至关重要。本文比较了从绿灯荧光体LaPO_4:Ce^(3+),Tb^(3+)回收稀土元素的两种机制:在湿法冶金酸浸工艺前与溶剂冶金机械化学浸出工艺前的机械活化机制。稀土元素浸出率在机械活化后增加60%,完成机械化学浸出工艺后增加98%。高分辨率透射电子显微镜(HR-TEM)成像揭露了系统元素浸出率增加的原因:浸出与浸出模式的改善可归因于晶体形态从单晶体到多晶体的转变。多晶形材料的雏晶尺寸减小至纳米级,使化学单元出现不规则填充,导致晶体内缺陷颗粒边界的增加,从而增强浸出工艺。发明了一种溶剂冶金法将机械活化与浸出工艺结合成一个步骤,这有利于降低运营成本。其结果是简单、高效的工艺提供了更加绿色的荧光体废物回收替代途经。

关键词：机械化学稀土元素荧光体废物球磨研磨溶剂冶金

Modelling the bed characteristics in fluidised-beds for top-spray coating processes

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Particuology 2012年第6期10卷 649-662页

作者： Mike Vanderroost Frederik Ronsse koen Dewettinck Jan G.Pieters Department of Biosystems Engineering Ghent UniversityCoupure links 6539000 GhentBelgium Laboratory of Food Technology and Engineering Ghent UniversityCoupure links 6539000 GhentBelgium

A particle sub-model describing the bed characteristics of a bubbling fluidised bed is presented. Atomisation air, applied at high pressures via a nozzle positioned above the bed for spray formation, is incorporated in the model since its presence has a profound influence on the bed characteristics, though the spray itself is not yet considered. A particle sub-model is developed using well-known empirical relations for particle drag force, bubble growth and velocity and particle distribution above the fluidised-bed surface. Simple but effective assumptions and abstractions were made concerning bubble distribution, particle ejection at the bed surface and the behaviour of atomisation air flow upon impacting the surface of a bubbling fluidised bed, The model was shown to be capable of predicting the fluidised bed characteristics in terms of bed heights, voidage distributions and solids volume fractions with good accuracy in less than 5 min of calculation time on a regular desktop PC. It is therefore suitable for incorporation into general process control models aimed at dynamic control for process efficiency and product quality in top-spray fluidised bed coating processes.

关键词： Fluidised bed Modelling Voidage distribution Fluidised bed characteristics Multiphase flow Coating process

SIZE MATTERS:PITCH DIMENSIONS CONSTRAIN INTERACTIVE TEAM BEHAVIOUR IN SOCCER

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Journal of Systems Science & Complexity 2013年第1期26卷 85-93页

作者： FRENCKEN Wouter VAN DER PLAATS Jorrit VISSCHER Chris LEMMINK koen University Medical Center Groningen University of GroningenCenter for Human Movement Sciences Hanze University of Applied Sciences School of Sports Studies Football Club Groningen

Pitch size varies in official soccer matches and differently sized pitches are adopted for tactical purposes in small-sided training *** interactive team behaviour emerges under constraints,the authors evaluate the effect of pitch size(task) manipulations on interactive team behaviour in small-sided soccer *** 4-a-side(plus goalkeepers) small-sided games were played:a reference game(30×20 m),length manipulation(24×20 m),width manipulation(30×16 m),and a combination(24×16 m).Using position data(100Hz),three measures quantifying the teams' interaction were calculated:longitudinal inter-team distance,lateral inter-team distance,and surface area *** and standard deviations,correlations and coupling values were *** correlations were calculated over a 3-s window to evaluate interaction *** expected,a shorter pitch results in smaller longitudinal inter-team distance,lateral inter-team distance decreased for narrow pitches,and smaller total playing area resulted in decreased surface ***,a crossover effect was present;length and width manipulations also triggered changes in lateral and longitudinal direction ***-team distances and surface area difference differed significantly across *** patterns differed across conditions for all ***,highly tactically relevant,soccer teams seem to adapt their interactive behaviour according to pitch size in small-sided games.

关键词：行为约束足球场间距尺寸事务足球游戏交互模式距离和

Study on Pollution Cost Control Model under Asymmetric Information Based on Principal Agent

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Journal of Systems Science and Information 2021年第5期9卷 549-557页

作者： Lina WANG koen MILIS Stephen POELMANS School of Economics and Management Hainan Normal UniversityHaikou 571158China Campus Vesta Education Management IndustryBrusselsBelgium Faculty of Economics and Management Hogeschool-Universiteit BrusselKULeuven AssociationWarmoesberg 26Brussel 1000Belgium

Pollution cost control is key to solve pollution *** paper takes pollution control cost of pollution control contract between management authority and pollutant discharge enterprise as research object,considers pollution control quality level,pollution control quality inspection and pollution control cost model,and establishes pollution control cost model of management authority and pollutant discharge enterprise,including rational constraints of pollutant discharge *** it analyzes principal-agent relationship between the two under condition of asymmetric information,and un-observability of pollution control level is shown as hiding information of sewage *** essence,it is problem of adverse selection in *** control cost of management is objective *** first order condition of pollution control cost of sewage enterprise is transformed into state space equation,and optimal control of problem is solved by using maximum *** particular,management authority,as principal,uses pollution control provisions to reward,punish and encourage pollutant discharge enterprises as agents.

关键词： principal agent asymmetric information pollution cost control

Supplementing oat hulls to the diet of suckling piglets altered their intestinal tract and colonic microbiota development

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Animal Nutrition 2023年第1期12卷 284-296页

作者： Hubèrt M.J.van Hees koen Chiers Leo A.den Hartog Theo A.T.G.van Kempen Dominiek Maes Sam Millet Geert P.J.Janssens Department of Veterinary and Biosciences Ghent UniversityMerelbekeBelgium Trouw Nutrition Research and Development Amersfoortthe Netherlands Department of Pathology Ghent UniversityMerelbekeBelgium Animal Nutrition Wageningen University and ResearchWageningenthe Netherlands Department of Animal Science North Carolina State UniversityRaleighNCUSA Department of Reproduction Obstetrics and Herd HealthGhent UniversityMerelbekeBelgium ILVO(Flanders Research Institute for Agriculture Fisheries and Food)MelleBelgium

Current study evaluated the effect of a fine and coarsely ground insoluble dietary fibre source on the gastrointestinal development of suckling *** hulls(OH)were selected as a model feedstuff,rich in cellulose,lignin,and insoluble dietary *** experimental supplemental diets were formulated:a finely ground,low fibre and nutrient dense diet served as control(CON).For the 2 high fibre diets,15%heat-treated starch in CON was exchanged with OH,either finely(OH-f)or coarsely ground(OH-c).Litters of 10 primi-and multiparous sows(mean litter size 14.6±0.84)were *** a litter,experimental diets were allotted to triplets of 4 *** approximately 12 d of age,piglets’individual feed intakes were recorded 2 times per day when separated from their dam for 70 *** could suckle with their dam for the remainder of the *** d 24 and 25,from the total pool of 120 piglets,seven healthy well-eating piglets per treatment were selected for post-mortem evaluation,resulting in 14 replicates per *** of OH-c and OH-f did not impede clinical health and production performance of *** full stomach weights tended to be greater for OH-c compared to OH-f whereas CON was intermediate(P=0.083).Supplementing OH significantly increased ileal villus height and caecal dry matter concentration(P<0.05).For the colon,OH increased its length,contents weight,short-chain fatty acid concentration and reduced total bacterial count as well asγ-proteobacteria count and proportion(P<0.05).The OH-c treatment specifically increased full gastrointestinal tract weight and caecum contents weight compared to piglets fed CON and ***,OH-c reduced colonic crypt depth when compared to OH-f(P=0.018).In conclusion,supplementing OH to a diet for suckling piglets exerted subtle developmental effects on gastrointestinal morphology and colonic microbial *** effects were largely independent from the particle size of the OH.

关键词： Oat hull Insoluble fibre Gastrointestinal development Suckling piglet

Development of polymer–fullerene solar cells

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National Science Review 2016年第2期3卷 222-239页

作者： Fengling Zhang Olle Ingans Yinhua Zhou koen Vandewal Biomolecular and organic electronics Department of PhysicsChemistry and Biology(IFM)Linkoping University Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Institut fr Angewandte Photophysik Technische Universitt Dresden

Global efforts and synergetic interdisciplinary collaborations on solution-processed bulk-heterojunction polymer solar cells(PSCs or OPVs) made power conversion efficiencies over 10%*** rapid progress of the field is credited to the synthesis of a large number of novel polymers with specially tunable optoelectronic properties,a better control over the nano-morphology of photoactive blend layers,the introduction of various effective interfacial layers,new device architectures and a deeper understanding of device *** will review the pioneering materials for polymer-fullerene solar cells and trace the progress of concepts driving their *** discuss the evolution of morphology control,interfacial layers and device structures fully exploring the potential of photoactive *** order to guide a further increase in power conversion efficiency of OPV,the current understanding of the process of free charge carrier generation and the origin of the photovoltage is summarized followed by a perspective on how to overcome the limitations for industrializing PSCs.

关键词： polymer-fullerene solar cells electron donors and acceptors morphology interfacial layer device physics