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| 1 | Predicting geogenic groundwater fluoride contamination throughout China显示文摘Endemic fluorosis exists in almost all provinces of China.The long-term ingestion of groundwater containing high concentrations of fluoride is one of the main causes of fluoro-sis.We used artificial neural network to model the relationship between groundwater fluo-ride concentrations from throughout China and environmental variables such as climatic,geological.and soil parameters as proxy predictors.The results show that the accuracy and area under the receiver operating characteristic curve of the model in the test dataset are 80.5%and 0.86%,respectively,and climatic variables are the most effective predictors.Based on the artificial neural network model,a nationwide prediction risk map of fluoride concen-trations exceeding 1.5 mg/L with a 0.5×0.5 arc minutes resolution was generated.The high risk areas are mainly located in western provinces of Xinjiang,Tibet,Qinghai,and Sichuan,and the northern provinces of Inner Mongolia,Hebei and Shandong.The total number of people estimated to be potentially at risk of fluorosis due to the use of untreated high flu-oride groundwater as drinking water is about 89 million,or 6%of the population.The high fluoride groundwater risk map helps the authorities to prioritize areas requiring mitigation measures and thus facilitates the implementation of water improvement and defluorida-tion projects. | Hailong Cao Xianjun Xie Yanxin Wang Hongxing Liu | 2022 | Journal of Environmental Sciences2022,34,5: | 3 |
| 2 | Biogas by two-stage microbial anaerobic and semi-continuous digestion of Chinese cabbage waste显示文摘Anaerobic digestion of Chinese cabbage waste was investigated through a pilot-scale two-stage digester at a mesophilic temperature of 37 °C. In the acidification digester, the main product was acetic acid, with the maximum concentration of 4289 mg·L-1on the fourth day, accounting for 50.32% of total volatile fatty acids. The oxidation reduction potential(ORP) and NH+4-N level decreased gradually with hydraulic retention time(HRT)of acidification. In the second digestion phase, the maximum methanogenic bacterial concentration reached9.6 × 1010ml-1at the organic loading rate(OLR) of 3.5–4 kg VS·m-3, with corresponding HRT of 12–16 days.Accordingly, the optimal biogas production was 0.62 m3·(kg VS)-1, with methane content of 65%–68%. ORP and NH+4-N levels in the methanizer remained between- 500 and- 560 m V and 2000–4500 mg·L-1, respectively. Methanococcus and Methanosarcina served as the main methanogens in the anaerobic digester. | Xiaoying Dong Lijie Shao Yan Wang Wei Kou Yanxin Cao Dalei Zhang | 2015 | Chinese Journal of Chemical Engineering2015,23,5: | 0 |
| 3 | Degradation of metoprolol by UV/sulfite as an advanced oxidation or reduction process:The significant role of oxygen显示文摘The degradation of metoprolol(MTP)by the UV/sulfite with oxygen as an advanced reduction process(ARP)and that without oxygen as an advanced oxidation process(AOP)was comparatively studied herein.The degradation of MTP by both processes followed the first-order rate law with comparable reaction rate constants of 1.50×10^(-3)sec^(−1)and 1.20×10^(-3)sec^(−1),respectively.Scavenging experiments demonstrated that both e^(−)_(aq)and H·played a crucial role in MTP degradation by the UV/sulfite as an ARP,while SO_(4)^(·−)was the dominant oxidant in the UV/sulfite AOP.The degradation kinetics of MTP by the UV/sulfite as an ARP and AOP shared a similar pH dependence with a minimum rate obtained around pH 8.The results could be well explained by the pH impacts on the MTP speciation and sulfite species.Totally six transformation products(TPs)were identified from MTP degradation by the UV/sulfite ARP,and two additional ones were detected in the UV/sulfite AOP.The benzene ring and ether groups of MTP were proposed as the major reactive sites for both processes based on molecular orbital calculations by density functional theory(DFT).The similar degradation products of MTP by the UV/sulfite process as an ARP and AOP indicated that e^(−)_(aq)/H·and SO_(4)^(·−)might share similar reaction mechanisms,primarily including hydroxylation,dealkylation,and H abstraction.The toxicity of MTP solution treated by the UV/sulfite AOP was calculated to be higher than that in the ARP by the Ecological Struc-ture Activity Relationships(ECOSAR)software,due to the accumulation of TPs with higher toxicity. | Ying Cao Juan Li Yanxin Zhao Yumeng Zhao Wei Qiu Suyan Pang Jin Jiang | 2023 | Journal of Environmental Sciences2023,,6: | 0 |
| 4 | Development of the automatic navigation system for combine harvester based on GNSS显示文摘An automatic navigation system was developed to realize automatic driving for combine harvester,including the mechanical design,control method and software design.First of all,for the harvester modified with the automatic navigation system,a dynamic calibration method of the rear wheel center position was proposed.The control part included the navigation controller and the steering controller.A variable universe fuzzy controller was designed to the navigation controller,which used fuzzy control to change the fuzzy universe of input and output dynamically,that means,under the condition that the fuzzy rules remain unchanged,the fuzzy universe changes with the change of input,which is an adaptive fuzzy control method and can modify the control strategy in time.To realize the automatic navigation of the harvester,the decision result of the navigation controller based on the variable universe fuzzy control was input into the steering controller,and then the electric steering wheel was controlled to rotate.To test the performance of the designed automatic navigation system,the field experiment was carried out.When the combine harvester was navigating linearly at a speed of 0.8 m/s,the overall root mean square error(RMSE)of the lateral deviation was 5.87 cm.The test results showed that the system was designed could make the combine track the preset path smoothly and stably,and the tracking accuracy was at the centimeter level. | Shichao Li Man Zhang Ruyue Cao Yuhan Ji Zhenqian Zhang Han Li Yanxin Yin | 2021 | International Journal of Agricultural and Biological Engineering2021,14,5: | 0 |