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排序方式: 共有575条查询结果,搜索用时 265 毫秒
281.
Journal of Material Cycles and Waste Management - This study aims to promote and revitalise quality control by efficiently separating impurities from recycled fine aggregates and soil. To meet this... 相似文献
282.
Lee Hyun-Kyu Choi Jung-Weon Kim Jin-Hee Kim Cho-Rong Choi Sang-June 《Environmental science and pollution research international》2021,28(31):42014-42023
Environmental Science and Pollution Research - Composite beads consisting of Ca alginate mixed with zinc ferrocyanide (ZnFC) and Cyanex 272 were synthesized in order to selectively adsorb Cs+ and... 相似文献
283.
Ji Eun Lee Hang Seok Choi Yong Chil Seo 《Journal of Material Cycles and Waste Management》2014,16(4):665-676
For designing an efficient circulating fluidized bed reactor, understanding the complex hydrodynamic characteristics in the reactor is required. Hence, in the present study, the modeling and simulation of the circulating fluidized bed gasifier using plastic waste were carried out with Eulerian-Granular approach. Several cases were investigated as changing superficial gas velocities or sizes of plastic waste particle. Firstly, cases were examined with four different velocities when the particle diameter is 1 mm. At the gas velocity of 6 or 8 m/s, gas volume fraction is more than 95 % throughout the reactor and particle velocity has positive value overall. Therefore, a circulating fluidized bed seems to be formed in both cases. Comparing those two cases, better solid mixing can be expected considering the mass fraction and solid velocity at the superficial gas velocity of 6 m/s. Thus this case was further studied for the effect of particle size. As the diameters of plastic waste particle are 1 or 3 mm, it is considered that a circulating fluidized bed is formed. And plastic waste and sand particles are well mixed throughout the reactor. However, the particle diameter increases over 3 mm then, it is very hard to maintain circulating fluidization condition. 相似文献
284.
Ganga Ram Maharjan Youn Shik Park Nam Won Kim Dong Seok Shin Jae Wan Choi Geun Woo Hyun Ji-Hong Jeon Yong Sik Ok Kyoung Jae Lim 《Frontiers of Environmental Science & Engineering》2013,7(1):109-119
A study was undertaken for the prediction of runoff flow from 0.8 ha field-sized agricultural watershed in South Korea using Soil and Water Assessment Tool (SWAT) sub-daily. The SWAT model with sub-daily configuration predicted flow from the watershed within the range of acceptable accuracy. The SWAT sub-daily simulations were carried out for a total of 18 rainfall events, 9 each for calibration and validation. Overall trend and extent of matching simulated flow for the rainfall events in 2007-2008 with measured data during the calibration process were coefficient of determination (R 2) value of 0.88 and Nash and Sutcliffe Efficiency (E NS) value of 0.88. For validation, R 2 and E NS values were 0.9 and 0.84, respectively. Whereas R 2 and E NS values for simulation results using daily rainfall data were 0.79 and -0.01, respectively, that were observed to be out of acceptable limits for the model simulation. The importance of higher time resolution (hourly) precipitation records for flow simulation were evaluated by comparing R 2 and E NS with 15 min, 2 h, 6 h and 12 h precipitation data, which resulted in lower statistics with increases in time resolution of precipitation data. The SWAT sub-daily sensitivity analysis was performed with the consideration of hydraulic parameter and was found as in the rank order of CN2 (curve number), ESCO (soil evaporation compensation factor), GW_DELAY (ground water delay time), ALPHA_BF ( base flow alpha factor), GWQMN ( a threshold minimum depth of water in the shallow aquifer required for return flow to occur) , REVAPMN (minimum depth of water in shallow aquifer for re-evaporation to occur) , LAT_TIME (lateral flow travel time) respectively. These sensitive parameters were evaluated at 10% higher and lower values of the parameters, corresponding to 70.5% higher and 23.2% lower in simulated flow out from the SWAT model. From the results obtained in this study, hourly precipitation record for SWAT sub-daily with Green-Ampt infiltration method was proven to be efficient for runoff estimation at field sized watershed with higher accuracies that could be efficiently used to develop site-specific Best Management Practices (BMPs) considering rainfall intensity, rather than simply using daily rainfall data. 相似文献
285.
Y.-B. Yi J.-L. Lee Y.-H. Choi S.-M. Park C.-H. Chung 《Environmental Chemistry Letters》2012,10(1):13-19
We report for the first time the direct conversion of raw grape berry biomass to hydroxymethylfurfural (HMF) using ionic liquid
solvents with metal chloride catalysts. Exploiting raw plant biomass as a biorefinery feedstock is innovative for sustainable
chemical industry. The use of the raw biomass to synthesize compounds can indeed lead to less energy consumption and less
CO2 emissions. Using raw plant biomass skips pretreatment steps that are required to produce biomaterials such as carbohydrates
or cellulosic biomass. Here, grape berry biomass was used as a raw chemical feedstock for the production of hydroxymethylfurfural,
a key platform intermediate for syntheses of future renewable biofuels. We examined 3 ionic liquid solvents, 3 reaction temperatures,
5 chloride catalysts, and 5 concentrations of HCl. We found an increasing HMF yields depending on reaction conditions. 1-octyl-3-methylimidazolium
chloride was most effective for HMF synthesis. Addition of HCl or metal chlorides alone showed little improvement. The highest
HMF yield of about 100 mg HMF per mL of grape biomass extract was obtained using 0.3 M HCl, [OMIM]Cl, and CrCl2 at 100°C for 3 h. Our study provides a model system of sustainable production of valuable compounds from raw plant biomass. 相似文献
286.
The present study examines the effects of training and development on organizational innovation. We specifically suggest that the training and development investments of an organization affect its innovative performance by promoting various learning practices. We empirically tested our hypothesis by using time‐lagged, multi‐source data collected from 260 Korean companies that represent diverse industries. Our analysis showed that corporate expenditure for internal training predicts interpersonal and organizational learning practices, which, in turn, increase innovative performance. The data also revealed that the positive relationship between interpersonal and organizational learning practices and innovative performance is stronger within organizations that have stronger innovative climates. By contrast, investment in employee development through financial support for education outside an organization poses a significant negative effect on its innovative performance and no significant effect on learning practices. The present study provides a plausible explanation for a mechanism through which the investment of an organization in employees enhances its innovative performance. Copyright © 2013 The Authors. Journal of Organizational Behavior published by John Wiley & Sons, Ltd. 相似文献
287.
Sanath KONDAVEETI Kwang Soon CHO Ramesh KAKARLA Booki MIN 《Frontiers of Environmental Science & Engineering》2014,8(5):784-791
Renewable algae biomass, Scenedesmus obliquus, was used as substrate for generating electricity in two chamber microbial fuel cells (MFCs). From polarization test, maximum power density with pretreated algal biomass was 102mW·m^2 (951mW·m^3) at current generation of 276mA·m^-2. The individual electrode potential as a function of current generation suggested that anodic oxidation process of algae substrate had limitation for high current generation in MFC. Total chemical oxygen demand (TCOD) reduction of 74% was obtained when initial TCOD concentration was 534mg · L^-1 for 150 h of operation. The main organic compounds of algae oriented biomass were lactate and acetate, which were mainly used for electricity generation. Other byproducts such as propionate and butyrate were formed at a negligible amount. Electrochemical Impedance Spectroscopy (EIS) analysis pinpointed the charge transfer resistance (112Ω ) of anode electrode, and the exchange current density of anode electrode was 1214 nA·cm^-2. 相似文献
288.
Muhammad Kashif Shahid Yunjung Kim Young-Gyun Choi 《Frontiers of Environmental Science & Engineering》2019,13(5):71
289.
Sewon Kim Dongseop Lee Jongwon Lee Seung-Kyong You Hangseok Choi 《Journal of Material Cycles and Waste Management》2012,14(4):360-370
In this study, a series of laboratory chamber tests was carried out to evaluate the applicability of a porous concrete pile fabricated with recycled aggregates for soft ground improvement. The recycled aggregate porous concrete pile (RAPP) has been developed to replace natural aggregates and to overcome technical problems associated with the conventional compaction piling systems. The laboratory chamber tests for evaluating the performance of RAPP were carried out with a cylindrical mold of 280?mm in internal diameter and 580?mm in height. A replacement area ratio of 5?% and three different loading steps were applied in the chamber tests. The experimental results of the surface settlement, excess pore pressure and vertical stress distribution versus time were compared with those of the sand compaction pile (SCP) reinforced composite ground under the same experimental condition. In addition, the experimental results were compared with the numerical simulation using ABAQUS. The current study shows that the settlement reduction in the RAPP-reinforced system is?significantly enhanced due to load transfer from the soil formation to the RAPP. Furthermore, the comparison of consolidation rates shows that the RAPP can also accelerate the consolidation of soft clay formation because the RAPP behaves as a vertical drain. 相似文献
290.
Kyoung Jae Lim Bernard A. Engel Zhenxu Tang Joongdae Choi Ki‐Sung Kim Suresh Muthukrishnan Dibyajyoti Tripathy 《Journal of the American Water Resources Association》2005,41(6):1407-1416
The separation of the base flow component from a varying streamflow hydrograph is called “hydrograph analysis.” In this study, two digital filter based separation modules, the BFLOW and Eckhardt filters, were incorporated into the Web based Hydrograph Analysis Tool (WHAT) system. A statistical component was also developed to provide fundamental information for flow frequency analysis and time series analysis. The Web Geographic Information System (GIS) version of the WHAT system accesses and uses U.S. Geological Survey (USGS) daily streamflow data from the USGS web server. The results from the Eckhardt filter method were compared with the results from the BFLOW filter method that was previously validated, since measured base flow data were not available for this study. Following validation, the two digital filter methods in the WHAT system were run for 50 Indiana gaging stations. The Nash‐Sutcliffe coefficient values comparing the results of the two digital filter methods were over 0.91 for all 50 gaging stations, suggesting the filtered base flow using the Eckhardt filter method will typically match measured base flow. Manual separation of base flow from streamflow can lead to inconsistency in the results, while the WHAT system provides consistent results in less than a minute. Although base flow separation algorithms in the WHAT system cannot consider reservoir release and snowmelt that can affect stream hydrographs, the Web based WHAT system provides an efficient tool for hydrologic model calibration and validation. The base flow information from the WHAT system can also play an important role for sustainable ground water and surface water exploitation, including irrigation and industrial uses, and estimation of pollutant loading from both base flow and direct runoff. Thus, best management practices can be appropriately applied to reduce and intercept pollutant leaching if base flow contributes significant amounts of pollutants to the stream. This Web GIS based system also demonstrates how remote, distributed resources can be shared through the Internet using Web programming. 相似文献