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Momentum and heat transfer of a special case of the unsteady stagnation-point flow

Applied Mathematics and Mechanics(English Edition) 2020年第1期41卷 51-82页

作者： t.g.FANg F.j.waNg Mechanical and Aerospace Engineering Department North Carolina State University

this paper investigates the unsteady stagnation-point flow and heat transfer over a moving plate with mass transfer,which is also an exact solution to the unsteady Navier-Stokes(NS)*** boundary layer energy equation is solved with the closed form solutions for prescribed wall temperature and prescribed wall heat flux *** wall temperature and heat flux have power dependence on both time and spatial *** solution domain,the velocity distribution,the flow field,and the temperature distribution in the fluids are studied for different controlling *** parameters include the Prandtl number,the mass transfer parameter at the wall,the wall moving parameter,the time power index,and the spatial power *** is found that two solution branches exist for certain combinations of the controlling parameters for the flow and heat transfer *** heat transfer solutions are given by the confluent hypergeometric function of the first kind,which can be simplified into the incomplete gamma functions for special *** wall heat flux and temperature profiles show very complicated variation *** wall heat flux can have multiple poles under certain given controlling parameters,and the temperature can have significant oscillations with overshoot and negative values in the boundary *** relationship between the number of poles in the wall heat flux and the number of zero-crossing points is *** difference in the results of the prescribed wall temperature case and the prescribed wall heat flux case is *** given in this paper provide a rare closed form analytical solution to the entire unsteady NS equations,which can be used as a benchmark problem for numerical code validation.

关键词： unsteady stagnation point flow Navier-Stokes(NS)equations analytical solution heat transfer

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Review:Resuspension of wall deposits in spray dryers

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journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第11期8卷 1762-1774页

作者： HANUS M.j. LANgRISH t.A.g. School of Chemical and Biomolecular Engineering University of Sydney Sydney NSW 2006 Australia

wall deposition occurs in spray dryers when dried or partially dried particles contact and adhere to the walls during operation, thus reducing the yield of product collected. wall deposits also present a product contamination risk and a fire or explosion risk when spray drying products that oxidize exothermically, such as milk powder. Re-entrainment is the resuspension of spray dryer wall deposits into the main gas stream for collection as product. Literature suggests that the process for re-entrainment of particles from spray dryer wall deposits is strongly dependent on particle size and gas velocity.

关键词： wall deposition Spray dryers Dried particles Re-entrainment Adhesive forces

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generation of brain vascular heterogeneity:recent advances from the perspective of angiogenesis

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Neural Regeneration Research 2025年第7期20卷 2013-2014页

作者： Nathanael j.Lee Ryota L.Matsuoka Department of Neurosciences Lerner Research InstituteCleveland ClinicClevelandOHUSA Department of Molecular Medicine Cleveland Clinic Lerner College of MedicineCase Western Reserve UniversityClevelandOHUSA

Heterogeneous proper t i es of vascular endothelial cells in the brain:the brain displays large energy dynamics and consumption,and this high level of metabolic demands is fulfilled by a continuous supply of glucose and oxygen through its vascular *** vasculature consists of highly divergent blood vessel branches,giving rise to a dense network of capillaries that supply blood to all cells across the *** elaborated vascular network is thought to develop via angiogenesis,a process in which new blood vessels grow from pre-existing *** capillaries exhibit organotypic features distinct from other tissues and are formed primarily by two major endothelial cell(EC)types:those that form the semi-permeable blood-brain barrier(BBB)and those that develop highly permeable pores known as fenestrae(Matsuoka et al.,2022).the structural and functional differences between BBB and fenestrated vascular ECs represent a fundamental feature of brain vasculature and form the foundation for both brain function and homeostasis.

关键词： angiogenesis homeostasis network

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Unsteady magnetohydrodynamic stagnation point flow — closed-form analytical solutions

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Applied Mathematics and Mechanics(English Edition) 2019年第4期40卷 449-464页

作者： t.g.FANg F.j.waNg Bo gAO Mechanical and Aerospace Engineering Department North Carolina State University School of Energy & Power Engineering Jiangsu University

this paper investigates the unsteady stagnation point flow and heat transfer of magnetohydrodynamic(MHD) fluids over a moving permeable flat surface. the unsteady Navier-Stokes(NS) equations are transformed into a similarity nonlinear ordinary differential equation, and a closed form solution is obtained for the unsteadiness parameter of 2. the boundary layer energy equation is transformed into a similarity equation,and is solved for a constant wall temperature and a time-dependent uniform wall heat flux case. the solution domain, velocity, and temperature profiles are calculated for different combinations of parameters including the Prandtl number, mass transfer parameter, wall moving parameter, and magnetic parameter. two solution branches are obtained for certain combinations of the controlling parameters, and a stability analysis demonstrates that the lower solution branch is not stable. the present solutions provide an exact solution to the entire unsteady MHD NS equations, which can be used for validating the numerical code of computational fluid dynamics.

关键词： unsteady stagnation point flow stretching/shrinking sheet magnetohy-drodynamic(MHD) Navier-Stokes(NS)equation

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DISSOLUtION KINEtICS OF PHOSPHAtE ORE IN ACIDIC SOLUtIONS

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Chinese journal of Chemical Engineering 1994年第2期2卷 13-22页

作者：马三剑 E.t.M.j.Martynowicz g.j.Witkamp g.M.vanRosmalen Faculty of Chemical technology and Material Science Delft University of TechnologyLeeghwaterstraat 442628RZ DelftThe Netherlands

the dissolution kinetics of Florida and jordan phosphate ore was studied in diluted nitric acid (0.2, 0.5, 1.0 mol ·L-1), and in phosphoric acid (55 wt% H3PO4) aqueous solutions. It was found that the hydrogen ions concentration is a controlling factor, but the calcium ions concentration can not affect the dissolution rate in the range of 0.0 and 2.0 wt% Ca2+. the effects of temperature, stirring intensity and the size of ore particles were also investigated. the transfer of hydrogen ion depends on the diffusion, while the calcium ions transfer is assumed to be depended on mechanically stripping. the shrinking core model with hydrogen ions diffusion control match the experimental results.

关键词： dissolution kinetics phosphate ore diffusion mechanically stripping hydrogen calcium ions concentration shrinking core model

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Progress toward Steady-State Operation on tore Supra

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Plasma Science and technology 2004年第1期6卷 2101-2108页

作者： j.jacquinot g.t.Hoang on behalf of the tore Supra team Euratom-CEA Association CEA/DSM/DRFC CEA Cadarache F-13108 Saint-Paul-Lez-Durance FranceEuratom-CEA Association CEA/DSM/DRFC CEA Cadarache F-13108 Saint-Paul-Lez-Durance FranceEuratom-CEA Association CEA/DSM/DRFC CEA Cadarache F-13108 Saint-Paul-Lez-Durance France

Important technological and physics issues related to steady-state operationrequired for next step are being examined on tore Supra, after a major upgrade of internalcomponents in order to increase the heat extraction capability to 25 MW for 1000 s. Here, we showfirst experimental results, where all the plasma facing components were actively cooled duringpulses exceeding four minutes, with reactor-relevant heat load. New physics was observed innon-inductively driven plasmas, including a stationary peaked radial profile of the plasma densitygenerated by an anomalous inward pinch; and a regime characterized by sinusoidal oscillations ofcentral electron temperature, governed by non-linear coupling between heat transport and plasmacurrent analogous to a predator-prey mechanism.

关键词： steady-state operation tore supra, non-inductively driven plasma

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Energy System Selection for Small Underwater Vehicles

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journal of thermal Science 1994年第1期3卷 7-14页

作者： g.t.Reader j.g.Hawley 等 DepartmentofMechanicalEngineering UniversityofCalgaryCalgaryAlbertaCanada RoyalNavalEngineeringCol

the oceans cover almost three-quarters of the earth's surface and provide a highway for commerceor conquest and constitute a rich source of nutrients, materials and energy. the exploration and exploitation of oceanic resources accelerated in the 1970s because of the emerging offshore oil and gasindustry. the extraction and national protection of these and other resources will increase rapidlyin the next century and in support of these activities one of the most useful tools will be the smallunderwater vehicle. However, if these vehicles are to carry out the envisaged tasks in a cost--effectiveand mission-effective manner they will require high performance energy systems. A number of suchsystems are being developed and the problem arises as which one to select for a particular task. In thispaper the development of software based techniques for the selection of energy systems is described.

关键词： energy system selection small underwater vehicles

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tRANSIENt FLOWS AND PRESSURE waVES IN PIPES

引用

journal of Hydrodynamics 1995年第2期7卷 51-59页

作者： wang, Xiuqing Sun, j.g. Sha, W.t. Nuclear Industry Management Inst Beijing China

transient laminar flows and pressure-wave propagation in pipes, commonly called as water hammer, have been analyzed. A pressure-wave equation and a linearized velocity equation were derived from the equations of mass and momentum conservation. the waveform distortion due to viscous dissipation and elastic expansion of pipe wall was characterized by a dimensionless transmission number. the damping coefficients of pressure waves were found to be related to the roots of Bessel function. An exact solution of pressure-wave equation was obtained numerically. the relationship between the distortion of a traveling wave and transmission number was studied. the problem was also calculated with a general-purpose computer code, COMMIX, which solves exact mass conservation equation and Navier-Stokes equations. the computational results of the COMMIX code agreed well with the analytical solutions.

关键词： Computer simulation Differential equations Pipe flow water wave effects

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Effect of Pressure on Intermediate Valence States in Cerium Kondo Compounds

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journal of Rare Earths 2004年第1期22卷 7-12页

作者： Oomi g Kagayama t Smith j L Lacerda A H Kaji S Ohashi M Department of Physics Kyushu University Ropponmatsu Fukuoka 810-8560 Japan Department of Mechanical Engineering and Materials Sciences Kumamoto University Kumamoto 860-8555 Japan Materials Science and technology Los Alamos National Laboratory Los Alamos NM 87545 USA

Electrical resistance, thermal expansion, lattice constants of the intermediate valence materials, α-Ce and CeBe 13, were measured at high pressure. It is found that the grüneisen parameters of Kondo temperature t K are 13 and 42 for α-Ce and CeBe 13, respectively, and it decreases with increasing pressure. the magnetoresistance of α-Ce shows H2 dependence and its coefficient increases with pressure below 1 gPa, but becomes nearly constant above 1 gPa. the results indicate that the intermediate valence states are enhanced at high pressure indicating the enhancement of hybridization between the 4f electron and conduction band.

关键词： condensel physics intermediate valence materials cerium rare earths

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Comparison of esophageal capsule endoscopy and esophagogastroduodenoscopy for diagnosis of esophageal varices

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World journal of gastroenterology 2008年第28期14卷 4480-4485页

作者： Catherine t Frenette john g Kuldau Donald j Hillebrand jill Lane Paul j Pockros Division of gastroenterology and Hepatology Scripps ClinicLa JollaCaliforniaSan Francisco 94115United States

AIM： to investigate the utility of esophageal capsule endoscopy in the diagnosis and grading of esophageal varices. MEtHODS： Cirrhotic patients who were undergoing esophagogastroduodenoscopy （EgD） for variceal screening or surveillance underwent capsule endoscopy. two separate blinded investigators read each capsule endoscopy for the following results： variceal grade, need for treatment with variceal banding or prophylaxis with beta-blocker therapy, degree of portal hypertensive gastropathy, and gastric varices. RESULtS： Fifty patients underwent both capsule and EgD. Forty-eight patients had both procedures on the same day, and 2 patients had capsule endoscopy within 72 h of EgD. the accuracy of capsule endoscopy to decide on the need for prophylaxis was 74%, with sensitivity of 63% and specificity of 82%. Interrater agreement was moderate （kappa = 0.56）. Agreement between EgD and capsule endoscopy on grade of varices was 0.53 （moderate）. Inter-rater reliability was good （kappa = 0.77）. In diagnosis of portal hypertensive gastropathy, accuracy was 57%, with sensitivity of 96% and specificity of 17%. two patients had gastric varices seen on EgD, one of which was seen on capsule endoscopy. there were no complications from capsule endoscopy.CONCLUSION： We conclude that capsule endoscopy has a limited role in deciding which patients would benefit from EgD with banding or beta-blocker therapy. More data is needed to assess accuracy for staging esophageal varices, PHg, and the detection of gastric varices.

关键词： Esophageal varices Capsule endoscopy Portal hypertension

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