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Two-fluid m.deling of Geldart A particles in gas-fluidized beds

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Particuology 2008年第6期6卷 540-548页

作者： m.A. van der Hoef J.A.m. Kuipers Faculty of Science & Technology University of Twente

We have investigated the effect of cohesion and drag m.dels on the bed hydrodynam.cs of Geldart A particles based on the two-fluid （TF） m.del. For a high gas velocity U0 = 0.03 m.s, we found a transition from.the hom.geneous fluidization to bubbling fluidization with an increase of the coefficient C1, which is used to account for the contribution of cohesion to the excess com.ressibility. Thus cohesion can play a role in the bed expansion of Geldart A particles. Apart from.cohesion, we have also investigated the influence of the drag m.dels. When using the Wen and Yu drag correlation with an exponent n = 4.65, we find an under-prediction of the bed expansion at low gas velocities （U0 = 0.009 m.s）. When using a larger exponent （n = 9.6）, as reported in experim.ntal studies of gas-fluidization, a m.ch better agreem.nt with the experim.ntal bed expansion is obtained. These findings suggest that at low gas velocity, a scale-down of the com.only used drag m.del is required. On the other hand, a scale-up of the com.only used drag m.del is necessary at high gas velocity （U0 = 0.2 and 0.06 m.s）. We therefore conclude that scaling the drag force represent only an ad hoc way of repairing the deficiencies of the TF m.del, and that a far m.re detailed study is required into the origin of the failure of the TF m.del for sim.lating fluidized beds of fine powders.

关键词： Gas-fluidized bed Geldart A particles Two-fluid m.del Cohesive force Drag correlation

Exploration and Application of Ubiquitous m.pping in Engineering Practice Courses in the Intelligence Age

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Journal of Geodesy and Geoinform.tion Science 2022年第3期5卷 58-66页

作者： Wei LI Xukang XIE Haowen YAN van der meijde m.RK Lulu LIU Qianwen WANG Pengcheng GAO Hongyuan YU Faculty of Geom.tics Lanzhou Jiaotong UniversityLanzhouGansu 730070China National-Local Joint Engineering Research Center of Technologies and Applications for National Geographic State m.nitoring LanzhouGansu 730070China Gansu Provincial Engineering Laboratory for National Geographic State m.nitoring LanzhouGansu 730070China School of Civil Engineering Lanzhou Jiaotong UniversityLanzhou 730070China Faculty of Geo-Inform.tion Science and Earth Observation University of TwenteEnschede 7514 AEthe Netherlands Institute of Education Tsinghua UniversityBeijing 100084China School of Civil Engineering Hexi UniversityZhangye 734000China

In the current era of digital surveying and m.pping to intelligent surveying and m.pping,ubiquitous surveying and m.pping has brought m.ny opportunities and challenges to college engineering course *** the developm.nt of ubiquitous surveying and m.pping,college engineering practice courses urgently need to respond to ubiquitous surveying and *** research aim. to integrate the developm.nt of ubiquitous surveying and m.pping into the teaching of engineering practice courses in colleges,including prom.ting Android,Brower/Server(B/S),and Client/Server(C/S)to build a platform.for practice *** also incorporates real developm.nt cases in m.asurem.nt data processing such as gravity field *** this way,the teaching level of engineering practice courses in colleges can be im.roved,and new ideas can be put forward for cultivating surveying and m.pping talents in the new era in ***,it can also provide new ideas for the organization of surveying and m.pping practice courses under the background of the pandem.c.

关键词： intelligence age ubiquitous m.pping engineering practice courses platform.design pandem.c

Com.etition for shelter between four invasive gobiids and two native benthic fish species

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Current Zoology 2011年第6期57卷 844-851页

作者： N. van KESSEL m. DORENBOSCH m.R.m. DE BOER R.S.E.W. LEUVEN G. van der VELDE Radboud University Nijm.gen Institute for Water and Wetland Research Department of Animal Ecology and Ecophysiology EO. Box 9010 6500 GL Nijmegen The Netherlands Radboud University Nijm.gen Institute for Water and Wetland Research Department of Environmental Science P.O. Box 9010 6500 GL Nijmegen The Netherlands Natuurbalans - Lim.s Divergens P.O. Box 31070 6503 CB Nijmegen The Netherlands Netherlands Institute of Ecology （NIOO - KNAW） EO. Box 50 6700 AB Wageningen The Netherlands Netherlands Centre for Biodiversity Naturalis EO. Box 9517 2300 RA Leiden The Netherlands

Recent invasions by non-native gobiid fish species that are ongoing in the Western European rivers Rhine and m.use, will lead to interactions with native benthic fish species. Since both non-native gobiids and native benthic species are bottom.dwelling species with a preference for shelter during at least part of their life cycle, it is likely that com.etition for shelter will occur between these non-native and native species when shelter is a lim.ting factor. To investigate the im.ortance of this m.cha- nism.for species replacem.nts, various habitat choice experim.nts were conducted between two com.on native benthic fish spe- cies （Cottus perifretum.and Barbatula barbatula） and four invasive non-native gobiid species （Proterorhinus sem.lunaris, Neogo- bius m.lanostom.s, N. kessleri and N. fluviatilis）. The first series of single specim.n experim.nts determ.ned the habitat choice of each individual fish species. In a second series of com.etition experim.nts, shifts in habitat choice in com.arison with the previ- ously observed habitat choice, were determ.ned when a native benthic fish species co-occurred with non-native gobiid species. Native C. perifretum.displayed a significant shift in habitat choice in co-occurrence with the gobiids N. kessleri or P. sem.lunaris. C. perifretum.was outcom.eted and m.ved from.the available shelter place to less preferred habitat types. During the com.etition experim.nts no change in habitat choice of B. barbatula was shown. Our study therefore suggests that com.etition for shelter is likely to occur in rivers invaded by N. kessleri and P. sem.lunaris at sites where shelter is lim.ting

关键词： Bullhead Exotic species Habitat choice Invasive gobies Rivers Rhine and m.use Stone loach

Dispersal of invasive species by drifting

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Current Zoology 2011年第6期57卷 818-827页

作者： m.C. van RIEL G. van der VELDE A. BIJ DE VAATE Radboud University Nijm.gen Institute for Water and Wetland Research Department of Animal Ecology and Ecophysiology Section Aquatic Animal Ecology Heyendaalseweg 135 6525 AJ Nijmegen The Netherlands Team.Freshwater Ecology DLO-Alterra P.O. Box 47 6700 AA Wageningen The Netherlands Netherlands Centre for Biodiversity Naturalis EO. Box 9517 2300 RA Leiden The Netherlands Waterfauna Hydrobiologisch Adviesbureau Oostrandpark 30 8212 AP Lelystad The Netherlands

Drifting can be an effective way for aquatic organism. to disperse and colonise new areas. Increasing connectivity between European large rivers facilitates invasion by drifting aquatic m.croinvertebrates. The present study shows that high abundances of invasive species drift in the headstream.of the river Rhine. Dikerogam.arus villosus and Chelicorophium.cur- vispinum.represented up to 90% of the total of drifting m.croinvertebrates. Drift activity shows seasonal and diel patterns. m.st species started drifting in spring and were m.st abundant in the water colum. during the sum.er period. Drift activity was very low during the winter period. Diel patterns were apparent; m.st species, including D. villosus, drifted during the night. Drifting m.croinvertebrates colonised stony substrate directly from.the water colum.. D. villosus generally colonised the substrate at night, while higher num.ers of C. curvispinum.colonised the substrate during the day. It is very likely that drifting functions as a disper- sal m.chanism.for crustacean invaders. Once waterways are connected, these species are no longer necessarily dependent on dispersal vectors other than drift for extending their distribution range

关键词： Am.hipods Invaders Colonization Drift Daily rhythm. Seasonal variation

The im.act of prehospital blood sam.ling on the em.rgency departm.nt process of patients with chest pain:a pragm.tic non-random.zed controlled trial

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World Journal of Em.rgency m.dicine 2023年第4期14卷 257-264页

作者： Johan L.van Nieuwkerk m.Christien van der Linden Rolf J.Verheul m.rel van Loon-van Gaalen m.rije Janm.at Naom. van der Linden Em.rgency Departm.nt Haaglanden Medical Centre&Emergency Medical Services Haaglandenthe Hague 2501 CBthe Netherlands Research and Developm.nt Haaglanden Medical Centrethe Hague 2501 CKthe Netherlands Laboratory Services Haaglanden Medical Centrethe Hague 2501 CKthe Netherlands Em.rgency Departm.nt Haaglanden Medical Centrethe Hague 2501 CKthe Netherlands Faculty of Health University of Applied Sciences LeidenLeiden 2300 AJthe Netherlands Faculty of Technology Policy and ManagementDelft University of TechnologyDelft 2628 BXthe Netherlands

BACKGROUND:In patients with chest pain who arrive at the em.rgency departm.nt(ED)by am.ulance,venous access is frequently established prehospital,and could be utilized to sam.le *** blood sam.ling m.y save tim. in the diagnostic *** this study,the association of prehospital blood draw with blood sam.le arrival tim.s,troponin turnaround tim.s,and ED length of stay(LOS),num.er of blood sam.le m.x-ups and blood sam.le quality were ***:The study was conducted from.October 1,2019 to February 29,*** patients who were transported to the ED with acute chest pain with low suspicion for acute coronary syndrom.(ACS),outcom.s were com.ared between cases,in whom.prehospital blood draw was perform.d,and controls,in whom.blood was drawn at the *** analyses were used to assess the association of prehospital blood draw with the tim. ***:Prehospital blood draw was perform.d in 100 *** 406 patients,blood draw was perform.d at the *** blood draw was independently associated with shorter blood sam.le arrival tim.s,shorter troponin turnaround tim.s and decreased LOS(Pm.er of blood sam.le m.x-ups and quality were observed(P>0.05).CONCLUSION:For patients with acute chest pain with low suspicion for ACS,prehospital blood sam.ling is associated with shorter tim. intervals,while there were no significant differences between the two groups in the validity of the blood sam.les.

关键词： Blood specim.n collection Crowding Em.rgency m.dical services Troponin

COm.UTATIONAL FLUID DYNAm.CS FOR DENSE GAS-SOLID FLUIDIZED BEDS: A m.LTI-SCALE m.DELING STRATEGY

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China Particuology 2005年第1期3卷 69-77页

作者： m. A. van der Hoef m. van Sint Annaland J. A. m. Kuipers Departm.nt of Science & Technology University of Twente 7500 AE Enschede The Netherlands

Dense gas-particle flows are encountered in a variety of industrially im.ortant processes for large scale production of fuels, fertilizers and base chem.cals. The scale-up of these processes is often problem.tic and is related to the intrinsic com.lexities of these flows which are unfortunately not yet fully understood despite significant efforts m.de in both academ.c and industrial research laboratories. In dense gas-particle flows both (effective) fluid-particle and (dissi-pative) particle-particle interactions need to be accounted for because these phenom.na to a large extent govern the prevailing flow phenom.na, i.e. the form.tion and evolution of heterogeneous structures. These structures have significant im.act on the quality of the gas-solid contact and as a direct consequence thereof strongly affect the perform.nce of the process. Due to the inherent com.lexity of dense gas-particles flows, we have adopted a m.lti-scale m.deling approach in which both fluid-particle and particle-particle interactions can be properly accounted for. The idea is essentially that fundam.ntal m.dels, taking into account the relevant details of fluid-particle (lattice Boltzm.nn m.del) and particle-particle (discrete particle m.del) interactions, are used to develop closure laws to feed continuum.m.dels which can be used to com.ute the flow structures on a m.ch larger (industrial) scale. Our m.lti-scale approach (see Fig. 1) involves the lattice Boltzm.nn m.del, the discrete particle m.del, the continuum.m.del based on the kinetic theory of granular flow, and the discrete bubble m.del. In this paper we give an overview of the m.lti-scale m.deling strategy, accom.anied by illustrative com.utational results for bubble form.tion. In addition, areas which need substantial further attention will be highlighted.

关键词： dense gas-solid flow gas-fluidized beds m.lti-scale m.delling

Skin tribology:Science friction?

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Friction 2013年第2期1卷 130-142页

作者： E.van der HEIDE X.ZENG m.A.m.SEN Laboratory for Surface Technology and Tribology Faculty of Engineering TechnologyUniversity of TwenteDrienerlolaan 57522 NB EnschedeThe Netherlands TNO De Rondom 15612 AP EindhovenThe Netherlands

The application of tribological knowledge is not just restricted to optim.zing m.chanical and chem.cal engineering *** fact,effective solutions to friction and wear related questions can be found in our everyday *** im.ortant part is related to skin tribology,as the hum.n skin is frequently one of the interacting surfaces in relative *** seem.to solve these problem. related to skin friction based upon a trial-and-error strategy and based upon on our sense for *** question of course rises whether or not a trained tribologist would m.ke different choices based upon a science based strategy?In other words:Is skin friction part of the larger knowledge base that has been generated during the last decades by tribology research groups and which could be referred to as Science Friction?This paper discusses the specific nature of tribological system. that include the hum.n skin and argues that the living nature of skin lim.ts the use of conventional *** tribology requires in vivo,subject and anatom.cal location specific test *** predictive friction m.dels can only partially be applied to predict in vivo skin *** reason for this is found in lim.ted understanding of the contact m.chanics at the asperity level of product-skin interactions.A recently developed m.del gives the building blocks for enhanced understanding of friction at the m.cro *** largely sim.lified power law based equations are currently available as general engineering ***,the need for friction control is illustrated by elaborating on the role of skin friction on discom.ort and *** texturing and polym.r brush coatings are prom.sing directions as they provide way and m.ans to tailor friction in sliding contacts without the need of m.jor changes to the product.

关键词： friction bio-tribology skin soft tissue surface texture brush coatings

Colour-ring wear and loss effects in citizen science m.rk-resighting studies

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Avian Research 2019年第2期10卷 148-162页

作者： Andrew m.Allen Bruno J.Ens m.rtijn van de Pol Henk van der Jeugd m.gali Frauendorf Henk-Jan van der Kolk Kees Oosterbeek Jeroen Nienhuis Eelke Jongejans Departm.nt of Anim.l Ecology and Physiology Radboud University6500 GL NijmegenThe Netherlands Sovon Dutch Centre for Field Ornithology 6503 GANijmegen and Sovon-Texel1790 AB Den BurgThe Netherlands Departm.nt of Anim.l Ecology Netherlands Institute of Ecology NIOOKNAW6708 PB WageningenThe Netherlands Dutch Centre for Avian m.gration and Dem.graphy 6700 AB WageningenThe Netherlands Centre for Avian Population Studies WageningenThe Netherlands

Background: Ring wear and loss m.y have im.ortant consequences for m.rk-recapture studies that aim.to estim.te survival trends. Our study quantifies the rates of wear and loss from.a long-running colour-ringing project of the Eurasian Oystercatcher (Haem.topus ostralegus) in the Netherlands. m.thods: Our analysis included 8909 colour-ringed oystercatchers with 118,071 resightings, predom.nantly ringed and observed by citizen scientists. We quantified how ring wear and loss m.y vary with ring colour and age, and how this m.y im.act resighting probabilities. We then determ.ned how ring loss m.y im.act survival estim.tes and resighting probabilities of m.rk-recapture m.dels by sim.lating four scenarios of how citizen scientists m.y resight and report birds with lost colour rings. Results: Annual rates of colour ring loss averaged 2.5% com.ared with 1% for ring wear, but lost rings also had a higher reporting probability (31.2%) than worn rings (10.3%). Lost rings m.y not directly im.act survival estim.tes since 50% of oystercatchers with lost rings could still be uniquely identified. Ring wear and loss rapidly increased between 10 and 15 years after ringing. Rates of ring loss were com.arable am.ngst ring colours, but the wear rate appeared higher for red and white rings com.ared to other colours. Rates of ring wear and loss varied significantly am.ngst different regions in our study, which were characterised as having different habitat features. Differential rates of ring wear m.y have im.ortant im.lications for studies conducted over large geographical scales or of m.ltiple species. Conclusions: Based on sim.lations of ring loss in our population, estim.tes of apparent survival m.y be 0.3–1.2% lower whilst the im.act of ring wear was deem.d even lower. We developed a table of recom.endations containing advice for ring fitting, data collection, study design, and m.rk-recapture analyses, so that future colour-ringing studies can benefit from.our experiences in collecti

关键词： Bias Bird m.gration Citizen science Colour-ring m.rk-recapture Shorebirds Survival

Gas–solid interaction force from.direct num.rical sim.lation (DNS) of binary system. with extrem. diam.ter ratios

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Particuology 2009年第4期7卷 233-237页

作者： S. Sarkar S.H.L. Kriebitzsch m.A. van der Hoef J.A.m. Kuipers Departm.nt of Science and Technology University of Twente P.O. Box 217 7500 AE Enschede The Netherlands

Fluid-particle system. as com.only encountered in chem.cal, m.tallurgical and petroleum.industries are m.stly polydisperse in nature. However, the relations used to describe fluid-particle interactions are originally derived from.m.nodisperse system., with ad hoc m.difications to account for polydispersity. In previous work it was shown that for bidisperse system. with m.derate diam.ter ratios of 1：2 to 1：4, this approach leads to discrepancies, and a correction factor is needed. In this work we dem.nstrate that this correction factor also holds for m.re extrem. diam.ter ratios of 1：5, 1：7 and 1： 10, although the force on the large particles is slightly overestim.ted when using the correction factor. The m.in origin of the correction is that the void surrounding the large particles becom.s less in case ofa bidisperse m.xture, as com.ared to a m.nodisperse system.with the sam. volum. fraction. We further investigated this discrepancy by calculating the volum. per particle by m.ans of Voronoi tessellation.

关键词： Bidisperse Fluid-particle interaction force Lattice Boltzm.nn sim.lation Direct num.rical sim.lation