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12 results on '"Wang, Zeting"'

5. Multiple Metabolic Engineering Strategies to Improve Shikimate Titer in Escherichia coli.

Author

Bo, Taidong, Wu, Chen, Wang, Zeting, Jiang, Hao, Wang, Feiao, Chen, Ning, and Li, Yanjun

Subjects
ESCHERICHIA coli, SYNTHETIC proteins, QUORUM sensing, CHIMERIC proteins, PLANT enzymes
Abstract

Shikimate is a valuable chiral precursor for synthesizing oseltamivir (Tamiflu®) and other chemicals. High production of shikimate via microbial fermentation has attracted increasing attention to overcome the unstable and expensive supply of shikimate extracted from plant resources. The current cost of microbial production of shikimate via engineered strains is still unsatisfactory, and thus more metabolic strategies need to be investigated to further increase the production efficiency. In this study, we first constructed a shikimate E. coli producer through the application of the non-phosphoenolpyruvate: carbohydrate phosphotransferase system (non-PTS) glucose uptake pathway, the attenuation of the shikimate degradation metabolism, and the introduction of a mutant of feedback-resistant 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthase. Inspired by the natural presence of bifunctional 3-dehydroquinate dehydratase (DHD)-shikimate dehydrogenase (SDH) enzyme in plants, we then designed an artificial fusion protein of DHD-SDH to decrease the accumulation of the byproduct 3-dehydroshikimate (DHS). Subsequently, a repressed shikimate kinase (SK) mutant was selected to promote shikimate accumulation without the supplementation of expensive aromatic substances. Furthermore, EsaR-based quorum sensing (QS) circuits were employed to regulate the metabolic flux distribution between cell growth and product synthesis. The final engineered strain dSA10 produced 60.31 g/L shikimate with a yield of 0.30 g/g glucose in a 5 L bioreactor. [ABSTRACT FROM AUTHOR]

Published
2023
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7. A Novel Double Closed-loop Control Method for Single-phase PWM Rectifier

Author

Zhang Hu, Wang Zeting, and Zhu Guiqing

Subjects
Loop (topology), Rectifier, Control and Systems Engineering, Computer science, Control theory, Integrator, Power factor, PWM rectifier, Decoupling (electronics), Inner loop, Voltage
Abstract

The research object is the single-phase PWM rectifier in this paper. The goal of DC voltage dynamic response speed improvement and unit power factor realization is the rectifier oriented. Based on current inner loop DQ decoupling control and voltage outer loop adaptive fuzzy PI control, a double closed-loop control method for single-phase PWM rectifier is proposed. Firstly, based on the second-order generalized integrator algorithm, the DQ current decoupling control mathematical model is established by analyzing the rectifier decoupling control. Secondly, fuzzy PI control algorithm is designed for voltage outer loop control. Finally, simulation verification is carried out. Simulation results prove that the proposed control strategy has good dynamic performance.

Published
2020

8. An Improved Model-Free Finite Control Set Predictive Power Control for PWM Rectifiers

Author

Yongchang Zhang, Zeyu Min, Haitao Yang, Wang Zeting, and Dong Jiang

Subjects
Model predictive control, Control theory, Computer science, Robustness (computer science), Distortion, Predictive power, PWM rectifier, Pulse-width modulation, Power control, Power (physics)
Abstract

The performance of conventional finite control set predictive control (FCSPC) is deteriorated when model parameters are not accurately known. To improve the robustness against model mismatches, model-free FCSPC (MF-FCSPC), which relies on only sensored information, has been proposed in the existing literature. However, the prior MF-FCSPC suffers from random power spikes and higher current distortions. In this paper, a MF-FCSPC based on an enhanced mechanism for storing and updating current difference is proposed, which shows strong robustness as that of the prior MF-FCSPC but still maintaining good performance as like a well-tuned FCSPC. To verify the effectiveness of the developed method, several simulation and experimental tests were carried out on a two-level PWM rectifier platform. The obtained results confirm the feasibility and superiority of the proposed MF-FCSPC when compared with the conventional FCSPC and prior MF-FCSPC.

Published
2021

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