Refractory pollutants, including lignin, tannic acid, chlortetracycline, and EDTA, were destroyed by an electrochemical oxidation method to evaluate the applicability of this method for industrial wastewater pretreatment. Operation parameters, such as supporting electrolyte, current density, and electrolyte concentration, have been investigated for their influences on COD removal efficiencies during electrolysis. In addition, gel permeation chromatography (GPC), Microtox test, and total organic halogen (TOX) analyses were performed to monitor the changes of organic characteristics of these refractory pollutants. Experimental results show that, among sulfate, nitrate, and chloride, chloride was the best supporting electrolyte, and during electrolysis, both COD and color removal efficiencies were improved by increasing current density and chloride concentration. From GPC analysis results, the electrochemical oxidation process readily destroys high-molecular-weight (HMW) organics. Microtox test results also show that the process can reduce the toxicity of these refractory organic compounds. In addition, TOX concentrations were found to increase at the beginning but then decline during the electrolysis. The above results suggest that the electrochemical oxidation process, which has good efficacy for detoxification and destruction of refractory pollutants, is a promising method for wastewater pretreatment.
This article presents the results of an acoustic analysis of vowels and plosives/affricates produced by 45 Mandarin-speaking children with hearing impairment. Vowel production is represented and categorized into three groups by vowel space size calculated with normalized F1 and F2 values of corner vowels. The correlation between speech intelligibility and language abilities assessed by the level of word comprehension and the complexity of sentence structure is statistically significant. Vowel space grouping is correlated with speech intelligibility and spike percentage of plosives/affricates production. The generalized linear model analysis also shows that the level of word comprehension and the degree of hearing loss are the two most significant factors in predicting speech intelligibility. The statistical results suggest that the interplay of acoustic characteristic and speech ability is complex.
The issue of processing and understanding spontaneous speech interests speech engineers and linguists, because spontaneous speech is the most natural and the most frequent form of language used for communication. However, the lack of well-defined databases of spontaneous speech prohibits the scale and the depth of spontaneous speech research to a great extent. By using the methodology of corpus linguistics, this paper shows that linguistic theories can be examined, approved or disproved by quantitative empirical analyses. The studies introduced in this paper contain a pioneering work on corpus-based analyses of syllable contractions in spontaneous Mandarin by construing spontaneous Mandarin database incorporated with linguistic considerations into the spontaneous speech phenomena. Corpus-based results presented in this paper not only confirm characteristics of syllable contraction with respect to Chinese phonology, but also provide new insights into lexical factors that influence the production of syllable contractions.
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