1,721,077 research outputs found
Anaerobic Biodegradation of Wastewater Containing VFA and Alcohol Generated from an Innovative Two-Stage Process Producing H2 and CH4 from Food Waste
No full textDevelopment of an innovative two-stage process, a combination of acidogenic hydrogenesis and methanogenesis
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Voltage doubler rectified boost-integrated half bridge (VDRBHB) converter for digital car audio amplifiers
No full textA new voltage doubler rectified boost-integrated half bridge converter for digital car audio amplifiers is proposed. The proposed converter shows low conduction loss due to low voltage stress of the secondary diodes, no de magnetizing current for the transformer, and a lack of stored energy in the transformer. Moreover, since the primary MOSFETs are turned-on under zero voltage switching conditions and the secondary diodes are turned-off under zero current switching conditions, the proposed converter has minimized switching losses. In addition, the input filter can be minimized due to a continuous input current, and an output filter does not need an inductor in the proposed converter. Therefore, the proposed converter has the desired features, high efficiency and low profile, for a viable power supplies for digital car audio amplifiers. A 60-W industrial sample of the proposed converter has been implemented for digital car audio amplifiers with a measured efficiency of 88.3% at nominal input voltage
Two-phase anaerobic treatment system for fat-containing wastewater
No full textThis study was conducted to investigate the feasibility of a two-phase anaerobic treatment system for fat-containing wastewater. The two-phase system was composed of a continuously stirred tank reactor for acidogenesis and an upflow anaerobic sludge blanket (UASB) reactor for methanogenesis. Its performance was compared with a conventional single-phase system of a UASB reactor treating synthetic wastewater containing major long-chain fatty acids (LCFAs). LCFAs did not cause any significant problem up to the LCFA mixture loading rate of 1.21 kg LCFA-COD m(-3) day(-1) (3500 mg LCFA-COD dm(-3)) in both systems. However, the efficiency of the single-phase system deteriorated at loading rates above 1.38kg LCFA-COD m(-3) day(-1) (4000 mg LCFA-COD dm(-3)), while that of the two-phase system was still satisfactory. More than 19.2% of LCFAs were degraded and 11.5% of unsaturated LCFAs were saturated in the acidogenesis of the two-phase system, which led to the enhanced specific methane production rate and the reduced scum layer of the subsequent UASB reactor. (C) 2003 Society of Chemical Industry
Current-fed energy-recovery circuit for plasma display panel
No full textA new current-fed energy-recovery circuit for a plasma display panel is proposed. All power switches are turned on with zero-voltage-switching, and its sustaining voltage is greatly reduced with the aid of the discharge current compensation. Furthermore, it features a simpler structure, less mass, lower current stress, and lower electromagnetic interface than prior circuits. It is well suited for wall-hanging colour TVs
A resonant energy-recovery circuit for plasma display panel employing gas-discharge current compensation method
No full textA resonant energy-recovery circuit for a plasma display panel (PDP) employing a gas-discharge current compensation method is proposed. Its main concept is to make the resonant circuit biased by V-s and 0 V instead of V-s/2 in charging and discharging the PDP, respectively. This operation helps the PDP to be fully charged and discharged and all main switches turned on under zero-voltage switching. Moreover, since the inductor current can compensate the large gas-discharge current, the current stresses on main power switches can be considerably reduced and all main switches have the turn-on,timing margin, which ensures the no voltage drop across the PDP. Therefore, all these features could favorably provide a high energy-recovery capability, more, accumulated wall charge, reduced sustaining voltage, and low electromagnetic interference. Therefore, the proposed circuit is expected to be well suited for a hang-on-the-wall PDP TV
Cost effective zero-voltage and zero-current switching current-fed energy-recovery display driver for AC plasma display panel
No full textA new cost effective zero-voltage (ZVS) and zero-current switching (ZCS) current-fed energy-recovery display driver for a plasma display panel (PDP) is proposed. It features a simpler structure, less mass, and lower cost of production. Furthermore, since all power switches are turned on or off under ZVS or ZCS 9 it has several favorable advantages such as an improved electromagnetic interference, low switching losses, and reduced burden on the cooling system. Particularly, since the current source built in the inductor can compensate the large gas-discharge current, main inverter switches have the reduced current stress and turn-on timing margin. Therefore, the undesirable voltage notch problem caused by the improperly controlled gate signal can be solved, which enables the panel to light at lower voltage such as 143 V compared with about 165 V of the prior circuit. To confirm the operation, validity, and features of the proposed circuit, experimental results from a prototype built with a 6-in test PDP are presented
The optimisation of food waste addition as a co-substrate in anaerobic digestion of sewage sludge
No full textFood waste has been regarded as the main source of various environmental pollution in Korea due to the high volatile solids (VS) and moisture content caused by the features of dietary habits. The feasibility of food waste as a co-substrate in anaerobic digestion of sewage sludge was investigated in mesophilic and thermophilic conditions using batch tests. Cumulative methane production, dissolved organic carbon (DOC) and volatile fatty acids (VFA) were monitored to find the optimal mixing ratios of food waste and sewage sludge for the enhanced performance of co-digestion. It was observed that adequately mixed food waste led to the enhanced methane production both at mesophilic and thermophilic conditions. However, a conventional linear regression conducted for the optimisation of co-substrate mixing ratios was not accurate in describing exact methane production trends of co-digestion because of the different biodegradability of substrates. Therefore, a remodified Gompertz equation showing nonlinear relationship between variables was developed to find exact information with the same experimental data obtained at 29 VS/l generally used in biochemical methane potential (BMP) tests. Based on an influential parameter, methane production rate (MPR), the optimal mixing ratios of food waste were 39.3% and 50.1% in mesophilic and thermophilic conditions, respectively. To confirm the application of the remodified Gompertz equation, secondary batch tests were conducted with the Substrate concentrations of 1-4g VS/l. In overall range tested, the confident mixing ratios of food waste was adjusted to 30-40% and 40% in mesophilic and thermophilic conditions, respectively. The most significant factor for enhanced performance was the improved organic carbon content provided by additional food waste
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