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Journal of Materials Science & Technology 2021年第18期77卷 196-208页

作者： h.L.wei F.Q.Liu L.wei T.T.Liu w.h.liao School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing.210094China State Key Laboratory of Solidification Processing Northwestern Poly technical UniversityXi'an710072China

Laser directed energy deposition(DED)involves complex physical processes,and the trial and error examinations are time consuming and cost *** research paradigm can be reshaped using advanced phenomenological models via computing the spatiotemporal variations of the build *** this work,multi-layer and multi-track laser DED of Ti-6 Al-4 V were systematically explored on multiple scales including the 1D track,the 2D layer and the 3D full build considering the complex transport of energy,mass,and momentum in the moving freeform molten *** results showed that convex,nearflat,and wavy builds were generated using gradually larger hatch *** profiles of individual tracks and layers were extracted through the unique advantages of the *** individual tracks exhibited various patterns and rotated with specific inclinations to form distinct layer *** net increments of the deposit generated upon the printing of a new track during the continuous deposition process showed that the smaller hatch spacing caused higher overlap rate of horizontally adjacent tracks but lower remelting rate of vertically adjacent tracks in neighboring *** 3D numerical model was validated with corresponding experiments for various process *** scientific findings can provide useful insights for further researches of DED.

关键词： Additive manufacturing Multi-layer and multi-track Numerical model Build features Molten pool

Influences of residual stress and micro-deformation on microstructures and mechanical properties for Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy produced by laser powder bed fusion

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Journal of Materials Science & Technology 2021年第16期75卷 174-183页

作者： C.C.Zhang h.L.wei T.T.Liu L.Y.Jiang T.Yang w.h.liao National Joint Engineering Research Center of NC Forming Technology and Equipment School of Mechanical EngineeringNanjing University of Science and TechnologyNanjing 210094China

Laser powder bed fusion(LPBF)yields unique advantages during the fabrication of titanium *** the present work,Ti-6.5 Al-3.5 Mo-1.5 Zr-0.3 Si alloy specimens with excellent mechanical performances were fabricated by *** as-built specimens displayed relatively high strength and ductility under modest volume energy densities(VEDs),whereas they manifested high strength with low ductility under high *** investigate the key reason of this phenomenon,the specimens were designed with two VEDs ranges of 60 J/mm^(3) and 85 J/mm^(3).Special attention was paid to the influences of residual stress and micro-deformation on microstructures and mechanical properties for the first *** results indicated that the residual stresses and relative density of the 60 J/mm^(3) range specimens were higher than that of the 85 J/mm3 range *** multiplication and dislocation movement promoted by the residual stress were hindered by the initialα’phase grain boundary(prior-α’GB),leading to the formation ofα’metastable *** mean tensile strength and elongation of the 60 J/mm^(3) range specimens were 1248.1 MPa and 12.3%,respectively,whereas the corresponding values for the 85 J/mm^(3) range specimens were 1405.3 MPa,5.0%,*** deformation,the strength and ductility of the specimens were first improved by lamellar structures generated from prior-α’phases,and then effectively enhanced by the interaction between the{10–12}twins and ***,pores significantly reduced the ductility;hence,high VED specimens with large twins and numerous large pores increased the strength and reduce the ductility.

关键词： Laser powder bed fusion Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy Residual stress Twin Mechanical properties

Towards sustainable adversarial training with successive perturbation generation

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Frontiers of Information Technology & Electronic Engineering 2024年第4期25卷 527-539页

作者： wei LIN Lichuan liao College of Computer Science and Mathematics Fujian University of TechnologyFuzhou 350118China College of Economics and Management Xi’an University of TechnologyXi’an 710048China Fujian Provincial Key Laboratory of Big Data Mining and Applications Fujian University of TechnologyFuzhou 350118China

Adversarial training with online-generated adversarial examples has achieved promising performance in defending adversarial attacks and improving robustness of convolutional neural network ***,most existing adversarial training methods are dedicated to finding strong adversarial examples for forcing the model to learn the adversarial data distribution,which inevitably imposes a large computational overhead and results in a decrease in the generalization performance on clean *** this paper,we show that progressively enhancing the adversarial strength of adversarial examples across training epochs can effectively improve the model robustness,and appropriate model shifting can preserve the generalization performance of models in conjunction with negligible computational *** this end,we propose a successive perturbation generation scheme for adversarial training(SPGAT),which progressively strengthens the adversarial examples by adding the perturbations on adversarial examples transferred from the previous epoch and shifts models across the epochs to improve the efficiency of adversarial *** proposed SPGAT is both efficient and effective;e.g.,the computation time of our method is 900 min as against the 4100 min duration observed in the case of standard adversarial training,and the performance boost is more than 7%and 3%in terms of adversarial accuracy and clean accuracy,*** extensively evaluate the SPGAT on various datasets,including small-scale MNIST,middle-scale CIFAR-10,and large-scale *** experimental results show that our method is more efficient while performing favorably against state-of-the-art methods.

关键词： Adversarial training Adversarial attack Stochastic weight average Machine learning Model generalization

Optimization of ferroelectricity and endurance of hafnium zirconium oxide thin films by controlling element inhomogeneity

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Journal of Advanced Ceramics 2024年第7期13卷 1023-1031页

作者： Fei Yan Ke Cao Yang Chen Jiajia liao Min liao Yichun Zhou Shaanxi Key Laboratory of high-Orbits-Electron Materials and Protection Technology for Aerospace School of Advanced Materials and NanotechnologyXidian UniversityXi’an 710126China Xi’an Key Laboratory of Reconfigurable Chip and Materials School of Advanced Materials and NanotechnologyXidian UniversityXi’an 710126China Frontier Research Center of Thin Films and Coatings for Device Applications Academy of Advanced Interdisciplinary ResearchXidian UniversityXi’an 710126China

Ferroelectric thin films based on hfO2 have garnered increasing attention worldwide,primarily due to their remarkable compatibility with silicon and scalability,in contrast to traditional perovskite-structured ferroelectric ***,significant challenges remain in their widespread commercial utilization,particularly concerning their notable wake-up effect and limited *** address these challenges,we propose a novel strategy involving the inhomogeneous distribution of hf/Zr elements within thin films and explore its effects on the ferroelectricity and endurance of hf_(0.5)Zr_(0.5)O_(2) thin *** techniques such as grazing incidence X-ray diffraction,transmission electron microscopy,and piezoresponse force microscopy,we investigated the structural characteristics and domain switching behaviors of these *** experimental results indicate that the inhomogeneous distribution of hf/Zr contributes to improving the frequency stability and endurance while maintaining a large remnant polarization in hf_(0.5)Zr_(0.5)O_(2) ferroelectric thin *** adjusting the distribution of Zr/hf within the hf_(0.5)Zr_(0.5)O_(2) thin films,significant enhancements in the remnant polarization(2Pr>35μC/cm2)and endurance(>109)along with a reduced coercive voltage can be ***,the fabricated ferroelectric thin films also exhibit high dielectric tunability(≥26%)under a low operating voltage of 2.5 V,whether in the wake-up state or *** study offers a promising approach to optimize both the ferroelectricity and endurance of hfO_(2)-based thin films.

关键词： ferroelectric capacitors thin films ferroelectricity hafnium zirconium oxide

Organic Brønsted Acid-Catalyzed Stereoselective Cationic RAFT Polymerization:The Effect of RAFT Agents

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Chinese Journal of Polymer Science 2024年第6期42卷 711-717页

作者： Zheng-Yi Zhang Zan Yang Yun liao Sai-hu liao Key Laboratory of Molecule Synthesis and Function Discovery(Fujian Province University) College of ChemistryFuzhou UniversityFuzhou350108China State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical EngineeringXiamen UniversityXiamen361005China Beijing National Laboratory for Molecular Sciences Beijing100190China

The tacticity of vinyl polymers is a key factor affecting the properties of ***,organic Brønsted acids have been demonstrated as effective catalysts for the development of highly stereoselective cationic reversible addition-fragmentation chain transfer(RAFT)polymerizations of vinyl ethers,in which the use of RAFT agents could allow the control the molecular weight and tacticity of polymer products ***,the effect of RAFT agents on the tacticity-regulation remains elusive and lacks of *** this study,we synthesized four types of RAFT agents and evaluated their influence in the stereoselective cationic polymerization of isobutyl vinyl ether in the presence of PADI as a Brønsted acid catalyst,which unveils that the Z group of RAFT agents could not only affect the polydispersity of the products,but also exert a profound effect on the *** extensive screening of the RAFT agents,high stereoregularity(isotacticity,90%m)was obtained when using dithiocarbonate ester-type RAFT agents with a benzyloxy Z group.

关键词： Bronsted acid catalysis Stereoselective cationic polymerization RAFT polymerization Chain transfer agents Tacticity

Interface property of dissimilar Ti-6Al-4V/AA1050 composite laminate made by non-equal channel lateral co-extrusion and heat treatment

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Defence Technology（防务技术） 2024年第3期33卷 197-208页

作者： Juan liao Mengmeng Tian Xin Xue School of Mechanical Engineering and Automation Fuzhou UniversityFuzhou 350116China

The purpose of this paper is to examine the effect of processing parameters and subsequent heat treatments on the microstructures and bonding strengths of Ti-6Al-4V/AA1050 laminations formed via a non-equal channel lateral co-extrusion *** microstructural evolution and growth mechanism in the diffusion layer were discussed further to optimize the bonding quality by appropriately adjusting process *** electron microscopes(SEM),energy dispersive spectrometer(EDS),and X-ray diffraction(XRD)were used to characterize interfacial diffusion *** shear test was used to determine the mechanical properties of the interfacial diffusion *** experimental results indicate that it is possible to co-extrusion Ti-6Al-4V/AA1050 compound profiles using non-equal channel lateral *** heat treatment processes affect the thickness of the diffusion *** the temperature and time of heat treatment increase,the thickness of the reaction layers increases ***,the shear strength of the Ti-6Al-4V/AA1050 composite interface is proportional to the diffusion layer *** is observed that a medium interface thickness results in superior mechanical performance when compared to neither a greater nor a lesser interface *** characterization of all heat treatments reveals that the only intermetallic compound observed in the diffusion layers is TiAl_(3).Due to the inter-diffusion of Ti and Al atoms,the TiAl_(3) layer grows primarily at AA1050/TiAl_(3) interfaces.

关键词： Shear strength Co-extrusion heat treatment Microstructure Intermetallic compounds

Synergistic extraction and separation of thorium from rare earths in chloride media using mixture of Cextrant 230 and Cyanex 923

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Journal of Rare Earths 2024年第4期42卷 759-767页

作者： hui wang Shengting Kuang wuping liao School of Rare Earths University of Science and Technology of ChinaHefei230026China Institute of Material and Chemistry Ganjiang Innovation AcademyChinese Academy of SciencesGanzhou341000China State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun130022China

In order to lower the usage of expensive Cyanex 923 and increase the extraction capacity of the system of Cextrant 230,the synergistic extraction of thorium from chloride media by a mixture of Cextrant 230 and Cyanex 923 was *** maximum synergistic enhancement coefficient(R)of 1.53 is obtained at 1:1 molar ratio of Cextrant 230/Cyanex *** syne rgistic extracted species of Th^(4+)is determined as ThCl_(4)·2Cextrant 230·Cyanex *** synergistic extraction of Th^(4+)is an entropy-driven exothermic *** loading capacity of 0.60 mol/L mixed extractant for thorium is about 17.10 g/L(calculated as ThO_(2)),and the loaded thorium in the organic phase can be effectively stripped by distilled *** comparison,rare earth cations are barely extracted under the similar conditions,suggesting that the mixtures can be applied to separate thorium from rare earths.A cascade extraction process was developed based on the synergistic extraction system to separate thorium from the hydrochloric acid leaching of *** content of thorium in the leaching solution decreases obviously from 19.90 mg/L to1.4μg/L by 3 stages of extraction,which is superior to sole Cextrant 230 or Cyanex *** introduction of Cextrant 230 into the extraction system not only lowers the usage of Cyanex 923 but also enhances the selective extraction of thorium at low acidity,implying that the synergistic extraction system can selectively extract thorium more efficiently and economically than the sole systems.

关键词： Synergistic extraction Cextrant 230 Cyanex 923 Thorium Rare earths

Thermodynamic property of sandwich cylindrical shell structure with metallic wire mesh:Numerical modeling and experimental analysis

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Chinese Journal of Aeronautics 2024年第1期37卷 138-152页

作者： Xin XUE Guojian ShEN Juan liao Institute of Metal Rubber&Vibration Noise School of Mechanical Engineering and AutomationFuzhou UniversityFuzhou 350116China Fujian Shuikou Power Generation Group Co. LTDFuzhou 350000China

As a new addition to lightweight composite structures,the sandwich cylindrical shell with a metallic wire mesh core has emerged as a promising solution for thermodynamic performance analysis at elevated *** intricate interwoven cellular formations within the metallic wire mesh pose difficulties for thermo-mechanical modeling and property ***,the constitutive models employed to characterize hysteresis phenomena were presented,comprising isotropic elasticity,Bergstrom-Boyce model,Ogden hyper-elasticity,and parameter identification through mechanical examinations at varying ***,the finite element modeling of cylindrical shell structures was determined for modal and steady-state dynamic ***,the experimental procedures were carried out,including the preparation of the sandwich cylindrical shell and the dynamic testing *** first-order natural frequency of the cylindrical shell structure is close to the resonance frequency of the dynamic test results,with a maximum error of 6.5%,demonstrating the accuracy of the simulation *** compared to the solid-core cylindrical shell,the average insertion loss of the sandwich cylindrical shell structure within the frequency range of 10–1000 hz at room temperature is up to 11.09 ***,at elevated temperatures,the average insertion loss of the sandwich cylindrical shell decreases but fluctuates as the temperature changes.

关键词： Energy dissipation Metallic matrix composites Numerical analysis Sandwich structure Thermodynamic properties

The quasi-Gramian solution of a non-commutative extension of the higher-order nonlinear Schr?dinger equation

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Communications in Theoretical Physics 2024年第3期76卷 51-61页

作者： h w A Riaz J Lin Department of Physics Zhejiang Normal UniversityJinhua 321004China

The nonlinear Schr?dinger(NLS)equation,which incorporates higher-order dispersive terms,is widely employed in the theoretical analysis of various physical *** this study,we explore the non-commutative extension of the higher-order NLS *** treat real or complex-valued functions,such as g_(1)=g_(1)(x,t)and g_(2)=g_(2)(x,t)as non-commutative,and employ the Lax pair associated with the evolution equation,as in the commutation *** derive the quasi-Gramian solution of the system by employing a binary Darboux *** soliton solutions are presented explicitly within the framework of *** visually understand the dynamics and solutions in the given example,we also provide simulations illustrating the associated ***,the solution can be used to study the stability of plane waves and to understand the generation of periodic patterns within the context of modulational instability.

关键词： integrable systems Darboux transformation solitons

An indicator model for assessing community resilience to the COVID-19 pandemic and its validation: A case study in hong Kong

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Journal of Safety Science and Resilience 2024年第2期5卷 222-234页

作者： Nan liao Muhammad Nawaz Departnent of Geography Faculty Art and Social SciencesSingapore 65166666Singapore

The COVID-19 outbreak had a significant negative impact on the world,and the fifth wave of COVID-19 in hong Kong brought a considerable shock to Chinese *** is a growing call for more resilient ***,empirical evidence and validation of modeling studies of resilience indicators for urban community responses to the COVID-19 pandemic still need to be *** this study,a resilience assessment indicator model comprising 4 subsystems,7 indicators,and 12 variables was developed to assess the resilience of hong Kong communities in response to COVID-19(i.e.,Resilience Index).Furthermore,this study utilized regression models such as geographically weighted regression(GwR)and multiscale GwR(MGwR)to validate the resilience model proposed in this study at the model and variable *** the regression model,the Resilience Index and the individual variables in the resilience model are explanatory variables,and the outcomes of the COVID-19 pandemic(confirmed cases,confirmation rate,discharged cases,discharge rate)are dependent *** results showed that:(i)the resilience of hong Kong communities to the COvID-19 pandemic was not strong in general and showed some clustered spatial distribution characteristics;(i)the validation results at the model level showed that the Resilience Index did not explain the consequences of the COvID-19 pandemic to a high degree;(ii)the validation results at the variable level showed that the MGwR model was the best at identifying the relationships between explanatory variables and the dependent variable;and(iv)compared with the model-level assessment results,the variable-level assessment explained the consequences of the COvID-19 pandemic better than the model level assessment *** above analysis and the spatial distribution maps of the resilience variables can provide empirically based and targeted insights for policymakers.

关键词： Resilience Community resilience CoVID-19pandemic Resilience assessment indicator model Resilience model validation MGwR