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Eversible duoprism mechanism

Ruiming LI,Yan-An YAO

Frontiers of Mechanical Engineering 2016, Volume 11, Issue 2, Pages 159-169 doi: 10.1007/s11465-016-0398-6

Abstract:

In this study, a novel duoprism mechanism that demonstrates a fascinating eversion motion is developed. The mechanism comprises three scalable platforms and nine retractable limbs and is constructed by inserting prismatic and revolute joints into the edges and vertices of the duoprism, respectively. According to mobility and kinematic analyses, the mechanism has five degrees of freedom. Six inputs, including a redundant one, are required to overcome singularity and achieve an eversion motion. In the eversion motion, three platforms expand/contract synchronously, and the mechanism continuously turns inside out. The detailed gaits of eversion motion along an ellipse and a circle after a cycle are illustrated with two examples. A kinematic simulation is conducted, and a manual prototype is fabricated to verify the feasibility of the eversible duoprism mechanism.

Keywords： duoprism eversion motion singularity over-constrained

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Fuzzy force control of constrained robot manipulators based on impedance model in an unknown environment

LIU Hongyi, WANG Fei, WANG Lei

Frontiers of Mechanical Engineering 2007, Volume 2, Issue 2, Pages 168-174 doi: 10.1007/s11465-007-0028-4

Abstract: To precisely implement the force control of robot manipulators in an unknown environment, a control strategy based on fuzzy prediction of the reference trajectory in the impedance model is developed. The force tracking experiments are executed in an open-architecture control system with different tracking velocities, different desired forces, different contact stiffnesses and different surface figurations. The corresponding force control results are compared and analyzed. The influences of unknown parameters of the environment on the contact force are analyzed based on experimental data, and the tunings of predictive scale factors are illustrated. The experimental results show that the desired trajectory in the impedance model is predicted exactly and rapidly in the cases that the contact surface is unknown, the contact stiffness changes, and the fuzzy force control algorithm has high adaptability to the unknown environment.

Keywords： predictive tracking corresponding stiffness algorithm

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Robust train speed trajectory optimization: A stochastic constrained shortest path approach

Li WANG, Lixing YANG, Ziyou GAO, Yeran HUANG

Frontiers of Engineering Management 2017, Volume 4, Issue 4, Pages 408-417 doi: 10.15302/J-FEM-2017042

Abstract: uncertainties and generate a robust speed trajectory, this study specifically proposes distance-speed networks overThe problem of interest is formulated as a stochastic constrained shortest path problem with travel time

Keywords： train speed trajectory optimization railway operation stochastic programming

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A constrained neural network model for soil liquefaction assessment with global applicability

Yifan ZHANG, Rui WANG, Jian-Min ZHANG, Jianhong ZHANG

Frontiers of Structural and Civil Engineering 2020, Volume 14, Issue 5, Pages 1066-1082 doi: 10.1007/s11709-020-0651-2

Abstract: A constrained back propagation neural network (C-BPNN) model for standard penetration test based soildata set is compiled, covering more than 600 liquefaction sites from 36 earthquakes in 10 countries over

Keywords： soil liquefaction assessment case history dataset constrained neural network model existing knowledge

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Dynamic characteristics analysis of active constrained layer damping plate with various boundary conditions

Jing LU, Yu XIANG, Qiao NI

Frontiers of Mechanical Engineering 2011, Volume 6, Issue 4, Pages 449-455 doi: 10.1007/s11465-011-0240-0

Abstract: converse piezoelectric effect, expressions of piezoelectric membrane internal forces in the piezoelectric constrainedThe control equations of the piezoelectric constrained layer and host plate were obtained in accordingBased on the layer wised principle, the integrated first order differential equation of an active constrained

Keywords： active constrained layer damping (ACLD) plate dynamic characteristics semi-analytical method extended

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New approaches to water purification for resource-constrained settings: Production of activated biochar

Mohit Nahata, Chang Y. Seo, Pradeep Krishnakumar, Johannes Schwank

Frontiers of Chemical Science and Engineering 2018, Volume 12, Issue 1, Pages 194-208 doi: 10.1007/s11705-017-1647-x

Abstract: This problem is most acute in remote, resource-constrained rural settings in developing countries.At a temperature of 450 °C, the loading of DAP over cellulose is systematically varied, and its effect, leading to the possibility of an activated biochar production scheme on a small scale in resource-constrained

Keywords： cellulose DAP activation heteroatom microporous

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Pulse Transiently Chaotic Neural Network for Nonlinear Constrained Optimization

Li Ying,Cao Hongzhao,Hu Yunchang,Shang Xiuming

Strategic Study of CAE 2004, Volume 6, Issue 5, Pages 45-48

Abstract: part optima and the global with its abundance dynamical characteristic, when is used in nonlinear non-constrained

Keywords： PTCNN penalty function nonlinear constrained optimization

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Hybrid genetic algorithm for bi-objective resource-constrained project scheduling

Fikri KUCUKSAYACIGIL, Gündüz ULUSOY

Frontiers of Engineering Management 2020, Volume 7, Issue 3, Pages 426-446 doi: 10.1007/s42524-020-0100-x

Abstract: In this study, we considered a bi-objective, multi-project, multi-mode resource-constrained project scheduling

Keywords： algorithm injection procedure maximum cash balance multi-objective multi-project multi-mode resource-constrained

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Manufacturing cost constrained topology optimization for additive manufacturing

Jikai LIU, Qian CHEN, Xuan LIANG, Albert C. TO

Frontiers of Mechanical Engineering 2019, Volume 14, Issue 2, Pages 213-221 doi: 10.1007/s11465-019-0536-z

Abstract: This paper presents a manufacturing cost constrained topology optimization algorithm considering thedeveloping the sensitivity result, the metallic additive manufacturing part can be optimized with strictly constrained

Keywords： topology optimization manufacturing cost additive manufacturing powder bed

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Geometrically constrained isogeometric parameterized level-set based topology optimization via trimmed

Yingjun WANG,David J. BENSON

Frontiers of Mechanical Engineering 2016, Volume 11, Issue 4, Pages 328-343 doi: 10.1007/s11465-016-0403-0

Abstract:

In this paper, an approach based on the fast point-in-polygon (PIP) algorithm and trimmed elements is proposed for isogeometric topology optimization (TO) with arbitrary geometric constraints. The isogeometric parameterized level-set-based TO method, which directly uses the non-uniform rational basis splines (NURBS) for both level set function (LSF) parameterization and objective function calculation, provides higher accuracy and efficiency than previous methods. The integration of trimmed elements is completed by the efficient quadrature rule that can design the quadrature points and weights for arbitrary geometric shape. Numerical examples demonstrate the efficiency and flexibility of the method.

Keywords： isogeometric analysis topology optimization level set method arbitrary geometric constraint trimmed element

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Hohmann transfer via constrained optimization None

Li XIE, Yi-qun ZHANG, Jun-yan XU

Frontiers of Information Technology & Electronic Engineering 2018, Volume 19, Issue 11, Pages 1444-1458 doi: 10.1631/FITEE.1800295

Abstract: Via static and dynamic constrained optimizations, the solution to the Hohmann transfer problem is re-discovered

Keywords： Hohmann transfer Nonlinear programming Constrained optimization Calculus of variations

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Reductive amination of -hexanol to -hexylamine over Ni–Ce/-AlO catalysts

Frontiers of Chemical Science and Engineering 2023, Volume 17, Issue 1, Pages 82-92 doi: 10.1007/s11705-022-2181-z

Abstract: The amination of alkyl alcohols is one of the most promising paths in synthesis of aliphatic amines. Herein, cerium doped nickel-based catalysts were synthesized and tested in a gas-phase amination of n-hexanol to n-hexylamine. It was found that the activity of the Ni/γ-Al₂O₃ catalyst is significantly improved by doping an appropriate amount of cerium. The presence of cerium effectively inhibits the agglomeration of nickel particle, resulting in better Ni dispersion. As Ni particle size plays critical role on the catalytic activity, higher turnover frequency of n-hexanol amination was achieved. Cerium doping also improves the reduction ability of nickel and enhances the interactions between Ni and the catalyst support. More weak acid sites were also found in those cerium doped catalysts, which promote another key step—ammonia dissociative adsorption in this reaction system. The overall synergy of Ni nanoparticles and acid sites of this Ni–Ce/γ-Al₂O₃ catalyst boosts its superior catalytic performance in the amination of n-hexanol.

Keywords： amination alcohol cerium nickel acidity interaction

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Supersonic flows over cavities

FANG Tianwen, DING Meng, ZHOU Jin

Frontiers in Energy 2008, Volume 2, Issue 4, Pages 528-533 doi: 10.1007/s11708-008-0055-9

Abstract: The characteristics of supersonic cold flows over cavities were investigated experimentally and numerically

Keywords： supersonic different ratio

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A solution to stochastic unit commitment problem for a wind-thermal system coordination

B. SARAVANAN,Shreya MISHRA,Debrupa NAG

Frontiers in Energy 2014, Volume 8, Issue 2, Pages 192-200 doi: 10.1007/s11708-014-0306-x

Abstract: commitment problem considering the volatile nature of wind and formulating the UC problem as a chance constrainedproblem in which the load is met with high probability over the entire time period.

Keywords： unit commitment (UC) randomness wind generation univariate chance constrained

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Efficient conversion of lignin to alkylphenols over highly stable inverse spinel MnFeO catalysts

Frontiers of Chemical Science and Engineering 2023, Volume 17, Issue 8, Pages 1085-1095 doi: 10.1007/s11705-022-2236-1

Abstract: The aromatic properties of lignin make it a promising source of valuable chemicals and fuels. Developing efficient and stable catalysts to effectively convert lignin into high-value chemicals is challenging. In this work, MnFe₂O₄ spinel catalysts with oxygen-rich vacancies and porous distribution were synthesized by a simple solvothermal process and used to catalyze the depolymerization of lignin in an isopropanol solvent system. The specific surface area was 110.5 m²∙g^–1, which substantially increased the active sites for lignin depolymerization compared to Fe₃O₄. The conversion of lignin reached 94%, and the selectivity of alkylphenols exceeded 90% after 5 h at 250 °C. Underpinned by characterizations, products, and density functional theory analysis, the results showed that the catalytic performance of MnFe₂O₄ was attributed to the composition of Mn and Fe with strong Mn–O–Fe synergy. In addition, the cycling experiments and characterization showed that the depolymerized lignin on MnFe₂O₄ has excellent cycling stability. Thus, our work provides valuable insights into the mechanism of lignin catalytic depolymerization and paves the way for the industrial-scale application of this process.

Keywords： lignin depolymerization spinel catalysts hydrogenation