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Jia, Shiru,Yu, Haifeng,Lin, Yongxian,Dai, Yujie Korean Society for Biotechnology and Bioengineerin 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 $2.79{\times}10^5$. 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 $245^{\circ}C$ 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.
Case Study for Ship Ad-hoc Networks under a Maritime Channel Model in Coastline Areas
( Xin Su ),( Haifeng Yu ),( Kyunghi Chang ),( Seung-geun Kim ),( Yong-kon Lim ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.10
ITU-R M.1842-1, as a well-known specification dedicated to maritime mobile applications, has standardized wireless transmission protocols according to the particular characteristics of a maritime communications scenario. A time division multiple access (TDMA) frame structure, along with modulation schemes to achieve a high data rate, has been described clearly in ITU-R M.1842-1. However, several specification items are still under “to be decided” status, which brings ambiguity to research works. In addition, the current version of ITU-R M.1842-1 is focused mainly on maritime transmissions in open-sea areas, where the cyclic prefix (CP) is set to zero and only 16-QAM is used in the multi-carrier (MC) system. System performance might be dramatically degraded in coastline areas due to the inter-symbol interference (ISI) caused by selective fading. This is because there is a higher probability that the signal will be reflected by obstacles in coastline areas. In this paper, we introduce the transmission resource block (TRB) dedicated to ITU-R M.1842-1 for a ship ad-hoc network (SANET), where the pilot pattern of TRB is based on the terrestrial trunked radio (TETRA). After that, we evaluated SANET performance under the maritime channel model in a coastline area. In order to avoid noise amplification and to overcome the ISI caused by selective fading, several strategies are suggested and compared in the channel estimation and equalization procedures, where the link-level simulation results finally validate our proposals.
Seismic behavior of coupled wall structure with innovative quickly replaceable coupling beams
YONG-LIANTANG,Haifeng Yu,Xiaoyong Liang,Jianjun Yu,Pengcheng Li,Wei Wang,Qizhi Wang 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.45 No.2
In order to improve the seismic resilience of coupled wall structure, coupling beam with fuse has been developed to reduce the post-earthquake damage. However, the fuses often have a build-up I-shaped section and are relatively heavy to be replaced. Moreover, the fuse and the beam segments are usually connected by bolts and it is time-consuming to replace the damaged fuse. For reducing the repair time and cost, a novel quickly replaceable coupling beam with buckling-restrained energy dissipaters is developed. The fuse of the proposed coupling beam consists of two chord members and bar-typed energy dissipaters placed at the corners of the fuse. In this way, the weight of the energy dissipater can be greatly reduced. The energy dissipaters and the chords are connected with hinge and it is convenient to take down the damaged energy dissipater. The influence of ratio of the length of coupling beam to the length of fuse on the seismic performance of the structure is also studied. The seismic performance of the coupled wall system with the proposed coupling beam is compared with the system with reinforced concrete coupling beams. Results indicated that the weight and post-earthquake repair cost of the proposed fuse can be reduced compared with the typical I-shaped fuse. With the increase of the ratio of the beam length to the fuse length, the interstory drift of the structure is reduced while the residual fuse chord rotation is increased.
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.
On $\pi\mathfrak{F}$-embedded subgroups of finite groups
Wenbin Guo,Haifeng Yu,LI ZHANG 대한수학회 2016 대한수학회보 Vol.53 No.1
A chief factor $H/K$ of $G$ is called $\mathfrak{F}$-central in $G$ provided $(H/K)\rtimes (G/C_{G}(H/K))\in\mathfrak{F}$. A normal subgroup $N$ of $G$ is said to be $\pi\mathfrak{F}$-hypercentral in $G$ if either $N=1$ or $N\neq1$ and every chief factor of $G$ below $N$ of order divisible by at least one prime in $\pi$ is $\mathfrak{F}$-central in $G$. The symbol $Z_{\pi\mathfrak{F}}(G)$ denotes the $\pi\mathfrak{F}$-hypercentre of $G$, that is, the product of all the normal $\pi\mathfrak{F}$-hypercentral subgroups of $G$. We say that a subgroup $H$ of $G$ is $\pi\mathfrak{F}$-embedded in $G$ if there exists a normal subgroup $T$ of $G$ such that $HT$ is $s$-quasinormal in $G$ and $(H\cap T)H_G/H_G\leq Z_{\pi\mathfrak{F}}(G/H_G)$, where $H_G$ is the maximal normal subgroup of $G$ contained in $H$. In this paper, we use the $\pi\mathfrak{F}$-embedded subgroups to determine the structures of finite groups. In particular, we give some new characterizations of $p$-nilpotency and supersolvability of a group.
A Survey on the Underwater Communication Network Projects
Woon Kim,Haifeng Yu,KyungHi Chang 한국통신학회 2014 한국통신학회 학술대회논문집 Vol.2014 No.1
The development on the underwater (UW) communication network for sea observation is on the rise due to increasing importance of its applications such as oceanography, marine commercial operation and military surveillance. This paper gives overview of several underwater communication network projects conducted by active member for the ocean studies such as U.S.A., Canada, Erope, and Japan. The UW projects for shallow sea observation include SEAWEB and PLUSNet, and deep sea observation project includes GEOSTAR. The network architecture and communication method for each project mentioned above are described in this paper. As introducing various kinds of projects, this paper can be a guidance for future research on underwater network project.
Design of Slot Structure and Pilot Pattern for Underwater Acoustic Downlink Channel below 10kHz
Jinhui Liu,Haifeng Yu,KyungHi Chang 한국통신학회 2016 한국통신학회 학술대회논문집 Vol.2016 No.1
Though underwater acoustic (UWA) channel is the most challenging due to its time varying and frequency selective characteristics, UWA communications draw lots of attention to satisfy the increasing demand of the various applications. In this paper, for the purpose of providing high data rate and reliable services for UWA communications, slot structure as well as the pilot pattern is designed based on the UWA channel characteristics below 10 kHz. MCS level for the downlink application is also optimized by the system performance evaluation at link-level.