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A modified multi-objective particle swarm optimiz.tion approach and its application to the design of a deepwater composite riser

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Acta Mechanica Sinica 2018年第2期34卷 275-284页

作者： Y.z.eng j.chen Department of Mechanics Huazhong University of Science and TechnologyWuhan 430074China Hubei Key Laboratory for Engineering Structural Analysis and Safety Assessment Wuhan 430074China

A modified multi-objective particle swarm optimiz.tion method is proposed for obtaining Pareto-optimal solutions effectively. Different from traditional multiobjective particle swarm optimiz.tion methods, Kriging meta-models and the trapez.id index are introduced and integrated with the traditional one. Kriging meta-models are built to match expensive or black-box functions. By applying Kriging meta-models, function evaluation numbers are decreased and the boundary Pareto-optimal solutions are identified rapidly. For bi-objective optimiz.tion problems, the trapez.id index is calculated as the sum of the trapez.id’s area formed by the Pareto-optimal solutions and one objective axis. It can serve as a measure whether the Pareto-optimal solutions converge to the Pareto front. Illustrative examples indicate that to obtain Paretooptimal solutions, the method proposed needs fewer function evaluations than the traditional multi-objective particle swarm optimiz.tion method and the non-dominated sorting genetic algorithm II method, and both the accuracy and the computational efficiency are improved. The proposed method is also applied to the design of a deepwater composite riser example in which the structural performances are calculated by numerical analysis. The design aim was to enhance the tension strength and minimiz. the cost. Under the buckling constraint, the optimal trade-off of tensile strength and material volume is obtained. The results demonstrated that the proposed method can effec tively deal with multi-objective optimiz.tions with black-box functions.

关键词： Multi-objective particle swarm optimiz.tion Kriging meta-model Trapez.id index Deepwater composite riser

The Hardy-Weinberg principle and its applications in modern population genetics

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Frontiers in Biology 2010年第4期5卷 348-353页

作者： john j.chen Department of Preventive Medicine State University of New York at Stony BrookStony BrookNY 11794-8036USA

The discovery of the Hardy-Weinberg principle marked the beginning of the field of population *** the past hundred years,it has provided a starting point for many population genetic *** this review,the Hardy-Weinberg principle,its statistical testing,and several of its applications in various modern population genetic research areas,including allelic variability and selection in the human leukocyte antigen region,microsatellite genotyping error detection,and accuracy of haplotype estimation,are discussed.

关键词： the Hardy-Weinberg principle statistical testing population genetics human leukocyte antigens microsatellite genotyping haplotype estimation

Systematic approaches to improving the performance of polyoxometalates in non-aqueous redox flow batteries

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journal of Energy Chemistry 2020年第11期29卷 115-124页

作者： Yuan Cao jee-jay j.chen Mark A.Barteau Department of Chemical Engineering University of MichiganAnn ArborMI 48109United States Applied Materials 14J Fuller RoadAlbanyNY 12203United States Department of Chemical Engineering and Department of Chemistry Texas A&M UniversityCollege StationTX 77843United States

Polyoxometalates have been explored as multi-electron active species in both aqueous and non-aqueous redox flow batteries. Although non-aqueous systems in principle offer a wider voltage window for redox flow battery operation, realiz.tion of this potential requires a judicious choice of solvent as well as polyoxometalate properties. We demonstrate here the superior performance of N,N-dimethylformamide(DMF)compared to acetonitrile as a solvent for redox flow batteries based on Li3PMo12O40. This compound displays two 1-electron transfers in acetonitrile but can access an extra quasi-reversible 2-electron redox process in DMF. A cell containing 10 mM solution of Li3PMo12O40 in DMF produced a cell voltage of 0.7 V with 2-electron transfers(State of Charge = 60%) and showed a good cyclability. As a means to boost energy density, operation of the redox flow battery at a higher concentration of 0.1 M Li3PMo12O40 produced cells with cell voltage of 0.6 V in acetonitrile and a cell voltage of 1.0 V in DMF;both showed excellent coulombic efficiencies of more than 90% over the course of 30 cycles. Energy density was also increased by employing an asymmetric cell with different polyoxometalates on each side to extend cell ***6P2W18O62 exhibited 3 quasi-reversible 2-electron transfers in the potential range between-2.05 V and-0.5 V vs. Ag/Ag+. 10 mM Li6P2W18O62/Li3PMo12O40 in DMF produced a cell with cell voltage of 1.3 V involving 4-electron transfers(State of Charge = 50%) with coulombic efficiency of nearly 100% and energy efficiency of nearly 70% throughout the test with more than 20 cycles. These promising results demonstrate proof-of-concept approaches to improving the performance of polyoxometalates in non-aqueous redox flow batteries.

关键词： Polyoxometalate Energy density Redox flow battery Non-aqueous battery Cyclic voltammetry Bulk electrolysis

Nanoscale viscoelastic properties and adhesion of polydimethylsiloxane for tissue engineering

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Acta Mechanica Sinica 2014年第1期30卷 2-6页

作者： j.chen K.E.Wright M.A.Birch School of Mechanical & Systems Engineering Newcastle University Arthritis Research UK (ARUK) Tissue Engineering Centre Institute of Cellular MedicineNewcastle UniversityUK Research UK (ARUK) Tissue Engineering Centre Institute of Cellular MedicineNewcastle UniversityUK St james’ University Hospital University of Leeds UK

It has shown that altering crosslink density of biopolymers will regulate the morphology of Mesenchymal Stem Cells （MSCs） and the subsequent MSCs differentia- tion. These observations have been found in a wide range of biopolymers. However, a recent work published in Nature Materials has revealed that MSCs morphology and differen- tiation was unaffected by crosslink density of polydimethyl- siloxane （PDMS）, which remains elusive. To understand such unusual behaviour, we use nanoindentation tests and modelling to characteriz. viscoelastic properties and sur- face adhesion of PDMS with different base：crosslink ratio varied from 50：1 （50D） to 10：1 （10D）. It has shown that lower crosslink density leads to lower elastic moduli. De- spite lower nanoindentation elastic moduli, PDMS with lowest crosslink density has higher local surface adhesion which would affect cell-biomaterials interactions. This work suggests that surface adhesion is likely another important physical cue to regulate cell-biomaterials interactions.

关键词： Bioploymer- Nanoindentation- Viscoelasticity Surface adhesion

Decoloriz.tion of Direct Black 22 by Aspergillus ficuum

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journal of Environmental Sciences 2001年第4期13卷 472-475页

作者： Dong, X.-j. Du, z.-y. chen, z. Dept. of Biology/Environmental Sci. Wenzhou Normal College Wenzhou 325003 China

The decoloriz.tion of Direct Black 22 by Aspergillus ficuum has been studied. It was found that Aspergillus ficuum could effectively decoloriz. Direct Black 22 especially when grown as pelleted mycelia. Results showed that the media containing Direct Black 22 at 50 mg/L could be decoloriz.d by 98.05% of the initial color in 24 h. The optimum pH and temperature of decoloriz.tion are 4.0 and 33 °C respectively. Aeration was quite beneficial to decoloriz.tion. Medium composition and the concentration of Direct Black 22 could affect the rate of decoloriz.tion. The dye degraded products assayed by UV-visible spectrophotometer and macroscopic observation showed that the decoloriz.tion of Direct Black 22 by mycelial pellets includes two important processes: bioadsorption and biodegradation. The degradation experiment agree with the Michaelis-Menten kinetics equation.

关键词： Bioassay Biodegradation Color Concentration (process) Dyes pH Ultraviolet spectrophotometers

New methods to find solutions and analyz. stability of equilibrium of nonholonomic mechanical systems

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Acta Mechanica Sinica 2018年第6期34卷 1136-1144页

作者： j.chen Y.X.Guo F.X.Mei School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China School of Physics Liaoning UniversityShenyang 110000China

A large proportion of constrained mechanical systems result in nonlinear ordinary differential equations,for which it is quite difficult to find analytical *** initial motions method proposed by Whittaker is effective to deal with such problems for various constrained mechanical systems,including the nonholonomic systems discussed in the first part of this paper,where in addition to differential equations of motion,nonholonomic constraints *** final equations of motion for these systems are obtained in the form of corresponding power ***,an alternative,direct method to determine the initial values of higher-order derivatives(q)0,(q)0,…is proposed,being different from that of *** second part of this work analyz.s the stability of equilibrium of less complex,nonholonomic mechanical systems represented by gradient *** discuss the stability of equilibrium of such systems based on the properties of the gradient *** advantage of this novel method is its avoidance of the difficulty of directly establishing Lyapunov functions aimed at such unsteady nonlinear ***,these theoretical considerations are illustrated through four examples.

关键词： Nonholonomic system Initial motions Gradient system Lyapunov function Stability

INTERFACIAL DEBONDING OF FRC UNDER CYCLIC LOADING

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Acta Metallurgica Sinica(English Letters) 2004年第3期17卷 327-330页

作者： Q.j.z.u Y.H.chen j.chen Department of Civil Engineering Hebei Institute of Technology Tangshan 063009 China School of Civil Engineering Beijing Jiaotong University Beijing 100044 ChinaDepartment of Civil Engineering Hebei Institute of Technology Tangshan 063009 China

With the increasingly use of FRC (fiber-reinforced composite) in urban lifelines, me-chanical properties investigation is very important for disaster resistance, especiallythe investigation of fatigue properties. Based on the shear-lag model, an usual com-posite model under cyclic loading is established. According to the Paris formula, therelationship between interfacial fatigue parameters and the number of cycles is ob-tained under the cyclic loading. Interfocial fatigue properties of this model and thegrowth of the interfacial fatigue crack are analyz.d. And the Poisson ratio is consid-ered also.

关键词： interfacial debonding fiber matrix cyclic loading crack growth

Fabrication and Mechano-sensing Characteristics of Bending Polypyrrole Actuator

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journal of Wuhan University of Technology(Materials Science) 2025年第1期40卷 240-245页

作者： chen jinyou HU Wei School of Automotive Engineering Hunan Financial&Industrial Vocational-technical CollegeHengyang 421002China College of Mechanical and Electrical Engineering Hunan Agricultural UniversityChangsha 410128China

To prepare a conductive polymer actuator with decent performance,a self-built experimental platform for the preparation of polypyrrole film is *** of the essential goals is to examine the mechanical characteristics of the actuator in the presence of various combinations of process parameters,combined with the orthogonal test method of"four factors and three levels".The bending and sensing characteristics of actuators of various siz.s are methodically examined using a self-made bending polypyrrole *** functional relationship between the bending displacement and the output voltage signal is established by studying the characteristics of the actuator sensor subjected to various degrees of *** experimental results reveal that the bending displacement of the actuator tip almost exhibits a linear variation as a function of length and *** the voltage reaches 0.8 V,the bending speed of the actuator tends to be ***,the mechanical properties of the self-assembled polypyrrole actuator are verified by the design and fabrication of the microgripper.

关键词： conductive polymer polypyrrole mechanical characteristics actuators sensing characteristics

Characteriz.tion of geological uncertainties from limited boreholes using copula-based coupled Markov chains for underground construction

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Underground Space 2024年第3期16卷 94-105页

作者： Fan Wang Heng Li Gang Li z.eng-jun You Elton j.chen National Center of Technology Innovation for Digital Construction Huazhong University of Science and TechnologyWuhan 430074China Department of Civil and Hydraulic Engineering Huazhong University of Science and TechnologyWuhan 430074China Department of Building and Real Estate The Hong Kong Polytechnic UniversityKowloon 999077Hong KongChina Shanghai Tunnel Engineering Co. Ltd.Shanghai 200032China Wuhan Metro Group Co.Ltd. Wuhan 430070China

This paper proposes an efficient method for quantifying the stratigraphic uncertainties and modeling the geological formations based on *** Markov chains are used to describe the soil transitions along different directions,and the transition probability matrices(TPMs)of the Markov chains are analytically expressed by *** copula expression is efficient since it can represent a large TPM by a few unknown *** to the analytical expression of the TPMs,the likelihood function of the Markov chain model is given in an explicit *** estimation of the TPMs is then re-casted as a multi-objective constrained optimiz.tion problem that aims to maximiz. the likelihoods of two independent Markov chains subject to a set of parameter *** the method which determines the TPMs by counting the number of transitions between soil types,the proposed method is more statistically ***,a random path sampling method is presented to avoid the directional effect problem in *** soil type at a location is inferred from its nearest known neighbors along the cardinal directions.A general form of the conditional probability,based on Pickard’s theorem and Bayes rule,is presented for the soil type *** proposed stratigraphic characteriz.tion and simulation method is applied to real borehole data collected from a construction site in Wuhan,*** is illustrated that the proposed method is accurate in prediction and does not show an inclination during simulation.

关键词： Geological stratigraphy Markov chain Transition probability matrix Statistical method Copula