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journal of Iron and Steel Research(International) 2022年第5期29卷 819-835页

作者： j.L.Guo t.j.chen State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals Lanzhou University of TechnologyLanzhou730050GansuChina

the effects of H_(2)SO_(4)concentration and current in electrochemical corrosion on surface layer softening or plasticizing of Q235 steel bar and their effects on subsequent electrochemical cold drawing(ECD)were investigated.the results indicate that the electrochemical corrosion can soften or plasticize the surface layer of Q235 steel bar and then make the subsequent ECD be conducted more easily.the softening degree and thickness of the surface layer are continuously enhanced with increasing corrosion rate,i.e.,increasing H_(2)SO_(4)concentration or current,due to the generation of more vacancy clusters in deeper regions of surface layer.these vacancy clusters then relax dislocations through being absorbed during ECD,and the formation and movement of additional dislocation flux are thereby enhanced,resulting in the further obvious decrease in the drawing force.It is also due to the enhanced formation and movement of additional dislocation flux that the dislocation density and thus the hardness of the surface layer are decreased,as well as that the texture structure is weakened.these behaviors are enhanced as the corrosion rate increases.

关键词： Electrochemical corrosion Electrochemical cold drawing Surface layer softening Vacancy Additional dislocation flux

Formation of tiAlSi intermetallics during heating ti-A356 Al mixed powder compact at semisolid temperature

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journal of Materials Science & technology 2021年第35期94卷 247-263页

作者： M.Gao t.j.chen Z.X.Zhang State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals Lanzhou University of TechnologyLanzhou 730050China

Due to the similarity in composition and crystal structure of some ti Al Si ternary intermetallics,it is quite difficult to accurately confirm their physic characteristics,and thus,to tailor microstructure to improve mechanical properties of metal materials related to the ti Al Si intermetallics.therefore,the formation process of ti Al Si intermetallics was investigated during heating ti-A356 mixed powder compact at a A356 alloy semisolid temperature of 595℃.the results indicated that two kinds of intermetallics ofτ1(tetragonal,I41/amd)andτ2(orthorhombic,Cmcm)generated,and both the concentration and supply direction of ti atoms,which are related to local breakage of oxide films on neighboring ti and A356 alloy powders,determined the phase and morphology of the intermetallics.τ1 andτ2 crystals all had an intrinsic plate morphology,butτ2 crystals were thinner due to more anisotropic growth resulted from their high density of stacking faults(SFs).τ1 lamellar domains generated during growth ofτ2 crystals,which were accompanied by decrease in density of SFs.the combined effect of size difference and internal energy difference betweenτ1 andτ2 crystals made largeτ1 crystals coarsen at the expense ofτ2 crystals in Ostwald ripening,leading them to finally evolve into an agglomerate of largeτ1 plates.

关键词： Intermetallics Stacking faults Growth Phase transformation

Effects of layer interactions on instantaneous stability of finite Stokes flows

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Applied Mathematics and Mechanics(English Edition) 2024年第1期45卷 69-84页

作者： chen ZHAO Zhenli chen C.t.MUtASA Dong LI School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China

the stability analysis of a finite Stokes layer is of practical importance in flow control. In the present work, the instantaneous stability of a finite Stokes layer with layer interactions is studied via a linear stability analysis of the frozen phases of the base flow. the oscillations of two plates can have different velocity amplitudes, initial phases, and frequencies. the effects of the Stokes-layer interactions on the stability when two plates oscillate synchronously are analyzed. the growth rates of two most unstable modes when δ t equal, and δ = δ*/h*, where δ*and h*are the Stokes-layer thickness and the half height of the channel, respectively. However, their vorticities are different. the vorticity of the most unstable mode is symmetric, while the other is asymmetric. the Stokes-layer interactions have a destabilizing effect on the most unstable mode when δ tabilizing effect when δ > 0.68. However, the interactions always have a stabilizing effect on the other unstable mode. It is explained that one of the two unstable modes has much higher dissipation than the other one when the Stokes-layer interactions are strong. We also find that the stability of the Stokes layer is closely related to the inflectional points of the base-flow velocity profile. the effects of inconsistent velocity-amplitude, initial phase, and frequency of the oscillations on the stability are analyzed. the energy of the most unstable eigenvector is mainly distributed near the plate of higher velocity amplitude or higher oscillation frequency. the effects of the initial phase difference are complicated because the base-flow velocity is extremely sensitive to the initial phase.

关键词： finite Stokes layer instantaneous stability Stokes-layer interaction asynchronous oscillation

Surface engineering with ionic polymers on membranes for boron removal

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Frontiers of Chemical Science and Engineering 2024年第5期18卷 61-69页

作者： Xiting Zhang chenyi Fang j Paul chen Sui Zhang Department of Chemical and Biomolecular Engineering National University of SingaporeSingapore 117576Singapore Department of Civil and Environmental Engineering National University of SingaporeSingapore 119260Singapore College of Chemistry and Environmental Engineering Shenzhen UniversityShenzhen 518060China

Removal of boric acid from seawater and wastewater using reverse osmosis membrane technologies is imperative and yet remains inadequately addressed by current commercial membranes.Existing research efforts performed post-modification of reverse osmosis membranes to enhance boron rejection,which is usually accompanied by substantial sacrifice in water permeability.this study delves into the surface engineering of low-pressure reverse osmosis membranes,aiming to elevate boron removal efficiency while maintaining optimal salt rejection and water permeability.Membranes were modified by the self-polymerization and co-deposition of dopamine and polystyrene sulfonate at varying ratios and concentrations.the surfaces became smoother and more hydrophilic after modification.the optimum membrane exhibited a water permeability of 9.2±0.1 L·m^(-2)·h^(-1)·bar^(-1),NaCl rejection of 95.8%±0.3%,and boron rejection of 49.7%±0.1%and 99.6%±0.3%at neutral and alkaline pH,respectively.the water permeability is reduced by less than 15%,while the boron rejection is 3.7 times higher compared to the blank membrane.this research provides a promising avenue for enhancing boron removal in reverse osmosis membranes and addressing water quality concerns in the desalination process.

关键词： membrane low-pressure reverse osmosis boron surface engineering

In situ characterization of particle formation in spray flame synthesis using wide-angle light scattering

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Particuology 2024年第3期86卷 304-312页

作者： Simon Aβmann Franz j.t.Huber Stefan Will Lehrstuhl für technische thermodynamik(Ltt) Friedrich-Alexander-Universitat Erlangen-Nürnberg(FAU)Erlangen91058Germany Erlangen Graduate Schoolin Advanced Optical technologies(SAOt) Friedrich-Alexander-Universitat Erlangen-Nurnberg(FAU)Erlangen91052Germany Competence Unit Engineering of Advanced Materials(EAM) Friedrich-Alexander-Universitat Erlangen-Nürnberg(FAU)Erlangen91052Germany

Wide-angle light scattering(WALS)was used for in situ measurements of droplet and nanoparticle size distributions during the synthesis of titania and iron oxide particles from liquid precursor solutions in the standardized SpraySyn burner for spray flame synthesis.titania was synthesized from titanium tetraisopropoxide(ttIP)and iron oxide from iron(II)nitrate nonahydrate(INN)using ethanol(EtOH)as solvent.Scattering images were taken at heights up to 120 mm above the burner surface and classified into droplet and particle scattering.Droplet size distributions were derived from a sequential analysis of scattering data containing the oscillating Mie pattern,the lognormal size distribution parameters for spherical and fractal particle fractions from a multivariate approach on averaged particle scattering data.the results show that the precursor addition leads to altered evaporation behavior and even droplet disruption probably induced by puffing or micro-explosions compared to pure EtOH.In the case of ttIP(a hygroscopic alkoxide),the synthesis of a large fraction of spheres was observed,while the nitrate INN leads to the formation of mostly fractal aggregates.

关键词： Spray flame synthesis Metal oxide particles Elastic light scattering Droplet size distribution Nanoparticle morphology Particle size distribution

A REDUCED ORDER SCHWARZ MEtHOD FOR NONLINEAR MULtISCALE ELLIPtIC EQUAtIONS BASED ON tWO-LAYER NEURAL NEtWORKS

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journal of Computational Mathematics 2024年第2期42卷 570-596页

作者： Shi chen Zhiyan Ding Qin Li Stephen j.Wright Mathematics Department University of Wisconsin-MadisonMadisonWI 53706USA Department of Mathematics University of California-BerkeleyBerkeley CA 94720USA Mathematics Department and Discovery Institute University of Wisconsin-Madison MadisonWI 53706USA Computer Sciences Department University of WisconsinMadisonWI 53706USA

Neural networks are powerful tools for approximating high dimensional data that have been used in many contexts,including solution of partial differential equations(PDEs).We describe a solver for multiscale fully nonlinear elliptic equations that makes use of domain decomposition,an accelerated Schwarz framework,and two-layer neural networks to approximate the boundary-to-boundarymap for the subdomains,which is the key step in the Schwarz procedure.Conventionally,the boundary-to-boundary map requires solution of boundary-value elliptic problems on each subdomain.By leveraging the compressibility of multiscale problems,our approach trains the neural network offline to serve as a surrogate for the usual implementation of the boundary-to-boundary map.Our method is applied to a multiscale semilinear elliptic equation and a multiscale p-Laplace equation.In both cases we demonstrate significant improvement in efficiency as well as good accuracy and generalization performance.

关键词： Nonlinear homogenization Multiscale elliptic problem Neural networks Do-main decomposition

GraphFlow+:Exploiting Conversation Flow in Conversational Machine Comprehension with Graph Neural Networks

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Machine Intelligence Research 2024年第2期21卷 272-282页

作者： jing Hu Lingfei Wu Yu chen Po Hu Mohammed j.Zaki School of Computer Science Central China Normal UniversityWuhan 430079China Pinterest San Francisco 94016USA Meta Mountain View 94039USA Rensselaer Polytechnic Institute Troy 12180USA

the conversation machine comprehension(MC)task aims to answer questions in the multi-turn conversation for a single passage.However,recent approaches don’t exploit information from historical conversations effectively,which results in some references and ellipsis in the current question cannot be recognized.In addition,these methods do not consider the rich semantic relationships between words when reasoning about the passage text.In this paper,we propose a novel model GraphFlow+,which constructs a context graph for each conversation turn and uses a unique recurrent graph neural network(GNN)to model the temporal dependencies between the context graphs of each turn.Specifically,we exploit three different ways to construct text graphs,including the dynamic graph,static graph,and hybrid graph that combines the two.Our experiments on CoQA,QuAC and DoQA show that the GraphFlow+model can outperform the state-of-the-art approaches.

关键词： Conversational machine comprehension(MC) reading comprehension question answering graph neural networks(GNNs) natural language processing(NLP)

Recent Developments in Metallic Degradable Micromotors for Biomedical and Environmental Remediation Applications

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Nano-Micro Letters 2024年第3期16卷 1-35页

作者： Sourav Dutta Seungmin Noh Roger Sanchis Gual Xiangzhong chen Salvador Pané Bradley j.Nelson Hongsoo Choi Department of Robotics and Mechatronics Engineering Daegu Gyeongbuk Institute of Science and Technology(DGIST)Daegu 42988Republic of Korea DGISt‑EtH Microrobotics Research Center DGISTDaegu 42988Republic of Korea Multi‑Scale Robotics Lab Institute of Robotics and Intelligent SystemsETH Zurich8092 ZurichSwitzerland Institute of Optoelectronics State Key Laboratory of Photovoltaic Science and TechnologyShanghai Frontiers Science Research Base of Intelligent Optoelectronics and PerceptionFudan UniversityShanghai 200433People’s Republic of China

Synthetic micromotor has gained substantial attention in biomedicine and environmental remediation.Metal-based degradable micromotor composed of magnesium(Mg),zinc(Zn),and iron(Fe)have promise due to their nontoxic fuel-free propulsion,favorable biocompatibility,and safe excretion of degradation products Recent advances in degradable metallic micromotor have shown their fast movement in complex biological media,efficient cargo delivery and favorable biocompatibility.A noteworthy number of degradable metal-based micromotors employ bubble propulsion,utilizing water as fuel to generate hydrogen bubbles.this novel feature has projected degradable metallic micromotors for active in vivo drug delivery applications.In addition,understanding the degradation mechanism of these micromotors is also a key parameter for their design and performance.Its propulsion efficiency and life span govern the overall performance of a degradable metallic micromotor.Here we review the design and recent advancements of metallic degradable micromotors.Furthermore,we describe the controlled degradation,efficient in vivo drug delivery,and built-in acid neutralization capabilities of degradable micromotors with versatile biomedical applications.Moreover,we discuss micromotors’efficacy in detecting and destroying environmental pollutants.Finally,we address the limitations and future research directions of degradable metallic micromotors.

关键词： Magnesium Zinc Iron Biodegradable microrobot Biomedical Environmental

Reply to the note by Li Piani et al.

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Defence technology（防务技术） 2024年第1期31卷 603-606页

作者： t.Li Piani j.Weerheijm L.j.Sluys tU Delft Stevinweg 12628 CNDelftthe Netherlands tNO PO Box 452280 AARijswijkthe Netherlands NLDA Faculty of Military Sciences1781 CADen Helderthe Netherlands

In 2017,a ballistic phenomenological model was proposed by the authors of Ref.[1] to numerically simulate the experimental depths of small caliber projectiles impacting walls made of adobe.the opportunity for a new model in the field revealed from the observation that two older models recently used by the authors of Ref.[2] shared a linear relationship between the penetration depth P and the impacting velocity v_(O).

关键词： Penetration Adobe Modeling

A proton birdcage coil integrated with interchangeable single loops for multi-nuclear MRI/MRS

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journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2024年第2期25卷 168-180页

作者： Yi ZHANG Zhiyan QUAN Feiyang LOU Yujiao FANG Garth j.tHOMPSON Gao chen Xiaotong ZHANG Department of Neurosurgery the Second Affiliated HospitalSchool of MedicineZhejiang UniversityHangzhou310009China Key Laboratory of Precise treatment and Clinical translational Research of Neurological Diseases Hangzhou310009China MOE Frontier Science Center for Brain Science and Brain-machine Integration Zhejiang UniversityHangzhou310058China Interdisciplinary Institute of Neuroscience and technology College of Biomedical Engineering&Instrument ScienceZhejiang UniversityHangzhou310027China School of Medicine Zhejiang UniversityHangzhou310020China iHuman Institute School of Life Science and TechnologyShanghaiTech UniversityShanghai201210China College of Electrical Engineering Zhejiang UniversityHangzhou310027China

Energy metabolism is fundamental for life.It encompasses the utilization of carbohydrates,lipids,and proteins for internal processes,while aberrant energy metabolism is implicated in many diseases.In the present study,using three-dimensional(3D)printing from polycarbonate via fused deposition modeling,we propose a multi-nuclear radiofrequency(RF)coil design with integrated 1H birdcage and interchangeable X-nuclei(^(2)H,^(13)C,^(23)Na,and^(31)P)single-loop coils for magnetic resonance imaging(MRI)/magnetic resonance spectroscopy(MRS).the single-loop coil for each nucleus attaches to an arc bracket that slides unrestrictedly along the birdcage coil inner surface,enabling convenient switching among various nuclei and animal handling.Compared to a commercial 1H birdcage coil,the proposed 1H birdcage coil exhibited superior signal-excitation homogeneity and imaging signal-to-noise ratio(SNR).For X-nuclei study,prominent peaks in spectroscopy for phantom solutions showed excellent SNR,and the static and dynamic peaks of in vivo spectroscopy validated the efficacy of the coil design in structural imaging and energy metabolism detection simultaneously.

关键词： Energy metabolism Magnetic resonance imaging(MRI) Magnetic resonance spectroscopy(MRS) Multi-nuclear Radiofrequency coil three-dimensional(3D)printing