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Biological sulfate (SO42−) reduction was examined in anaerobic sequential batch reactors (ASBRs) operated under different hydraulic retention times (HRTs) ranging from 12 to 36 h and COD (Chemical Oxygen Demand)/SO42−) ratios of 2.4, 1.6 and 0.8. Competition between SO42− reducing bacteria (SRBs), methane producing archaea (MPAs) and homoacetogens (HACs) was examined in controls and cultures treated with linoleic acid (LA). The ASBR performance was influenced by the COD/SO42− ratio in control cultures with a SO42− reduction of 87% at a COD/SO42− ratio of 0.8. At a 12 h HRT, in both control and LA treated cultures, greater than 75% SO42− removal was observed under all the conditions examined. In control reactors operating at a 36 h HRT, high levels of MPAs belonging to Methanobacteriales and Methanosarcinales were detected; however, in comparison, under low COD/SO42− ratio and with decreasing HRT conditions, a relative increase in SRBs belonging to Desulfovibrio and Desulfatibacillum was observed. Adding 0.5 g·L−1 LA suppressed Methanobacteriales, while increasing the LA concentration to 1 g·L−1 completely suppressed MPAs with a relative increase in SRBs. HACs belonging to Bacteroidetes were observed in the control and in cultures operated at 12 h HRT with a COD/SO42− ratio of 1.6 and fed 0.5 g·L−1 LA; however, with all other LA levels (0.5 and 1.0 g·L−1) and HRTs (12, 24 and 36 h), HACs were not detected.

Taguchi statistical design, an orthogonal array (OA) method, was used to study the impact of the COD/SO42− ratio, hydraulic retention time (HRT) and linoleic acid (LA) concentration on sulfate (SO42−) reduction in an anaerobic sequencing batch reactor using glucose as the electron donor. Based on the OA, optimum condition for maximum SO42− reduction was evaluated. Increasing the COD/SO42− ratio and HRT caused decreasing SO42− reduction while increased SO42− reduction was observed with increasing LA concentration (1 g L−1). In control (not fed LA) cultures, higher SO42− reduction (87% ± 3%) was observed at a low COD/SO42− ratio of 0.8. This indicates that increasing SO42− reduction was observed at increasing SO42− loading rates. In general, results from this study reveal that limiting the substrate concentration with high SO42− levels (low COD/SO42− ratio) favors high SO42− removal. Surface plots were used to evaluate the significant interactions between the experimental factors. Accuracy of the model was verified using an analysis of residuals. Optimum conditions for maximum SO42− reduction (97.61%) were observed at a COD/SO42− ratio of 0.8 (level 1), 12 h HRT (level 1) together with 1000 mg L−1 LA addition (level 3). In general, the Taguchi OA provided a useful approach for predicting the percent SO42− reduction in inhibited mixed anaerobic cultures within the factor levels investigated.

The constant modulus algorithm (CMA) is an excellent technique for blind channel equalization. Recently signed error version of CMA (SE-CMA) and dithered signed error version (DSE-CMA) have been proposed which afford overall computational efficiency. We propose three different error functions for faster convergence. This would be essential for communication systems, which cannot afford a high startup delay or for systems, where the channel's impulse response is rapidly fluctuating. One of these algorithms relies on the idea of a variable step size, which increases the rate of convergence. Index Terms--Blind equalization, constant modulus algorithm, error function, speed of convergence.

Biological sulfate (SO42-) reduction was examined in anaerobic sequential batch reactors (ASBRs) operated under different hydraulic retention times (HRTs) ranging from 12 to 36 h and COD (Chemical Oxygen Demand)/SO42- ratios of 2.4, 1.6 and 0.8. Competition between SO42- reducing bacteria (SRBs), methane producing archaea (MPAs) and homoacetogens (HACs) was examined in controls and cultures treated with linoleic acid (LA). The ASBR performance was influenced by the COD/SO42- ratio in control cultures with a SO42- reduction of 87% at a COD/SO42- ratio of 0.8. At a 12 h HRT, in both control and LA treated cultures, greater than 75% SO42- removal was observed under all the conditions examined. In control reactors operating at a 36 h HRT, high levels of MPAs belonging to Methanobacteriales and Methanosarcinales were detected; however, in comparison, under low COD/SO42- ratio and with decreasing HRT conditions, a relative increase in SRBs belonging to Desulfovibrio and Desulfatibacillum was observed. Adding 0.5 g∙L-1 LA suppressed Methanobacteriales, while increasing the LA concentration to 1 g∙L-1 completely suppressed MPAs with a relative increase in SRBs. HACs belonging to Bacteroidetes were observed in the control and in cultures operated at 12 h HRT with a COD/SO42- ratio of 1.6 and fed 0.5 g∙L-1 LA; however, with all other LA levels (0.5 and 1.0 g∙L-1) and HRTs (12, 24 and 36 h), HACs were not detected. [ABSTRACT FROM AUTHOR]

Taguchi statistical design, an orthogonal array (OA) method, was used to study the impact of the COD/SO4 2– ratio, hydraulic retention time (HRT) and linoleic acid (LA) concentration on sulfate (SO4 2–) reduction in an anaerobic sequencing batch reactor using glucose as the electron donor. Based on the OA, optimum condition for maximum SO4 2– reduction was evaluated. Increasing the COD/SO4 2– ratio and HRT caused decreasing SO4 2– reduction while increased SO4 2– reduction was observed with increasing LA concentration (1 g L-1). In control (not fed LA) cultures, higher SO4 2– reduction (87% ± 3%) was observed at a low COD/SO4 2– ratio of 0.8. This indicates that increasing SO4 2– reduction was observed at increasing SO4 2– loading rates. In general, results from this study reveal that limiting the substrate concentration with high SO4 2– levels (low COD/SO4 2– ratio) favors high SO4 2– removal. Surface plots were used to evaluate the significant interactions between the experimental factors. Accuracy of the model was verified using an analysis of residuals. Optimum conditions for maximum SO4 2– reduction (97.61%) were observed at a COD/SO4 2– ratio of 0.8 (level 1), 12 h HRT (level 1) together with 1000 mg L-1 LA addition (level 3). In general, the Taguchi OA provided a useful approach for predicting the percent SO4 2– reduction in inhibited mixed anaerobic cultures within the factor levels investigated. [ABSTRACT FROM AUTHOR]

Proposes three different error functions for faster convergence of the constant modulus algorithm for blind channel equalization. Uses of blind equalizers; Purpose of showing the signed error versions of the constant modulus algorithm; Assumptions used in the construction of error functions.

Focuses on the wavelet-based coder-decoder (codec) structure defined for baseband waveform coding. Given numerical results for bandwidth efficiency; Comparison between several different wavelets; How the wavelets obey Nyquist pulse shaping condition and provide a unified framework for analog pulse shaping concepts of communication.