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排序方式: 共有9100条查询结果,搜索用时 15 毫秒
111.
Gwang-Suk You Ji-Whan Ahn Gi-Chun Han Hee-Chan Cho 《Korean Journal of Chemical Engineering》2006,23(2):237-240
This study measures the neutralizing capacity of bottom ash from municipal solid waste incineration of different particle
sizes. We examine the effect of particle size on the weathering process, a method popularly used for stabilization of heavy
metals in incineration of bottom ash. The distribution of particle sizes in municipal solid waste incineration bottom ash
is rather broad, ranging from fine powder to as large as 40 mm in diameter. Although considered a by-product highly suitable
as a road construction material, the high level of heavy metal leaching is an obstacle to its reuse. Weathering, a method
used to reduce heavy metal leaching, is a lengthy process taking over thee months to complete. The chief reaction involved
in weathering is carbonation occurring between Ca(OH)2 in bottom ash and CO2(g) in the atmosphere. During this process, CaCO3 is produced, causing the pH level to drop from over 12 to about 8.2 and reducing heavy metal leaching. In this paper, we
attempt to determine the particle size best suited for reducing the period required for weathering bottom ash by identifying
characteristics of different particle sizes that affect heavy metal leaching and neutralization. 相似文献
112.
Pd catalysts supported on TiO2, ZrO2, ZSM-5, MCM-41 and activated carbon were used in catalytic wet oxidation of hydrocarbons such as phenol, m-cresol and m-xylene.
It was found that the Pd/TiO2 catalyst was highly effective in the wet oxidation of hydrocarbon. The activities of catalysts with various hydrocarbon species,
catalyst support, oxidation state of catalyst performed in a 3-phase slurry reactor show that reaction on Pd surface is more
favorable than that in aqueous phase and that the active site is oxidized Pd in catalytic wet air oxidation of hydrocarbons.
Based on the experimental results, a plausible reaction mechanism of wet oxidation of hydrocarbons catalyzed over Pd/TiO2 catalyst was proposed. This catalyst is superior to other oxide catalysts because it suppressed the formation of hardly-degradable
organic intermediates and polymer. 相似文献
113.
Wang-Gi Kim Jaeyoung Yang Sangsup Han Chanhwi Cho Chang-Ha Lee Hanju Lee 《Korean Journal of Chemical Engineering》1995,12(5):503-511
An experimental and theoretical study is performed for bulk separation of H2/CO2 mixture (70/30 volume %) by PSA process with zeolite 5A, a process widely used commercially in conjunction with the catalytic
steam reforming of natural gas or naphtha. For the optimized adsorption conditions of PSA, the characteristics of adsorption/desorption
characteristics have been studied through breakthrough and desorption experiments under various conditions. The purge-to-feed
ratio is important to the H2 product purity only at a long adsorption step time. H2 could be concentrated from 70% in the feed to 99.99% at H2 recovery of 67.5%. The results of all five steps in PSA are successfully predicted by the LDF model considering an energy
balance and nonlinear isotherm. For the model, the effective diffusivities (D,) are obtained separately from the uptake curves
of H2 and CO2. The Langmuir-Freundlich isotherm is used to correlate the experimental equilibrium data and is very well fitted to the results. 相似文献
114.
Won-Ho Lee Hyoun-Ee Kim Seong-Jai Cho 《Journal of the American Ceramic Society》1997,80(10):2737-2740
Microstructural evolution of gas-pressure-sintered Si3 N4 with Yb2 O3 as a sintering aid was observed. Microstructures typical for in situ toughened Si3 N4 , i.e., large elongated grains randomly distributed in a fine matrix, were observed. However, the size of the elongated grains near the surface was much larger than that at the center, resulting in two distinct regions: an inner region and an outer region. The smaller the amount of Yb2 O3 added, the larger the difference in the size of the elongated grains between the outer and inner regions. The difference between microstructures was diminished when 16 wt% Yb2 O3 was added. The microstructural change with Yb2 O3 content was attributed to the evaporation of Yb-containing liquid phase from the surface. 相似文献
115.
Hyeon Gyu Kim Yoo Hyun Park Yang Hyun Cho Myoung Ho Kim 《Journal of Intelligent Information Systems》2014,43(2):323-347
The join is an important operator in processing data streams. To produce outputs continuously over unbounded data streams, sliding windows are generally used to limit the scope of the join at a certain time. In the existing join algorithms, only a simple type of windows have been considered, which are updated whenever a new data item arrives on any input stream. On the other hand, a more common type of windows have not been addressed yet, whose intervals are updated periodically, i.e., slid by a predefined time interval. In this paper, we consider the time-slide windows in joining multiple data streams. The algorithm for the time-slide window join can vary according to (i) how frequently the join is evaluated and (ii) which structure is used for windowing. Regarding this, possible algorithms are discussed, and experimental results that compare their performances are provided in this paper. 相似文献
116.
Fault identification for process monitoring using kernel principal component analysis 总被引:2,自引:0,他引:2
In this research, we develop a new fault identification method for kernel principal component analysis (kernel PCA). Although it has been proved that kernel PCA is superior to linear PCA for fault detection, the fault identification method theoretically derived from the kernel PCA has not been found anywhere. Using the gradient of kernel function, we define two new statistics which represent the contribution of each variable to the monitoring statistics, Hotelling's T2and squared prediction error (SPE) of kernel PCA, respectively. The proposed statistics which have similar concept to contributions in linear PCA are directly derived from the mathematical formulation of kernel PCA and thus they are straightforward to understand. The main contribution of this work is that we firstly suggest a fault identification method especially applicable to process monitoring using kernel PCA. To demonstrate the performance, the proposed method is applied to two simulated processes, one is a simple nonlinear process and the other is a non-isothermal CSTR process. The simulation results show that the proposed method effectively identifies the source of various types of faults. 相似文献
117.
The onset of thermal convection in a translucent porous layer is considered. Attention is focused on the effect of radiative heat transfer on the critical Rayleigh-Darcy number and the convection cell shape. If we consider the contribution of radiative heat transfer, the basic temperature profile is non-linear and the thermal convective instability is influenced by the ratio of conduction to radiation heat flux, the temperatures at the boundary surfaces, and radiative parameters such as wall emissivity, scattering albedo and extinction coefficient as well as the usual Rayleigh-Darcy number. Effects of these parameters on the onset of convective instability are investigated with the help of linear stability theory employing the Darcy's law and the radiative transport equation simplified by the P1 approximation. The increased effective thermal conductivity due lo the radiation inhibits the onset of convection and causes increased critical Rayleigh-Darcy number and decreased convection cell size. The results of the present work may be exploited to find out the optimal diameter of aerogel pellets and the air pressure in the double pane window filled with the translucent silica aerogel granules to suppress natural convection. 相似文献
118.
The farnesoid X receptor (FXR, NR1H4) has been recognized as an attractive therapeutic target because it is a nuclear hormone
receptor that controls the expression level of cholesterol-7α-hydroxylase, which in turn regulates bile acid production and
cholesterol excretion. To compare receptor activity between each domain and the full-length protein, human FXR cDNA was cloned
from a human liver cDNA library. Three human FXR cDNA, designated FXR20, FXR33, and FXR53 cDNA, were subcloned and ligated into a pET28a expression vector. Each protein was expressed in Escherichia coli (BL21) and purified by nickel-nitrilotriacetic acid column chromatography. Approximately 5 mg of FXR33 (1–182 amino acids deleted from FXR, 37 kDa) and 2 mg of FXR53 (the full-length protein of FXR, 59 kDa) was purified from 1 L of Luria-Bertani culture, achieving at least 90% purity. The
coactivator recruitment assay for FXR activation was carried out with the three variants of the FXR protein by using dissociation-enhanced
lanthanide fluoroimmunoassay-europium-N1-labeled anti-His antibody. From an optimized assay, a saturated hyperbolic fluorescence signal curve was produced when 250
nM of FXR33 and 100 nM of steroid receptor coactivator-1 peptide, a coactivator of FXR consisting of 26 amino acids, were used with a
concentration dependence on chenodeoxycholic acid (from 0 to 200 μM). The ligand-binding domain of FXR (FXR33) was the most suitable protein for studying the activation of FXR with a fluorescence-based assay, because it showed better
structural stability than either the full length of FXR (FXR53) or the DNA-binding domain of FXR (FXR20). 相似文献
119.
Sung‐Jun Cho 《应用聚合物科学杂志》2003,88(8):1904-1910
The polymerization of ?‐caprolactam between the interlamellar spaces of the [TEACOOH]–montmorillonite intercalations complex was attempted using Na–montmorillonite and 10‐carboxy‐n‐decyltriethylammonium bromide to achieve [TEACOOH]–polycaprolactam–montmorillonite, in which montmorillonite (inorganic polymer) is chemically bonded with the polycaprolactam (organic polymer). The results of X‐ray and IR analysis for the samples obtained after polymerization showed that the polymerization reaction has been successfully accomplished. For the purpose of studying the polymeric reaction product more precisely, we have isolated the polymerized product from the silicate layers and analyzed it with X‐ray diffractometer and IR spectrometer. Comparison of the results of X‐ray and IR analysis between the isolated polymer and the polymer that was synthesized by the reaction of ?‐caprolactam only with the organic cation without montmorillonite showed that both obtained polymers are the same compounds. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1904–1910, 2003 相似文献
120.
Sang-Chul Jung Sun-Jae Kim Nobuyuki Imaishi Yong-Ick Cho 《Applied catalysis. B, Environmental》2005,55(4):253-257
TiO2 photocatalyst films having an anatase crystal structure with different thickness were prepared by the low-pressure metal–organic chemical vapor deposition (LPMOCVD) to examine the effect of growth conditions on photocatalytic activity. Film thickness was linearly proportional to the deposition time. Structure of the film was strongly dependent on the deposition time. In early stage of deposition, fine particles deposit on the substrate. As increasing the deposition time, crystal orientation is gradually selected following the Kolmogorov model and c-axis oriented columnar crystals become dominant. The photocatalytic activity strongly depends on the film deposition time (or film thickness) in nonlinear way. The optimum thickness of TiO2 catalyst film grown by LPMOCVD may locate between 3 and 5 μm. 相似文献