Reduced‑order controller design for Cuk converters based on objective holographic feedback

Jiyong Li,Pengcheng Zhou,Hengyu Pan,Duanzheng Feng,Bin Liu 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.2

Since the Cuk converter is a non-minimum phase system with an unstable internal dynamic, it is challenging to employ control methods such as input–output linearization to ensure the closed-loop system stability. This paper proposes an objective holographic feedback nonlinear control (OHFNC) method without static deviation to regulate fourth-order Cuk converters. A Cuk converter operating in the continuous conduction mode is adopted, and the input inductor current and output capacitor voltage of the system are selected as control target quantities. The OHFNC method aims to configure a nonlinear system with poles near the equilibrium point, and place them in desired positions. The target quantities are separately constrained by feedback coefficients, which forces them to converge to their corresponding reference trajectories. Accordingly, an integration link is introduced to compensate for the reference current error when the system is heavily loaded. Finally, simulation and experimental results show that the OHFNC method has a stronger robustness and a faster transient response than fractional-order PIλ dual-loop control.

A serine/threonine phosphatase 1 of Streptococcus suis type 2 is an important virulence factor

Lihua Fang,Jingjing Zhou,Pengcheng Fan,Yunkai Yang,Hongxia Shen,Weihuan Fang 대한수의학회 2017 Journal of Veterinary Science Vol.18 No.4

Streptococcus suis is regarded as one of the major pathogens of pigs, and Streptococcus suis type 2 (SS2) is considered a zoonotic bacterium based on its ability to cause meningitis and streptococcal toxic shock-like syndrome in humans. Many bacterial species contain genes encoding serine/threonine protein phosphatases (STPs) responsible for dephosphorylation of their substrates in a single reaction step. This study investigated the role of stp1 in the pathogenesis of SS2. An isogenic stp1 mutant (stp1) was constructed from SS2 strain ZJ081101. The stp1 mutant exhibited a significant increase in adhesion to HEp-2 and bEnd.3 cells as well as increased survival in RAW264.7 cells, as compared to the parent strain. Increased survival in macrophage cells might be related to resistance to reactive oxygen species since the stp1 mutant was more resistant than its parent strain to paraquat-induced oxidative stress. However, compared to parent strain virulence, deletion of stp1 significantly attenuated virulence of SS2 in mice, as shown by the nearly double lethal dose 50 value and the lower bacterial load in organs and blood in the murine model. We conclude that Stp1 has an essential role in SS2 virulence.

Low noise optimization of two-stage gearbox housing structure based on acoustic contribution analysis and topology optimization

Le Qi,Jianxing Zhou,Pengcheng Jin,Mingming Wang,Yongzheng Su,Hengyu Zhou,Guochun Liu,Lirui Song 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.9

In this paper, a rib layout optimization method that can efficiently reduce the radiated noise of gearboxes is proposed. Taking the secondary gearbox as the research object, the radiated noise of the housing is calculated using the FEM/BEM method, the process of determining the region with the maximum acoustic contribution is illustrated, and a topology optimization model that can reduce the air noise on the field points of the gearbox is established with the surface normal velocity of the region as the optimization target. The method is applied to add new noise reduction ribs on the surface of the gearbox. The results show that after combining the topology optimization with the acoustic contribution analysis, the sound pressure in the area with the highest sound pressure on the gearbox sound field is significantly reduced by adding new noise reduction ribs according to the optimization results.

Simplified topology optimization of damping layer in plate structures for vibration and acoustic response

Le Qi,Quanwei Cui,Cheng Wang,Xueyan Sun,Janxing Zhou,Pengcheng Jin,Guochun Liu,Lirui Song 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.12

In this paper, a simplified acoustic optimization method is proposed to replace the sound power with the maximum normal velocity of the surface as a direct target, a topological optimization model of the variable density method is established to reduce the acoustic radiation of the structure, and the relationship between the form of damping distribution and the acoustic radiation is investigated. The complex modulus model is used to describe the viscoelastic material intrinsic relationship of the damping layer. The effects of different excitation frequencies on the topology optimization results are discussed. The radiated noise is simulated using the finite element method and the boundary element method. Five plates are fabricated according to the damping layer layout for different single-frequency excitations. Modal and acoustic experiments are carried out to validate the proposed method. The numerical and experimental results show that there is a significant reduction in the sound pressure level (SPL).

Implementation of SHM system for Hangzhou East Railway Station using a wireless sensor network

Yanbin Shen,Wenwei Fu,Yaozhi Luo,Chung Bang Yun,Dun Liu,Pengcheng Yang,Guang Yang,Guangen Zhou 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.27 No.1

Structural health monitoring (SHM) is facilitated by new technologies that involve wireless sensor networks (WSNs). The main benefits of WSNs are that they are distributed, are inexpensive to install, and manage data effectively via remote control. In this paper, a wireless SHM system for the steel structure of Hangzhou East Railway Station in China is developed, since the state of the structural life cycle is highly complicated and the accompanying internal force redistribution is not known. The monitoring system uses multitype sensors, which include stress, acceleration, wind load, and temperature sensors, as the measurement components for the structural features, construction procedure, and on-site environment. The sensor nodes communicate with each other via a flexible tree-type network. The system that consists of 323 sensors is designed for the structure, and the data acquisition process will continue throughout its whole life cycle. First, a full-scale application of SHM using a WSN is described in details. Then, it focuses on engineering practice and data analysis. The current customized WSN has been demonstrated to have satisfactory durability and strong robustness; hence, it well satisfies the requirements for multi-type sensors to operate in a large area. The data analysis results demonstrate that the effects of the construction process and the environment on the super-large-scale structure have been captured accurately. Those effects include the stress variation throughout the construction process, the dynamic responses that are caused by passing trains, the strain variation caused by temperature change over the long term, and the delay in the wind-pressure history.

Histone demethylase KDM4A plays an oncogenic role in nasopharyngeal carcinoma by promoting cell migration and invasion

Zhao Jingyi,Li Bingyan,Ren Yongxia,Liang Tiansong,Wang Juan,Zhai Suna,Zhang Xiqian,Zhou Pengcheng,Zhang Xiangxian,Pan Yuanyuan,Gao Fangfang,Zhang Sulan,Li Liming,Yang Yongqiang,Deng Xiaoyu,Li Xiaole,C 생화학분자생물학회 2021 Experimental and molecular medicine Vol.53 No.-

Compelling evidence has indicated the vital role of lysine-specific demethylase 4 A (KDM4A), hypoxia-inducible factor-1α (HIF1α) and the mechanistic target of rapamycin (mTOR) signaling pathway in nasopharyngeal carcinoma (NPC). Therefore, we aimed to investigate whether KDM4A affects NPC progression by regulating the HIF1α/DDIT4/mTOR signaling pathway. First, NPC and adjacent tissue samples were collected, and KDM4A protein expression was examined by immunohistochemistry. Then, the interactions among KDM4A, HIF1α and DDIT4 were assessed. Gain- and loss-of-function approaches were used to alter KDM4A, HIF1α and DDIT4 expression in NPC cells. The mechanism of KDM4A in NPC was evaluated both in vivo and in vitro via RT-qPCR, Western blot analysis, MTT assay, Transwell assay, flow cytometry and tumor formation experiments. KDM4A, HIF1α, and DDIT4 were highly expressed in NPC tissues and cells. Mechanistically, KDM4A inhibited the enrichment of histone H3 lysine 9 trimethylation (H3K9me3) in the HIF1α promoter region and thus inhibited the methylation of HIF1α to promote HIF1α expression, thus upregulating DDIT4 and activating the mTOR signaling pathway. Overexpression of KDM4A, HIF1α, or DDIT4 or activation of the mTOR signaling pathway promoted SUNE1 cell proliferation, migration, and invasion but inhibited apoptosis. KDM4A silencing blocked the mTOR signaling pathway by inhibiting the HIF1α/DDIT4 axis to inhibit the growth of SUNE1 cells in vivo. Collectively, KDM4A silencing could inhibit NPC progression by blocking the activation of the HIF1α/DDIT4/mTOR signaling pathway by increasing H3K9me3, highlighting a promising therapeutic target for NPC.

Negative sequence control for DC voltage balancing in three‑phase cascaded H‑bridge rectifiers considering DC‑port failures

Xinyu Zhu,Xiao Liang,Kaiyue Gong,Xu Peng,Jun Cai,Xiaohan Liu,Chao Zhou,Siqi An,Chao Wu,Pengcheng Han 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.12

As a vital component of power electronic transformers (PET), the reliability of a cascaded H-bridge rectifier (CHBR) is essential. Therefore, in this paper, a DC-port voltage balance strategy considering DC-port failure is researched to ensure the stable operation of a CHBR. However, if the DC-port voltage balance strategy is adopted to realize the single-phase balance of a CHBR, the three-phase currents become unbalanced. This paper uses a negative sequence control (NSC) strategy that is conducive to balancing DC-port voltage to achieve three-phase current balance. For the DC-port voltage balance, the matrix generation modulation (MGM) algorithm is proposed. In addition, the DC-port voltage balance boundary is analyzed to determine the range of the DC-port voltage balance in the CHBR. A 3-module cascading topology is adopted to demonstrate the MGM algorithm and the NSC strategy. Through experiments, results show the correctness and feasibility of the proposed strategy.