The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Uendo Lee - One of the best experts on this subject based on the ideXlab platform.
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quasi equilibrium thermodynamic model with empirical equations for air steam biomass gasification in fluidized beds
Fuel Processing Technology, 2014Co-Authors: Youngil Lim, Uendo LeeAbstract:Abstract Gasification is one of the most promising technologies for converting biomass into a fuel. This study presents a simple and practical biomass gasification model based on thermodynamic equilibrium to find effective operating conditions of the air–steam gasification system in fluidized-beds. The carbon conversion fraction empirically obtained was involved in a global gasification reaction. Two empirical equations as the non-equilibrium factor expressing the deviation from equilibrium were derived as the function of the equivalence ratio ( ER ) from 43 experimental data sets of various operating conditions and different feedstocks. One energy balance was also solved for determining the gasification temperature ( T ). After the producer gas composition with respect to ER and steam to biomass ratio ( SBR ) was obtained from the air–steam biomass gasification (ASBG) model, process performances such as lower heating value, heat efficiency, net heat efficiency, and H 2 /CO molar ratio were evaluated. An effective operating area was suggested from the Contour Plot of the process performances with respect to ER and SBR in the auto-thermal gasification temperature from 700 to 830 °C.
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Quasi-equilibrium thermodynamic model with empirical equations for air–steam biomass gasification in fluidized-beds
Fuel Processing Technology, 2014Co-Authors: Youngil Lim, Uendo LeeAbstract:Abstract Gasification is one of the most promising technologies for converting biomass into a fuel. This study presents a simple and practical biomass gasification model based on thermodynamic equilibrium to find effective operating conditions of the air–steam gasification system in fluidized-beds. The carbon conversion fraction empirically obtained was involved in a global gasification reaction. Two empirical equations as the non-equilibrium factor expressing the deviation from equilibrium were derived as the function of the equivalence ratio ( ER ) from 43 experimental data sets of various operating conditions and different feedstocks. One energy balance was also solved for determining the gasification temperature ( T ). After the producer gas composition with respect to ER and steam to biomass ratio ( SBR ) was obtained from the air–steam biomass gasification (ASBG) model, process performances such as lower heating value, heat efficiency, net heat efficiency, and H 2 /CO molar ratio were evaluated. An effective operating area was suggested from the Contour Plot of the process performances with respect to ER and SBR in the auto-thermal gasification temperature from 700 to 830 °C.
Youngil Lim - One of the best experts on this subject based on the ideXlab platform.
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quasi equilibrium thermodynamic model with empirical equations for air steam biomass gasification in fluidized beds
Fuel Processing Technology, 2014Co-Authors: Youngil Lim, Uendo LeeAbstract:Abstract Gasification is one of the most promising technologies for converting biomass into a fuel. This study presents a simple and practical biomass gasification model based on thermodynamic equilibrium to find effective operating conditions of the air–steam gasification system in fluidized-beds. The carbon conversion fraction empirically obtained was involved in a global gasification reaction. Two empirical equations as the non-equilibrium factor expressing the deviation from equilibrium were derived as the function of the equivalence ratio ( ER ) from 43 experimental data sets of various operating conditions and different feedstocks. One energy balance was also solved for determining the gasification temperature ( T ). After the producer gas composition with respect to ER and steam to biomass ratio ( SBR ) was obtained from the air–steam biomass gasification (ASBG) model, process performances such as lower heating value, heat efficiency, net heat efficiency, and H 2 /CO molar ratio were evaluated. An effective operating area was suggested from the Contour Plot of the process performances with respect to ER and SBR in the auto-thermal gasification temperature from 700 to 830 °C.
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Quasi-equilibrium thermodynamic model with empirical equations for air–steam biomass gasification in fluidized-beds
Fuel Processing Technology, 2014Co-Authors: Youngil Lim, Uendo LeeAbstract:Abstract Gasification is one of the most promising technologies for converting biomass into a fuel. This study presents a simple and practical biomass gasification model based on thermodynamic equilibrium to find effective operating conditions of the air–steam gasification system in fluidized-beds. The carbon conversion fraction empirically obtained was involved in a global gasification reaction. Two empirical equations as the non-equilibrium factor expressing the deviation from equilibrium were derived as the function of the equivalence ratio ( ER ) from 43 experimental data sets of various operating conditions and different feedstocks. One energy balance was also solved for determining the gasification temperature ( T ). After the producer gas composition with respect to ER and steam to biomass ratio ( SBR ) was obtained from the air–steam biomass gasification (ASBG) model, process performances such as lower heating value, heat efficiency, net heat efficiency, and H 2 /CO molar ratio were evaluated. An effective operating area was suggested from the Contour Plot of the process performances with respect to ER and SBR in the auto-thermal gasification temperature from 700 to 830 °C.
Fang Chen - One of the best experts on this subject based on the ideXlab platform.
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Optimization of oxalic acid pretreatment of moso bamboo for textile fiber using response surface methodology
Cellulose, 2014Co-Authors: Bo Hong, Linzheng Chen, Guoxin Xue, Qin Xie, Fang ChenAbstract:In this article, samples of moso bamboo were pretreated with oxalic acid under various process conditions. Response surface methodology was applied to optimize the pretreatment conditions. A three-variable quadratic polynomial regression model was obtained to predict the cellulose content, lignin removal and hemicellulose solubilization. The reliability of the model was also evaluated by the key elements obtained from analysis of variance of the coefficients. The surface response Plot and Contour Plot of the effects were studied to further examine the interactions of the three factors and determine the optimum levels of each factor. Finally, the optimized conditions for oxalic acid pretreatment were temperature 178.4 °C, 3.68 % oxalic acid and 28.4 min, respectively. The maximum predicted value of cellulose content in the residue fraction was 64.98 %, along with 79.43 % lignin removal and 96.71 % hemicellulose solubilization after the oxalic acid pretreatment.
Myeong-ki Hong - One of the best experts on this subject based on the ideXlab platform.
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The relationship between post-stent strut apposition and follow-up strut coverage assessed by a Contour Plot optical coherence tomography analysis.
JACC. Cardiovascular interventions, 2014Co-Authors: Jung-sun Kim, Byeong-keuk Kim, Dong-ho Shin, Donghoon Choi, Yangsoo Jang, Myeong-ki HongAbstract:Objectives This study sought to evaluate the relationship between post-stent strut apposition and follow-up strut coverage using Contour Plot optical coherence tomographic analysis. Background Tracking the fate of interested regions of struts at different time points has not been investigated. Methods Post-intervention and 6-month follow-up optical coherence tomographic evaluations were performed in 82 patients treated with biolimus- (n = 37) or sirolimus-eluting stents (n = 45). Post-stent apposition was classified as embedded, apposed, or malapposed. For volumetric stent evaluation, the post-intervention strut-artery distance and the neointimal thickness at follow-up were measured as a function of the circumferential arc length and longitudinal stent length. Computer-generated Contour Plots of the strut-artery distance and neointimal thickness were compared. Results The percentages of embedded and malapposed struts after intervention were 1.8% (Interquartile range [IQR]: 0.6% to 6.2%) and 2.3% (IQR: 0.5% to 5.2%), respectively. The percentages of uncovered and malapposed struts at 6 months were 16.0% (IQR: 7.4% to 33.3%) and 0% (IQR: 0% to 0.7%), respectively. The percentage of uncovered struts at 6 months varied significantly with post-stent strut apposition (0% [IQR: 0% to 11.4%] in embedded, 16.3% [IQR: 8.1% to 31.3%] in apposed, and 26.8% [IQR: 0% to 56.3%] in malapposed, p Conclusions The optical coherence tomography–guided optimization of stent strut apposition enhances strut coverage at follow-up. This comprehensive method for evaluating strut apposition may provide more useful information to understanding the serial changes in strut coverage. (Neointimal Coverage After Implantation of Biolimus Eluting Stent With Biodegradable Polymer: Optical Coherence Tomographic Assessment According to the Treatment of Dyslipidemia and Hypertension and the Types of Implanted Drug-Eluting Stents; NCT01502904 )
Rudolph A. Marcus - One of the best experts on this subject based on the ideXlab platform.
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Global Potential Energy Contour Plots for Chemical Reactions. Stepwise vs Concerted 2 + 2 Cycloaddition
Journal of the American Chemical Society, 1995Co-Authors: Rudolph A. MarcusAbstract:A global Contour Plot is described for reactions involving stepwise or concerted addition of two ethylenes to form cyclobutane. The relevant isomers of the various species and of the reaction paths, with plains or valleys, minima, saddle points, and domes or conical intersections, are described. Two collective asymmetric coordinates are introduced as axes for the Plot, which presents an overview of the system and which complements the usual 2-dimensional cuts of the many-dimensional potential energy surface. Other global coordinates are also introduced. The Plot involves a pointwise minimization of the potential energy with respect to the coordinates not used as axes. A permutation symmetry can be used to derive the various coordinates. Free energy and entropy (or number of states) curves versus a reaction coordinate are discussed.
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Global potential energy Contour Plots for chemical reactions. Multiple reaction paths, bifurcations, and applicability of transition-state theory
The Journal of Physical Chemistry, 1991Co-Authors: Rudolph A. MarcusAbstract:A global reduced-dimensional potential energy Contour Plot is described for the simultaneous representation of reactions X-3Y ⇌ X_2 + XY, X_3Y ⇌ X + X_2Y, and X_2 + YX ⇌ X_2Y + X, where the X's may be different. The analysis provides some insight into the nature of the transition states, the role of bifurcations, and the applicability of transition-state theory (TST). Recent results of a quantum chemistry calculation for the X = H, Y = 0 system are discussed in these terms. More generally, some Topographical conditions for the inapplicability of TST are suggested. This limitation of TST arises from a preempting of the transition state for one reaction by another and appears to be relatively rare.