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Microstructure investigation of dynamic recrystallization in hard machining: From thermodynamic irreversibility

Binxun LI, Xinzhi ZHANG, Song ZHANG

Frontiers of Mechanical Engineering 2021, Volume 16, Issue 2,   Pages 315-330 doi: 10.1007/s11465-020-0612-4

Abstract: The drastically changed thermal, mechanical, and chemical energies within the machined surface layer during hard machining tend to initiate microstructural alteration. In this paper, attention is paid to the introduction of thermodynamic potential to unravel the mechanism of microstructure evolution. First, the thermodynamic potential-based model expressed by the Helmholtz free energy was proposed for predicting the microstructure changes of serrated chip and the machined surface layer. Second, the proposed model was implemented into a validated finite element simulation model for cutting operation as a user-defined subroutine. In addition, the predicted irreversible thermodynamic state change in the deformation zones associated with grain size, which was reduced to less than 1 m from the initial size of 1.5 m on the machined surface, was provided for an in-depth explanation. The good consistency between the simulated results and experimental data validated the efficacy of the developed model. This research helps to provide further insight into the microstructure alteration during metal cutting.

Keywords： thermodynamic irreversibility     Helmholtz free energy     microstructure evolution     dynamic recrystallization    

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Optimization of power and efficiency for an irreversible Diesel heat engine

Shiyan ZHENG, Guoxing LIN

Frontiers in Energy 2010, Volume 4, Issue 4,   Pages 560-565 doi: 10.1007/s11708-010-0018-9

Abstract: presented, in which the heat loss between the working fluid and the ambient during combustion, the irreversibility

Keywords： Diesel heat engine     irreversibility     power output     efficiency     parameter optimization    

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Effect of ligand chain length on hydrophobic charge induction chromatography revealed by molecular dynamics simulations

Lin ZHANG, Yan SUN

Frontiers of Chemical Science and Engineering 2013, Volume 7, Issue 4,   Pages 456-463 doi: 10.1007/s11705-013-1357-y

Abstract: The ligand chain length has a significant effect on both the probability and the irreversibility of the

Keywords： adsorption     desorption     irreversibility     protein conformational transition     molecular dynamics simulation    

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Effect of variable heat capacities on performance of an irreversible Miller heat engine

Xingmei YE

Frontiers in Energy 2012, Volume 6, Issue 3,   Pages 280-284 doi: 10.1007/s11708-012-0203-0

Abstract: Based on the variable heat capacities of the working fluid, the irreversibility coming from the compression

Keywords： Miller cycle     variable heat capacity     irreversibility     parametric optimization    

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Unified cycle model of a class of internal combustion engines and their optimum performance characteristics

Shiyan ZHENG

Frontiers in Energy 2011, Volume 5, Issue 4,   Pages 367-375 doi: 10.1007/s11708-011-0170-x

Abstract: The unified cycle model of a class of internal combustion engines is presented, in which the influence of the multi-irreversibilities mainly resulting from the adiabatic processes, finite-time processes and heat leak loss through the cylinder wall on the performance of the cycle are taken into account. Based on the thermodynamic analysis method, the mathematical expressions of the power output and efficiency of the cycle are calculated and some important characteristic curves are given. The influence of the various design parameters such as the high-low pressure ratio, the high-low temperature ratio, the compression and expansion isentropic efficiencies etc. on the performance of the cycle is analyzed. The optimum criteria of some important parameters such as the power output, efficiency and pressure ratio are derived. The results obtained from this unified cycle model are very general and useful, from which the optimal performance of the Atkinson, Otto, Diesel, Dual and Miller heat engines and some new heat engines can be directly derived.

Keywords： internal combustion engine     irreversibility     power output     efficiency     optimization    

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Exergetic sustainability evaluation and optimization of an irreversible Brayton cycle performance

Mohammad H. AHMADI,Mohammad-Ali AHMADI,Esmaeil ABOUKAZEMPOUR,Lavinia GROSU,Fathollah POURFAYAZ,Mokhtar BIDI

Frontiers in Energy 2019, Volume 13, Issue 2,   Pages 399-410 doi: 10.1007/s11708-017-0445-y

Abstract: Owing to the energy demands and global warming issue, employing more effective power cycles has become a responsibility. This paper presents a thermodynamical study of an irreversible Brayton cycle with the aim of optimizing the performance of the Brayton cycle. Moreover, four different schemes in the process of multi-objective optimization were suggested, and the outcomes of each scheme are assessed separately. The power output, the concepts of entropy generation, the energy, the exergy output, and the exergy efficiencies for the irreversible Brayton cycle are considered in the analysis. In the first scheme, in order to maximize the exergy output, the ecological function and the ecological coefficient of performance, a multi-objective optimization algorithm (MOEA) is used. In the second scheme, three objective functions including the exergetic performance criteria, the ecological coefficient of performance, and the ecological function are maximized at the same time by employing MOEA. In the third scenario, in order to maximize the exergy output, the exergetic performance criteria and the ecological coefficient of performance, a MOEA is performed. In the last scheme, three objective functions containing the exergetic performance criteria, the ecological coefficient of performance, and the exergy-based ecological function are maximized at the same time by employing multi-objective optimization algorithms. All the strategies are implemented via multi-objective evolutionary algorithms based on the NSGAII method. Finally, to govern the final outcome in each scheme, three well-known decision makers were employed.

Keywords： entropy generation     exergy     Brayton cycle     ecological function     irreversibility    

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Modelling autogenous expansion for magnesia concrete in arch dams

JIN Feng, LUO Xiaoqing, ZHANG Chuhan, ZHANG Guoxin

Frontiers of Structural and Civil Engineering 2008, Volume 2, Issue 3,   Pages 211-218 doi: 10.1007/s11709-008-0025-7

Abstract: and mixing of concrete; 2) the autogenous expansion of Magnesia Concrete is irreversible due to the irreversibility

Keywords： field-measured     irreversibility     temperature     irreversible     element arch    

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Title Author Date Type Operation

Microstructure investigation of dynamic recrystallization in hard machining: From thermodynamic irreversibility

Binxun LI, Xinzhi ZHANG, Song ZHANG

Journal Article

Optimization of power and efficiency for an irreversible Diesel heat engine

Shiyan ZHENG, Guoxing LIN

Journal Article

Effect of ligand chain length on hydrophobic charge induction chromatography revealed by molecular dynamics simulations

Lin ZHANG, Yan SUN

Journal Article

Effect of variable heat capacities on performance of an irreversible Miller heat engine

Xingmei YE

Journal Article

Unified cycle model of a class of internal combustion engines and their optimum performance characteristics

Shiyan ZHENG

Journal Article

Exergetic sustainability evaluation and optimization of an irreversible Brayton cycle performance

Mohammad H. AHMADI,Mohammad-Ali AHMADI,Esmaeil ABOUKAZEMPOUR,Lavinia GROSU,Fathollah POURFAYAZ,Mokhtar BIDI

Journal Article

Modelling autogenous expansion for magnesia concrete in arch dams

JIN Feng, LUO Xiaoqing, ZHANG Chuhan, ZHANG Guoxin

Journal Article