The aim of this study was to evaluate the pollutant degradation ability and the microbial community of aerobic granular sludge（AGS）in the modified vertical baffle reactors (VBRs) in the treatment of domestic wastewater. The reactor was started by seeding sludge from the aerobic chamber of the domestic sewage treatment plant (1–15 days, phase 1). The removal efficiency of pollutants under different aeration rate and hydraulic retention time (HRTs) was studied (16–90 days, phase 2). Under optimal conditions (HRT = 20 h, aeration rate = 1.2 m3/h), the 90–day continuous stabilization experiment (91–180 days, stage 3) was performed. The removal efficiencies of COD, NH3–N, TN and TP were 99.48 ± 0.86%, 99.48 ± 1.19%, 76.34 ± 8.91% and 95.02 ± 4.25%, respectively, which met the discharge standard of 1A China (GB 18918–2002). Besides, the formation mechanism and structure of aerobic granular sludge were studied and the relationship between pollutant degradation and extracellular polymer substances (EPS) was analyzed. The conclusions shows that the values of polysaccharide (PS) was increased significantly which was conducive to the bridging among particles to form AGS. The results of functional microbial communities showed that Proteobacteria was the most abundant phylum in aerobic sludge, while the Nitrospira was the dominant bacteria in genus level, as well as Candidatus–Accumulibacter and other functional bacteria were also abundant. This proved that a variety of functional bacteria coexist, and can achieve the effect of simultaneous removal of multiple contaminants.
In this paper, a forced air cooling all-solid-state DC circuit breaker (voltage level DC750V, rated current DC1000A) for low-voltage distribution system is developed. Its core heating component is IGCT assembly, which consist of 2 IGCTs in parallel and 2 IGCTs in reverse parallel, then assembled with a radiator, which is composed of press-blocks, gravity heat pipes and heat fins. The test results show that the heat dissipation scheme can meet the requirements of all-solid-state DC circuit breaker.
Abstract Among the different antibiotics, tetracycline hydrochloride (TCH) is one of the most commonly used. In this study, the activated sodium persulfate (SPS) process induced by microwave (MW) energy was used to treat TCH. The effect of different operational parameters of MW/SPS-treated TCH, such as SPS concentration, TCH concentration, initial pH, and MW power, was investigated. The concentration changes of TCH were determined using a spectrophotometer. The results of radical scavenger experiments indicated that the sulfate radical () was stronger than the hydroxyl radical (·OH). On the basis of high performance liquid chromatography–mass spectrometry (HPLC–MS) analysis, a possible degradation pathway of TCH was proposed. This research indicates that the MW/SPS system is a promising prospect for the treatment of TCH.
In this paper, three feature selection methods and three machine learning regression models are used to select the best feature subset from the feature set to predict compound energy performance. By comparing the matching performance of different feature selection methods and machine learning models, the experimental results show that Ant Colony Optimization is used for feature selection and the Support Vector Regression model is used for the best prediction effect. The research in this paper can provide references for the prediction of new material properties in the future.
The motor-driven high-voltage circuit breaker actuator requires high dynamic response of the motor, but when the motor is controlled by vector control technology, the current controller does not achieve complete decoupling of the motor, and the influence of the coupling term will be enhanced with the increase of the speed, which greatly affects the dynamic response accuracy of the motor. Therefore, in this paper, firstly, the existing decoupling methods are analyzed and studied to improve the dynamic response characteristics of the permanent magnet synchronous motor (PMSM) in operation. Secondly, to further improve the dynamic tracking performance of the current loop, a predictive controller is introduced in the feedback link in combination with the predictive control algorithm to replace the measured value with the predicted value as the feedback input of the controller, so that the regulator output and the feedback input can be synchronized in timing, which is expected to eliminate the influence of the one-shot lag delay of the digital controller. Then, under this control method, the parameter selection method is further investigated when the controller is a PI controller. Simulation and experimental results show that the proposed scheme can effectively improve the dynamic response performance of the current loop, enable the circuit breaker to quickly track the command signal, the motion characteristics are stable, and the breaking speed meets the requirements.
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