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Swelling of Spherical Polyelectrolyte Gels

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Chinese Journal of Polymer Science 2024年第9期42卷 1386-1392,I0009页

作者： Ming-Yu Duan Jia-Dong Chen Yi-Ming Liu Zhao-Feng Peng Guang Chen Department of advanced manufacturing and Robotics College of EngineeringPeking UniversityBeijing 100871China

Polyelectrolyte(PE)gels,distinguished by their unique stimuli-responsive swelling behavior,serve as the basis of broad applications,such as artificial muscles and drug *** this work,we present a theoretical model to analyze the electrostatics and its contribution to the swelling behavior of PE gels in salt *** minimizing the free energy of PE gels,we obtain two distinct scaling regimes for the swelling ratio at equilibrium with respect to the salt *** compare our predictions for the swelling ratio with experimental measurements,which show excellent *** addition,we employ a finite element method to assess the applicability range of our theoretical model and *** anticipate that our model will also provide valuable insights into drug adsorption and release,deformation of red blood cells,4D printing and soft robotics,where the underlying mechanism of swelling remains enigmatic.

关键词： Gels Polyelectrolytes Swelling Stimuli-responsive Electrostatic interaction Cell model

Synthesis of size-controlled and dispersible Sm2Fe17N3 magnetic particles by reduction diffusion process using molten salt

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Journal of Rare Earths 2024年第11期42卷 2105-2111页

作者： Junhua Xi Zhi Yang Muhammad Haseeb Yuanyuan Chen Xiaofeng Nie Liying Cong Qiong Wu Enfeng Fu Hongguo Zhang Weiqiang Liu Ming Yue faculty of Materials and manufacturing Key Laboratory of Advanced Functional MaterialsMinistry of Education of ChinaBeijing University of Technology

The synthesis of size-controlled Sm2Fe17magnetic particles is a prerequisite for the fabrication of highperformance Sm2Fe17N3permanent magnetic ***,Sm2Fe17was synthesized using a costeffective reduction-diffusion *** calcium chloride molten salt was introduced to control the particle size and achieve a single phase of *** effects of reduction-diffusion reaction temperature and the amount of added calcium chloride on the phase constitution and microstructure of the final product of reduction-diffusion were systematically *** an appropriate amount of calcium chloride can effectively inhibit the overgrowth and sintering of the reduced *** employing the strategy of adding 20 wt% of calcium chlorides into the green compacts,we were able to successfully synthesize uniform Sm2Fe17particles that are well-dispersed,with an average size of 2.2 μ***,by combining the optimal reduction-diffusion conditions and the nitriding process,the hard magnetic Sm2Fe17N3material was successfully *** study could be useful for the development of high-performance Sm2Fe17N3magnetic materials utilizing reduction-diffusion technology.

关键词： Molten salt Permanent magnets Rare earths Reduction-diffusion Sm2Fe17N3

Effect of post rolling stress on phase transformation behavior of microalloyed dual phase steel

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Journal of Iron and Steel Research International 2024年第3期31卷 688-699页

作者： Wen-quan Sun Sheng-yi Yong Tie-heng Yuan Ting-song Yang An-rui He Chao Liu Rui-chun Guo National engineering Research Center for advanced Rolling and Intelligent manufacturing University of Science and Technology BeijingBeijing 100083China

The slow phase transformation of microalloyed dual phase steel makes the nonuniform stress and temperature fields during the post rolling cooling process have a significant impact on the phase transformation *** the relatively slow phase transformation of DP780 steel within the microalloyed dual phase steel series,the influence of stress on the phase transformation behavior of DP780 steel was *** quantify the nonuniform thermal and stress conditions in the steel coil,a thermo-mechanical coupled finite element model of the hot-rolled strip cooling process was *** on the simulation data,DP780 steel was chosen as the research material,and Gleeble 3500 thermal simulation equipment was used for experimental *** thermal expansion curves were analyzed through regression to establish the dynamic model of DP780 steel phase transformation under ***,metallographic analysis was conducted to determine phase transformation type and grain size of DP780 *** results confirmed that the stress promotes the occurrence of semi-diffusion-type bainite ***,an appropriate level of stress facilitates the growth of bainitic grains,while the increased stress inhibits the growth of ferritic grains.

关键词： Microalloyed dual phase steel Stress Bainitic transformation Grain Finite element method

Grain-boundary segregation and grain growth in nanocrystalline substitutional solid solution alloys

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Journal of Materials Science & Technology 2024年第1期168卷 239-249页

作者： Fawei Tang Chao Hou Hao Lu Zhi Zhao Xiaoyan Song faculty of Materials and manufacturing Key Laboratory of Advanced Functional MaterialsMinistry of Education of ChinaBeijing University of TechnologyBeijing 100124China

A model for describing solute segregation at grain boundaries has been developed for substitutional solid solution alloys,which integrates multiple factors from atomic to microstructural scales.A concept of mo-lar Gibbs free energy of segregation was introduced to evaluate the segregating capability of the solute elements in a closed system,through which the influences of grain boundary structure,grain size,ma-terial composition,and external conditions were *** on the evaluation of various energy forms related to solute segregation and grain growth processes,the nature of the thermal stabilization of nanograin structures by solute segregation was disclosed.A criterion for the destabilization of nanostruc-tures,which is determined by the competition of the change rates between the molar Gibbs free energy of segregation and the total energy of grain boundaries with grain size,has been *** study provided guideline to achieve high-temperature stability of nanograin structures of solid solution alloys even for the weakly segregating nanocrystalline systems.

关键词： Substitutional solid solution Grain boundary segregation Thermal stabilization Solute concentration Grain size

Dynamic Modeling and Experimental Verification of an RPR Type Compliant Paralle Mechanism with Low Orders

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Chinese Journal of Mechanical engineering 2024年第3期37卷 83-94页

作者： Shuang Zhang Jingfang Liu Huafeng Ding Yanbin Zhang School of Mechatronics engineering Henan University of Science and TechnologyLuoyangHenanChina faculty of Materials and manufacturing College of Mechanical Engineering and Applied Electronics TechnologyBeijing University of TechnologyBeijingChina Key laboratory of advanced manufacturing technology Beijing University of TechnologyBeijingChina School of Mechanical engineering and Electronic Information China University of Geosciences(Wuhan)WuhanChina Center of Machinery Equipment advanced manufacturing of Henan Province LuoyangChina

Efficiency of calculating a dynamic response is an important point of the compliant mechanism for posture *** modeling with low orders of a 2R1T compliant parallel mechanism is studied in the *** mechanism with two out-of-plane rotational and one lifting degrees of freedom(DoFs)plays an important role in posture *** on elastic beam theory,the stiffness matrix and mass matrix of the beam element are established where the moment of inertia is *** improve solving efficiency,a dynamic model with low orders of the mechanism is established based on a modified modal synthesis ***,each branch of the RPR type mechanism is divided into a ***,a set of hypothetical modes of each substructure is obtained based on the C-B ***,dynamic equation of the whole mechanism is established by the substructure assembly.A dynamic experiment is conducted to verify the dynamic characteristics of the compliant mechanism.

关键词： Compliant parallel mechanism Dynamic model Modal synthesis method Dynamic experiment

Synergistic Effects of Carbon Nanotube(CNT)and Reduced Graphene Oxide(RGO)on Mechanical and Thermal Properties of ZK61 Alloy

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Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 577-585页

作者： Fanjing Meng Wenbo Du Ning Ding Jian Sun Xian Du Ke Liu Shubo Li College of Materials Science and engineering Faculty of Materials and ManufacturingBeijing University of TechnologyBeijing 100124China

The hybrid of carbon nanotube(CNT)and reduced graphene oxide(RGO)reinforced ZK61 composite was fabricated by a hot extrusion *** with the raw ZK61 alloy and single-reinforced composites,the hybrid-reinforced by RGO+CNT complex exhibited significant enhancements both in mechanical and thermal *** adjusting the proportion of RGO and CNT in ZK61 alloy,the obtained optimum ZK61/(0.06 wt%RGO+0.54 wt%CNT)composite exhibited increase of 25.4%in yield strength,26.5%in ultimate tensile strength,104%in failure strain and 30.4%in thermal conductivity,respectively,in comparison with ZK61 *** superior properties of the nano-hybrid composite are attributed to the synergetic effects of RGO and CNT,leading to a uniform dispersion and integrated structure as well as the enhanced interfacial bonding with *** strengthening ability of RGO and CNT was calculated to quantify their individual contribution to the improvement in mechanical and thermal properties of the ZK61 matrix *** RGO+CNT hybrids provide a promising way to develop Mg matrix composites with impressive performances.

关键词： Mg matrix composite Carbon nanotube Reduced graphene oxide Mechanical performance Thermal conductivity

Modification of the CuO electronic structure for enhanced selective electrochemical CO_(2) reduction to ethylene

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Nano Research 2024年第8期17卷 7194-7202页

作者： Xin Wu Zhuang Tong Yunliang Liu Yaxi Li Yuanyuan Cheng Jingwen Yu Peng Cao Chunqiang Zhuang Qiuzhong Shi Naiyun Liu Xiang Liu Hongyu Liang Haitao Li Institute for Energy Research School of Energy and Power EngineeringJiangsu UniversityZhenjiang 212013China faculty of Materials and manufacturing Beijing University of TechnologyBeijing 100124China Institute of Medicine&Chemical engineering Zhenjiang CollegeZhenjiang 212013China Institute of advanced manufacturing and Modern Equipment Technology School of Mechanical EngineeringJiangsu UniversityZhenjiang 212013China

Electrochemical carbon dioxide reduction reaction(CO_(2)RR)can produce value-added hydrocarbons from renewable electricity,providing a sustainable and promising approach to meet dual-carbon targets and alleviate the energy ***,it is still challenging to improve the selectivity and stability of the products,especially the C^(2+) *** we propose to modulate the electronic structure of copper oxide(CuO)through lattice strain construction by zinc(Zn)doping to improve the selectivity of the catalyst to *** performance and in situ characterization analyses show that the compressive strain generated within the CuO lattice and the electronic structure modulation by Zn doping enhances the adsorption of the key intermediate*CO,thereby increasing the intrinsic activity of CO_(2)RR and inhibiting the hydrogen precipitation *** the best catalysts had significantly improved ethylene selectivity of 60.5%and partial current density of 500 mA·cm^(–2),and the highest C^(2+) Faraday efficiency of 71.47%.This paper provides a simple idea to study the modulation of CO_(2)RR properties by heteroatom doped and lattice strain.

关键词： CO_(2) reduction heteroatom-doped lattice strain ethylene selectivity

Spectrum analysis of interval process model and its application in uncertain vibration analysis

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Science China(Technological Sciences) 2024年第8期67卷 2549-2564页

作者： LI JinWu JIANG Chao NI BingYu State Key Laboratory of advanced Design and manufacturing Technology for Vehicle College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China

In recent years, the authors have extended the traditional interval method into the time dimension to develop a new mathematical tool called the “interval process model” for quantifying time-varying or dynamic uncertainties. This model employs upper and lower bounds instead of precise probability distributions to quantify uncertainty in a parameter at any given time point. It is anticipated to complement the conventional stochastic process model in the coming years owing to its relatively low dependence on experimental samples and ease of understanding for engineers. Building on our previous work, this paper proposes a spectrum analysis method to describe the frequency domain characteristics of an interval process, further strengthening the theoretical foundation of the interval process model and enhancing its applicability for complex engineering problems. In this approach, we first define the zero midpoint function interval process and its auto/cross-power spectral density(PSD) functions. We also deduce the relationship between the auto-PSD function and the auto-covariance function of the stationary zero midpoint function interval process. Next, the auto/cross-PSD function matrices of a general interval process are defined, followed by the introduction of the concepts of PSD function matrix and cross-PSD function matrix for interval process vectors. The spectrum analysis method is then applied to random vibration problems, leading to the creation of a spectrum-analysis-based interval vibration analysis method that determines the PSD function for the system displacement response under stationary interval process excitations. Finally, the effectiveness of the formulated spectrum-analysis-based interval vibration analysis approach is verified through two numerical examples.

关键词： interval process spectrum analysis power spectral density(PSD) time-varying uncertainty uncertain vibration analysis

Analysis of mesoscopic mechanical dynamic characteristics of ballast bed with under sleeper pads

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Railway engineering Science 2024年第1期32卷 107-123页

作者： Xiong Yang Liuyang Yu Xuejun Wang Zhigang Xu Yu Deng Houxu Li faculty of Mechanical and Electrical engineering Kunming University of Science and TechnologyKunmingChina Yunnan Provincial Key Laboratory of advanced Equipment Intelligent manufacturing Technology KunmingChina

The meso-dynamical behaviour of a high-speed rail ballast bed with under sleeper pads(USPs)was *** geometrically irregular refined discrete element model of the ballast particles was constructed using 3D scanning techniques,and the 3D dynamic model of the rail-sleeper-ballast bed was constructed using the coupled discrete element method-multiflexible-body dynamics(DEM-MFBD)*** analyse the meso-mechanical dynamics of the ballast bed with USPs under dynamic load on a train and verify the correctness of the model in laboratory *** is shown that the deformation of the USPs increases the contact area between the sleeper and the ballast particles,and subsequently the number of contacts between *** the depth of the granular ballast bed increases,the contact area becomes larger,and the contact force between the ballast particles gradually *** the action of the elastic USPs,the contact forces between ballast particles are reduced and the overall vibration level of the ballast bed can be *** settlement of the granular ballast bed occurs mainly at the shallow position of the sleeper bottom,and the installation of the elastic USPs can be effective in reducing the stress on the ballast particles and the settlement of the ballast bed.

关键词： Under sleeper pads Ballast bed Discrete element method Mesoscopic mechanical dynamic characteristics