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TURBULENT BOUNDARY LAYER DEVELOPMENT IN THE ENTRANCE REGION OF A SMOOTH ROUND PIPE

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Journal of Hydrodynamics 1992年第3期4卷 17-26页

作者： ning, lizhong li, Jianzhong Shaanxi Inst of Mechanical Engineering Xi'an China

Feature of the turbulent boundary layer along a smooth round pipe is a fundamental to further study of inlet length and flow resistance, therefore, it has been of great significance both in practice and in theory. In this paper, the formulae for calculating the turbulent boundary layer thickness were obtained by solving the momentum integral equation of the boundary layer in which the assumption of the logarithmic law and the exponential law of velocity distribution were adopted. The method for calculating the mean flow velocity in the developing region of turbulent boundary layer in a round pipe was proposed. The relationship between the exponent n and the factor was studied and a formula for calculating the exponent n was obtained.

关键词： Boundary layer flow Boundary layers Turbulent flow

A COUNTER PROPAGATING WAVE STATE WITH A PERIODICALLY HORIZONTAL MOTION OF DEFECTS

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Journal of Hydrodynamics 2008年第5期20卷 567-573页

作者： ning li-zhong QI Xin YUAN Zhe SHI Feng Institute of Hydraulic Engineering Xi＇an University of Technology Xi＇an 710048 China

Convection in a horizontal fluid layer heated from below is one of models for studying patterns of convection in binary fluid mixtures and has been extensively studied. In this article, the convection structures in a rectangular cell were investigated for the aspect-ratio Г= 12 and the separation ratio ψ = -0.47. Simulations were preformed by solving the hydrodynamic equations using the SIMPLE method. A Counter Propagating Wave （CPW） state was found in binary fluid convection with a periodically horizontal motion of defects, and the pattern dynamics was further discuss.

关键词： Counter Propagating Wave (CPW) defect convection pattern dynamics

Embracing digital mindsets to ensure a sustainable future

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Frontiers of Environmental Science & Engineering 2024年第3期18卷 177-179页

作者： Chengjun li Riqing Yu Wenjing ning Huan zhong Christian Sonne Institute of Environmental Research at Greater Bay Area Guangzhou UniversityGuangzhou 510000China Department of Biology Center for EnvironmentBiodiversity and ConservationThe University of Texas at TylerTylerTX 75701USA School of Environment Nanjing UniversityNanjing 210000China Environmental and life Science Program Trent UniversityPeterboroughOntarioK9H 0A1Canada Faculty of Science and Technology Aarhus UniversityRoskildeDenmark 4000The Kingdom of Denmark Sustainability Cluster School of EngineeringUniversity of Petroleum&Energy StudiesDehradunUttarakhand 248001India

The 19th Asian Games astounded global audiences with an opening spectacle that showcased stunning digital fireworks(International Olympic Committee,2021;Zhe,2023).The groundbreaking display was brought to life through virtual reality(VR)and augmented reality(AR)*** sets a pioneering example to replace conventional fireworks in major international events as well as in other large-scale entertainment activities,marking a historic milestone in the pursuit of a sustainable and healthy future.

关键词： Wildlife Climate Change Heavy metals Noise LAN light pollution

Effect of solvent on the initiation mechanism of living anionic polymerization of styrene:A computational study

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Chinese Journal of Chemical Engineering 2024年第5期69卷 135-142页

作者： Shen li Yin-ning Zhou zhong-Xin liu Zheng-Hong Luo School of Chemical Engineering and Technology Hainan UniversityHaikou 570228China Department of Chemical Engineering School of Chemistry and Chemical EngineeringState Key Laboratory of Metal Matrix CompositesShanghai Jiao Tong UniversityShanghai 200240China

For living anionic polymerization(LAP),solvent has a great influence on both reaction mechanism and *** this work,by using the classical butyl lithium-styrene polymerization as a model system,the effect of solvent on the mechanism and kinetics of LAP was revealed through a strategy combining density functional theory(DFT)calculations and kinetic *** terms of mechanism,it is found that the stronger the solvent polarity,the more electrons transfer from initiator to solvent through detailed energy decomposition analysis of electrostatic interactions between initiator and solvent ***,we also found that the stronger the solvent polarity,the higher the monomer initiation energy barrier and the smaller the initiation rate ***,initiation is more favorable at lower temperatures based on the calculated results ofΔG_(TS).Finally,the kinetic characteristics in different solvents were further examined by kinetic *** is found that in benzene and n-pentane,the polymerization rate exhibits first-order ***,slow initiation and fast propagation were observed in tetrahydrofuran(THF)due to the slow free ion formation rate,leading to a deviation from first-order kinetics.

关键词： living anionic polymerization Solvent effect Reaction kinetics Computational chemistry Mathematical modeling Kinetic modeling

Constructing hierarchical ZSM-5 coated with small ZSM-5 crystals via oriented-attachment and in situ assembly for methanol-to-aromatics reaction

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Frontiers of Chemical Science and Engineering 2024年第7期18卷 41-53页

作者： ning Yang Tingjun Fu Chuntao Cao Xueqing Wu Huiling Zheng zhong li State Key Laboratory of Clean and Efficient Coal Utilization College of Chemical Engineering and TechnologyTaiyuan University of TechnologyTaiyuan 030024China

Developing hierarchical and nanoscale ZSM-5 catalysts for diffusion-limited reactions has received ever-increasing attention. Here, ZSM-5 architecture integrated with hierarchical pores and nanoscale crystals was successfully prepared via in situ self-assembly of nanoparticles-coated silicalite-1. First, the oriented attachment of amorphous nanoparticles on external surface of silicalite-1 was achieved by controlling the alkalinity of Si-Al coating solution. The partial exposure of the external surface of silicalite-1 ensured the uniform removal of silicon in the bulk phase for the creation of hierarchical pores during the subsequent desilication-recrystallization. The uniform removal of silicon species in the bulk phase was mainly due to the synergistic effect of surface protection and alkaline etching, which could be balanced by regulating the relative amount of tetrapropylammonium cation and OH– in desilication-recrystallization solution. Importantly, the removed silicon from silicalite-1 recrystallized and in situ assembled into final ZSM-5 nanocrystals induced by surface Si-Al nanoparticles. The hierarchical pores and nanoscale crystals on this integrated architecture not only promoted the removal of coke precursors from micropores but also provided large external specific surface (91 m^(2)·g^(-1)) for coke deposition. Consequently, a much longer catalytic lifetime was achieved for methanol-to-aromatics reaction compared to conventional hollow structure ZSM-5 (84 h vs 46 h), with relatively high stability.

关键词： hierarchical ZSM-5 nanocrystal integrated architecture diffusion coke

Outcomes of endoscopic sclerotherapy for jejunal varices at the site of choledochojejunostomy (with video): Three case reports

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World Journal of Gastroenterology 2024年第14期30卷 2059-2067页

作者： Jun liu Peng Wang li-Mei Wang Jing Guo ning zhong Department of Gastroenterology Qilu Hospital of Shandong UniversityJinan 250012Shandong ProvinceChina

BACKGROUND Hemorrhage associated with varices at the site of choledochojejunostomy is an unusual,difficult to treat,and often fatal manifestation of portal *** far,no treatment guidelines have been *** SUMMARY We reported three patients with jejunal varices at the site of choledochojejun-ostomy managed by endoscopic sclerotherapy with lauromacrogol/α-butyl cyanoacrylate injection at our institution between June 2021 and August *** reviewed all patient records,clinical presentation,endoscopic findings and treatment,outcomes and *** patients who underwent pancre-aticoduodenectomy with a Whipple anastomosis were examined using conven-tional upper gastrointestinal endoscopy for suspected hemorrhage from the afferent jejunal *** with stigmata of recent hemorrhage or active he-morrhage were observed around the choledochojejunostomy site in all three *** injection of lauromacrogol/α-butyl cyanoacrylate was carried out at jejunal varices for all three *** bleeding ceased and patency was observed for 26 and 2 months in two *** one patient with multiorgan failure and internal environment disturbance,rebleeding occurred 1 month after endoscopic sclerotherapy,and despite a second endoscopic sclero-therapy,repeated episodes of bleeding and multiorgan failure resulted in eventual *** We conclude that endoscopic sclerotherapy with lauromacrogol/α-butyl cyanoac-rylate injection can be an easy,effective,safe and low-cost treatment option for jejunal varicose bleeding at the site of choledochojejunostomy.

关键词： Endoscopic sclerotherapy Jejunal varices Choledochojejunostomy Portal vein hypertension Case report

Revealing the intrinsic mechanisms for accelerating nitrogen removal efficiency in the Anammox reactor by adding Fe(Ⅱ)at low temperature

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Chinese Chemical Letters 2024年第8期35卷 341-348页

作者： linjing li Wenlai Xu Jianyong ning Yaping zhong Chuyue Zhang Jiane Zuo Zhicheng Pan State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China National Postdoctoral Research Station Haitian Water GroupChengdu 610213China National Enterprise Technology Center Haitian Water GroupChengdu 610213China Water Safety and Water Pollution Control Engineering Technology Research Center in Sichuan Province Chengdu 610213China Laboratory of Municipal Wastewater Treatment Technology in Sichuan Province Chengdu 610213China Institute of Environment and Ecology Tsinghua Shenzhen International Graduate SchoolShenzhen 518055China

Fe(Ⅱ)is an essential trace element for anaerobic ammonium oxidation bacteria(AAOB)metabolism,and can improve the nitrogen removal efficiency of anaerobic ammonia oxidation(Anammox).Here we oper-ated two identical expanded granular sludge bed(EGSB)reactors at low temperature(15±3℃)for 154 *** 1(R_(1))received additional Fe(Ⅱ)(0.12 mmol/L)during the late startup phase,while reactor 0(R_(0))served as the control and did not receive extra Fe(Ⅱ).Nitrogen removal in R_(1)became stable at 55 d of operation,ten days earlier than R_(0).The nitrogen removal rate(NRR)of R_(1) was 1.64 kg N m^(−3)d^(−1)and its TN removal rate was as high as 89%,while R_(0)only reached 75%.The addition of Fe(Ⅱ)was fur-ther beneficial to aggregation and stability of the granular sludge,and the used sludge of both reactors showed enrichment for AAOB populations compared to the inoculum,for instance,increased abundance of Candidatus-Kuenenia and in particular of Candidatus-Brocadia(from 0.17%to 10.10%in R_(0)and 7.79%in R_(1)).Diverse microbial species and complex microbial network structure in R_(1)compared to R_(0)promoted the coupled denitrogenation by Anammox,dissimilatory nitrate reduction to ammonium(DNRA),nitrate-dependent Fe oxidation(NDFO),and ferric ammonium oxidation(Feammox).In addition,the microbial community in R_(1)was more resistant to short-term low temperature(2-7℃)starvation,illustrating a further positive effect of adding Fe(Ⅱ)during the startup phase of an Anammox reactor.

关键词： Ambient low temperature Anammox Fe(Ⅱ) Extracellular polymeric substances Microbial community Microbial network analysis

Determination of the chromosomal position effects for plug-and-play application in the Myxococcus xanthus chassis cells

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Synthetic and Systems Biotechnology 2024年第3期9卷 540-548页

作者： Xin-jing Yue Jia-rui Wang Jun-ning Zhao Zhuo Pan Yue-zhong li State Key Laboratory of Microbial Technology Institute of Microbial TechnologyShandong UniversityQingdaoPR China

The chromosomal position effect can significantly affect the transgene expression,which may provide an efficient strategy for the inauguration of alien genes in new hosts,but has been less explored *** bacterium Myxococcus xanthus harbors a large circular high-GC genome,and the position effect in this chassis may result in a thousand-fold expression variation of alien natural *** this study,we conducted transposon insertion at TA sites on the *** genome,and used enrichment and dilution indexes to respectively appraise high and low expression potentials of alien genes at insertion *** enrichment sites are characteristically distributed along the genome,and the dilution sites are overlapped well with the horizontal transfer *** experimentally demonstrated the enrichment sites as high expression integration sites(HEISs),and the dilution sites unsuitable for gene integration *** work highlights that HEISs are the plug-and-play sites for efficient expression of integrated genes.

关键词： Position effect High expression integration sites(HEISs) Myxococcus xanthus Tn-seq

Autonomous Recommendation of Fault Detection Algorithms for Spacecraft

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IEEE/CAA Journal of Automatica Sinica 2024年第1期11卷 273-275页

作者： Wenbo li Baoling ning the National Key Laboratory of Science and Technology on Space Intelligent Control Beijing Institute of Control EngineeringBeijing 100094China the School of Data Science and Technology Heilongjiang UniversityHarbin 150001China

Dear Editor, This letter deals with the problem of algorithm recommendation for online fault detection of spacecraft. By transforming the time series data into distributions and introducing a distribution-aware measure, a principal method is designed for quantifying the detectabilities of fault detection algorithms over special datasets.

关键词： fault introducing letter