The electrical nonlinearity of silicon modulators based on reversed PN junctions was found to severely limit the linearity of the modulators.This effect,however,was inadvertently neglected in previous studies.Consider...The electrical nonlinearity of silicon modulators based on reversed PN junctions was found to severely limit the linearity of the modulators.This effect,however,was inadvertently neglected in previous studies.Considering the electrical nonlinearity in simulation,a 32.2 dB degradation in the CDR3(i.e.,the suppression ratio between the fundamental signal and intermodulation distortion)of the modulator was observed at a modulation speed of 12 GHz,and the spurious free dynamic range was simultaneously degraded by 17.4 dB.It was also found that the linearity of the silicon modulator could be improved by reducing the series resistance of the PN junction.The frequency dependence of the linearity due to the electrical nonlinearity was also investigated.展开更多
Fouling behavior along the length of membrane module was systematically investigated by performing simple modeling and lab-scale experiments of forward osmosis （FO） membrane process. The flux distribution model deve...Fouling behavior along the length of membrane module was systematically investigated by performing simple modeling and lab-scale experiments of forward osmosis （FO） membrane process. The flux distribution model developed in this study showed a good agreement with experimental results, validating the robustness of the model. This model demonstrated, as expected, that the permeate flux decreased along the membrane channel due to decreasing osmotic pressure differential across the FO membrane. A series of fouling experiments were conducted under the draw and feed solutions at various recoveries simulated by the model. The simulated fouling experiments revealed that higher organic （alginate） fouling and thus more flux decline were observed at the last section of a membrane channel, as foulants in feed solution became more concentrated. Furthermore, the water flux in FO process declined more severely as the recovery increased due to more foulants transported to membrane surface with elevated solute concentrations at higher recovery, which created favorable solution environments for organic adsorption. The fouling reversibility also decreased at the last section of the membrane channel, suggesting that fouling distribution on FO membrane along the module should be carefully examined to improve overall cleaning efficiency. Lastly, it was found that such fouling distribution observed with co-current flow operation became less pronounced in counter- current flow operation of FO membrane process.展开更多
基金National Natural Science Foundation of China(NSFC)(61575189,61635011)
文摘The electrical nonlinearity of silicon modulators based on reversed PN junctions was found to severely limit the linearity of the modulators.This effect,however,was inadvertently neglected in previous studies.Considering the electrical nonlinearity in simulation,a 32.2 dB degradation in the CDR3(i.e.,the suppression ratio between the fundamental signal and intermodulation distortion)of the modulator was observed at a modulation speed of 12 GHz,and the spurious free dynamic range was simultaneously degraded by 17.4 dB.It was also found that the linearity of the silicon modulator could be improved by reducing the series resistance of the PN junction.The frequency dependence of the linearity due to the electrical nonlinearity was also investigated.
基金supported by the World Class University Program (Case Ⅲ) through the National Research Foundation of Koreafunded by the Ministry of Education, Science and Technology (R33-10046)the Fundamental R&D Program for Technology of World Premier Materials funded by the Ministry of Knowledge Economy, Korea
文摘Fouling behavior along the length of membrane module was systematically investigated by performing simple modeling and lab-scale experiments of forward osmosis （FO） membrane process. The flux distribution model developed in this study showed a good agreement with experimental results, validating the robustness of the model. This model demonstrated, as expected, that the permeate flux decreased along the membrane channel due to decreasing osmotic pressure differential across the FO membrane. A series of fouling experiments were conducted under the draw and feed solutions at various recoveries simulated by the model. The simulated fouling experiments revealed that higher organic （alginate） fouling and thus more flux decline were observed at the last section of a membrane channel, as foulants in feed solution became more concentrated. Furthermore, the water flux in FO process declined more severely as the recovery increased due to more foulants transported to membrane surface with elevated solute concentrations at higher recovery, which created favorable solution environments for organic adsorption. The fouling reversibility also decreased at the last section of the membrane channel, suggesting that fouling distribution on FO membrane along the module should be carefully examined to improve overall cleaning efficiency. Lastly, it was found that such fouling distribution observed with co-current flow operation became less pronounced in counter- current flow operation of FO membrane process.
