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Investigation of Narrow Pore Size Distribution on Carbon Dioxide Capture of Nanoporous Carbons
Long-Yue Meng,박수진 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.11
Nanoporous carbons with a high specific surface area were prepared directly from thermoplastic acrylic resin as carbon precursor and MgO powder as template by carbonization over the temperature range, 500-1000 °C. The effect of the carbonization temperature on the pore structure and CO2 adsorption capacity of the obtained porous carbon was examined. The textural properties and morphology of the porous carbon materials were analyzed by N2/−196 °C and CO2/0 °C adsorption/desorption isotherms, SEM and TEM. The CO2 adsorption capacity of the prepared porous carbon was measured at 25 °C and 1 bar and 30 bar. The specific surface area increased from 237 to 1251 m2/g, and the total pore volumes increased from 0.242 to 0.763 cm3/g with increasing the carbonization temperature. The carbonization temperature acts mainly by generating large narrow micropores and mesopores with an average pore size dependent on the level of carbonization of the MgO-templated nanoporous carbons. The results showed that the MgO-templated nanoporous carbons at 900 °C exhibited the best CO2 adsorption value of 194 mg/g at 1 bar.
Long-Yue Meng,박수진 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.1
In this work, the reduced graphene nanosheets were synthesized from pre-exfoliated graphite flakes. The pristine graphite flakes were firstly pre-exfoliated to graphite nanoplatelets in the presence of acetic acid. The obtained graphite nanoplatelets were treated by Hummer’s method to produce graphite oxide sheets and were finally exfoliated to graphene nanosheets by ultrasonication and reduction processes. The prepared graphene nanosheets were studied by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscopy (AFM), and transmission electron microscopy (TEM). From the results, it was found that the preexfoliation process showed significant influence on preparation of graphite oxide sheets and graphene nanosheets. The prepared graphene nanosheets were applied to the preparation of conductive materials, which yielded a greatly improved electrical resistance of 200 Ω/sq.
Preparation and characterization of agricultural waste-based porous carbons for adsorbents
( Long-yue Meng ),( Haili Pan ),박수진 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0
In this work, a series of porous carbons were used to delineate agricultural waste the role of micro-/meso-pores in CO2 adsorption. Porous carbons were prepared from corncob by the carbonization of a mixture with magnesium acetate. And then, the prepared porous carbons were activated with CO2. The textural properties of porous carbons were investigated by N2/77 K full isotherms and SEM. This result indicated that the porosity of porous carbons attributed to the MgO template and CO2 activation. It was also found that the CO2 activation led to an increase in CO2 adsorption efficiency of porous carbons, mainly due to an increase of microporosity on porous carbon surfaces.
Effect of Heat Treatment on CO<SUB>2</SUB> Adsorption of Ammonized Graphite Nanofibers
Long-Yue Meng,Ki-Sook Cho,Soo-Jin Park 한국탄소학회 2010 Carbon Letters Vol.11 No.1
In this work, graphite nanofibers (GNFs) were prepared by ammonia and heat treatment at temperatures up to 1000℃ to improve its CO2 adsorption capacity. The effects of the heat treatment on the textural properties and surface chemistry of the GNFs were investigated by N2 adsorption isotherms, XRD, and elemental analysis. We found that the chemical properties of GNFs were significantly changed after the ammonia treatment. Mainly amine groups were formed on the GNF surfaces such as lactam groups, pyrrole and pyridines. The GNFs treated at 500℃ showed highest CO2 adsorption capacity of 26.9 mg/g at 273 K in this system.
Yue-Long Lyu,Xiao-Xin Liu,Peng-Yuan Wang,Erni, Daniel,Qun Wu,Cong Wang,Nam-Young Kim,Fan-Yi Meng Institute of Electrical and Electronics Engineers 2016 IEEE transactions on antennas and propagation Vol.64 No.6
<P>In this paper, we propose an approach to realize substrate integrated waveguide (SIW)-based leaky-wave antennas (LWAs) supporting continuous beam scanning from backward to forward above the cutoff frequency. First, through phase delay analysis, it was found that SIWs with straight transverse slots support backward and forward radiation of the -1-order mode with an open-stopband (OSB) in between. Subsequently, by introducing additional longitudinal slots as parallel components, the OSB can be suppressed, leading to continuous beam scanning at least from -40 degrees through broadside to 35 degrees. The proposed method only requires a planar structure and obtains less dispersive beam scanning compared with a composite right/left-handed (CRLH) LWA. Both simulations and measurements verify the intended beam scanning operation while verifying the underlying theory.</P>
Sliding Mode Control of Three-Phase Four-Leg Inverters via State Feedback
Long-Yue Yang,Jian-Hua Liu,Chong-Lin Wang,Gui-Fu Du 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.5
To optimize controller design and improve static and dynamic performances of three-phase four-leg inverter systems, a compound control method that combines state feedback and quasi-sliding mode variable structure control is proposed. The linear coordinate change matrix and the state variable feedback equations are derived based on the mathematical model of three-phase four-leg inverters. Based on system relative degrees, sliding surfaces and quasi-sliding mode controllers are designed for converted linear systems. This control method exhibits the advantages of both state feedback and sliding mode control. The proposed controllers provide flexible dynamic control response and excellent stable control performance with chattering suppression. The feasibility of the proposed strategy is verified by conducting simulations and experiments.
A Novel Phase Locked Loop for Grid-Connected Converters under Non-Ideal Grid Conditions
Long-Yue Yang,Chong-Lin Wang,Jian-Hua Liu,Chen-Xi Jia 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.1
Grid synchronization is one of the key techniques for the grid-connected power converters used in distributed power generation systems. In order to achieve fast and accurate grid synchronization, a new phase locked loop (PLL) is proposed on the basis of the complex filter matrixes (CFM) orthogonal signal generator (OSG) crossing-decoupling method. By combining first-order complex filters with relation matrixes of positive and negative sequence voltage components, the OSG is designed to extract specific frequency orthogonal signals. Then, the OSG mathematical model is built in the frequency-domain and time-domain to analyze the spectral characteristics. Moreover, a crossing-decoupling method is suggested to decouple the fundamental voltage. From the eigenvalue analysis point of view, the stability and dynamic performance of the new PLL method is evaluated. Meanwhile, the digital implementation method is also provided. Finally, the effectiveness of the proposed method is verified by experiments under unbalanced and distorted grid voltage conditions.