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226 results on '"Guo, Yifeng"'

30. A versatilely high fidelity electric machines emulator for rapid testing of motor controller.

Author

Guo, Yifeng, Huang, Limin, Zhang, Min, He, Min, Zhong, Bin, and Fan, Dakun

Subjects
*ELECTRIC machines, *HARDWARE-in-the-loop simulation, *PERMANENT magnets, *ELECTRIC machinery, *MOTORS, *TYPHOONS
Abstract

Electric machines emulators (EMEs) based on hardware-in-the-loop (HIL), which effectively act as emulators to mimic the actual motor behavior of Interior Permanent Magnet (IPM) machines. EME is frequently used to evaluate motor controller and motor control methodologies prior to development. The inverse magnetization motor model, which is used as the basis for real-time simulation in this paper's proposal for an electric machine emulator system based on HIL, uses FEA to create the motor model data. The nonlinear features of the motor may be successfully replicated with this motor model, and the accuracy of the electric machine emulator can be enhanced by using a straightforward and trustworthy motor controller. The real-time simulation tool typhoon HIL is used in the study to develop a hardware-in-the-loop simulation platform for an IPM electric machines emulator. [ABSTRACT FROM AUTHOR]

Published
2024
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31. Morphology Refinement of Eutectic Carbides Assisted by Static Magnetic Field during Laboratory Electroslag Remelting Process.

Author

Ma, Chengkuan, Xia, Zhibin, Sun, Zhonghao, Zheng, Tianxiang, Shen, Zhe, Ding, Biao, Liu, Chunmei, Guo, Yifeng, Li, Qiang, and Zhong, Yunbo

Subjects
ELECTROSLAG process, MAGNETIC fields, EUTECTICS, CARBIDES, TEMPERATURE distribution, MORPHOLOGY
Abstract

A transverse static magnetic field (TSMF) is implemented in a laboratory electroslag remelting (ESR) experiment to control eutectic carbides morphology of Cr8 die steel herein. Under action of a TSMF, the temperature distribution of the molten pool becomes homogeneous, the local solidification time is shortened, and the interdendritic region space shrinks, which result in an evenly spaced distribution of solute atoms and a reduction in interdendritic segregation. Therefore, the formation and subsequent growth of eutectic carbides are further inhibited, thereby causing the generation of smaller and more uniform distributed eutectic carbides due to the application of the TSMF. Moreover, the increase of the number of Al2O3–(Ti,V)N inclusions serves to be the heterogeneous nucleus of carbides (inclusions also become finer) caused by TSMF, which also contributes to the refinements of eutectic carbides in Cr8 ingots. [ABSTRACT FROM AUTHOR]

Published
2024
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32. Numerical Simulation Study on Heat Transfer Characteristics of Particle‐Loaded Flow in Microchannels.

Author

Song, Kaixin, Guo, Yifeng, Wang, Zhibin, Jia, A. P. Lisi, Chen, Gang, Mo, Songping, and Chen, Ying

Subjects
*HEAT transfer, *MICROCHANNEL flow, *SPECIFIC heat capacity, *REYNOLDS number, *THERMAL conductivity, *COMPUTER simulation
Abstract

Particle suspension is considered powerful and perspective in enhancing heat transfer, but the unclear nature of particle‐loaded flow limits further understanding of particle suspension. Therefore, in this paper, orthogonal experiments and the arbitrary Lagrangian‐Eulerian method were used to investigate the heat transfer characteristics of particle‐loaded flow. Results indicate that when the particle is at the inlet of the microchannel, the factors arranged in important order are the Reynolds number, blockage ratio, particle initial position, specific heat capacity, and thermal conductivity. When the particle is far from the microchannel inlet, the factors arranged in important order are the Reynolds number, blockage ratio, particle initial position, thermal conductivity, and specific heat capacity. [ABSTRACT FROM AUTHOR]

Published
2024
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40. When Aryne Chemistry Meets Organosulfur Compounds.

Author

Tan, Jiajing, Feng, Xiaoying, Fan, Rong, Zhuang, Zhe, and Guo, Yifeng

Subjects
ARYNE, SIGMATROPIC rearrangements, RING-opening reactions, ZWITTERIONS, ARYLATION, SULFIDES, ORGANOSULFUR compounds
Abstract

This article explores the field of organosulfur chemistry and its applications in various industries. The authors specifically discuss their research on aryne chemistry and its interaction with organosulfur compounds. They detail their efforts in developing synthetic methodologies using sulfonium zwitterions and the unique reactivities of the resulting S(IV) intermediates. The article highlights their recent achievements in sigmatropic rearrangement, ring-opening reactions of cyclic sulfides, and selective arylation of thio-oxindoles. The authors aim to advance zwitterion chemistry and expand its applications through selectivity control and diversity-oriented synthesis. [Extracted from the article]

Published
2023
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46. High-Dimensional Portfolio Selection with Cardinality Constraints.

Author

Du, Jin-Hong, Guo, Yifeng, and Wang, Xueqin

Subjects
*RUSSELL 2000 Index, *INVESTORS, *STANDARD & Poor's 500 Index, *EXPECTED utility, *PORTFOLIO management (Investments)
Abstract

The expanding number of assets offers more opportunities for investors but poses new challenges for modern portfolio management (PM). As a central plank of PM, portfolio selection by expected utility maximization (EUM) faces uncontrollable estimation and optimization errors in ultrahigh-dimensional scenarios. Past strategies for high-dimensional PM mainly concern only large-cap companies and select many stocks, making PM impractical. We propose a sample-average-approximation-based portfolio strategy to tackle the difficulties above with cardinality constraints. Our strategy bypasses the estimation of mean and covariance, the Chinese walls in high-dimensional scenarios. Empirical results on S&P 500 and Russell 2000 show that an appropriate number of carefully chosen assets leads to better out-of-sample mean-variance efficiency. On Russell 2000, our best portfolio profits as much as the equally weighted portfolio but reduces the maximum drawdown and the average number of assets by 10% and 90%, respectively. The flexibility and the stability of incorporating factor signals for augmenting out-of-sample performances are also demonstrated. Our strategy balances the tradeoff among the return, the risk, and the number of assets with cardinality constraints. Therefore, we provide a theoretically sound and computationally efficient strategy to make PM practical in the growing global financial market. for this article are available online. [ABSTRACT FROM AUTHOR]

Published
2023
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47. Morphology Control of Metal Pool and Eutectic Carbides in Electroslag Remelted M2 HSS with an External Axial Static Magnetic Field.

Author

Zhao, Xuhui, Sun, Zhonghao, Xia, Zhibin, Liu, Chunmei, Shen, Zhe, Ding, Biao, Zheng, Tianxiang, Guo, Yifeng, Li, Qiang, and Zhong, Yunbo

Subjects
TOOL-steel, MAGNETIC fields, METALS, TEMPERATURE distribution, CARBIDES, HEAT transfer
Abstract

This study investigates the influence of a superimposed axial static magnetic field (ASMF) on the morphology of metal pool and eutectic carbides (ECs) in electroslag remelted M2 high-speed steel (HSS). The application of ASMF caused the metal pool to become shallower, and the solidified structure to expand axially, along with finer (i.e., more uniformly distributed and crystallographically oriented) ECs. Lorentz force-driven unidirectional circulation in slag pool was the primary cause of the metal pool's morphological adjustment; this resulted in a more homogenous temperature distribution in slag pool. Thus, the heat transfer from the slag pool to the metal pool became more uniform, creating a metal pool that is shallower. Additionally, local solidification time (LST) became shorter, while the number of (Ti, V)N-Al2O3 inclusions serving as heterogeneous nuclei for EC formation increased due to ASMF, enabling finer EC with more crystallographic orientations in ESR ingots. [ABSTRACT FROM AUTHOR]

Published
2023
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