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Experimental and numerical investigation to elucidate the fluid flow through packed beds with structured particle packings

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Particuology 2024年第6期89卷 218-237页

作者： Shirin Patil Christian Gorges Joel Lòpez Bonilla Moritz Stelter Frank Beyrau berend van wachem Laboratory of Technical Thermodynamics Otto-von-Guericke-Universität MagdeburgUniversitätsplatz 239106 MagdeburgGermany Chair of Mechanical Process Engineering Otto-von-Guericke-Universität MagdeburgUniversitätsplatz 239106 MagdeburgGermany

The present paper presents an experimental and numerical investigation of the dispersion of the gaseous jet flow and co-flow for the simple unit cell(SUC)and body-centred cubic(BCC)configuration of particles in packed *** experimental setup is built in such a way that suitable and simplified boundary conditions are imposed for the corresponding numerical framework,so the simulations can be done under very similar conditions as the ***,a porous plate is used for the co-flow to achieve the uniform velocity and the fully developed flow is ensured for the jet *** SUC and BCC particle beds consist of 3D-printed spheres,and the non-isotropy near the walls is mostly eliminated by placing half-spheres at the channel *** flow velocities are analysed directly at the exit of the particle bed for both beds over 36 pores for the SUC configuration and 60 pores for the BCC configuration,for particle Reynolds numbers of 200,300,and *** particle image velocimetry is experimentally arranged in such a way that the velocities over the entire region at the exit of the packed bed are obtained *** numerical method consists of a state-of-the-art immersed boundary method with adaptive mesh *** paper presents the pore jet structure and velocity field exiting from each pore for the SUC and BCC packed particle *** numerical and experimental studies show a good agreement for the SUC configuration for all flow *** the BCC configuration,some differences can be observed in the pore jet flow structure between the simulations and the experiments,but the general flow velocity distribution shows a good overall *** axial velocity is generally higher for the pores located near the centre of the packed bed than for the pores near the *** addition,the axial velocities are observed to increase near the peripheral pores of the packed *** behaviour is predominant for the BCC configuration as compared to t

关键词： Uniform particle packing Packed bed reactor Stereo particle image velocimetry Immersed boundary method

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Comparing two IBM implementations for the simulation of uniform packed beds

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Particuology 2024年第3期86卷 1-12页

作者： Christian Gorges Maximilian Brommer Christin Velten Siegmar Wirtz Enric Illana Mahiques Viktor Scherer Katharina Zahringer berend van wachem Mechanical Process Engineering Otto-von-Guericke-Universitat MagdeburgUniversitatsplatz 239106MagdeburgGermany Department of Energy Plant Technology Ruhr-Universitat BochumUniversitatsstraBe 15044780BochumGermany Laboratory of Fluid Dynamics and Technical Flows Otto-von-Guericke-Universitat MagdeburgUniversitatsplatz 239106MagdeburgGermany

Nowadays,the design of fixed packed bed reactors still relies on empirical correlations,which,especially for small tube to particle diameter ratios,are mostly too inaccurate because of the presence of wall ***,the simulation of fixed packed bed reactors plays an important role to predict and control the flow and process parameters in such,nowadays and in the *** of its straightforward applicability to non-uniform packings with particles of arbitrary shapes,the immersed boundary method(IBM)has advantages over other numerical methods and is used more and more *** paper compares two approaches of IBMs for the simulation of fixed bed reactors with spherical shaped *** classic,smooth approach is compared to the straightforward to implement blocked-off method for velocity fields above the fixed bed for particle Reynolds numbers of 300 and *** from experimental inline PIV-measurements of the reactor to be simulated serve as a basis for *** good agreement with the experiment is found for both simulation methodologies with higher resolutions,considering the more stable flow at a particle Reynolds number of *** in the different IBM approaches occurred for the more unsteady flow at a particle Reynolds number of *** to the blocked-off method,the smooth IBM reflects the formation of additional jets and recirculation zones better right above the bed,though increasing the fluid mesh resolution improves the accuracy of the blocked-off ***,a more diffusive behaviour is found for the blocked-off simulations due to the stairstep representation,which is avoided by using interpolation stencils as in the smooth *** higher mesh refinement in the blocked-off IBM this effect can be reduced,but this also increases the computational effort.

关键词： Immersed boundary method Packed bed reactor Uniform particle packing

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The effect of side walls on particles mixing in rotating drums

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Particuology 2023年第1期72卷 112-121页

作者： Aman Jain Fabien Evrard berend van wachem Chair of Mechanical Process Engineering Otto-von-Guericke-University MagdeburgUniversitaetsplatz 2Magdeburg 39106Germany

In this paper, we study the effects of the presence and shape of side walls and of the overall length of rotating cylindrical drums on the mixing of particles with differing sizes by application of the discrete element method (DEM). By varying the semi-axis of the spheroidally shaped side walls and the length of the overall drum, we observe the formation of circulation patterns near the side walls. Although there is a vast amount of literature studying mixing regimes in rotating drums, little is known about the effect of the side walls of the drum on particle mixing. The results of our study demonstrate that introducing curved side walls induces a strong circulation pattern near these side walls, but has, paradoxically, a negative impact on mixing and actually promotes segregation. The cause for this segregation is the difference in velocity of differently sized particles near the curved side walls. Large particles accumulate at the curved side walls, whereas small particles move away from the curved side walls. When the length of the drum is increased, the overall effect of the side walls is decreased, although it does remain observable, even in very large drums.

关键词： Discrete element method Rotating drums Particle mixing Side walls of rotating drums

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Gene therapy with caspase-3 small interfering RNA-nanoparticles is neuroprotective after optic nerve damage

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Neural Regeneration Research 2021年第12期16卷 2534-2541页

作者： Mohamed Tawfik Xiwei Zhang Lisa Grigartzik Peter Heiduschka Werner Hintz Petra Henrich-Noack berend van wachem Bernhard A.Sabel Institute of Medical Psychology Otto von Guericke University of MagdeburgMagdeburgGermany Institute of Process Engineering Otto von Guericke University of MagdeburgMagdeburgGermany Department of Ophthalmology Münster University HospitalMünsterGermany Department of Neurology with Institute of Translational Neurology Münster University HospitalMünsterGermany Center of Behavioral Brain Sciences(CBBS) MagdeburgGermany

Apoptosis,a key mechanism of programmed cell death,is triggered by caspase-3 protein and lowering its levels with gene therapy may rescue cell death after central nervous system *** developed a novel,non-viral gene therapy to block caspase-3 gene expression using small interfering RNA(siRNA)delivered by polybutylcyanoacrylate nanoparticles(CaspNPs).In vitro CaspNPs significantly blocked caspase-3 protein expression in C6 cells,and when injected intraocularly in vivo,CaspNPs lowered retinal capsase-3 immunofluorescence by 57.9%in rats with optic nerve ***,repeated retinal ganglion cell counts using confocal neuroimaging showed that post-traumatic cell loss after intraocular CaspNPs injection was only 36.1%versus 63.4%in lesioned *** non-viral gene therapy with siRNA-nanoparticles can selectively silence caspace-3 gene expression and block apoptosis in post-mitotic neurons,siRNA delivery with nanoparticles may be promising for neuroprotection or restoration of central visual system damage and other neurological *** animal study procedures were approved by the German National Act on the use of experimental animals(Ethic Committee Referat Verbraucherschutz,Veterinärangelegenheiten;Landesverwaltungsamt Sachsen-Anhalt,Halle,Germany,#IMP/G/01-1150/12 and#IMP/G/01-1469/17).

关键词： apoptosis brain caspase-3 drug delivery gene therapy in vivo confocal neuroimaging nanoparticles neurodegeneration neuroprotection retina siRNA

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A model for real-time computation of fuselage-rotor interference

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International Journal of Modeling, Simulation, and Scientific Computing 2017年第4期8卷 10-24页

作者： berend G.van der Wall Jianping Yin Institute of Flight Systems DLR Lilienthalplatz 738108 BraunschweigGermany Institute of Aerodynamics and Flow Technology DLR Lilienthalplatz 738108 BraunschweigGermany

A simple analytical real-time capable model to account for fuselage-induced velocities at rotor blade elements is described at the example of the Bo105 *** of the fuselage-induced flow fields in the volume of rotor operation above the fuselage are first computed by a panel method in the range of angle of attack and sideslip of±90°.The model parameters are then estimated based on these *** usefulness of the model in combinations of angle of attack and sideslip is demonstrated.

关键词： Helicopter aerodynamics fuselage-rotor interference real-time simulation

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The 5-HT2c receptor gene Cys23Ser polymorphism influences the intravaginal ejaculation latency time in Dutch Caucasian men with lifelong premature ejaculation

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Asian Journal of Andrology 2014年第4期16卷 607-610页

作者： Paddy KC Janssen Ron van Schaik berend Olivier Marcel D Waldinger Division of Pharmacology Utrecht Institute for Pharmaceutical Sciences Utrecht University Utrecht The Netherlands Department of Central Hospital Pharmacy Viecuri Hospital Venlo The Netherlands Department of Clinical Chemistry (AKC) Erasmus University Medical Center (Erasmus MC) Rotterdam The Netherlands Department of Psychiatry Yale University School of Medicine New Haven Connecticut USA Outpatient Department of Neurosexology HagaZiekenhuis The Hague The Netherlands.

It has been postulated that the persistent short intravaginal ejaculation latency time （IELT） of men with lifelong premature ejaculation （LPE） is related to 5-hydroxytryptamine （HT）2c receptor functioning. The aim of this study was to investigate the relationship of Cys23Ser 5-HT2c receptor gene polymorphism and the duration of IELT in men with LPE. Therefore, a prospective study was conducted in 64 Dutch Caucasian men with LPE. Baseline IELT during coitus was assessed by stopwatch over a 1-month period. All men were genotyped for Cys23Ser 5-HT2c receptor gene polymorphism. Allele frequencies and genotypes of Cys and Ser variants of 5-HT2c receptor gene polymorphism were determined. Association between Cys/Cys and Ser/Ser genotypes and the natural logarithm of the IELT in men with LPE ***. As a result, the geometric mean, median and natural mean IELT were 25.2, 27.0, 33.9s, respectively. Of all men, 20.0%, 10.8%, 23.1% and 41.5% ejaculated within 10, 10-20, 20-30 and 30-60s after vaginal penetration. Of the 64 men, the Cys/Cys and Ser/Ser genotype frequency for the Cys23Ser polymorphism of the 5-HT2c receptor gene was 81% and 19%, respectively. The geometric mean IELT of the wildtypes （Cys/Cys） is significantly lower （22.6s; 95% CI 18.3-27.8s） than in male homozygous mutants （Ser/Ser）（40.4s; 95% CI 20.3-80.4s）（P = 0.03）. It is concluded that Cys23Ser 5-HT2c receptor gene polymorphism is associated with the IELT in men with LPE. Men with Cys/Cys genotype have shorter IELTs than men with Ser/Ser genotypes.

关键词： 5-HT2c receptor gene Cys23Ser polymorphism intravaginal ejaculation latency time lifelong premature ejaculation

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Sensitive capacitive pressure sensors based on graphene membrane arrays

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Microsystems & Nanoengineering 2020年第1期6卷 176-184页

作者： Makars Siskins Martin Lee Dominique Wehenkel Richard van Rijn Tijmen W.de Jong Johannes R.Renshof berend C.Hopman Willemijn S.J.M.Peters Dejan Davidovikj Herre S.J.van der Zant Peter G.Steeneken Kavli Institute of Nanoscience Delft University of TechnologyLorentzweg 12628 CJ DelftThe Netherlands Applied Nanolayers B.V. Feldmannweg 172628 CT DelftThe Netherlands Department of Precision and Microsystems Engineering Delft University of TechnologyMekelweg 22628 CD DelftThe Netherlands

The high flexibility,impermeability and strength of graphene membranes are key properties that can enable the next generation of nanomechanical ***,for capacitive pressure sensors,the sensitivity offered by a single suspended graphene membrane is too small to compete with commercial ***,we realize highly sensitive capacitive pressure sensors consisting of arrays of nearly ten thousand small,freestanding double-layer graphene *** fabricate large arrays of small-diameter membranes using a procedure that maintains the superior material and mechanical properties of graphene,even after high-temperature *** sensors are readout using a low-cost battery-powered circuit board,with a responsivity of up to 47:8aF Pa^(−1) mm^(−2),thereby outperforming the commercial sensors.

关键词： graphene arrays thereby

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3D Volumetric PIV Measurements on a Hovering Model Rotor

3D Volumetric PIV Measurements on a Hovering Model Rotor

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第二届旋翼飞行器技术基础研究国际学术会议

作者： berend Gerdes van der Wall Hugues Richard DLR Institute of Flight Systems-Helicopter-Lilienthalplatz 7 D-38108 Braunschweig DLR Institute of Aerodynamics and Flow Technology-Technical Flows-Bunsenstraβe 10 D-37073 Gottingen

＜正＞A first application of volumetric Particle Image Velocimetry （3D-PIV） was performed in 2005 with a HOver TIp vortex Structure test （HOTIS） in the rotor preparation hall of DLR Braunschweig using a 40% Mach scaled model rotor of the Bol05. Major emphasis was placed on three component （3C） measurements in planes following each other as close as the resolution within each plane to form a 3D volume of the blade tip vortices. They were traced from their creation Ideg behind the trailing edge up to half a revolution. This paper deals with preliminary results obtained for vortex aging, RPM and thrust variation, and special effects observed in 3D volumetric data of young rotor blade tip vortices （age 3deg）. In addition to PIV the background oriented schlieren technique （BOS） was applied to measure optically the density within the core radius at young vortex age.

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Re： Gene mapping of serotoninergic system polymorphisms provides insight on pathology and treatment of men with lifelong premature ejaculation

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Asian Journal of Andrology 2014年第4期16卷 643-643页

作者： Paddy KC Janssen Ron van Schaik berend Olivier Marcel D Waldinger Department of Pharmaceutical Sciences Division of Pharmacology Utrecht University Utrecht The Netherlands.

We appreciate and thank Drs Saitz and Serefoglu for their positive and sympathetic words on our article.1 Indeed, our genetic studies have shown that 5-HTTLPR polymorphism, 5-HT1A receptor gene polymorphism and 5-HT2c receptor gene polymorphism are associated with the duration of the intravaginal ejaculatory latency time in men with lifelong premature ejaculation. In line with the remarks） we hope that our stopwatch method will be used by other investigators to investigate the role of serotonergic gene polymorphisms on the duration of the intravaginal ejaculatory latency time.

关键词： @@

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荷兰哈尔夫韦赫糖储厂改造

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建筑技艺 2010年第11期16卷 132-135页

作者： Jos van Eldonk Jarno van Essen Albert de Graaf berend Hoffmann April Kong Margon de Vries Ingenieursbureau Zonneveld Rotterdam Fedde de Weert Scagliola Brakkee 吴春花 M.J.de Nijsen Zonen Warmenhuizen

CSM糖厂地址位于哈尔夫韦赫(Halfweg),处于阿姆斯特丹和哈勒姆中间.项目的挑战在于将原有的工业基地变为—个舒适的、充满生机的区域.但这里紧邻Schiphol飞机场跑道,不能作为居住区,因此不得不考虑其他功能来激发活力,达到白天与夜晚一... 详细信息

CSM糖厂地址位于哈尔夫韦赫(Halfweg),处于阿姆斯特丹和哈勒姆中间.项目的挑战在于将原有的工业基地变为—个舒适的、充满生机的区域.但这里紧邻Schiphol飞机场跑道,不能作为居住区,因此不得不考虑其他功能来激发活力,达到白天与夜晚一样,工作日和休息日一样.最终将商业、办公、商店、美食广场、宾馆、影院、体育和休闲设,广泛地混合起来,形成了充满活力的环境氛围.

关键词：荷兰糖厂工业基地工业生产基地生产基地休闲设施 CSM 阿姆斯特丹钻石岛状硅酸盐矿物冷却塔冷水塔商店服务设施充满活力宾馆旅馆哈勒储藏库

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