Efficient Method to Include Joint Zones of Chord Members in Finite Element Model of Tubular Transmission Tower at Linear Elastic Stage

Haifeng Liu,Junke Han,Zhenmao Sun,Jingbo Yang,Fengli Yang,Xiyu Xu 한국강구조학회 2015 International Journal of Steel Structures Vol.15 No.4

To include the effects of the joint zones efficiently, firstly a chord member considering the joint zones is seen as a combination of three beams with different sections and its element stiffness matrix is derived; Secondly, based on the statistically geometrical properties of the joint zones and chord members in service, the coefficients in the element stiffness matrix of the varied section beam element related to the moments and shear forces greatly increase more than 70%, while the coefficients related to axial forces only increase less than 2%. Therefore, along with the other two inherent mechanical properties of member structures, it is essential to include the effects of the joint zones. Finally, the results by the finite element models where the chord members and the joint zones are simulated by four methods are compared, which proves the efficiency and the accuracy of the varied section beam element.

Facile and highly efficient fabrication of robust Ag nanowire-elastomer composite electrodes with tailored electrical properties

Yang, Ming,Kim, Sang Woo,Zhang, Shuye,Park, Dae Young,Lee, Chang-Woo,Ko, Yong-Ho,Yang, Haifeng,Xiao, Yong,Chen, Gang,Li, Mingyu The Royal Society of Chemistry 2018 Journal of Materials Chemistry C Vol.6 No.27

<P>The fabrication of Ag nanowire (AgNW) patterns on a working substrate is a critical step to prepare flexible/stretchable electronics. The conventional method of making AgNW patterns is based on a 2-D mask, which suffers some serious drawbacks, such as low material usage, difficulty in preparing complex patterns, and susceptibility to damaged pattern edges. To overcome these drawbacks, this study proposes the use of a 3-D mask, which when combined with a vacuum filtration system, allowed efficient fabrication of complex AgNW patterns with clear edges. In addition, we controlled the microstructure of the patterned AgNW/polydimethylsiloxane (PDMS) electrodes transferred from the membrane filter, obtaining stretchable electrodes with anisotropic electrical properties. Moreover, we greatly improved the stability and reliability of the patterned electrodes in long-term stretch/release tests by developing a PDMS/AgNW/PDMS sandwich structure. Based on these improvements, robust stretchable electrodes with a stretchability of over 80% uniaxial strain and tunable gauge factors ranging from 0.07 to 520 (a much wider range than previously reported) were fabricated by optimizing the AgNW deposition density and PDMS peel-off direction. Finally, we demonstrated the applicability of the proposed method by fabricating stretchable circuits which were able to either maintain a stable resistance or sensitively monitor various human motions, revealing its tremendous potential for applications in flexible/stretchable electronics.</P>

Hydrolytic performances of different organic compounds in different lignocellulosic biomass during anaerobic digestion

Haifeng Yang,Rui Deng,Junwei Jin,Yuling Wu,Xin Jiang,Jinhua Shi 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.4

Hydrolytic performances of different organic compounds in lignocellulosic biomass (LB) during anaerobic digestion (AD) are worth investigating due to the complex and refractory structure of lignocellulose. This study aimed to clarify the hydrolytic performances of different lignocellulosic components (hemicellulose, cellulose and lignin) and other typical organics (saccharides, protein and lipid) in AD process. Furthermore, an in-depth study of different lignocellulosic components mono-/co-digestive performances, as well as their effects on digestive systems were also designed to explain the mechanism. Kinetic models were specially applied to evaluate the hydrolytic process and make comparison among different lignocellulosic components. Results showed that hemicellulose obtained high degradation ratio (77.2-85.0%) during anaerobic digestion, while cellulose was difficult to hydrolyze without sufficient acidity. And organics (saccharides, protein and lipid) were much easier to be hydrolyzed than lignocellulose. Results also depicted that lignocellulose addition could efficiently enhance the volatile solid (VS) removals of digestive systems, while lignin existing in systems reduced the VS removal. The limited hydrolysis of lignocellulose hindered the degradation of total VS in digester. It is quite important to obtain high bioenergy conversion, pretreatments, which can destroy the lignin wrapping in LBs digestion. This study could provide a reference for the AD of LBs.

Mesoporous Materials with Spherical Morphology : Synthesis and Bioapplication

Yang, Haifeng,Yan, Yan,Zhao, Dongyuan 한국공업화학회 2004 Journal of Industrial and Engineering Chemistry Vol.10 No.7

Morphology control is one of the most interesting issues in the research field of mesoporous materials. It plays a very important role in understanding the basic synthesis mechanism of the kind of materials. Moreover, the future applications of mesoporous materials are strongly depended on their tunable macroscopical morphologies. Mesoporous materials with spherical morphology are quite attractive due to the potential applications in macromolecular separations, drug deliveries, catalysis supports and template agents for photonic crystals. Researches on synthesis and properties of the materials have been carried out for nearly ten years. In this article, several synthetic methods for both siliceous and non-siliceous mesoporous spheres are reviewed, including solution self-assembly, aerosol spraying and hard templating route. The mechanism of self-assembly in solution system is provided and the rational controls for synthetic conditions are specifically discussed. With the viewpoint of applications, some examples are given in the aspects of bioseparations, drug delivery and catalysis. A short summary has listed some overviews for future developments.

Enhanced corrosion resistance by polypyrrole and Ti3C2Tx-acrylic epoxy double-layer coating for 304SS bipolar plates of PEMFC

Haifeng Bian,Guoli Zhang,Qingxi Zhai,Yanyan Du,Yujie Ma,Beibei Yang,Shaochun Tang,Duan Bin,Xiangkang Meng,Hongbin Lu 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.122 No.-

Stainless steel (SS) is a promising material for designing bipolar plates (BPs), but their further applicationis limited by serious corrosion problems in the acidic environment. Ti3C2Tx is expected to be used for SSBPs coatings, while galvanic corrosion will occur after the damage of Ti3C2Tx coating. Herein, a PPY/Ti3C2Tx-AE double-layer coating (DC) is well-designed and prepared on 304SS BP, which is composedof an inner electropolymerized PPY layer and an outer Ti3C2Tx-acrylic epoxy layer. When tested in0.2 M HCl solution, the corrosion potential and corrosion current density of the DC are 38 mV and0.00927 lA cm2 respectively, which are superior to those of the PPY coating and the Ti3C2Tx coating. Moreover, the DC presents the best long-term stability among the three coatings. The excellent corrosionresistance is attributed to the barrier and anodic protection effects as well as the solution of galvanic corrosion. The new coating system provides a new insight into the design of DC coatings of SS BPs.

Behaviors of box-shape steel reinforced concrete composite beam

Yang, Chun,Cai, Jian,Wu, Yi,He, Jiangang,Chen, Haifeng Techno-Press 2006 Structural Engineering and Mechanics, An Int'l Jou Vol.22 No.4

Experimental studies on the behaviors of box-shape steel reinforced concrete (SRC) composite beams were conducted. Seven 1:3 scale model composite beams were tested to failure. Each of the beams was simply supported at the ends and two concentrated loads were applied at the one-third span and two-thirds span respectively. Experimental results indicate that the flexural strength can be enhanced when the ratio of flexural reinforcements and flange thickness of the shape steel are increased; the shear strength is enhanced with increase of web thickness of the shape steel. Insignificant effects of concrete in the box-shape steel are found on improving the flexural strength and shear strength of the box-shape SRC composite beams, thus concrete inside the box-shape steel can be saved, and the weight of the SRC beams can be decreased. Shear studs can strengthen the connection and co-work effects between the shape steel and the concrete and enhance the shear strength, but stud design for the composite beams should be further improved. Formulas for flexural and shear strength of the composite beams are proposed, and the calculated results are in good agreement with the experimental results. In general, the box-shape SRC composite beam is a kind of ductile member, and suitable for extensive engineering application.

Mining Implicit Correlations between Users with the Same Role for Trust-Aware Recommendation

( Haifeng Liu ),( Zhuo Yang ),( Jun Zhang ),( Xiaomei Bai ),( Wei Wang ),( Feng Xia ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.12

Trust as one of important social relations has attracted much attention from researchers in the field of social network-based recommender systems. In trust network-based recommender systems, there exist normally two roles for users, truster and trustee. Most of trust-based methods generally utilize explicit links between truster and trustee to find similar neighbors for recommendation. However, there possibly exist implicit correlations between users, especially for users with the same role (truster or trustee). In this paper, we propose a novel Collaborative Filtering method called CF-TC, which exploits Trust Context to discover implicit correlation between users with the same role for recommendation. In this method, each user is first represented by the same-role users who are co-occurring with the user. Then, similarities between users with the same role are measured based on obtained user representation. Finally, two variants of our method are proposed to fuse these computed similarities into traditional collaborative filtering for rating prediction. Using two publicly available real-world Epinions and Ciao datasets, we conduct comprehensive experiments to compare the performance of our proposed method with some existing benchmark methods. The results show that CF-TC outperforms other baseline methods in terms of RMSE, MAE, and recall.

Seismic Performance of New-type Box Steel Bridge Piers with Embedded Energy-Dissipating Shell Plates under Tri-directional Seismic Coupling Action

Haifeng Li,Xuanneng Gao,Yang Liu,Yongfeng Luo 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.1

Accurate numerical models are necessary to evaluate the seismic performance and load-bearing mechanism of new-type box steel bridge piers with embedded energy-dissipating shell plates under tri-directional seismic coupling action. Numerical simulations of seismic performance under six types of tri-directional seismic coupling action was conducted. The effects of this stress on the seismic performance of the new-type steel bridge piers was evaluated through analysis of damage mode, hysteresis curve, skeleton curve, stiffness and strength degradation characteristic, and energy-dissipating capacity. This study also compared the numerical analysis with experimental results in order to validate the accuracy of the proposed finite element model. Based on this model, the range of relevant parameters expanded and 88 numerical specimens were analysed for seismic performance, producing further information about the influence of thickness and curvature of the embedded shell plate, spacing of transverse stiffening ribs of the shell, axial compression ratio, and slenderness ratio. Results showed that tri-directional seismic coupling action significantly affects the specimen’s deformation capacity; the embedded shell plate effectively improves the piers’ loadcarrying and deformation capacity; and the thickness of the embedded shell plate, width-to-thickness ratio of the wall plate, axial compression ratio, and slenderness ratio significantly affect the seismic performance of the new-type steel bridge piers. To promote the ease of seismic design of new-type box steel bridge piers, this study used theoretical analysis and numerical simulation to calculate equations for the minimum height of the energy-dissipating zone of the bottom embedded shell plate. Finally, formulas were also established to calculate the relevant stability bearing capacity and displacement ductility factor of the new-type steel bridge piers under tri-directional seismic coupling action in order to improve their seismic design.

A Note for Restricted Information Markets

Yang Jianqi,Xiao Qingxian,Yan Haifeng 한국전산응용수학회 2009 Journal of applied mathematics & informatics Vol.27 No.5

This paper considers the problems of martingale measures and risk-minimizing hedging strategies in the market with restricted information. By constructing a general restricted information market model, the explicit relation of arbitrage and the minimal martingale measure between two different information markets are discussed. Also a link among all equivalent martingale measures under restricted information market is given. As an example of restricted information markets, this paper constitutes a jump-diffusion process model and presents a risk minimizing problem under different information. Through Itˆo formula and projection results in Schweizer[13], the explicit optimal strategy for different market information are given. This paper considers the problems of martingale measures and risk-minimizing hedging strategies in the market with restricted information. By constructing a general restricted information market model, the explicit relation of arbitrage and the minimal martingale measure between two different information markets are discussed. Also a link among all equivalent martingale measures under restricted information market is given. As an example of restricted information markets, this paper constitutes a jump-diffusion process model and presents a risk minimizing problem under different information. Through Itˆo formula and projection results in Schweizer[13], the explicit optimal strategy for different market information are given.

Identification of the large-conductance background K+ channel in mouse B cells as TREK-2.

Zheng, Haifeng,Nam, Joo Hyun,Pang, Bo,Shin, Dong Hoon,Kim, Ji Seon,Chun, Yang-Sook,Park, Jong-Wan,Bang, Hyowon,Kim, Woo Kyung,Earm, Yung E,Kim, Sung Joon American Physiological Society 2009 American journal of physiology. Cell physiology Vol.297 No.1

<P>Mouse B cells and their cell line (WEHI-231) express large-conductance background K(+) channels (LK(bg)) that are activated by arachidonic acids, characteristics similar to TREK-2. However, there is no evidence to identify the molecular nature of LK(bg); some properties of LK(bg) were partly different from the reported results of TREK type channels. In this study, we compared the properties of cloned TREK-2 and LK(bg) in terms of their sensitivities to ATP, phosphatidylinositol 4,5-bisphosphate (PIP(2)), intracellular pH (pH(i)), and membrane stretch. Similar to the previous findings of LK(bg), TREK-2 showed spontaneous activation after membrane excision (i-o patch) and were inhibited by MgATP or by PIP(2). The inhibition by MgATP was prevented by wortmannin, suggesting membrane-delimited regulation of TREKs by phosphoinositide (PI) kinase. The same was observed with the property of LK(bg); the activation of TREK-2 by membrane stretch was suppressed by U73122 (PLC inhibitor). As with the known properties of TREK-2, LK(bg) were activated by acidic pH(i) and inhibited by PKC activator. Finally, we confirmed the expression of TREK-2 in WEHI-231 by using RT-PCR and immunoblot analyses. The amplitude of background K(+) current and the TREK-2 expression in WEHI-231 were commonly decreased by genetic knockdown of TREK-2 using small interfering RNA. The downregulation of TREK-2 attenuated Ca(2+)-influx induced by arachidonic acid in WEHI-231. As a whole, these results strongly indicate that TREK-2 encodes LK(bg) in mouse B cells. We also newly suggest that the low activity of TREK-2 in intact cells is due to the inhibition by intrinsic PIP(2).</P>