Load Dispatching Control of Multiple-Parallel-Converters Rectifier to Maximize Conversion Efficiency

Dai Orihara,Hiroumi Saitoh,Yuji Higuchi,Tadatoshi Babasaki 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.3

In the context of increasing electric energy consumption in a data center, energy efficiency improvement is strongly emphasized. In a data center, electric energy is largely consumed by DC power supply system, which is based on a rectifier composed by multiple parallel converters. Therefore, rectifier efficiency must be improved for minimizing loss of DC power supply system. Rectifier efficiency can be modulated by load allocation to converters because converter efficiency depends on input AC power. In this paper, we propose a new control method to maximize rectifier efficiency. The method can control load allocation to converters by introducing active power converter control scheme and start-and-stop of converters. In order to illustrate optimal load allocations in a rectifier, a maximization problem of rectifier efficiency is formulated as a nonlinear optimization one. The problem is solved by Lagrangian relaxation method and the computation results provide the validity of proposed method.

Load Dispatching Control of Multiple-Parallel-Converters Rectifier to Maximize Conversion Efficiency

Orihara, Dai,Saitoh, Hiroumi,Higuchi, Yuji,Babasaki, Tadatoshi The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.3

In the context of increasing electric energy consumption in a data center, energy efficiency improvement is strongly emphasized. In a data center, electric energy is largely consumed by DC power supply system, which is based on a rectifier composed by multiple parallel converters. Therefore, rectifier efficiency must be improved for minimizing loss of DC power supply system. Rectifier efficiency can be modulated by load allocation to converters because converter efficiency depends on input AC power. In this paper, we propose a new control method to maximize rectifier efficiency. The method can control load allocation to converters by introducing active power converter control scheme and start-and-stop of converters. In order to illustrate optimal load allocations in a rectifier, a maximization problem of rectifier efficiency is formulated as a nonlinear optimization one. The problem is solved by Lagrangian relaxation method and the computation results provide the validity of proposed method.

An Optimization Method for Designing LDPC Analog Decoders Based on Frequent Subgraph Mining Algorithm

Yuan Gao,Yujie Lin,Jibo Dai 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.10

To lower the mapping complexity of designing analog decoders, a method to optimize the design of low-density parity-check (LDPC) analog decoders is proposed in this paper. Based on factor graphs and the sum-product algorithm, the LDPC decoding process on the factor graph and the construction of analog decoders are exploited. Then the frequent subgraph mining algorithm is introduced to search the isomorphic subgraphs in factor graphs. According to the output of the frequent subgraph mining algorithm which enumerates all the subgraphs in factor graphs, the mapping complexity of a LDPC analog decoder can be significantly reduced. Finally, a (40, 16) LDPC analog decoder is constructed using the proposed method. Simulation results show that the need to place gates and connections can be reduced 90% and 23%, respectively, and the ideal performance is obtained by carefully choosing unit currents and decoding time.

ROS-activated CXCR2+ neutrophils recruited by CXCL1 delay denervated skeletal muscle atrophy and undergo P53-mediated apoptosis

Xiang Yaoxian,Dai Junxi,Li Yao,You Zongqi,Zhang Junpeng,Huang Xinying,Nie Shuqi,Chen Yujie,Xu Lei,Liu Fengming,Jiang Junjian,Xu Jianguang 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-

Neutrophils are the earliest master inflammatory regulator cells recruited to target tissues after direct infection or injury. Although inflammatory factors are present in muscle that has been indirectly disturbed by peripheral nerve injury, whether neutrophils are present and play a role in the associated inflammatory process remains unclear. Here, intravital imaging analysis using spinning-disk confocal intravital microscopy was employed to dynamically identify neutrophils in denervated muscle. Slice digital scanning and 3D-view reconstruction analyses demonstrated that neutrophils escape from vessels and migrate into denervated muscle tissue. Analyses using reactive oxygen species (ROS) inhibitors and flow cytometry demonstrated that enhanced ROS activate neutrophils after denervation. Transcriptome analysis revealed that the vast majority of neutrophils in denervated muscle were of the CXCR2 subtype and were recruited by CXCL1. Most of these cells gradually disappeared within 1 week via P53-mediated apoptosis. Experiments using specific blockers confirmed that neutrophils slow the process of denervated muscle atrophy. Collectively, these results indicate that activated neutrophils are recruited via chemotaxis to muscle tissue that has been indirectly damaged by denervation, where they function in delaying atrophy.

Fractionation and Characterization of ε-Poly-L-lysine from Streptomyces albulus CGMCC 1986

Shiru Jia,Yujie Dai,Baoqing Fan,Guoliang Wang,Yuanyuan Jia,Peng Peng 한국식품과학회 2010 Food Science and Biotechnology Vol.19 No.2

ε-Poly-L-lysine (ε-PLL) produced by Streptomyces albulus CGMCC 1986 was fractionated using ultra-filtration technique with 2 and 5 kDa cut-offs of membrane. The number-average molecular weight of each fraction was determined by 1H nuclear magnetic resonance (NMR)method. The number-average molecular weights of the cutoffs of 5 and 2 kDa and the filtrate are 4,230.95, 3,687.80,and 1,900.82 Da, respectively. 1H NMR indicates the chemical shifts of α-H, β-H, γ-H, δ-H, and ε-H are very similar to all the fractions. Fourier transform-infrared (FTIR)spectra showed that the ε-PLL solid samples obtained by freeze-drying at pH 5 with molecular weights higher than 2 kDa take on a β-turn conformation, however, the fraction with molecular weight smaller than 2 kDa adopts random coil structure. The antibacterial test proved that the fraction between 2 and 5 kDa of membranes behaves the highest antibacterial activity than other fractions for the test strains of Staphylococcus aureus, Micrococcus luteus,Bacillus subtilis, Escherichia coli, and Shigella.

Medical Image Fusion based on Pulse Coupled Neural Network Combining with Compressive Sensing

AiliWang,Jiaying Zhao,Shiyu Dai,Yuji Iwahori,Yangyang Zhao 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.5

Image fusion is an important branch of information fusion, widely used in various fields, especially in medical field. So increasing the quality and efficiency of medical image fusion has great significance. Combining the advantages of pulse coupled neural networks with Compressive Sensing; this paper puts forward a novel image fusion method in NSCT transform domain. First, NSCT transform is applied to the source images, and the coefficients in low frequency coefficient are fused by mean rules. For high frequency coefficient, CS is applied and PCNN. Finally, inverse NSCT is applied to get the reconstructed image. The experimental results show that the fusion algorithm proposed in this paper in the performance and integration efficiency has better fusion results.

Medical Image Fusion in NSCT Domain Combining with Compressive Sensing

AiliWang,Jiaying Zhao,Yuji Iwahori,Shiyu Dai 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.5

In recent years, with the development of compressive sensing (CS) theory, it has been widely applied to each field including image fusion, and obtained better fusion effect. And CS can reduce dimensions and the amount of data characteristics as well as the large amount and high computation complex. Therefore, this paper proposes a novel medical image fusion method based on compressive sensing theory in non-subsampled contourlet transform (NSCT) domain. First, NSCT transform is applied to the source images, and the coefficients in low frequency subband are fused by mean rules. For high frequency subband, CS is applied and the coefficients are fused by neighborhood-energy-MAX (NE-MAX) rule, then inverse CS is used to get fused coefficients. Finally, inverse NSCT is applied to get the reconstructed image. The experimental results show that the fusion algorithm proposed in this paper is superior to fusion method based on WT-MAX and CS-MAX、CS-MEAN.

Performance of a modified alkaline lignin towards copper adsorption under different conditions

Chunli Zheng,Qiaorui Wang,Yujie Dai,Bo Zu,Yangyang Zhang,Tian C Zhang 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.3

Polyethyleneimine and carbon disulfide were employed to modify alkaline lignin (AL) in order to introduce -NH, -NH₂ and -CSS- groups. Its adsorption performance towards Cu(II) was evaluated based on the residual concentration (Cr) against the discharge permissible concentration for Cu(II) (2.0 mg/L) established by the World Health Organization. The evaluation was operated under different conditions such as adjusting the solution pH, Cu(II) coexisting with K(I), Na(I), Ca(II) or Mg(II), changing the contact time (t) and initial concentration of Cu(II) (C0), as well as regeneration. When t and C0 equaled to 180 min and 50 mg/L, Cr was less than 2.0 mg/L at pH of 5.03 to 5.65. Under the situation of Cu (II) coexisting with 50 mg/L of K(I), Na(I), Ca(II) or Mg(II), Cr was as low as 1.96, 1.53, 1.97 or 1.55 mg/L (t = 180 min, C0 = 50 mg/L), respectively. Even the modified AL was regenerated and reused four times, Cr was closed to 2 mg/L for each time (t = 180 min, C0 = 51 mg/L). By comparing with other lignin-based materials according to the adsorption equilibrium time, the maximum adsorption capacity, and Cr, the modified AL exhibited higher application potential in copper-loaded water treatment.

Characterization of Extracellular Polysaccharides from Nostoc flagelliforme Cells in Liquid Suspension Culture

Shiru Jia,Haifeng Yu,Yongxian Lin,Yujie Dai 한국생물공학회 2007 Biotechnology and Bioprocess Engineering Vol.12 No.3

Nostoc flagelliforme cells were studied with regard to the physico-chemical characterization of the extracellular polysaccharides (EPS) secreted in a liquid suspension culture. The hydrolyzed EPS were determined to be composed of four neutral sugars, which were glucose (43.2%), xylose (20.6%), galactose (29.9%), and mannose (6.3%). The glucuronic acid was the only uronic acid identified in the residue. The apparent molecular weight was estimated at 2.79 × 105. The Fourier transform infrared spectra showed that the EPS evidenced characteristics typical of non-sulfated polysaccharides. The UV spectrum and Bradford reaction indicated that there were no nucleic acids and proteins in them. The thermal analysis showed a decomposition peak at 245oC on the thermogravimetric (TG) curves. The scanning electron microscope (SEM) analysis indicated that the EPS possessed a porous structure. The observed microstructural irregularities indicated that the polysaccharide was a type of amorphous solid. These results showed that the EPS of N. flagelliforme cells might be employed as a substitute for those normally derived from field colonies. The results of this study may prove to be beneficial to the protection of the natural resource represented by N. flagelliforme.

Modern pollen distribution and its relationship with environmental difference in southwestern China

Tao Pan,Shaohong Wu,Erfu Dai,Yujie Liu 한국지질과학협의회 2010 Geosciences Journal Vol.14 No.1

Quantitative relationships between pollen and vegetation in the Longitudinal Range-Gorge Region (LRGR) are studied based on the pollen records of 35 surface soil samples and 7 vegetation quadrates. The spatial distribution of the pollen and the relative control of environmental factors are analyzed. Results are: (1) The R values, which designate the representation of pollen to vegetation, indicate a good quantitative relationship between surface pollen assemblages and local vegetation. (2) Significant differences in diversity of pollen flora, pollen amounts, major taxa, and vegetation between the east and the west sides of Ailao Mountain, an important geographical dividing line in LRGR, are recognized. (3) Obvious spatial differences of pollen assemblages are relevant to different regional topography and climatic conditions. These results suggest that the spatial differences between pollen assemblages would be caused by the different pattern of hydrothermal condition in the unique topography of the LRGR. The barrier function of the vertical mountain ranges, especially by the Ailao Mountain, may be a main factor in such environmental differences. Two separate monsoon circulations occurring in Pacific and Indian oceans result in different hydrothermal characteristics causing the regional differentiated patterns in the pollen assemblages in the study area.