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Velocity Profiles between Two Baffles in a Horizontal Circular Tube

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Journal of Thermal Science 2014年第6期23卷 544-551页

作者： tae-hyun chang Hae-Soo Lee Keon-Je Oh Doeg Hee Doh chang-Hoan Lee Senior Research Fellow of RESEAT Korea Institute of Science and Information Postdoctoral Research Fellow School of Mechanical Engineering of Kyungnam University School of Mechanical Engineering Kyungnam University Division of Mechanical and Energy Systems Engineering Korea Marine and Ocean University Korea Institute of Science and Technology Information

The shell and tube heat exchanger is an essential part of a power plant for recovering heat transfer between the feed water of a boiler and the wasted *** baffles are also an important element inside the heat *** materials influence the flow pattern in the *** influence of baffles in the velocity profiles was observed using a three-dimensional particle image velocimetry around baffles in a horizontal circular *** velocity of the particles was measured before the baffle and between them in the test *** show that the flows near the front baffle flow were parallel to the vertical wall,and then concentrate on the upper opening of the front *** flows circulate in the front and rear *** flow profiles are related to the Reynolds number(Re) or the flow *** velocity profiles at lower Re number showed a complicated mixing,concentrating on the lower opening of the rear baffle as front *** flow was employed in this study,which was produced using tangential velocities at the *** the entrance of the front baffle,the velocity vector profiles with swirl were much different from that without ***,velocities between two baffles are not much different from those without swirl.

关键词： Baffle Shell and tube Tangential inlet Swirl Particle image velocimetry

Extended protective effects of three dimensional cultured human mesenchymal stromal cells in a neuroinflammation model

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World Journal of Stem Cells 2025年第1期17卷 53-65页

作者： Ok-Hyeon Kim Hana Kang Eun Seo chang Younghyun Lim Young-Jin Seo hyun Jung Lee Department of Anatomy and Cell Biology College of MedicineChung-Ang UniversitySeoul 06974South Korea Department of Global Innovative Drugs Graduate School of Chung-Ang UniversitySeoul 06974South Korea Department of Life Science Chung-Ang UniversitySeoul 06974South Korea

BACKGROUND Human mesenchymal stromal cells(MSCs)possess regenerative potential due to pluripotency and paracrine ***,their stemness and immunomod-ulatory capabilities are sub-optimal in conventional two-dimensional(2D)*** To enhance the efficiency and therapeutic efficacy of MSCs,an in vivo-like 3D culture condition was *** MSCs were cultured on polystyrene(2D)or in a gellan gum-based 3D *** vitro,prostaglandin-endoperoxide synthase 2,indoleamine-2,3-dioxygenase,heme oxygenase 1,and prostaglandin E synthase gene expression was quantified by quantitative real-time polymerase chain *** were incubated with lipopolysaccharide(LPS)-treated mouse splenocytes,and prostaglandin E2 and tumor necrosis factor-alpha levels were measured by enzyme linked immuno-sorbent *** vivo,LPS was injected into the lateral ventricle of mouse brain,and MSCs were administered intravenously the next *** were sacrificed and analyzed on days 2 and *** Gellan gum polymer-based 3D culture significantly increased expression of octamer-binding transcription factor 4 and Nanog homeobox stemness markers in human MSCs compared to 2D *** 3D environment also heightened expression of cyclooxygenase-2 and heme-oxygenase 1,enzymes known for immunomodulatory functions,including production of prostaglandins and heme degradation,*** in 3D culture secreted more prostaglandin E2 and effectively suppressed tumor necrosis factor-alpha release from LPS-stimulated splenocytes and surpassed the efficiency of MSCs cultured in *** a murine neuroinflammation model,intravenous injection of 3D-cultured MSCs significantly reduced ionized calcium-binding adaptor molecule 1 and glial fibrillary acidic protein expression,mitigating chronic inflammation more effectively than 2D-cultured *** The microenvironment established in 3D culture serves as an in vivo mimetic,enhancing the immunomodulatory function of *** sugge

关键词： Mesenchymal stromal cells Three-dimensional culture Immunomodulatory function Neuroinflammation Cell therapy

Omnidirectional simulation analysis of thermomechanical coupling mechanism in inertia friction welding of Ni-based superalloy

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Chinese Journal of Aeronautics 2025年第1期38卷 202-216页

作者： chang-an LI Guoliang QIN Hao WANG School of Materials Science and Engineering Shandong UniversityJinan 250061China

The coupling between heat and pressure is the kernel of inertia friction welding(IFW)and is still not fully understood.A novel 3D fully coupled finite element model based on a plastic friction pair was developed to simulate the IFW process of a Ni-based superalloy and reveal the omnidirectional thermo-mechanical coupling mechanism of the friction *** numerical model successfully simulated the deceleration,deformation processes,and peak torsional moments in IFW and captured the evolution of temperature,contact pressure,and *** simulated results were validated through measured thermal history,optical macrography,and axial *** results indicated that interfacial friction heat was the primary heat source,and plastic deformation energy only accounted for 4%of the *** increase in initial rotational speed and friction pressure elevated the peak temperature,reaching a maximum of 1525.5K at an initial rotational speed of 2000 r/min and friction pressure of 400 *** interface heat generation could form an axial temperature gradient exceeding 320K/*** radial inhomogeneities of heat generation and temperature were manifested in a concentric ring distribution with maximum heat flux and temperature ranging from 2/5 to 2/3 *** radial inhomogeneities were caused by increasing linear velocity along the radius and an opposite distribution of contact pressure,which could reach 1.7 times the set pressure at the *** circumferential inhomogeneity of thermomechanical distribution during rotary friction welding was revealed for the first time,benefiting from the 3D *** deflection and transformation of distribution in contact pressure and Mises stress were indicators of plastic deformation and transition of quasi-steady state *** critical Mises stress was 0.5 times the friction pressure in this *** presented modeling provides a reliable insight into the thermo-mechanical coupling mechanism of IFW and lays a solid found

关键词： Inertia friction welding Thermo-mechanical coupling Inhomogeneity Numerical simulation Ni-based superalloy

Three-dimensional line-of-sight-angle-constrained leader-following cooperative interception guidance law with prespecified impact time

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Chinese Journal of Aeronautics 2025年第1期38卷 491-506页

作者： Hao YOU Xinlong chang Jiufen ZHAO Rocket Force University of Engineering Xi’an 710025China

To address the problem of multi-missile cooperative interception against maneuvering targets at a prespecified impact time and desired Line-of-Sight(LOS)angles in ThreeDimensional(3D)space,this paper proposes a 3D leader-following cooperative interception guidance ***,in the LOS direction of the leader,an impact time-controlled guidance law is derived based on the fixed-time stability theory,which enables the leader to complete the interception task at a prespecified impact ***,in the LOS direction of the followers,by introducing a time consensus tracking error function,a fixed-time consensus tracking guidance law is investigated to guarantee the consensus tracking convergence of the ***,in the direction normal to the LOS,by combining the designed global integral sliding mode surface and the second-order Sliding Mode Control(SMC)theory,an innovative 3D LOS-angle-constrained interception guidance law is developed,which eliminates the reaching phase in the traditional sliding mode guidance laws and effectively saves energy ***,it effectively suppresses the chattering phenomenon while avoiding the singularity issue,and compensates for unknown interference caused by target maneuvering online,making it convenient for practical engineering ***,theoretical proof analysis and multiple sets of numerical simulation results verify the effectiveness,superiority,and robustness of the investigated guidance law.

关键词： Three-dimensional cooperative interception Leader-following missiles Prespecified impact time LOS-angle-constrained Fixed-time stability Global integral sliding mode

Bound state noise-like pulses generation from composite filtering effects

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Optoelectronics Letters 2025年第3期21卷 142-148页

作者： chang Qingyu ZHANG Caishi College of Physics & Optoelectronic Engineering Jinan University Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology School of Physics and Optoelectronic EngineeringMacau University of Science and Technology School of Innovation Engineering Macau University of Science and Technology

This paper demonstrated the generation of multi-wavelength bound state noise-like pulse (BNLP) in a dispersion-managed composite-filtered fiber laser consisting of nonlinear polarization rotation (NPR) and *** the case of BNLP,the generation is caused by the interaction between two noise-like pulses (NLPs) induced by the comb-filtering effect,and bound state level can be artificially controlled in the *** work provides a new method for generating low-coherence pulses and establishes a research idea for the study of the comb-filtering effects.

关键词： A

Data-based neural controls for an unknown continuous-time multi-input system with integral reinforcement

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Control Theory and Technology 2025年第1期23卷 118-130页

作者： Yongfeng Lv Jun Zhao Wan Zhang Huimin chang College of Electrical and Power Engineering Taiyuan University of TechnologyTaiyuanShanxi030024China College of Transportation Shandong University of Science and TechnologyQingdao266590ShandongChina School of Mathematical Sciences Shanxi UniversityTaiyuan030006ShanxiChina

Integral reinforcement learning(IRL)is an effective tool for solving optimal control problems of nonlinear systems,and it has been widely utilized in optimal controller design for solving discrete-time ***,solving the Hamilton-Jacobi-Bellman(HJB)equations for nonlinear systems requires precise and complicated ***,the research and application of IRL in continuous-time(CT)systems must be further *** develop the IRL of a CT nonlinear system,a data-based adaptive neural dynamic programming(ANDP)method is proposed to investigate the optimal control problem of uncertain CT multi-input systems such that the knowledge of the dynamics in the HJB equation is ***,the multi-input model is approximated using a neural network(NN),which can be utilized to design an integral reinforcement ***,two criterion networks and one action network are constructed based on the integral reinforcement signal.A nonzero-sum Nash equilibrium can be reached by learning the optimal strategies of the multi-input *** this scheme,the NN weights are constantly updated using an adaptive *** weight convergence and the system stability are analyzed in *** optimal control problem of a multi-input nonlinear CT system is effectively solved using the ANDP scheme,and the results are verified by a simulation study.

关键词： Adaptive dynamic programming Integral reinforcement Neural networks Heuristic dynamic programming Multi-input system

Release characteristics of arsenic from sediments and its source or sink competition with phosphorus:A case of a great lake with grass-algae alternation

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Journal of Environmental Sciences 2025年第3期149卷 278-287页

作者： Shuhang Wang Yongsheng chang Wei Huang Dianhai Yang Feifei Che State Key Laboratory of Pollution Control and Resource Reuse College of Environmental Science and EngineeringTongji UniversityShanghai 200092China College of Environmental Science and Engineering Donghua UniversityShanghai 201620China National Engineering Laboratory for Lake Pollution Control and Ecological Restoration Chinese Research Academy of Environmental SciencesBeijing 100012China

The arsenic(As)release from sediments in great lakes is affected by various *** this study,the characteristics of As release fromsediments was investigated,and the As sources and sinks with the strengths in sediments from different areas(grass-type,algae-type,and grass-algae alternation areas)in great shallow lakes(Taihu Lake,China)were analyzed,and the influence of P competition in the process of As release was also *** results showed that changing trend of the values of equilibrium As concentration in sediments were consistent with the regional changes(0 to 28.12μg/L),and the sediments from algaetype areas had the higher *** sediments from western lake and northwest lake bay were a strong As and a weak P source,and the north lake bay had the opposite trend of these two *** P source competition with As from the sediments occurred in algae-type *** grass-type areas had strong As and P retention capacities,indicating a sink role of sediment with high As and P sorption *** degree of As and P saturation had similar trend in sediments,and the grass-type areas had the higher values,18.3%-21.4%and 15.31%-20.34%,*** analysis results showed that most of As release contribution was from the bottom(30-50 cm)sediments,and the surface(0-10 cm)sediments from algae-type areas contributed more to the overlying water than other region.

关键词： Arsenic Phosphorus Sediment Source and sink Contribution

Utilizing BP neural networks to accurately reconstruct the tritium depth profile in materials for BIXS

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Nuclear Science and Techniques 2025年第1期36卷 103-114页

作者： Chen Zhao Wei Jin Yan Shi chang-An Chen Yi-Ying Zhao Institute of Materials China Academy of Engineering PhysicsJiangyou 621908China

β-ray-induced X-ray spectroscopy(BIXS)is a promising method for tritium detection in solid materials because of its unique advantages,such as large detection depth,nondestructive testing capabilities,and low requirements for sample ***,high-accuracy reconstruction of the tritium depth profile remains a significant challenge for this *** this study,a novel reconstruction method based on a backpropagation(BP)neural network algorithm that demonstrates high accuracy,broad applicability,and robust noise resistance is *** average reconstruction error calculated using the BP network(8.0%)was much lower than that obtained using traditional numerical methods(26.5%).In addition,the BP method can accurately reconstruct BIX spectra of samples with an unknown range of tritium and exhibits wide applicability to spectra with various tritium ***,the BP network demonstrates superior accuracy and stability compared to numerical methods when reconstructing the spectra,with a relative uncertainty ranging from 0 to 10%.This study highlights the advantages of BP networks in accurately reconstructing the tritium depth profile from BIXS and promotes their further application in tritium detection.

关键词： β-ray-induced X-ray spectroscopy Tritium detection BP network Ridge regression Reconstruction problem

Long-duration aqueous Zn-ion batteries achieved by dual-salt highly-concentrated electrolyte with low water activity

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Journal of Energy Chemistry 2025年第2期101卷 778-785页

作者： Lvzhang Jiang Lingbo Yao Gege Wang chang Liu Xiaowei Chi Yu Liu Shanghai Institute of Ceramics Chinese Academy of Sciences University of Chinese Academy of Sciences

Aqueous Zn-ion batteries have attracted much attention due to their unique high safety and low-cost ***,their practical applications are at a slow pace due to their short cycle life,which fundamentally results from the instability of the positive/negative electrode interface in the traditional dilute aqueous electrolytes with high water *** highly concentrated electrolyte（HCE）has been considered as an effective *** previous studies of single salt-based HCE（SSHCE）,herein,a new dual-salt HCE（15 m ZnCl2+10 m NH4NH2SO3DS-HCE） was proposed for the first ***-HCE was proven to simultaneously possess higher conductivity than traditional dilute electrolytes and ultralow water activity of SS-HCE by the regulation of dual high-concentration salts on the solvation structure,which renders the Zn‖Zn symmetric cell the record-long cycling life of 2200 h compared with those with SS-HCE（30 m ZnCl2,300 h） and other reported ***,the Zn‖NH4V4O10full cell with DS-HCE demonstrated impressed rate capability within a wide-range current densities from 0.1 to 10 A ***,at the high current density of 5 A g-1,the full cell shows almost100% capacity retention after 4000 cycles,which indicates the promising future of the DS-HCE system for long-duration aqueous Zn-ion batteries.

关键词： Ammonium vanadate Aqueous zinc battery Cycling stability Electrolyte