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Numerical Study of Propulsion Mechanism for Oscillating Rigid and Flexible Tuna-Tails

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Journal of Bionic Engineering 2011年第4期8卷 406-417页

作者： liang Yang Yumin Su qing xiao State Key Laboratory of Autonomous Underwater Vehicle Harbin Engineering University Harbin 150001 P. R. China Department of Naval Architecture and Marine Engineering University of Strathelyde Glasgow G40LZ United Kingdom

Numerical study on the unsteady hydrodynamic characteristics of oscillating rigid and flexible tuna-tails in viscous flow-field is performed. Investigations are conducted using Reynolds-Averaged Navier-Stokes （RANS） equations with a moving adaptive mesh. The effect of swimming speed, flapping amplitude, frequency and flexure amplitude on the propulsion performance of the rigid and flexible tuna-tails are investigated. Computational results reveal that a pair of leading edge vortices develop along the tail surface as it undergoes an oscillating motion. The propulsive efficiency has a strong correlation with various locomotive parameters. Peak propulsive efficiency can be obtained by adjusting these parameters. Particularly, when input power coeffcient is less than 2.8, the rigid tail generates larger thrust force and higher propulsive efficiency than flexible tail. However, when input power coefficient is larger than 2.8, flexible tail is superior to rigid tail.

关键词： tuna-tail RANS propulsion mechanism hydrodynamic characteristics viscous flow-fields

Mechanism insight into the enhanced photocatalytic purification of antibiotic through encapsulated architectures coupling of crystalline Cu_(2)O/amorphous TiFe layer double hydroxide

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Journal of Materials Science & Technology 2023年第36期167卷 161-170页

作者： Lin Ye Shaodong Sun Xiaoli Yang Xiaoxi Chen Bian Yang Daqin Yun Xiaojing Yu man Yang qing Yang Shuhua liang Jie Cui Engineering Research Center of Conducting Materials and Composite Technology Ministry of EducationShaanxi Engineering Research Center of Metal-Based Heterogeneous Materials and Advanced Manufacturing TechnologyShaanxi Province Key Laboratory for Electrical Materials and Infiltration TechnologySchool of Materials Science and EngineeringXi’an University of TechnologyXi’an 710048China College of Energy Xiamen UniversityXiamen 361005China

Amorphous materials are one of the important candidates for improving heterogeneous photocata-lysts because of their unique electronic structures and abundant catalytic sites originating from dis-order atomic ***,there is still much room for the development of new crys-talline/amorphous heterogeneous composites for photocatalytic *** efficient synthetic strategies for preparing new crystalline/amorphous heterojunctions are highly ***,we have realized the deep optimization of photocatalytic activity by fabricating crystalline/amorphous Cu_(2)O/Ti-Fe layer double hydroxide(LDH)*** to the typical Z-scheme mechanism originating from the crystalline/amorphous interfaces,the photocharge separation and catalytic active sites obviously enhance compared to single Cu_(2)O and LDH *** expected,the photocatalytic removal of tetra-cycline(TC)of the as-prepared Cu_(2)O/Ti-Fe LDH was over 5.2 and 2.2 times those of the pristine Cu_(2)O nanospheres and Ti-Fe LDH *** work illustrates the origin of crystalline Cu_(2)O nanospheres encapsulated in amorphous Ti-Fe layer double hydroxide nanosheets for enhanced photocatalytic activity driven by visible light,and provide a general Cu_(2)O-templated solution-phase synthetic method for the synthesis of novel double-metal layer double hydroxide amorphous nanostructures.

关键词： Crystalline Cu_(2)O Amorphous Ti-Fe LDH Z-scheme mechanism Charge separation Photodegradation

Regioregular Asymmetric Diketopyrrolopyrrole Copolymers with Good Molecular Ordered Assembly Ability for High-performance Polymer Transistors

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Chinese Journal of Polymer Science 2023年第8期41卷 1215-1222,I0006页

作者： qing-qing Liu Jia-Xin Yang man Zhao Can Gao Bo Guan Huan-Li Dong Beijing National Laboratory for Molecular Sciences Key Laboratory of Organic SolidsInstitute of ChemistryChinese Academy of SciencesBeijing 100190China School of Chemical Sciences University of Chinese Academy of SciencesBeijing 100049China

Introduction of asymmetric units into conjugated polymers is an important strategy to regulate the photophysical and electronic properties of polymers,as asymmetric units can not only regulate solubility and energy levels,but also molecular stacking and orientation,thus giving much higher optoelectronic ***,very few studies have been reported in this *** semiconducting properties of conjugated polymers could be regulated through regioregularity ***,we took the asymmetric thiophene/pyridine side group DPP as core and developed the regioregular monomer T-Py-DPP through three steps:alkyl chain introduction,tin monomer coupling and NBS double *** T-Py-DPP monomer was polymerized into reg-PPy TDPP-2FBT with a head-to-head *** regioregularity of T-Py-DPP unit endowed reg-PPy TDPP-2FBT with backbone planarity,self-assembly orientation,network-like morphology and high crystallinity in films,thus the superior bipolar transport *** highest hole and electron mobilities of reg-PPy TDPP-2FBT were 0.93 and 0.57 cm^(2)·V^(-1)·s^(-1),respectively,with 40%improvement relative to the regiorandom polymer.

关键词： Asymmetric copolymers Regioregularity Good orientation Organic field-effect transistor Enhanced performance

Exceptional points enhance sensing in silicon micromechanical resonators

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Microsystems & Nanoengineering 2024年第1期10卷 17-25页

作者： man-Na Zhang Lei Dong Li-Feng Wang qing-An Huang Key Laboratory of MEMS of the Ministry of Education Southeast UniversityNanjing 210096China

Exceptional points(EPs)have recently emerged as a new method for engineering the response of open physical systems,that is,systems that interact with the *** systems at the EPs exhibit a strong response to a small ***,we show a method by which the sensitivity of silicon resonant sensors can be enhanced when operated at *** our experiments,we use a pair of mechanically coupled silicon micromechanical resonators constituting a parity-time(PT)-symmetric *** perturbations introduced on the mechanically coupled spring cause the frequency to split from the EPs into the PT-symmetric regime without broadening the two spectrum linewidths,and this frequency splitting scales with the square root of the perturbation *** overall signal-tonoise ratio is still greatly enhanced,although the measured noise spectral density of the EP sensing scheme has a slight increase comparable to the traditional *** results pave the way for resonant sensors with ultrahigh sensitivity.

关键词： resonant symmetric points

Generalized T3-plot for testing high-dimensional normality

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Frontiers of Mathematics in China 2016年第6期11卷 1363-1363,1364-1378页

作者： Mingyao AI Jiajuan liang man-Lai TANG LMAM School of Mathematical Sciences and Center for Statistical Science Peking University Beijing 100871 China Department of Marketing College of Business University of New Haven West Haven CT 06516 USA Department of Mathematics and Statistics School of Business Hang Seng Management College Hong Kong China

A new dimension-reduction graphical method for testing high- dimensional normality is developed by using the theory of spherical distributions and the idea of principal component analysis. The dimension reduction is realized by projecting high-dimensional data onto some selected eigenvector directions. The asymptotic statistical independence of the plotting functions on the selected eigenvector directions provides the principle for the new plot. A departure from multivariate normality of the raw data could be captured by at least one plot on the selected eigenvector direction. Acceptance regions associated with the plots are provided to enhance interpretability of the plots. Monte Carlo studies and an illustrative example show that the proposed graphical method has competitive power performance and improves the existing graphical method significantly in testing high-dimensional normality.

关键词： Dimension reduction graphical method high-dimensional data multivariate normality spherical distribution

Modified artificial neural network model with an explicit expression to describe flow behavior and processing maps of Ti2AlNb-based superalloy

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Journal of Iron and Steel Research International 2021年第11期28卷 1451-1462页

作者： Yan-qi Fu qing Zhao man-qian Lv Zhen-shan Cui School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Institute of Forming Technology and Equipment Shanghai Jiao Tong UniversityShanghai 200030China

The elevated-temperature deformation behavior of Ti2AlNb superalloy was observed by isothermal compression experiments in a wide range of temperatures(950–1200°C)and strain rates(0.001–10 s^(-1)).The flow behavior is nonlinear,strongly coupled,and *** constitutive models,namely the double multivariate nonlinear regression model,artificial neural network model,and modified artificial neural network model with an explicit expression,were applied to describe the Ti2AlNb superalloy plastic deformation *** comparative predictability of those constitutive models was further evaluated by considering the correlation coefficient and average absolute relative *** comparative results show that the modified artificial network model can describe the flow stress of Ti2AlNb superalloy more accurately than the other developed constitutive *** explicit expression obtained from the modified artificial neural network model can be directly used for finite element *** modified artificial neural network model solves the problems that the double multivariate nonlinear regression model cannot describe the nonlinear,strongly coupled,and multivariable flow behavior of Ti2AlNb superalloy accurately,and the artificial neural network model cannot be embedded into the finite element software ***,the modified artificial neural network model is mainly dependent on the quantity of high-quality experimental data and characteristic variables,and the modified artificial neural network model has not physical ***,the processing maps were applied to obtain the optimum processing parameters.

关键词： Modified artificial neural network model Ti2AlNb superalloy Double multivariate nonlinear regression model Explicit expression Processing map

Effect of austempering time on microstructure and properties of a low-carbon bainite steel

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International Journal of Minerals,Metallurgy and Materials 2020年第3期27卷 340-346页

作者： man Liu Guang Xu Jun-yu Tian qing Yuan Xin Chen The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and Technology

The effect of austempering time after the bainitic transformation on the microstructure and property in a low-carbon bainite steel was investigated by metallography and dilatometry. The results showed that by prolonging the austempering time after the bainite transformation, the amount of large-size martensite/austenite islands decreased, but no significant change of the amount and morphology of bainite were observed. In addition, more austenite with a high carbon content was retained by prolonging the holding time at the bainite transformation ***, with a longer holding time, the elongation was improved at the expense of a small decrease in tensile strength. Finally, the Avrami equation B(RF) = 1-exp(-0.0499 × t^0.7616) for bainite reaction at 350℃ was obtained for the tested steel. The work provided a reference for tailoring the properties of low-carbon steels.

关键词： austempering time retained austenite martensite/austenite island low-carbon bainite transformation kinetics

Genetic diversity and population structure of Camellia huana(Theaceae),a limestone species with narrow geographic range,based on chloroplast DNA sequence and microsatellite markers

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Plant Diversity 2020年第5期42卷 343-350页

作者： Shuang Li Shang-Li Liu Si-Yu Pei man-man Ning Shao-qing Tang Guangxi Key Laboratory of Rare and Endangered Animal Ecology College of Life ScienceGuangxi Normal UniversityGuilinChina Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection Ministry of EducationGuangxi Normal UniversityGuilinChina Longtan Nature Reserve management Center HechiChina College of Life Science Guangxi Normal UniversityGuilinGuangxi 541006China

Camellia huana is an endangered species with a narrow distribution in limestone hills of northern Guangxi and southern Guizhou provinces,*** used one chloroplast DNA(cpDNA)fragment and 12 pairs of microsatellite(simple sequence repeat;SSR)markers to assess the genetic diversity and structure of 12 *** populations.A total of 99 alleles were detected for 12 polymorphic loci,and eight haplotypes and nine polymorphic sites were detected within 5200 bp of *** populations showed a low level of genetic diversity(n=8,Hd=0.759,Pi=0.00042 for cpDNA,NA=3.931,HE=0.466 for SSRs),but high genetic differentiation between populations(FST=0.2159 for SSRs,FST=0.9318 for cpDNA).This can be attributed to the narrow distribution and limestone habitat of *** analysis divided natural *** populations into two groups,consistent with their geographical ***,we suggest that five natural *** populations should be split into two units to be managed effectively.

关键词： Camellia huana Genetic diversity Genetic structure Conservation implications

Activity origin and design principles for atomic vanadium anchoring on phosphorene monolayer for nitrogen reduction reaction

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Nano Research 2020年第11期13卷 2925-2932页

作者： Xiongyi liang Xiangxuan Deng Chen Guo Chi-man Lawrence Wu Department of Materials Science and Engineering City University of Hong KongHong KongChina

Conversion of inert N2 molecules into NH3 via electrochemical methods is an environmentally friendly alternative to replace the traditional Haber-Bosch ***,the development of highly efficient catalyst is still ***,we report a density functional theory(DFT)based high-throughput screening to investigate the potential of 23 atomic transition metals(Sc,Ti,V,Cr,Mn,Fe,Co,Ni,Cu,Zn,Y,Zr,Nb,Mo,Tc,Ru,Rh,Pd,Ag,Cd,W,Pt and Au)supported on phosphorene monolayer as electrocatalyst for nitrogen reduction reaction(NRR).Our theoretical results demonstrate that V single atom anchoring on phosphorene monolayer exhibits good thermal stability,selectivity and excellent catalytic activity with a low overpotential of 0.18 ***,rational design principles and electronic descriptor between the intrinsic electronic properties and activation barrier have been *** work offers a new promising noble metal-free catalyst for NRR and reveals profound insights into the activity origin to guide further design.

关键词： high-throughput screening density functional theory phosphorene electronic descriptor single atomic catalyst transition metal