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Ni nanoparticles confined by yolk-shell structure of CNT-mesoporous carbon for electrocatalytic conversion of CO_(2): Switching CO to formate

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Journal of Energy Chemistry 2022年第7期31卷 224-229,I0006页

作者： juan Du Aibing chen College of Chemical and Pharmaceutical Engineering Hebei University of Science and TechnologyShijiazhuang 050018HebeiChina

Electrochemical reduction of CO_(2)(CO_(2)ER) to formate has been a promising route to produce value-added *** low-cost and efficient electrocatalysts with high product selectivity is still a grand ***,a novel Ni nanoparticles-anchored CNT coated by mesoporous carbon with yolk-shell structure (CNT/Ni@mC) catalysis was designed for CO_(2)*** nanoparticles were confined in the cavity between CNT and mesoporous carbon shell and the confined space can be controlled by tuning the amount of silica *** mesoporous carbon shell and confined space are beneficial to charge transmission during CO_(2)*** contrast to previous studies,the CNT/Ni@mC catalyst presents selectivity toward formate rather than *** in situ attenuated total reflection Fourier transform infrared spectroscopy measurements indicate the presence of a COO* intermediate that converts to formate under CO_(2)ER *** well-defined structural feature of the confined space of the Ni-based catalyst for selective CO_(2)ER to formate may facilitate in-depth mechanistic understandings on structural factors that affect CO_(2)ER performance.

关键词： Carbon dioxide electrochemical reduction Nickel-based catalyst Formate Yolk-shell CNT

Strain-induced martensitic transformation in biomedical Co-Cr-W-Ni alloys

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Rare Metals 2020年第3期39卷 241-249页

作者： zi-Yi Zhu Li Meng Leng chen School of Materials Science and Engineering University of Science and Technology BeijingBeijing100083China Metallurgical Technology Institute Central Iron and Steel Research InstituteBeijing100081China

The nucleation,variant selection,and orientation dependence of the strain-induced martensitic transformation(SIMT)process in biomedical Co-Cr-W-Ni alloys were *** experimental results show that theε-hexagonal-close-packed phase was preferentially formed at theΣ3 twin boundaries and high-angle grain boundaries during the tensile *** theoretical analysis shows that the variant selection of SIMT is governed by Schmid’s ***,the SIMTedε-phase did not form equally on the two sides of the annealing twins,even though they had the same Schmid *** phenomenon is related to the mechanical work developed by the formation of theε-*** the side which has both high Schmid factor and high mechanical work can initiate the SIMT process.A strongfiber texture was formed,and theε-variants tended to appear in grains with orientations close to theanddirections during the tensile *** results can provide theoretical guidance for controlling the SIMT process of Co-Cr-W-Ni alloys to fabricate more reliable stents.

关键词： Biomedical Co-Cr-W-Ni alloys Straininduced martensitic transformation Nucleation Variant selection Orientation dependence

Boundary Control of Coupled Non-Constant Parameter Systems of Time Fractional PDEs with Different-Type Boundary Conditions

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Journal of Systems Science & Complexity 2023年第1期36卷 273-293页

作者： chen juan ZHUANG Bo Aliyun School of Big Data Changzhou UniversityChangzhou 213164China School of Information Engineering Binzhou UniversityBinzhou 256600China

This paper addresses a boundary state feedback control problem for a coupled system of time fractional partial differential equations(PDEs)with non-constant(space-dependent)coefficients and different-type boundary conditions(BCs).The BCs could be heterogeneous-type or ***,this coupled system has different BCs at the uncontrolled side for heterogeneous-type and the same BCs at the uncontrolled side for *** main contribution is to extend PDE backstepping to the boundary control problem of time fractional PDEs with space-dependent parameters and different-type *** the backstepping transformation and the fractional Lyapunov method,the Mittag-Leffler stability of the closed-loop system is obtained.A numerical scheme is proposed to simulate the fractional case when kernel equations have not an explicit solution.

关键词： Boundary control coupled systems heterogeneous mittag-leffler stability time fractional PDEs with space-dependent coefficients

Scaling Behaviors of Polymers on Lipid Membranes:Coupling of Polymer Chain Dynamics and Surface Thermal Fluctuations

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Chinese Journal of Polymer Science 2023年第3期41卷 459-464,I0010页

作者： zi-Ren chen Wu Zhou Lei Shen School of Chemistry Chemical Engineering and Life ScienceWuhan University of TechnologyWuhan 430070China

Despite extensive researches on the motion of polymer chains on lipid membranes,the effect of membrane fluctuations on polymer chain dynamics remains poorly *** we report single molecule tracking experiments that allow for comparable measurements of polymer chain diffusion dynamics on nanotubular and planar phospholipid *** observe a super-diffusion behavior and no apparent chain-length-dependent mobility of polymer chains on nanotubular membranes,while a Brownian motion and apparent chain-lengthdependent mobility of polymer chains on planar *** suggest the super-diffusion nature of polymer chains may be due to the thermal-fluctuations of lipid nanotubes,which can be described from a statistical thermodynamic phenomenon coupling of polymer chain dynamics and surface thermal *** suggest that the existence of surface environment fluctuations should influence the dynamics of the adsorbed polymer *** study provides previously uncharacterized insights into polymer diffusion dynamics on thermal-fluctuating flexible surfaces,which is essential to understanding the effect of environment fluctuations on polymer chain behaviors.

关键词： Polymer diffusion Lipid membrane Scaling behavior

Dynamic model and performance analysis of landing buffer for bionic locust mechanism

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Acta Mechanica Sinica 2016年第3期32卷 551-565页

作者： Dian-Sheng chen zi-Qiang Zhang Ke-Wei chen Robotic Institute Beihang University

The landing buffer is an important problem in the research on bionic locust jumping robots, and the different modes of landing and buffering can affect the dynamic performance of the buffering process significantly. Based on an experimental observation, the different modes of landing and buffering are determined, which include the different numbers of landing legs and different motion modes of legs in the buffering process. Then a bionic locust mechanism is established, and the springs are used to replace the leg muscles to achieve a buffering effect. To reveal the dynamic performance in the buffering process of the bionic locust mechanism, a dynamic model is established with different modes of landing and buffering. In particular, to analyze the buffering process conveniently, an equivalent vibration dynamic model of the bionic locust mechanism is *** the support forces of the ground to the leg links, which can be obtained from the dynamic model, the spring forces of the legs and the impact resistance of each leg are the important parameters affecting buffering performance, and evaluation principles for buffering performance are proposed according to the aforementioned parameters. Based on the dynamic model and these evaluation principles, the buffering performances are analyzed and compared in different modes of landing and buffering on a horizontal plane and an inclined plane. The results show that the mechanism with the ends of the legs sliding can obtain a better dynamic performance. This study offers primary theories for buffering dynamics and an evaluation of landing buffer performance,and it establishes a theoretical basis for studies and engineering applications.

关键词： Bionic locust mechanism Landing and buffering Dynamic model Buffering performance

Bayesian networks modeling for thermal error of numerical control machine tools

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第11期9卷 1524-1530页

作者： Xin-hua YAO Jian-zhong FU zi-chen chen College of Mechanical and Energy Engineering Zhejiang University Hangzhou 310027 China Zhejiang Provincial Key Lab of Advanced Manufacturing Technology Hangzhou 310027 China

The interaction between the heat source location, its intensity, thermal expansion coefficient, the machine system configuration and the running environment creates complex thermal behavior of a machine tool, and also makes thermal error prediction difficult. To address this issue, a novel prediction method for machine tool thermal error based on Bayesian networks (BNs) was presented. The method described causal relationships of factors inducing thermal deformation by graph theory and estimated the thermal error by Bayesian statistical techniques. Due to the effective combination of domain knowledge and sampled data, the BN method could adapt to the change of running state of machine, and obtain satisfactory prediction accuracy. Ex- periments on spindle thermal deformation were conducted to evaluate the modeling performance. Experimental results indicate that the BN method performs far better than the least squares (LS) analysis in terms of modeling estimation accuracy.

关键词： Bayesian networks (BNs) Thermal error model Numerical control (NC) machine tool

Effective Nikuradse Roughness on the Mobile Plan Bed

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China Ocean Engineering 2018年第6期32卷 730-736页

作者： chen Xin LI Yong ZHANG zi-chao Beijing Engineering Research Center of Safety and Energy Saving Technology for Water Supply Network System China Agricultural University Tianjin Centre China Geological Survey School of Electric Power North China University of Water Resources and Electric Power

Nikuradse roughness(ks) is very important in the sediment transport prediction because it is related to the evaluations of the velocity distribution, shear stress and erosion depth. Dimensionless Nikuradse roughness(ks/D,where D is the sediment diameter) is usually given 1–2.5 on the immobile plan bed or at low shear stress. But it behaves differently on the mobile plan bed at high shear stress with much sediment picked up to movement when the Shields parameter(Θ) is larger than 0.8–1.0. The effective Nikuradse roughness on the mobile plan bed was derived indirectly from the erosion depth correlated to the mobile plan bed thickness considering the mass conservation in the present study. The proposed erosion depth confirmed the relation to the Shields parameters with an extra factor consisting of suspended sediment and its damping to turbulence. The decrement of the erosion depth caused by the increment of the sediment diameter at large shear stress was obtained, which was usually absent in classical empirical formulas based on the bedload theory. Good agreement with experiments was achieved by the present prediction of the Nikuradse roughness, erosion depth and sediment transport rate. Discussion was mainly focused on the prediction improvement caused by considering the impact of suspended sediment and its damping to turbulence.

关键词： mobile plan bed Nikuradse roughness oscillatory sheet flow sediment transport

A Novel Genetic Algorithm Preventing Premature Convergence by Chaos Operator

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Journal of Central South University 2000年第2期12卷 100-103页

作者： LIU juan CAI zi-xing LIU Jian-qin College of Information Science and Engineering Central South University of TechnologyChangsha 410083China

An improved genetic algorithm (GA) is proposed based on the analysis of population diversity within the framework of Markov chain. The chaos operator to combat premature convergence concerning two goals of maintaining diversity in the population and sustaining the convergence capacity of the GA is introduced. In the CHaos Genetic Algorithm (CHGA), the population is recycled dynamically whereas the most highly fit chromosome is intact so as to restore diversity and reserve the best schemata which may belong to the optimal solution. The characters of chaos as well as advanced operators and parameter settings can improve both exploration and exploitation capacities of the algorithm. The results of multimodal function optimization show that CHGA performs simple genetic algorithms and effectively alleviates the problem of premature convergence.

关键词： chaos genetic algorithm premature convergence population diversity

Anomalous pattern of ocean heat content during different phases of the solar cycle in the tropical Pacific

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Atmospheric and Oceanic Science Letters 2017年第1期10卷 9-16页

作者： HUO Wen-juan XIAO zi-Niu State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China College of Earth Science University of Chinese Academy of Sciences Beijing China

Solar radiation is a forcing of the climate system with a quasi-11-year *** a quasi-period forcing,the influence of the phase of the solar cycle on the ocean system is an interesting topic of *** this paper,the authors investigate a particular feature,the ocean heat content（OHC）anomaly,in different phases of the total solar irradiance（TSI） *** results show that almost opposite spatial patterns appear in the tropical Pacific during the ascending and declining phases of the TSI *** analysis reveals the presence of the quasi-decadal（11-year） solar signal in the SST,OHC and surface zonal wind anomaly field over the tropical Pacific with a high level of statistical confidence（95%）.It is noted that the maximum centers of the ocean temperature anomaly are trapped in the upper ocean above the main pycnocline,in which the variations of OHC are related closely with zonal wind and ocean currents.

关键词： Ocean heat content anomaly total solar irradiance solar cycle tropical Pacific