Self-adjusting strategy based on rotating injection for sensorless control of high-power PMSM drives

Xiaofan Wang,Xiaochun Fang,Zhi Wang,Zhihong Zhong,Yizhi Wang,Fei Lin,Zhongping Yang 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

As a sensorless control method suitable for permanent magnet synchronous motor (PMSM) at lowspeed, rotating high-frequency injection method will face some special problems in high power applications. On the one hand, the low switching frequency limits the injected signal frequency, which is very close to the fundamental frequency. On the other hand, under heavy load conditions, the fundamental current amplitude is several hundred times of the negative sequence current. This will result in difficulty in signal extraction. In this paper, current spectrum is analyzed quantitatively based on the parameters of PMSM drive for rail vehicles, which illustrates the limitations of conventional bandpass filters. A method based on self-adjusting filter is proposed. The negative sequence current is successfully extracted, and the precise rotor position is obtained under the condition of variable speed and variable load. Based on a fullscale test platform the effectiveness of the proposed method is proved.

Experimental Study on Dynamic Water Grouting of Modified Water-Soluble Polyurethane

Xiaofan Liu,Junguang Wang,Kun Huang,Fengyun Li 대한토목학회 2019 KSCE Journal of Civil Engineering Vol.23 No.9

In underground project, water inrush disaster often occurs, resulting in a large number of casualties and economic losses. To solve these problems, grouting is one of the main techniques for controlling water inrush. At present, the research results on the treatment of water inrush by grouting are based on anhydrous or hydrostatic grouting. However, the study of dynamic water grouting is relatively few and the grouting materials are a little bit. In this paper, water-soluble polyurethane was selected as grouting material, modified by adding hydroxypropyl methyl cellulose, and the bond strength and microstructure change before and after modification are studied via bond strength experiment and microscopic observation. In addition, the WPU (water-soluble polyurethane) diffusion regularity of dynamic water grouting is studied by indoor flat grouting test. The research also adopts the Bingham fluid model according to the slurry characteristics to derive the grouting diffusion radius. The results show that the compactness of HPMC (hydroxypropyl methyl cellulose)-WPU is improved, the heterogeneity is reduced by 50.4%, and the bonding strength is increased by 153%. Therefore, the anti-scour ability of the HPMC-WPU is enhanced. The deviation of the WPU in the X-axis diffusion radius is 7.7 cm, and the HPMC-WPU is 4.39 cm. What’s more, the formula of grouting diffusion radius is derived. By comparing the formula with experiment results, the deviation is less than 15%, therefore, the formula has the significance of guiding engineering practice.

Screening and Characterization of an Aerobic Nitrifying-denitrifying Bacterium from Activated Sludge

Xiaofan Qiu,Tianwen Wang,Xiaomin Zhong,Guocheng Du,Jian Chen 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.2

Taking advantage of the good biocompatibility and high efficiency of nitrogen removal with microbes,nitrifying and denitrifying bacteria, are becoming increasingly more widely used for wastewater treatment and prevention of eutrophication. In this research, an aerobic nitrifying-denitrifying bacterium was successfully screened from activated sludge and identified as Pseudomonas sp. (CCTCC No M2010209) by the 16S rDNA sequence. The activity verification confirmed its nitrifying-denitrifying capability of removing ammonium, nitrate and nitrite nitrogen. The types of carbon sources and carbon-nitrogen ratio greatly influenced the removal efficiency of NH4+-N and NO3−-N. When the initial concentrations of NH4+-N and NO3−-N in synthetic wastewater were less than 70 and 50mg/L, the nitrogen removal rates reached 94 and 90% in 9 h, respectively. Preliminary comparisons of nitrogen removal capacity between this isolate and other commercial preparations in the treatment of synthetic wastewater revealed its promising potential to be used in the actual wastewater treatment.

The FvCYP714C2 gene plays an important role in gibberellin synthesis in the woodland strawberry

Xiaofan Guo,Zhibing Xie,Yang Zhang,Shouming Wang 한국유전학회 2021 Genes & Genomics Vol.43 No.1

Background Fragaria vesca, the woodland strawberry, is a diploid relative of the cultivated strawberry. A GA-defcient mutant was found in ethyl methanesulfonate (EMS)-mutagenized lines of the Fragaria vesca accession ‘Yellow Wonder’. Objective CYP714C2 was found to be diferentially expressed using RNA-seq analysis. It is necessary to identify the function of this gene. Methods In order to identify the function of this gene, it was cloned and transformed into Arabidopsis thaliana. Results The DNA sequence of CYP714C2 was found to be 1940 bp in length, with an open reading frame (ORF) of 1539 bp that is predicted to encode a protein of 512 amino acids. The hydrophilicity of this protein is low and it is unstable. The highest relative expression of FvCYP714C2 was found in the leaves, followed by the pedicels, and low expression levels were found in the other tissues examined. Constitutive expression of FvCYP714C2 signifcantly promoted the growth of transgenic A. thaliana plants; transgenic Arabidopsis plants grew faster and grew well than wild type Col-0 plants. GA1+3 contents of the genetically modifed Arabidopsis lines were signifcantly higher than that in the wild type. Conclusion We conclude that FvCYP714C2 is a gene that functions in the gibberellin biosynthesis pathway in strawberry.

“One-Time” versus Staged Multivessel Intervention in Intermediate to Very High-Risk Patients with Non-ST-Segment Elevation Acute Coronary Syndromes

Xiaofan Yu,Yi Li,Qiancheng Wang,Ming Liang,Kai Xu,Yaling Han 대한심장학회 2016 Korean Circulation Journal Vol.46 No.6

Background and Objectives: To compare clinical outcomes of staged versus “one-time” percutaneous coronary intervention (PCI) in intermediate to very high-risk patients with non–ST-segment elevation acute coronary syndromes (NSTE-ACS) and multivessel coronary disease (MVD). Subjects and Methods: 1531 NSTE-ACS patients with multivessel PCI and meeting the criteria of intermediate to very high risk were screened from a prospectively registered database obtained from General Hospital of Shenyang Military Region between 2008 and 2012. They were categorized into “one-time” PCI (n=859) and staged PCI (n=672) according to intervention strategy. The primary outcomes included a 3-year major adverse cardiac event (MACE), a composite of cardiac death, myocardial infarction (MI), and target vessel revascularization. Results: At 3 years, no significant differences in MACE (20.8% vs. 19.7%, p=0.608) and cardiac death/MI (7.1% vs. 9.1%, p=0.129) were observed between the two groups. After propensity score matching, there was no statistical significance in MACE (18.9% vs. 21.8%, p=0.249); whereas cardiac death/MI was significantly lower in the staged PCI group (7.0% vs.11.1%, p=0.033). Ninety-day landmark analysis showed that the staged PCI group had a lower 90-day incidence of MACE (1.2% vs. 3.3%, p= 0.037) and cardiac death/MI (0.7% vs. 2.6%, p=0.031). For the 90-day to 3-year follow-up period, the incidences of MACE (17.9% vs. 19.1%, p=0.641) and cardiac death/MI (6.3% vs. 8.7%, p=0.191) were similar in both groups. Conclusion: In intermediate- to very high-risk NSTE-ACS patients with MVD, staged PCI is superior to “one-time” PCI in terms of cardiac death/MI.

A potential red-emitting phosphor with high color-purity for near-UV light emitting diodes

Zhengliang Wang,Yaling Zhang,Li Xiong,Xiaofan Li,Junming Guo,Menglian Gong 한국물리학회 2012 Current Applied Physics Vol.12 No.4

New red tungstates phosphors, Na5La1-xLnx(WO4)4 (Ln = Eu, Sm) and Na5Eu1-xSmx(WO4)4, were prepared by solid-state reaction technique. And their structure and photo-luminescent properties were investigated. The introduction of Sm3+ broadened the excitation band around 400 nm of the phosphors,and strengthened the red emission. And the possible energy transfer process from Sm3þ to Eu3+ is discussed. The single red LED was fabricated by combining InGaN chip with Na5Eu0.94Sm0.06(WO4)4 as red phosphor, intense red light can be observed by naked eyes. Then the phosphor Na5Eu0.94Sm0.06(WO4)4 may be a good candidate for red component of near-UV InGaN-based W-LEDs,because of efficient red-emitting with broadened absorption around 400 nm and appropriate CIE chromaticity coordinates (x = 0.65, y = 0.34).

Modeling of SACK-based Fast Retransmission and Recovery

Zhiming Wang,Xiaoping Zeng,Xiaofan Jia,Xue Liu,Li Chen 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.6

Selective acknowledgment (SACK)-based retransmission and recovery mechanism has been implemented in most of current transmission control protocol (TCP) stacks. A new SACK-based loss recovery algorithm is defined in RFC6675 under standard track. Existing models in literatures on modeling TCP SACK, which usually use SACK-based retransmission and recovery mechanism, is no longer accurate for two reasons: 1) they ignore transmission of new packets before retransmission of the last loss; 2) they are based on the strategy that pipe is decreased by 2 upon receipt of a partial ACK, where pipe is the estimated number of outstanding packets. This paper develops a new method to derive the expected number of new packets transmitted between retransmission of the first loss and the last, proposes a model that estimates the expected number of packets transmitted during fast retransmission and recovery phase (FRR) and the corresponding expected duration based on RFC6675. The numerical results show that the proposed model can accurately estimate the expected number of packets transmitted during FRR and the corresponding expected duration based on RFC6675.

Distribution of Cadherin in the Parahippocampal Area of Developing Domestic Chicken Embryos

He Zhou,XiaoFan Wang,Juntang Lin,Ze Zhao,Cheng Chang 한국뇌신경과학회 2020 Experimental Neurobiology Vol.29 No.1

Hippocampal formation is important in spatial learning and memory. Members of the cadherin superfamily are observed in the neural system with diverse spatial and temporal expression patterns and are involved in many biological processes. To date, the avian hippocampal formation is not well understood. In this study, we examined the expression of cadherin mRNA in chicken and mouse brains to investigate the morphological and cytoarchitectural bases of hippocampal formation. Profiles of the spatiotemporal expression of cadherin mRNAs in the developing chicken embryonic parahippocampal area (APH) are provided, and layer-specific expression and spatiotemporal expression were observed in different subdivisions of the APH. That fact that some cadherins (Cdh2, Cdh8, Pcdh8 and Pcdh10) showed conserved regional expression both in the hippocampus and entorhinal cortex of mice and the hippocampal formation of chickens partially confirmed the structural homology proposed by previous scientists. This study indicates that some cadherins can be used as special markers of the avian hippocampal formation.

Numerical calculation and optimization designs in engine cooling water pump

Li Wei,Wang Chuan,Shi Weidong,Zhao Xiaofan,Yang Yongfei,Pei Bing 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.5

The cavitation damage in the Engine cooling water pump (ECWP) is the key factor that shortens the lifespan of automobile cooling systems, and causes vibration and noise. To improve cavitation performance and external characteristics of ECWP, three optimized models were designed on the basis of WP7 diesel ECWP. The whole flow fields in three models and the prototype pump were numerically simulated, employing the time averaged Navier-Stokes equation, the standard k-ε turbulent model and Zwart-Gerber-Belamri multiphase flow model by ANSYS-CFX software. Pressure distribution, turbulent kinetic energy distribution, bubble volume fraction distribution, external characteristics and cavitation performance of the prototype pump and optimized models were compared and analyzed. The results show that the external characteristics and cavitation performance of the optimized models are significantly better than that in the prototype pump. Through decreasing the inlet blade angle and wrap angle, extending the blade to inlets and extending a certain inclination in the blade, shock loss in blade inlet was reduced and so, the performance of pump will be improved. The flow condition at blade inlet will also be improved greatly, which in turn improves cavitation performance. When reducing the quantity of blades, the excretion coefficient will drop, flow area of blade inlet becomes bigger, but head has a little drop. And the pump optimized by reducing the quantity of blades has the optimal cavitation performance among three optimized models. With the decrease of impeller diameter, the absolute pressure in the critical cavitation point becomes bigger, the inlet bubble volume fraction at the same absolute pressure increases while cavitation performance gets worse. The obtained numerical results were compared with the experimental ones, and the outcome showed the same tendency between the two along with acceptable error.

VCD

Liang Runpeng,Hua Jun,Wang Xiaofan 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10

In a complex network, communities are groups of nodes that are densely connected inside while sparsely connected to the outside. The study of such communities is crucial in exploring the structure of a network, especially when small communities form larger ones that in turn group together to build even larger ones, resulting in a hierarchy. Besides, fence-sitting nodes, nodes shared among different communities, are common in real networks. Although a large amount of network visualization tools are available, few could visualize the hierarchical community structure and fence-sitting nodes. Thus, we proposed visualization methods and accordingly developed a network visualization tool to dynamically uncover the hierarchical community structure and reveal fence-sitting nodes. Tests on a yeast network yielded satisfying results.