New PWM Technique for Two-Phase Brushless DC Motor Drives

Lin, Hai,Kwon, Byung-Il The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.5

A new PWM technique for a two-phase BLDC motor fed by a two-phase eight-switch inverter is proposed in this paper. It is well known that a two-phase eight-switch inverter can significantly improve power output compared with a two-phase six-switch inverter in a two-phase motor drive. To drive the two-phase BLDC motor simply and effectively, two normal PWM strategies are investigated to manage speed regulation. However, under the conditions of low speed and light load, especially during the braking process, the current in a short time of one period is near zero, which is a discontinuous waveform every half period. To solve it, a novel PWM technique is investigated to improve the operational performance of normal technique. Using the new PWM scheme, the current continues every half period and the braking performance is improved. The effectiveness of the proposed PWM method is verified through the experiments.

Space-vector PWM Techniques for a Two-Phase Permanent Magnet Synchronous Motor Considering a Reduction in Switching Losses

Lin, Hai,Zhao, Fei,Kwon, Byung-il The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.3

Two PWM techniques using space vector pulse-width modulation (SVPWM) are proposed for a two-phase permanent magnet synchronous motor (PMSM) driven by a two-phase eight-switch inverter. A two-phase motor with two symmetric stator windings is usually driven by a two-phase four-, six-, or eight-switch inverter. Compared with a four- and six-switch inverter, a two-phase eight-switch inverter can achieve larger power output. For two-phase motor drives, the SVPWM technique achieves more efficient DC bus voltage utilization and less harmonic distortion of the output voltage. For a two-phase PMSM fed by a two-phase eight-switch inverter under a normal SVPWM scheme, each of the eight PWM trigger signals for the inverter have to be changed twice in a cycle, causing a higher PWM frequency. Based on the normal SVPWM scheme, two effective SVPWM schemes are investigated in order to reduce the PWM frequency by rearranging four comparison values, while achieving the same function as the normal PWM scheme. A detailed explanation of the normal and two proposed SVPWM schemes is illustrated in the paper. The experimental results demonstrate that the proposed schemes achieve a better steady performance with lower switching losses compared with the normal scheme.

An Improved Flux Observer for Sensorless Permanent Magnet Synchronous Motor Drives with Parameter Identification

Lin, Hai,Hwang, Kyu-Yun,Kwon, Byung-Il The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.3

This paper investigates an improved stator flux linkage observer for sensorless permanent magnet synchronous motor (PMSM) drives using a voltage-based flux linkage model and an adaptive sliding mode variable structure. We propose a new observer design that employs an improved sliding mode reaching law to achieve better estimation accuracy. The design includes two models and two adaptive estimating laws, and we illustrate that the design is stable using the Popov hyper-stability theory. Simulation and experimental results demonstrate that the proposed estimator accurately calculates the speed, the stator flux linkage, and the resistance while overcoming the shortcomings of traditional estimators.

Association of Cyclin D1 Variants with Head and Neck Cancer Susceptibility: Evidence from a Meta-analysis

Lin, Hai,Fang, Lian,Lin, Dong Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.14

Whether cyclin D1 (CCND1) gene variants increase susceptibility to head and neck cancer (HNC) is undetermined. Therefore, we performed the present meta-analysis to systematically assess any possible association between CCND1 variants (G870A and G1722C) and HNC risk. Seventeen studies for CCND1 G870A and three studies for CCND1 G1722C were included. Overall, CCND1 polymorphisms (G870A and G1722C) had no association with increased HNC risk (p>0.05). In the subgroup analysis by smoking status, significantly increased HNC risk was found among smokers under allele contrast, homozygous comparison and recessive models (p<0.05), smoking carriers of A allele and AA genotype appearing at elevated risk. In conclusion, while there was overall a lack of any association between CCND1 polymorphisms (G870A and G1722C) and HNC risk, smokers carrying the A allele and AA genotype of the CCND1 G870A polymorphism may be susceptible to HNC development.

Digital Implementation of PWM Techniques for Two-phase Eight-switch Inverter fed Brushless DC Motor Drives

Lin, Hai,You, Yong-Min,Cheon, Sung-Rock,Kwon, Byung-Il The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.2

This paper reports an investigation of pulse width modulation (PWM) techniques for two-phase brushless DC (BLDC) motors fed by a two-phase eight-switch inverter in a fan application. The three-phase BLDC motor is widely applied in industry; however, a lower-cost two-phase BLDC motor and drive circuit has been greatly in demand in recent years. In this paper, we introduce a mathematical model of the two-phase BLDC motor with sinusoidal back electromotive forces (EMFs) based on traditional three-phase BLDC motors. To simplify the drive algorithm and speed up its application, we analyze the principle of block commutation for a two-phase BLDC motor drive in the 180-electrical-degree conduction mode, and we further propose five PWM schemes to improve the commutation performance of the two-phase BLDC drive. The effectiveness of the proposed PWM methods is verified through experiments.

An Innovative Approach for Regular Expression Matching Based on NoC Architecture

Cui Linhai 보안공학연구지원센터 2014 International Journal of Smart Home Vol.8 No.1

Method of Voltage Sag Causes Based on Bidirectional LSTM and Attention Mechanism

Hong Wang,Linhai Qi,Yongshuo Ma,Jiehui Jia,Zhicong Zheng 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.3

The voltage sags’ cause recognition is the basis for formulating governance plans and clarifying liabilities for accidents. For voltage sag cause recognition methods based on physical characteristics, new challenges are presented in terms of accuracy, adaptability and algorithm efciency. Deep learning is a method based on characterizing and learning data. The efcient mechanism of autonomous feature learning can efectively overcome the problems of information loss and generalization ability based on existing physical property methods. The long short-term memory network (LSTM) has the characteristics of memory and can better learn the data characteristics with time series characteristics. Bidirectional LSTM can consider historical information and future information compared with standard LSTM, and has more processing for time series data. While using the attention mechanism can highlight the key infuencing factors in the time series and improve the recognition accuracy of the model. For the transient sag time series data, this paper proposes a multi-layer structure based on bidirectional LSTM and attention mechanism to classifcation recognition. The experiment uses simulation data and measured data to prove that the model has good recognition ability and good anti-noise performance in the recognition of voltage sag causes, and can be reliably applied in practical engineering.

Sp1-Induced SETDB1 Overexpression Transcriptionally Inhibits HPGD in a β-Catenin-Dependent Manner and Promotes the Proliferation and Metastasis of Gastric Cancer

Fan, Yaguan,Yang, Libo,Ren, Yi,Wu, Yunhua,Li, Linhai,Li, Lihua The Korean Gastric Cancer Association 2022 Journal of gastric cancer Vol.22 No.-

Purpose: Gastric cancer (GC) has high morbidity and mortality, the cure rate of surgical treatment and drug chemotherapy is not ideal. Therefore, development of new treatment strategies is necessary. We aimed to identify the mechanism underlying Sp1 regulation of GC progression. Methods and Methods: The levels of Sp1, β-catenin, SET domain bifurcated 1 (SETDB1), and 15-hydroxyprostaglandin dehydrogenase (HPGD) were detected by quantitative reverse transcription polymerase chain reaction and western blot analysis. The targets of SETDB1 were predicted by AnimalTFDB, and dual-luciferase reporter assay was used for confirming the combination of Sp1, β-catenin, and SETDB1. HGC27 or AGS cells (1×10⁶ cells/mouse) were injected into mice via the caudal vein for GC model establishment. The level of Ki67 was detected using immunohistochemistry, and hematoxylin and eosin staining was performed for evaluating tumor metastasis in mice with GC. Results: HPGD was inhibited, while the protein levels of Sp1, β-catenin, and SETDB1 were up-regulated in GC tissues and cell lines. HPGD overexpression or SETDB1 silencing inhibited the proliferation, invasion, and migration of GC cells, and Sp1 regulated the proliferation, invasion, and migration of GC cells in a β-catenin-dependent manner. Furthermore, HPGD served as a target of SETDB1, and it was negatively regulated by SETDB1; additionally, Sp1 and β-catenin bound to the SETDB1 promoter and negatively regulated HPGD expression. We proved that Sp1 regulated GC progression via the SETDB1/HPGD axis. Conclusions: Our findings revealed that Sp1 transcriptionally inhibited HPGD via SETDB1 in a β-catenin-dependent manner and promoted the proliferation and metastasis of GC cells.

Crystal structure of the nicotinamidase/pyrazinamidase PncA from <i>Bacillus subtilis</i>

Shang, Fei,Chen, Jinli,Wang, Lulu,Jin, Liming,Zou, Linhai,Bu, Tingting,Dong, Yuesheng,Ha, Nam-Chul,Nam, Ki Hyun,Quan, Chunshan,Xu, Yongbin Elsevier 2018 Biochemical and biophysical research communication Vol.503 No.4

<P><B>Abstract</B></P> <P>The nicotinamidase/pyrazinamidase PncA is a member of a large family of hydrolase enzymes that catalyze the deamination of nicotinamide to nicotinic acid. PncA also functions as a pyrazinamidase in a wide variety of eubacteria and is an essential coenzyme in many cellular redox reactions in living systems. We report the crystal structure of substrate-free PncA from <I>Bacillus subtilis</I> (BsPncA) at 2.0 Å resolution to improve our understanding of the PncA family. The structure of BsPncA consists of an α/β domain and a subdomain. The subdomain of BsPncA has a different conformation than that of PncA enzymes from other organisms. The B-factor analysis revealed a rigid structure of the α/β domain, while the subdomain is highly flexible. Both dimers and tetramers were observed in BsPncA protein crystals, but only dimers were observed in solution. Our results provide useful information that will further enhance our understanding of the molecular functions of PncA family members.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Crystal structure of <I>B. Subtilis</I> PncA consists of an α/β domain and a subdomain. </LI> <LI> The metal-binding site of BsPncA is located at the bottom of a large cavity between the core and the subdomain. </LI> <LI> Zinc ion is pentahedrally coordinated within several highly conserved amino acid residues and one water molecule. </LI> <LI> Both dimers and tetramers were observed in BsPncA protein crystals, but only dimers were observed in solution. </LI> </UL> </P>

Implication of the chemical index of alteration as a paleoclimatic perturbation indicator: an example from the lower Neoproterozoic strata of Aksu, Xinjiang, NW China

Haifeng Ding,Dongsheng Ma,Chunyan Yao,Qizhong Lin,Linhai Jing 한국지질과학협의회 2016 Geosciences Journal Vol.20 No.1

The Neoproterozoic successions in the Aksu region, NW China, which lies unconformably on the Precambrian Aksu Group basement, comprises the Qiaoenbrak, Yuermeinak, Sugetbrak, and Chigebrak formations (from bottom to top). The two lowermost units include two distinct glacial diamictites, which indicate distinct episodes of glaciations. We report the major and trace element (including rare earth element) data for the Qiaoenbrak, Yuermeinak, and Sugetbrak formations to identify the paleoclimatic perturbations. The chemical index of alteration (CIA) values show variations from Qiaoenbrak to Yuermeinak, then Sugetbrak formations. The diamictites have relatively lower chemical index of alteration values (45.23–59.64) than inter-, post- and non-glacial sediments (48.28–66.96). This result supported the condition that the diamictites underwent relatively weak chemical weathering from a dry-cold sedimentary environment, which is associated with the sedimentary facies description. The lower Neoproterozoic successions recoded at least two glaciations, one is Qiaoenbrak glaciation and the other is Yuermeinak glaciation.