Sequence Pulse Modulation for Voltage Balance in a Cascaded H-Bridge Rectifier

Xu Peng,Xiaoqiong He,Pengcheng Han,Xiaolan Lin,Zeliang Shu,Shibin Gao 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.3

With the development of multilevel converters, cascaded single-phase H-bridge rectifiers (CHBRs) has become widely adopted in high-voltage high-power applications. In this study, sequence pulse modulation (SPM) is proposed for CHBRs. SPM is designed to balance the dc-link voltage and maintain the smooth changes of switch states. In contrast to phase disposition modulation, SPM balances the dc-link voltage even after removing the load of one submodule. The operation principle of SPM is deduced, and the unbalance degree of SPM is analyzed. All the proposed approaches are experimentally verified through a prototype of a four-module (nine-level) CHBR. Conclusions are drawn in accordance with the results of SPM and its imbalance degree analysis.

L-lysine and L-arginine inhibit the oxidation of lipids and proteins of emulsion sausage by chelating iron ion and scavenging radical

Xu, Peng,Zheng, Yadong,Zhu, Xiaoxu,Li, Shiyi,Zhou, Cunliu Asian Australasian Association of Animal Productio 2018 Animal Bioscience Vol.31 No.6

Objective: To evaluate the effects of L-lysine (Lys)/L-arginine (Arg) on lipid and protein oxidation of emulsion sausage during storage and its possible mechanism. Methods: Four samples were prepared based on the presence or absence of additional sodium isoascorbate, Lys, or Arg: sample A (control), sample B (0.05 g of sodium isoascorbate), sample C (0.4 g of Lys), and sample D (0.4 g of Arg). Peroxide value (POV), thiobarbituric reactive substances (TBARS), protein carbonyls and thiols were measured. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical-scavenging, ferrous ion-chelating ability were also measured. Results: Compared with the control, the sample treated with sodium isoascorbate, Lys or Arg had significantly lower POV during the initial 20 days, TBARS during the initial 15 days. Protein carbonyls were significantly lower compared Sample B, C, and D with A during the later storage (10 to 25 days); basically, protein thiols became lower during storage when the samples were treated with sodium isoascorbate, Lys, or Arg. Both Lys and Arg had weak reducing power but strong ferrous ion-chelating activity and DPPH radical- and hydroxyl radical-scavenging activity. Conclusion: Both Lys and Arg effectively inhibited the oxidation of lipids and proteins in emulsion sausage by scavenging free radicals and chelating ferrous ions. The results obtained may be favorable for the prevention of lipid and protein oxidation during processing and storage of meat products.

Capacitors Energy Strategy Based Cascaded H-Bridge Converter for DC Port Failures

Xu Peng,Xiaohan Liu,Guolong Yang,Xijun Liu,Lixia Gao,Xinyu Zhu 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.5

In this paper, a capacitors energy strategy based Cascaded H-bridge Converter (CHBC) for steady DC link voltage is proposed, which allow the CHBC to work while DC power fails. The topology of the CHBC is analyzed to construct the proposed strategy. The capacitors energy strategy is deduced based on the principle that the DC link voltage should be steady, the switch state should be smooth and the switch frequency should be normal. Experiments based on a three-module prototype, including static experiment, start experiment and step change experiment, proves the correctness of the strategy. They also verified the excellent fault tolerance ability and good dynamic performance of the proposed strategy.

Effects of restitution coefficient and material characteristics on dynamic response of planar multi-body systems with revolute clearance joint

Xupeng Wang,Geng Liu,Shangjun Ma,Ruiting Tong 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.2

To study the effects of restitution coefficient and material parameters on the dynamic characteristics of planar multi-body systems with revolute clearance joints, a comprehensive methodology for clearance revolute joints in a planar multibody system is presented and analyzed. A new nonlinear contact force model, which accounts for the axial length of bearing and has a wide suitable range of impact situation, is presented to evaluate the contact force between journal and bearing. Furthermore, a modified Coulomb friction force model also presented to consider the effect of friction in clearance joint. Then, a typical journal-bearing model and a planar slider-crank mechanism has revolute clearance joint are used as examples. From the main numerical results under the different restitution coefficient and material parameters, it can be concluded that coefficient of restitution has significant effects on dynamic response of multi-body systems with revolute clearance joint. Additionally, materials of journal and bearing with smaller Young’s modulus will cause obvious delay on dynamic response of multi-body systems.

Dynamic analysis of planar mechanical systems with clearance joints using a new nonlinear contact force model

Xupeng Wang,Geng Liu,Shangjun Ma 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.4

We investigated the dynamic behavior of planar mechanical systems with clearance joints. First, the contact effect in clearance joint was studied using a new nonlinear contact force model, and the rationality of this model was verified by the results of numerical simulations, which are based on a journal and bearing contact model. Then, the dynamic characteristics of a planar slider-crank mechanism with clearance were analyzed based on the new nonlinear contact force model, and the friction effect of clearance joint was also considered using modified Coulomb friction model. Finally, the numerical results of the influence of clearance size on the acceleration of slider are presented, and compared with the published experimental results. The numerical and experimental results show that the new nonlinear contact force model presented in this paper is an effective method to predict the dynamic behavior of planar mechanical system with clearance joints, and appears to be suitable for a wide range of impact situations, especially with low coefficient of restitution.

Modeling and simulation of revolute joint with clearance in planar multi-body systems

Xupeng Wang,Geng Liu 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.10

An improved nonlinear elastic-damping contact force model, based on accounting for the axial dimension of bearing and journal, energydissipation during contact process and the nonlinear power exponent from material, is established to evaluate the contact force ofrevolute joint with clearance. The friction effect was also determined using the modified Coulomb friction model. Numerical simulationwas carried out to discuss the influence of clearance size on the kinematic and dynamic characteristics of the planar slider-crank mechanism,which has a clearance joint between the connecting rod and slider. The numerical results point out that the existence of joint clearancecauses high peaks on the kinematic and dynamic system’s characteristics. Even if the clearance size is small, it also causes obvioushigh frequency shaking of the slider acceleration, joint reaction force and the crank moment.

Single-Phase Voltage-Fed Z-Source Matrix Converter

Fang, Xupeng,Liu, Jie Journal of International Conference on Electrical 2012 Journal of international Conference on Electrical Vol.1 No.2

This paper proposes a novel single-phase ac-ac converter topology based on the Z-source concept. The converter provides buck-boost function and plays the role of frequency changer. Compared to the traditional ac-dc-ac converter, it uses fewer devices, realizes direct ac-ac power conversion, and has a simpler circuit structure, so as to have higher efficiency and better circuit characteristics. Compared to the traditional matrix converter, it provides a wider voltage regulation range. The circuit topology, operating principle, control method and simulation results are given in this paper, and the rationality and feasibility is verified.

3',4',5',5,7-Pentamethoxyflavone Sensitizes Cisplatin-Resistant A549 Cells to Cisplatin by Inhibition of Nrf2 Pathway

Xiangyu Hou,Xupeng Bai,Xiaoli Gou,Hang Zeng,Chen Xia,Wei Zhuang,Xinmeng Chen,Zhongxiang Zhao,Min Huang,Jing Jin 한국분자세포생물학회 2015 Molecules and cells Vol.38 No.5

Nuclear factor erythroid 2-related factor 2 (Nrf2) is an important redox-sensitive transcription factor that regulates the expression of several cytoprotective genes. More recently, genetic analyses of human tumors have indicated that Nrf2 may cause resistance to chemotherapy. In this study, we found that the expression levels of Nrf2 and its target genes GCLC, HO-1, NQO1 were significantly higher in cisplatinresistant A549 (A549/CDDP) cells than those in A549 cells, and this resistance was partially reversed by Nrf2 siRNA. 3',4',5',5,7-Pentamethoxyflavone (PMF), a natural flavonoid extracted from Rutaceae plants, sensitized A549/CDDP to CDDP and substantially induced apoptosis compared with that of CDDP alone treated group, and this reversal effect decreased when Nrf2 was downregulated by siRNA. Mechanistically, PMF reduced Nrf2 expression leading to a reduction of Nrf2 downstream genes, and in contrast, this effect was decreased by blocking Nrf2 with siRNA. Taken together, these results demonstrated that PMF could be used as an effective adjuvant sensitizer to increase the efficacy of chemotherapeutic drugs by downregulating Nrf2 signaling pathway.

Dynamic and motion consistency analysis for a planar parallel mechanism with revolute dry clearance joints

Bicai Xu,Xupeng Wang,Xiaomin Ji,Ruiting Tong,Yanmin Xue 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.7

The aim of the research was to introduce a methodology for dynamic response and motion consistency research on multibody system with multiple revolute clearance joints. An improved impact force model and a modified friction force model were introduced to evaluate the effects of impact and friction in clearance joints. A planar parallel mechanism which has two clearance joints in the left wing and the right wing was also used as an example. From the results based on different conditions, clearance has slight influence on the angular displacement and angular velocity, but obvious effect on angular acceleration. And with same clearance values of left wing and right wing, the motion consistency of the parallel mechanism is very good, which means the dynamic response of two wings is almost symmetrical. When the two clearance joints have different clearance values, the motion consistency and relative error between two wings are much obvious, especially the angular acceleration.

Luteimonas dalianensis sp. nov., an Obligate Marine Bacterium Isolated from Seawater

Yanjuan Xin,Xupeng Cao,Peichun Wu,Song Xue 한국미생물학회 2014 The journal of microbiology Vol.52 No.9

A marine bacterial strain, designated OB44-3T, was isolatedfrom a crude oil-contaminated seawater sample collectednear Dalian Bay, China. Cells of strain OB44-3T were Gramnegative,aerobic, rod-shaped, and oxidase- and catalasepositive. The major fatty acids were branched-chain saturatediso-C15:0 (27.9%) and unsaturated iso-C17:1 ω9c (14.8%). The DNA G+C content was 64.6 mol%. Phylogenetic analysisbased on the 16S rRNA gene sequence indicated thatstrain OB44-3T was a member of the genus Luteimonas (95–96% 16S rRNA gene sequence similarity); its closest neighborswere the type strains of Luteimonas terricola (96% sequencesimilarity), Luteimonas mephitis (96%), and Luteimonaslutimaris (96%). On the basis of phenotypic, chemotaxonomic,and phylogenetic distinctiveness, strain OB44-3Twas considered to represent a novel species of the genusLuteimonas. The name Luteimonas dalianensis sp. nov. isproposed, with strain OB44-3T (=CGMCC 1.12191T =JCM18136T) as the type strain.