HGO and neural network based integral sliding mode control for PMSMs with uncertainty

Ge, Yang,Yang, Lihui,Ma, Xikui The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.5

This paper proposes an integral sliding mode control that integrates a high-gain observer (HGO) and a radial basis function neural network (RBFNN) for a permanent magnet synchronous motor (PMSM) with uncertainty. Since the second-order motion equation of the PMSM is used to improve the control performance, the speed derivative, which cannot be measured directly, is required. Thus, the HGO is designed to estimate the unknown state (speed derivative). In addition, the RBFNN is designed to approximate the compounded disturbance including the lumped disturbance of system and the HGO error effect. Unlike previous studies, the output of the RBFNN is compensated by both the controller and the HGO to improve the system robustness and observer accuracy. The sliding function and the HGO error are both taken into account in the RBFNN to explicitly guarantee the stability of the whole system. To demonstrate the superiority of the proposed method, comparative simulations and experiments were carried out in different cases.

Effects of metakaolin and PVA fiber on the compressive strength of shotcrete under different curing conditions

Yang Guoqiang,Guo Gang,Wang Lihui,Wang Changchang,Sun Tao 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.3

In this paper, wet shotcrete spraying experiments were carried out under different temperature and humidity conditions withdifferent dosage of metakaolin (MK) and different length of polyvinyl alcohol fiber (PVA fiber). And the influence of differentcontent of metakaolin and different length of PVA fiber on the compressive strength of tidal shotcrete under different curingconditions was explored. The results show that the compressive strength of shotcrete increases first and then decreases withthe increase of MK content and PVA fiber length under the curing condition of normal temperature and constant humidity. However, under the curing condition of high temperature and humidity, the compressive strength of shotcrete tended toincrease with the increase of MK content. Under the condition of high temperature and high humidity curing, the compressivestrength of shotcrete is lower than that of shotcrete under normal temperature and constant humidity curing. This study canprovide theoretical support for the application of sprayed concrete in different environments.

Characterization and development of EST-SSR markers to study the genetic diversity and populations analysis of Jerusalem artichoke (Helianthus tuberosus L.)

Shipeng Yang,Qiwen Zhong,Jie Tian,Lihui Wang,Mengliang Zhao,Li Li,Xuemei Sun 한국유전학회 2018 Genes & Genomics Vol.40 No.10

In recent years, Jerusalem artichoke has received widespread attention as a novel source of sugar, biofuel, and animal feed. Currently, only few gDNA-SSRs derived from sunflower were verified in the Jerusalem artichoke; therefore, it is particularly important to develop SSR primer markers that belonged to Jerusalem artichoke resources. Using EST data to develop EST-SSR markers is simple and effective. In order to understand the general characteristics of SSR markers in Jerusalem artichoke EST sequences and accelerate the use of SSR markers in Jerusalem artichoke research. This study used 40,370 sequenced unigene fragments and MISA software to identify SSR loci. The 48 pairs of EST-SSR primers assessed for the identification of 45 varieties of Jerusalem artichoke. Cluster, genetic diversity parameters and AMOVA analysis was conducted using the genetic similarity coefficient, revealing genetic differences between 48 genetic material. A total of 1204 SSR loci were identified with 13 different types of repeats, distributed among 1020 EST sequences, of which trinucleotide repeats were the most common, accounting for 38.21% of the total SSR loci. Among the 44 repeat motifs, AG/CT, AAG/ CTT, and ATC/ATG motifs had the highest frequencies, accounting for 22.45, 14.71, and 7.84% of all motifs, respectively. From these sequences, 48 pairs of EST-SSR primers were designed, and 22 primer pairs for loci with high polymorphism were selected to analyze the genetic diversity of 45 Jerusalem artichoke germplasm sources. The results indicated that the variation range of the effective number of alleles for 22 primers ranged between 1.7502 and 4.5660. The Shannon’s information index ranged between 0.6200 and 1.6423. The variation range of PIC ranged between 0.3121 and 0.6662 with an average of 0.5184. Cluster analysis was conducted using the genetic similarity coefficient, revealing significant genetic differences between Asian and European genetic material. Cluster analysis revealed a relationship between the genotypes and geographic origins of the Jerusalem artichoke. The results of AMOVA as well as the genetic identity and genetic distance in the Jerusalem artichoke population showed that there presented certain genetic heterogeneity in Jerusalem artichoke genetic structure of 45 samples from seven different geographic populations. The Jerusalem artichoke EST-SSR marker system established in this study provides an effective molecular marker system for future research focused on Jerusalem artichoke genetic diversity and the breeding of new varieties.

Nanotherapeutics with immunoregulatory functions for the treatment of bacterial infection

Dongliang Yang,Meng Ding,Yanni Song,Yanling Hu,Weijun Xiu,Lihui Yuwen,Yannan Xie,Yingnan Song,Jinjun Shao,Xuejiao Song,Heng Dong 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00

The advent of drug-resistant pathogens results in the occurrence of stubborn bacterial infections that cannot betreated with traditional antibiotics. Antibacterial immunotherapy by reviving or activating the body’s immune systemto eliminate pathogenic bacteria has confrmed promising therapeutic strategies in controlling bacterial infections. Subsequent studies found that antimicrobial immunotherapy has its own benefts and limitations, such as avoidingrecurrence of infection and autoimmunity-induced side efects. Current studies indicate that the various antibacterialtherapeutic strategies inducing immune regulation can achieve superior therapeutic efcacy compared with mono therapy alone. Therefore, summarizing the recent advances in nanomedicine with immunomodulatory functionsfor combating bacterial infections is necessary. Herein, we briefy introduce the crisis caused by drug-resistantbacteria and the opportunity for antibacterial immunotherapy. Then, immune-involved multimodal antibacterialtherapy for the treatment of infectious diseases was systematically summarized. Finally, the prospects and challengesof immune-involved combinational therapy are discussed.

A Precise Fault Location Method Independent of Line Parameters Based on Positive and Negative Sequence Fault Components

Zhao Lihui,Zhu Jingwei,Yang Hongzhe 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.6

A precise and robust fault location method based on positive and negative sequence fault components for transmission lines is proposed, with synchro phasor data. This method utilizes the information of current and voltage synchronously measured by the phasor measurement units at both ends of the line, and does not require line parameters. The line parameters are not constant due to load and weather conditions and other factors, which aff ects the accuracy of most ranging algorithms relying on line parameters. For asymmetric faults, positive sequence and negative sequence fault components are used to locate the fault location, and for symmetric faults, positive sequence fault components are used to locate the fault location. The method is added to the synchronization data self-diagnosis procedure to further improve the accuracy of positioning. Then, the paper presents the method derivation and the simulation results by PSCAD/EMTDC under diff erent path resistance, fault type, fault inception angle, load current, and line transposition, measurement error. The simulation results prove that the method effi ciently and accurately determines the fault location.

Brain Tumor Segmentation Using Geodesic Region-based Level Set without Re-initialization

Hongzhe Yang,Lihui Zhao,Songyuan Tang 보안공학연구지원센터(IJSIP) 2014 International Journal of Signal Processing, Image Vol.7 No.1

EXISTENCE AND GLOBALLY EXPONENTIAL STABILITY OF PERIODIC SOLUTION OF IMPULSIVE FUZZY BAM NEURAL NETWORKS WITH DISTRIBUTED DELAYS AND VARIABLE COEFFICIENTS

Zhang, Qianhong,Yang, Lihui,Liao, Daixi The Korean Society for Computational and Applied M 2012 Journal of applied mathematics & informatics Vol.30 No.5

In this paper, a class of impulsive fuzzy bi-directional associative memory (BAM) neural networks with distributed delays and variable coefficients are considered. Using Lyapunov functional method and fixed point theorem, we derived some sufficient conditions for the existence and globally exponential stability of unique periodic solution of the networks. The results obtained are new and extend the previous known results. In addition, an example is given to show the effectiveness of our results obtained.

Research on the Effect of Flow Stress Calculation on Aluminum Alloy Sheet Deformation Behavior Based on Warm Bulging Test

Gaoshen Cai,Lihui Lang,Kangning Liu,Sergei Alexandrov,Dongxing Zhang,Xiying Yang,Chan Guo 대한금속·재료학회 2015 METALS AND MATERIALS International Vol.21 No.2

Confirmation of material properties is an important research area for determining metals deformation behavior. In order to research the effect of flow stress calculation on aluminum alloy sheet deformation behavior,warm sheet bulging test was carried out to obtain bulging height - pressure curves with different bulging heightsand diameters in this study. Based on the bulging parts profile data measured by three coordinate measuringmachine, the least square circle fitting radius were fitted. Existing theoretical models for radius of curvatureand thickness were compared and best models were selected to obtain more accurate stress - strain curves bycalculating the bulging flow stress. Combination model was used to calculate the bulging height - pressurecurves obtained by bulging test and the stress-strain curves with different temperatures and pressure rates wereobtained. A monotonous increasing function was resulted which is of great significance in the area of formabilityand deformation behavior of warm sheet hydroforming.

EXISTENCE AND GLOBALLY EXPONENTIAL STABILITY OF PERIODIC SOLUTION OF IMPULSIVE FUZZY BAM NEURAL NETWORKS WITH DISTRIBUTED DELAYS AND VARIABLE COEFFICIENTS

Qianhong Zhang,Lihui Yang,Daixi Liao 한국전산응용수학회 2012 Journal of applied mathematics & informatics Vol.30 No.5

In this paper, a class of impulsive fuzzy bi-directional associative memory (BAM) neural networks with distributed delays and variable coefficients are considered. Using Lyapunov functional method and fixed point theorem, we derived some sufficient conditions for the existence and globally exponential stability of unique periodic solution of the networks. The results obtained are new and extend the previous known results. In addition,an example is given to show the effectiveness of our results obtained.

Analysis of Electromagnetic Immunity Experiment for Field Installation of Intelligent Equipment in Substation

Ji Jianfei,Wang Lihui,Yuan Yubo,Yang Yifei 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.1

With the increase of voltage level and more and more secondary devices are located in field, the secondary circuit of substation is in a strong electromagnetic environment. Because the secondary circuit is affected by the interference of switch operations, there are many trip accidents happened in substations without any fault in recently years, which constitutes a serious threat to the power network and harms the safe operation of the electric power system. It is of great theoretical significance and practical value to study the Electromagnetic Compatibility problem of the transformer substations substation secondary circuit. In this paper, the abnormal phenomenon of one 110kV intelligent substation merging unit is described. And the reason of the abnormal phenomenon is analyzed. Firstly, the Electromagnetic Compatibility experiments specified by the IEC61000-4 standard are carried out. Furthermore, to verify the anti–interference performance of the merging unit, the Electromagnetic Compatibility experiments above the standard are carried out. The structure of merging unit is improved until the merging unit operates normally. Secondly, to quantitatively analyze the disturbance strength, the electromagnetic disturbance signal is recorded, and the characteristics of amplitude and time-frequency of the recorded signal are analyzed. Thirdly, the characteristics of the logged signal are compared to the IEC61000-4 standard. Finally, this paper puts forward some suggestions about improving the Electromagnetic Compatibility performance of merging unit.