An Improved Flux Estimator for Gap Flux Orientation Control of DC-Excited Synchronous Machines

Yajun Xu,Jianguo Jiang 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.2

Flux estimation is a significant foundation of high-performance control for DC-excited synchronous motor. For almost all flux estimators, such as the flux estimator based on phase locked loop (PLL), DC drift causes fluctuations in flux magnitude. Furthermore, significant dynamic error may be introduced at transient conditions. To overcome these problems, this paper proposes an improved flux estimator for the PLL-based algorithm. Filters based on the generalized integrator are used to avoid flux fluctuation problems caused by the DC drift at the back electromotive force. Programmable low-pass filters are employed to improve the dynamic performance of the flux estimator, and the cutoff frequency of the filter is determined by the dynamic factor. The algorithm is verified by a 960V/1.6MW industrial prototype. Simulation and experimental results show that the proposed estimator can estimate the flux more accurately than the PLL-based algorithm in a cycloconverter-fed DC-excited synchronous machine vector control system.

An Improved Flux Estimator for Gap Flux Orientation Control of DC-Excited Synchronous Machines

Xu, Yajun,Jiang, Jianguo The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.2

Flux estimation is a significant foundation of high-performance control for DC-excited synchronous motor. For almost all flux estimators, such as the flux estimator based on phase locked loop (PLL), DC drift causes fluctuations in flux magnitude. Furthermore, significant dynamic error may be introduced at transient conditions. To overcome these problems, this paper proposes an improved flux estimator for the PLL-based algorithm. Filters based on the generalized integrator are used to avoid flux fluctuation problems caused by the DC drift at the back electromotive force. Programmable low-pass filters are employed to improve the dynamic performance of the flux estimator, and the cutoff frequency of the filter is determined by the dynamic factor. The algorithm is verified by a 960V/1.6MW industrial prototype. Simulation and experimental results show that the proposed estimator can estimate the flux more accurately than the PLL-based algorithm in a cycloconverter-fed DC-excited synchronous machine vector control system.

Structural characterization and applications of ITS2 from rice leaffolders Cnaphalocrocis medinalis and Marasmia patnalis (Lepidoptera: Pyralidae)

Yajun Yang,ZhihongWu,Xu-Song Zheng,Zhong-Xian Lu,Hong-Xing Xu 한국응용곤충학회 2017 Journal of Asia-Pacific Entomology Vol.20 No.2

Cnaphalocrocis medinalis and Marasmia patnalis are important rice insect pests in Asia and have similarmorphologic features and same feeding patterns. Understanding the molecular difference of the two leaffolders is helpful to their identification and clarification of their phylogenetic class in the Pyraloidea. In this study, we determined and analyzed the nucleotide sequences of nuclear rDNA internal transcribed spacer 2 (ITS2) in the two rice leaffolders from 9 populations (six C. medinalis populations collected from China, Philippine, Thailand, and Vietnam, and threeM. patnalis populations from Philippine, Thailand, and Vietnam) and compared interspecies variation of IST2 among different geographic populations and intraspecies variation of ITS2 from Pyraloidea. Phylogenetic trees were constructed on the two leaffolders and other Pyraloidea species using Maximum Parsimony method. Results showed that the ITS2 sequences differed in the two leaffolders. Compared to C. medinalis, ITS2 ofM. patnalis had small deletion at the sites of 41, 72, 81, 304 and an insertion at the site of 337. Interspecies variation results showed that three C. medinalis populations fromSoutheast Asia (VN, PH, and TH) arewith small divergence compared to NJ andHZ, and small divergencewas observed among threeM. patnalis populations (VN, PH, and TH). Intraspecies variation results showed that two leaffolderswere with close relationship compared to the other Pyraloidea. Phylogenetic trees showed that two leaffolderswere grouped togetherwithMaruca vitrata. These results indicated that the ITS2 sequences differed in the two leaffolders could potentially be used in the distinguishing of the two rice leaffolders and the determination on the phylogeny of species.

Developmental Effects of Dietary Nucleotides in Second-Generation Weaned Rats

Meihong Xu,Yi Ma,Linlin Xu,Yajun Xu,Yong Li 한국식품영양과학회 2013 Journal of medicinal food Vol.16 No.12

The aim of the present study was to evaluate dietary effects of dietary nucleotides (NTs) on developmental parameters in second-generation Sprague-Dawley rats. Experimental design was set up as six groups, including one control and five nucleotide administered groups, doses ranged from 0.01% to 1.28% nucleotides. First-generation (F0) rats were divided into two terms: (1) fed for 90-day study; (2) mated for offspring (F1). After weaning, each group of second-generation F1 rats was fed the control diet. Evaluating parameters were weight gain and food utilization ratios of rats, hematological and biochemical parameters, and organ pathology. The results showed that there was a greater weight gain and food utilization ratio in weaned rats (F0 and F1). Furthermore, weight gain and food utilization ratios were increased in the first 2 weeks of F1 male and the first week of F1 female rats. There were no significant changes in blood indicators of NT groups with the exception of decrease in aspartate aminotransferase and serum uric acid levels. Overall, it was demonstrated that NT supplements could promote the early growth and development at a 0.01% dose. Although NTs may have cumulative reproductive effects, they were safe even at a high-dose supplementation. Additionally, NT supplementation could promote restoration and optimize liver function.

Effects of SRBSDV-infected rice plants on the fitness of vector and non-vector rice planthoppers

Hong-Xing Xu,Hong-Xing Xu,Xu-Song Zheng,Yajun Yang,Jue-Feng Zhang Zhang,Zhong-Xian Lu 한국응용곤충학회 2016 Journal of Asia-Pacific Entomology Vol.19 No.3

Southern rice black-streaked dwarf virus (SRBSDV) is a new member of the genus Fijivirus and transmitted by whitebacked planthopper (WBPH), Sogatella furcifera (Horváth). The rice area affected by SRBSDV and the subsequent damages are increasing rapidly. In current study, we evaluated the effects of SRBSDV-infected plants on the ecological fitness and the tolerance to adverse environmental factors of vector WBPH and non-vector brown planthopper (BPH), Nilaparvata lugens (Stål). Our study revealed that the fitness of WBPH and BPH were both influenced by feeding on SRBSDV-infected rice. Fecundity ofWBPH feeding on the SRBSDV-infected rice plants were higher than those on healthy plants, nymphal duration of male WBPH prolonged markedly by 0.77 d (P b 0.05), while the weight of brachypterous female adults significantly decreased (P b 0.05), and the average survival time shortened both at 26 °C and 31 °C, respectively. Median lethal time of WBPH on SRBSDV-infected and healthy rice plants were 80 h and 112 h at 26 °C, 64 h and 88 h at 31 °C, respectively. As for non-vector BPH, nymph survival rate decreased significantly by 11.22% (P b 0.05) and the longevity of female adults also shortened (P b 0.05), while hatchability of BPH eggs increased (P b 0.05). Survival time of BPH feeding on healthy rice at 26 °Cwas significant longer than those feeding on healthy and infected rice at 31 °C. The above results imply that the vectorWBPH suffers much stronger effects than non-vector BPH fromfeeding on SRBSDVinfected rice plants.

CoMP Transmission for Safeguarding Dense Heterogeneous Networks with Imperfect CSI

( Xu Yunjia ),( Huang Kaizhi ),( Hu Xin ),( Zou Yi ),( Chen Yajun ),( Jiang Wenyu ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.1

To ensure reliable and secure communication in heterogeneous cellular network (HCN) with imperfect channel state information (CSI), we proposed a coordinated multipoint (CoMP) transmission scheme based on dual-threshold optimization, in which only base stations (BSs) with good channel conditions are selected for transmission. First, we present a candidate BSs formation policy to increase access efficiency, which provides a candidate region of serving BSs. Then, we design a CoMP networking strategy to select serving BSs from the set of candidate BSs, which degrades the influence of channel estimation errors and guarantees qualities of communication links. Finally, we analyze the performance of the proposed scheme, and present a dual-threshold optimization model to further support the performance. Numerical results are presented to verify our theoretical analysis, which draw a conclusion that the CoMP transmission scheme can ensure reliable and secure communication in dense HCNs with imperfect CSI.

Water-Preserved Mining Technology and Practice in Typical High Intensity Mining Area of China

( Yajun Sun ),( Zhimin Xu ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

ShenDong mining area is China's important coal production base and typical high intensity mining field, which is also a typical fragile ecological environment of arid and semi-arid areas. High intensity mining area coal production and ecological environment coordinated development is an important research topic in the area. High intensity in coal mining production and coordinated development of ecological environment is an important research topic in the area. Aiming at the lack of water resources in arid and semi-arid, fragile ecological environment in Shendong mining area, this paper puts forward the partition of hydrogeological structure and the water-preserved mining by studying the structure characteristics of hydrological geology, coal strata structure type, etc. On this basis, according to different hydrogeological structure type, it puts forward the the basic principles of water preserving mining in ShenDong mining area and key technology of water-preserved mining such as coal mining important water source area in mining area, thick bedrock aquifer, burning rocks aquifer, water transfer storage and use of mine water resources. Finally, combining with the typical mine, it carries out the key technology of the engineering practice and achieves good application effect. The paper’s research result has a certain guiding significance to guide the arid and semi-arid area of west China in protective exploitation of water resources.

Research on the Law of Mining Induced Water Conduction Fissure in Arid Mining Area, China

( Xu Zhimin ),( Sun Yajun ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

With the focus on the gradual westward shifting of coal resources development in China, the western region has become the main production areas. In general, the ecological environment is relatively weak due to the low precipitation and high evaporation. Taking the Dananhumining area in Hami coalfield, Xinjiang, as an example, in view of the late diagenesis time, low physical intensity and easily muddy disintegration of Jurassic coal-rich strata in this area, similar material simulation and numerical simulation are used. Based on the field observation and comparison of the neighboring coalmines, several significant rules are studied including the development and evolution process, the development height and morphological characteristics, the permeability evolution law in roof water flowing fractured zone and the water protection during coal mining (water-preserved mining).The results shows that in the Jurassic coal-rich strata, the development ratio of water flowing fractured fissure is generally between 13.09 and 15.67, and the overall morphology is characterized by “terrace-type”. Fracture and permeability coefficient evolution in the range of mining impacts reflect the characteristics of “stable increase-fluctuation-recovery stability”, and the permeability coefficient of aquifer increases obviously reaching 3-5 times within the influence range of the height of water flowing fractured zone. The main coal seam roof in the study area has the “high aquifuge under multi-aquifer structure” structural characteristics, which possess the basic hydro-geological preconditions for water retention. Combined with the protection seam’ stability, the upper aquifer of iii-1 static reserves, the development potential and the comprehensive evaluation of the water-preserved mining feasibility in the research area, and the significance of water protection during coal mining in arid mining area are discussed.

Bacterial Community Shift during the Startup of a Full-Scale Oxidation Ditch Treating Sewage

( Yajun Chen ),( Lin Ye ),( Fuzheng Zhao ),( Lin Xiao ),( Shupei Cheng ),( Xu-xiang Zhang ) 한국미생물 · 생명공학회 2017 Journal of microbiology and biotechnology Vol.27 No.1

The oxidation ditch (OD) is one of the most widely used processes for treating municipal wastewater. However, the microbial communities in the OD systems have not been well characterized, and little information about the shift of bacterial community during the startup process of the OD systems is available. In this study, we investigated the bacterial community changes during the startup period (over 100 days) of a full-scale OD. The results showed that the bacterial community dramatically changed during the startup period. Similar to the activated sludge samples in other studies, Proteobacteria (accounting for 26.3%-48.4%) was the most dominant bacterial phylum in the OD system, but its relative abundance declined nearly 40% during the startup process. It was also found that Planctomycetes proliferated greatly (from 4.79% to 13.5%) and finally replaced Bacteroidetes as the second abundant phylum in the OD system. Specifically, some bacteria affiliated with genus Flavobacterium exhibited remarkable decreasing trends, whereas bacterial species belonging to the OD1 candidate division and Saprospiraceae family were found to increase during the startup process. Despite of the bacterial community shift, the organic matter, nitrogen, and phosphorus in the effluent were always in low concentrations, suggesting the functional redundancy of the bacterial community. Moreover, by comparing with the bacterial community in other municipal wastewater treatment bioreactors, some potentially novel bacterial species were found to be present in the OD system. Collectively, this study improved our understandings of the bacterial community structure and microbial ecology during the startup of a full-scale wastewater treatment bioreactor.

Supplement of High Protein-Enriched Diet Modulates the Diversity of Gut Microbiota in WT or PD-1H-Depleted Mice

( Yajun Xie ),( Ping Zhao ),( Zhigang Han ),( Wei Li ),( Dan Shi ),( Lei Xu ),( Qiying Yi ) 한국미생물생명공학회(구 한국산업미생물학회) 2021 Journal of microbiology and biotechnology Vol.31 No.2

Supplement of high-protein food plays an important role in improving the symptoms of malnutrition and the immune capacity of the body, but the association of high-protein diet and gut microbiota remained unaddressed. Here, we systematically analyzed the internal organs and gut microbiota in C57(WT) or PD-1H-depleted (KO) mice (T cells were activated) fed with pupae or feed for six weeks. We observed that the body weight gain in the mice fed with pupae increased less significantly than that of the feed group, while the villi and small intestine lengths in the pupa group were reduced compared with that of mice given feed. However, the average body weight of the KO mice increased compared with that of the WT mice fed with pupae or feed. Pupae increased the concentration of blood glucose in WT, but not in KO mice. Moreover, in the feed group, there was no difference in the weight of the internal organs between the WT and KO mice, but in the pupae-fed group, liver weight was decreased and spleen weight was increased compared with that of KO mice. The amounts/plural/amounts of Melainabacteria, Chloroflexi, and Armatimonadetes were specifically upregulated by pupae, and this upregulation was weakened or eliminated by PD-1H depletion. Some bacteria with high abundance in the feed-fed KO mice, such as Deferribacteres, Melainabacteria, Acidobacteria, Bacteroidetes, Spirochaetes and Verrucomicrobia, were decreased in pupae-fed KO mice, and Proteobacteria and Deinococcus were specifically enriched in pupae-fed KO mice. Bacteroidetes, Firmicutes and Akkermansia were associated with weight loss in the pupaefed group while Lachnospiraceae and Anaerobiospirillum were related glucose metabolism and energy consumption. Based on high-throughput sequencing, we discovered that some gut bacteria specifically regulated the metabolism of a high-protein diet, and PD-1H deficiency improved life quality and sustained blood glucose. Moreover, PD-1H responses to high-protein diet through modulating the type and quantity of gut bacteria. These findings provide evidence about the association among gut microbiota, T cell activation (for PD-1H depletion) and high-protein diet metabolism, have important theoretical significance for nutrition and health research.