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排序方式: 共有225条查询结果,搜索用时 93 毫秒
1.
Ana M. García José M. Villora Diego A. Moreno Carlos Ranninger Pío Callejas M. Flora Barba 《Journal of the American Ceramic Society》2003,86(12):2200-2202
The objective of this research was to study the removal of cadmium and lead from an aqueous solution through a biological treatment. For this purpose a glass-ceramic material was manufactured from industrial and urban wastes. Biofilms of microorganisms found in wastewater were developed on its surface, and continuous tests were conducted in the presence and absence of the biofilm to analyze the glass-ceramic's ability to remove the heavy metals from an aqueous environment. The results suggest that this bioremediation process, developed on an industrial scale, could represent an alternative to the chemical processes currently used. 相似文献
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The Fe/ZrO2 catalyst (1% Fe by weight) shows a strong adsorption capacity toward the nitric oxide (at room temperature the ratio NOFe is ca. 0.5) as a consequence of the formation of a highly dispersed iron phase after reduction at 500–773 K. Nitric oxide is adsorbed mainly as nitrosyl species on the reduced surface where the Fe2+ sites are prevailing, but it is easily oxidised by oxygen forming nitrito and nitrato species adsorbed on the support. However, in the presence of a reducing gas such as hydrogen, carbon monoxide, propane and ammonia at 473–573 K the Fe-nitrosyl species react producing nitrogen, nitrous oxide, carbon dioxide and water, as detected by FTIR and mass spectrometers. The results show that nitric oxide reduction is more facile with hydrogen containing molecules than with CO, probably due the co-operation of spillover effects. Experiments carried out with the same gases in the presence of oxygen show, however, a reduced dissociative activity of the surface iron sites toward the species NOχ formed by NO oxidation and therefore the reactivity is shifted to higher temperatures. 相似文献
4.
A novel process was developed for the bitumen emulsion upgrading, wherein emulsion breaking and upgrading occurred in the same reactor using H2 generated in situ from the water in the emulsion via the water gas shift reaction (WGSR). In this study, dibenzothiophene (DBT) was chosen as a model compound to investigate the effect of water and in situ H2 on hydrodesulfurization (HDS). All the experiments were performed in a 1-L autoclave reactor at temperatures between 300 and 380 °C using in situ H2 and ex situ H2 (externally supplied H2) over a dispersed Mo catalyst formed from phosphomolybdic acid (PMA). At very low water content, water was found to promote the HDS reaction in the ex situ H2 run probably because it facilitates the formation of more active dispersed MoSx species. At higher water content, however, water inhibits every individual reaction in the reaction network in the HDS of DBT, blocking the hydrogenation pathway more than the hydrogenolysis pathway. The relative reactivity of the in situ and ex situ H2 depends on the water content present in the reaction system. At an optimized mole ratio of H2O:CO (1.35), higher HDS activity was observed in the in situ H2 run compared to ex situ H2 run, and particularly, the hydrogenation pathway was promoted in the in situ H2 run. 相似文献
5.
Flora S. Tsai 《Expert systems with applications》2011,38(5):5330-5335
Blog mining addresses the problem of mining information from blog data. Although mining blogs may share many similarities to Web and text documents, existing techniques need to be reevaluated and adapted for the multidimensional representation of blog data, which exhibit dimensions not present in traditional documents, such as tags. Blog tags are semantic annotations in blogs which can be valuable sources of additional labels for the myriad of blog documents. In this paper, we present a tag-topic model for blog mining, which is based on the Author-Topic model and Latent Dirichlet Allocation. The tag-topic model determines the most likely tags and words for a given topic in a collection of blog posts. The model has been successfully implemented and evaluated on real-world blog data. 相似文献
6.
Globally, wastewater treatment plants are under pressure to handle high concentration sludge in a sludge treatment line. Unawareness of the non-Newtonian behaviour of the thickened sludge has the potential to cause unexpected problems when the fluid behaviour changes from turbulent to laminar flow. In this study, sludge apparent viscosity was plotted as a function of total suspended solids concentration (TSS) and shear rate. Then, the transition velocity based on several predictive models in the literature was determined. This analysis provides a practical basis for the prediction of the pipe flow behaviour of thickened sludge in troubleshooting and engineering design. 相似文献
7.
Flora S. Tsai 《Expert systems with applications》2012,39(5):4965-4971
This paper describes the usage of dimensionality reduction techniques for computer facial animation. Techniques such as Principal Components Analysis (PCA), Expectation-Maximization (EM) algorithm for PCA, Multidimensional Scaling (MDS), and Locally Linear Embedding (LLE) are compared for the purpose of facial animation of different emotions. The experimental results on our facial animation data demonstrate the usefulness of dimensionality reduction techniques for both space and time reduction. In particular, the EMPCA algorithm performed especially well in our dataset, with negligible error of only 1-2%. 相似文献
8.
Joseph E. Williams Ramesh Goel Joseph R. V. Flora Radisav Vidic 《Canadian Metallurgical Quarterly》2005,131(11):1583-1588
A two-stage mathematical model was developed to describe adsorbate removal in a dead-end powdered activated carbon/ultrafiltration (PAC/UF) membrane process. Para-nitrophenol (PNP) was used as the model organic compound. The first stage accounted for adsorbate removal during transport from the initial PAC contact with the PNP solution to the membrane system, and the second stage accounted for additional PNP removal due to the retention of the PAC in a growing bed on the membrane surface. The PAC adsorptive capacity was described using the Langmuir isotherm, whose parameters were estimated from isotherm experiments. Transport of the PNP through the PAC particle was described using the homogeneous surface diffusion model and the surface diffusivity was estimated from batch experiments. The two stage model predicted the effluent concentrations from the PAC/UF process during the early stages of the experiments, but model improvements are required to more accurately predict the latter stages. A batch model can be used to describe the effluent PNP concentration from the PAC/UF process if dispersion is neglected. 相似文献
9.
The feasibility of electric current prompted aerobic biodegradation of NH4+–N in an attached growth bioreactor system is demonstrated. Nitrification was induced at electric current densities of 1.25 and 2.5?mA/cm2 and with pure oxygen supplied at a rate equivalent to 1.25?mA/cm2 when the bioreactor was operated in batch mode at 6 days detention time. About 84% (27?mg/L)?NH4+–N loss was observed at the end of each detention period during all three experimental conditions, indicating that the electric current did not negatively impact the rate of nitrification. Nitrite accumulation was observed during the initial stages of nitrification experiments with 1.25?mA/cm2 current intensity, but nitrite did not accumulate during the other two sets of nitrification experiments. A mathematical model formulated to obtain the rates of biological reactions showed that rates of NH4+–N removal are similar for all aeration conditions. Abiotic experiments showed that NH4+–N was not removed electrolytically and via stripping, confirming that NH4+–N disappearance is due to biological activity. 相似文献
10.
This study describes trajectories of substance use and dependence from adolescence to adulthood. Identified consumption groups include heavy drinking/heavy drug use, moderate drinking/experimental drug use, and light drinking/rare drug use. Dependence groups include alcohol only, drug only, and comorbid groups. The heavy drinking/heavy drug use group was at risk for alcohol and drug dependence and persistent dependence and showed more familial alcoholism, negative emotionality, and low constraint. The moderate drinking/experimental drug use group was at risk for alcohol dependence but not comorbid or persistent dependence and showed less negative emotionality and higher constraint. Familial alcoholism raised risk for alcohol and drug use and dependence in part because children from alcoholic families were more impulsive and lower in agreeableness. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献