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Yuanyuan Yao,Chang-chuan Yin,Xiaoshi Song,Norman C. Beaulieu 한국통신학회 2016 Journal of communications and networks Vol.18 No.3
The performance of large-scale cognitive radio (CR) networkswith secondary users sustained by opportunistically harvestingradio-frequency (RF) energy from nearby primary transmissionsis investigated. Using an advanced RF energy harvester, asecondary user is assumed to be able to collect ambient primary RFenergy as long as it lies inside the harvesting zone of an active primarytransmitter (PT). A variable power (VP) transmission modeis proposed, and an energy-based opportunistic spectrum access(OSA) strategy is considered, under which a secondary transmitter(ST) is allowed to transmit only if its harvested energy is largerthan a predefined transmission threshold and it is outside the guardzones of all active PTs. The transmission probability of the STs isderived. The outage probabilities and the throughputs of the primaryand the secondary networks, respectively, are characterized. Compared with prior work, the throughput can be increased byas much as 29%. The energy-based OSA strategy can be generallyapplied to a non-CR setup, where distributed power beacons(PBs) are deployed to power coexisting wireless signal transmitters(WSTs) in a wireless powered sensor network.
Yuanyuan Ge,Zhili Li,Yan Kong,Quanpeng Song,Kunqi Wang 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.6
Bi-functionalized lignin with amino and sulfonic groups (ASL) was synthesized via Mannich reaction andsulfomethylation. It was systematically characterized by FT-IR, element analysis, surface charge and XPS. Effects of initial pH, contact time and initial metal ion concentration on the adsorption of Cu(II) and Pb(II)onto ALS were studied. Results indicated that the biosorbent showed excellent performance for metalseven from low pH solutions. The adsorption kinetics and isotherms could be described well with Pseudosecond-order and D–R model, respectively. Further investigation of the metal-loaded ASL by FT-IR andXPS elucidated the amino and sulfonic groups reacted with metals in different way.
Oil film stiffness and damping in an elastohydrodynamic lubrication line contact-vibration
Yuanyuan Zhang,Hua iju Liu,Caichao Zhu,Mingyong Liu,Chaosheng Song 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.7
An elastohydrodynamic lubrication line contact-vibration model is proposed to study the stiffness and damping of the oil film existed in the EHL contact region. An initial mutual approach between interacting surfaces, which deviates from the steady-state balanced position, is assumed under the free contact-vibration to predict the response of the mutual approach. An inertia term, which represents the acceleration of the gap motion, is added to the classical force balance equation to form the equation of motion of the mutual approach. Response of the mutual approach is solved based upon the solving of the contact-dynamic model. The oil stiffness is calculated according to the natural frequency of the response under damped and non-damped conditions, the latter of which represents dry contact conditions. The oil film damping is calculated in terms of the principle of the energy conservation which utilizes the whole history of response compared with the log decrement method. Effect of the normal load, the rolling speed and the amplitude of the regular sinusoidal surface waviness on the oil film stiffness, the contact stiffness and the oil film damping are studied. The study provides an insight on the oil film dynamic characteristics of lubricated contact-vibration problems which appear in gears, bearings, etc. The results show that the oil film damping factor decreases with the increasing normal load as well as the increasing rolling speed. The oil film stiffness increases with the normal load and decreases with the rolling speed. Also, compared to the contact stiffness, the oil film stiffness makes less contribution to the total stiffness. The surface waviness amplitude has little effect on the oil film stiffness and the oil film damping.
A Mannich base biosorbent derived from alkaline lignin for lead removal from aqueous solution
Yuanyuan Ge,Quanpeng Song,Zhili Li 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.23 No.-
A Mannich base biosorbent (AML) was prepared by grafting alkaline lignin (AL) with methylamine and formaldehyde. The effects of dosages, reaction time, pH and temperature of reaction on the nitrogen content of AML were investigated. A maximum nitrogen content of the Mannich base could reach to 8.32%. It was characterized by scanning electron microscopy (SEM), element analysis, and gel permeation chromatography (GPC). Kinetic adsorption suggested AML possessed fast adsorption for Pb2+ and followed a second-order model. Adsorption equilibrium results indicated AML had a maximum uptake of 60.5 mg/g for Pb2+ which was 4.2-fold higher than AL. The AML has good potential for cleanup of wastewater.
High Temperature Oxidation Resistance of NiCoCrAl High Entropy Alloy Coating on the TiAl Alloy
Yuanyuan Sun,Qiang Miao,Wenping Liang,Kai Zang,Yuting Wu,Haiyang Yu,Mengjuan Yin,Xiguang Gao,Yindong Song 대한금속·재료학회 2024 METALS AND MATERIALS International Vol.30 No.1
The high entropy alloy coating is considered as one of the most promising methods to improve the high-temperature oxidationresistance of titanium aluminum alloys due to its fine mechanical property and thermal stability. However, the high entropyalloy coating prepared so far has poor coating quality, and low coating forming efficiency and there are certain requirementsfor the substrate alloys. To this end, a NiCoCrAl high entropy alloy coating was developed using the double glow plasmaalloying technique on the TiAl alloy. The morphology, phase structure, and high temperature oxidation resistance of thecoating were comprehensively studied. The results indicate that a uniform and dense coating with a single solid solution offace-centered cube phase formed on the alloy surface. Furthermore, isothermal oxidation test was performed, and the oxidationfailure process of the TiAl substrate and the NiCoCrAl-coated sample with different oxidation times was analyzed. It isfound that the coating efficiently prevented the TiAl alloy from degeneration for up to 100 h at 900 °C.
Crowded Cluster Cores: An Algorithm for Deblending in Dark Energy Survey Images
Zhang, Yuanyuan,McKay, Timothy A.,Bertin, Emmanuel,Jeltema, Tesla,Miller, Christopher J.,Rykoff, Eli,Song, Jeeseon Astronomical Society of the Pacific 2015 Publications of the Astronomical Society of the Pa Vol.127 No.957
Zhou, Yuanyuan,Lee, Ilbok,Kim, Daeun,Han, Seunghee,Kim, Jae-Kwang,Lee, Donghyun,Ko, Song Won,Pyo, Sung Gyu,Son, Hyungbin,Yoon, Songhun American Scientific Publishers 2017 Journal of nanoscience and nanotechnology Vol.17 No.1
<P>Using a stabilizing agent-assisted co-assembly method, a novel nanocomposite of mesoporous carbon embedded with uniform tungsten oxide nanorods is obtained, which is converted into carbon-sheathed tungsten oxide nanoparticles by delicate calcination and further reduction. Through optimization of tungsten content, it is found that highly crystalline tungsten oxide nanoparticles are uniformly coated with an ultra-thin carbon layer. When applied into electrochemical charge-storage electrodes for supercapacitor and lithium-ion battery, an excellent average capacitance (129 F g(-1), above 400 F cm(-3)), higher rate performance and significantly advanced cycle stability are observed. These improved charge storage properties are attributed to improved electrical conductivity and enhanced structural stability, which is induced by uniform carbon coating on partially reduced tungsten oxide nanoparticles.</P>
Effect of chitooligosaccharide on the inhibition of SARS-CoV-2 main protease
Wang Qian,Song Yuanyuan,Kim Mungu,한세광,Jiang Ge 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00
The main protease (Mpro) is a crucial target for severe acute respiratory syndrome coronavirus (SARS-CoV-2). Chitooligosaccharide (CS) has broad-spectrum antiviral activity and can effectively inhibit the activity of SARS-CoV. Here, based on the high homology between SARS-CoV-2 and SARS-CoV, this study explores the effect and mechanism of CS with various molecular weights on the activity of SARS-CoV-2 Mpro.We used fluorescence resonance energy transfer (FRET), UV–Vis, synchronous fluorescence spectroscopy, circular dichroism (CD) spectroscopy and computational simulation to investigate the molecular interaction and the interaction mechanism between CS and SARS-CoV-2 Mpro.Four kinds of CS with different molecular weights significantly inhibited the activity of Mpro by combining the hydrogen bonding and the salt bridge interaction to form a stable complex. Glu166 appeared to be the key amino acid. Among them, chitosan showed the highest inhibition effect on Mpro enzyme activity and the greatest impact on the spatial structure of protein. Chitosan would be one of the most potential anti-viral compounds.This study provides the theoretical basis to develop targeted Mpro inhibitors for the screening and application of anti-novel coronavirus drugs.