The plow of the submarine plowing trencher is one of the main functional mechanisms, and its optimization is very important. The design parameters play a very significant role in determining the requirements of the to...The plow of the submarine plowing trencher is one of the main functional mechanisms, and its optimization is very important. The design parameters play a very significant role in determining the requirements of the towing force of a vessel. A multi-objective genetic algorithm based on analytical models of the plow surface has been examined and applied in efforts to obtain optimal design of the plow. For a specific soil condition, the draft force and moldboard surface area which are the key parameters in the working process of the plow are optimized by finding the corresponding optimal values of the plow blade penetration angle and two surface angles of the main cutting blade of the plow. Parameters such as the moldboard side angle of deviation, moldboard lift angle, angular variation of the tangent line, and the spanning length are also analyzed with respect to the force of the moldboard surface along soil flow direction. Results show that the optimized plow has an improved plow performance. The draft forces of the main cutting blade and the moldboard are 10.6% and 7%, respectively, less than the original design. The standard deviation of Gaussian curvature of moldboard is lowered by 64.5%, which implies that the smoothness of the optimized moldboard surface is much greater than the original.展开更多
Combined with anti-waterlogging ditches, irrigation with treated paper mill effluent （TPME） and plowing were applied in this study to investigate the effects of remediation of degraded coastal sa- line-alkaline wetl...Combined with anti-waterlogging ditches, irrigation with treated paper mill effluent （TPME） and plowing were applied in this study to investigate the effects of remediation of degraded coastal sa- line-alkaline wetlands. Three treatments were employed, viz., control （CK）, irrigated with 10 cm depth of TPME （I）, and plowing to 20 cm deep before irrigating 10 cm depth ofTPME （IP）. Results show that both I-treatment and IP-treatment could improve soil structure by decreasing bulk density by 5% and 8%. Irrigation with TPME containing low salinity stimulated salts leaching instead of accumulating. With anti-waterlogging ditches, salts were drained out of soil. Irrigation with 10 cm depth of TPME lowered total soluble salts in soil and sodium adsorption ration by 33% and 8%, respective!y, but there was no significant difference compared with CK, indicating that this irrigation rate was not heavy enough to remarkably reduce so!l salinity and sodicity, Thus, in-i： gation rate should be enhanced in order to reach better effects of desalinization and desodication. Irrigation with TPME significantly increased soil organic matter, alkali-hydrolyzable nitrogen and available phosphorus due to the abundant organic matter in TPME. Plowing increased soil air circulation, so as to enhance mineralization of organic matter and lead to the loss of organic matter; however, plowing significantly improvedsoil alkali-hydrolyzable nitrogen and available phosphorus. Improvements of physicochemical properties in I-treatment and IP-treatment both boosted soil microbial population and activity. Microbial biomass carbon increased significantly by 327% （I-treatment） and 451% （IP-treatment）, while soil respiration increased significantly by 316% （I-treatment） and 386% （IP-treatment）. Urease and dehydrogenase activities in both I-treatment and IP-treatment were significantly higher than that in CK. Phosphatase in IP-treatment was significantly higher than that in CK. Compared to I-treatment, IP-treatment improved all of the soil properties except for soil organic matter. The key to remediation of degraded sa- line-alkaline wetlands is to decrease soil salinity and sodicity; thus, irri- gation plus plowing could be an ideal method of soil remediation.展开更多
ALTHOUGH Zhao Zijian＇s business card shows his office is in Beijing, he spends half the year on business trips to Africa. Zhao, who hails from central ChinEs Henan Province. has been in the agricultural and construct...ALTHOUGH Zhao Zijian＇s business card shows his office is in Beijing, he spends half the year on business trips to Africa. Zhao, who hails from central ChinEs Henan Province. has been in the agricultural and construction machinery business for decades, and is now the general manager of China- Africa Machinery Corp. （CAMACO）. He is involved in agricultural and construction machinery investment and trade in Africa.展开更多
With the rapid development of semiconductors,the number of materials needed to be polished sharply increases.The material properties vary significantly,posing challenges to chemical mechanical polishing(CMP).According...With the rapid development of semiconductors,the number of materials needed to be polished sharply increases.The material properties vary significantly,posing challenges to chemical mechanical polishing(CMP).Accordingly,the study aimed to classify the material removal mechanism.Based on the CMP and atomic force microscopy results,the six representative metals can be preliminarily classified into two groups,presumably due to different material removal modes.From the tribology perspective,the first group of Cu,Co,and Ni may mainly rely on the mechanical plowing effect.After adding H_(2)O_(2),corrosion can be first enhanced and then suppressed,affecting the surface mechanical strength.Consequently,the material removal rate(MRR)and the surface roughness increase and decrease.By comparison,the second group of Ta,Ru,and Ti may primarily depend on the chemical bonding effect.Adding H_(2)O_(2)can promote oxidation,increasing interfacial chemical bonds.Therefore,the MRR increases,and the surface roughness decreases and levels off.In addition,CMP can be regulated by tuning the synergistic effect of oxidation,complexation,and dissolution for mechanical plowing,while tuning the synergistic effect of oxidation and ionic strength for chemical bonding.The findings provide mechanistic insight into the material removal mechanism in CMP.展开更多
基金Supported the National Natural Science Foundation of China （No. 51179040） Natural Science Foundation of Heilongjiang Province （No. E200904）
文摘The plow of the submarine plowing trencher is one of the main functional mechanisms, and its optimization is very important. The design parameters play a very significant role in determining the requirements of the towing force of a vessel. A multi-objective genetic algorithm based on analytical models of the plow surface has been examined and applied in efforts to obtain optimal design of the plow. For a specific soil condition, the draft force and moldboard surface area which are the key parameters in the working process of the plow are optimized by finding the corresponding optimal values of the plow blade penetration angle and two surface angles of the main cutting blade of the plow. Parameters such as the moldboard side angle of deviation, moldboard lift angle, angular variation of the tangent line, and the spanning length are also analyzed with respect to the force of the moldboard surface along soil flow direction. Results show that the optimized plow has an improved plow performance. The draft forces of the main cutting blade and the moldboard are 10.6% and 7%, respectively, less than the original design. The standard deviation of Gaussian curvature of moldboard is lowered by 64.5%, which implies that the smoothness of the optimized moldboard surface is much greater than the original.
基金financially supported by the National Science & Technology supporting Program of China (NO. 2010BAC68B01 NO. 2011BAC02B01)+1 种基金the Science and Technology Planning Program of Shandong Province (NO. 2008GG10006024 NO. 2008GG3NS07005)
文摘Combined with anti-waterlogging ditches, irrigation with treated paper mill effluent （TPME） and plowing were applied in this study to investigate the effects of remediation of degraded coastal sa- line-alkaline wetlands. Three treatments were employed, viz., control （CK）, irrigated with 10 cm depth of TPME （I）, and plowing to 20 cm deep before irrigating 10 cm depth ofTPME （IP）. Results show that both I-treatment and IP-treatment could improve soil structure by decreasing bulk density by 5% and 8%. Irrigation with TPME containing low salinity stimulated salts leaching instead of accumulating. With anti-waterlogging ditches, salts were drained out of soil. Irrigation with 10 cm depth of TPME lowered total soluble salts in soil and sodium adsorption ration by 33% and 8%, respective!y, but there was no significant difference compared with CK, indicating that this irrigation rate was not heavy enough to remarkably reduce so!l salinity and sodicity, Thus, in-i： gation rate should be enhanced in order to reach better effects of desalinization and desodication. Irrigation with TPME significantly increased soil organic matter, alkali-hydrolyzable nitrogen and available phosphorus due to the abundant organic matter in TPME. Plowing increased soil air circulation, so as to enhance mineralization of organic matter and lead to the loss of organic matter; however, plowing significantly improvedsoil alkali-hydrolyzable nitrogen and available phosphorus. Improvements of physicochemical properties in I-treatment and IP-treatment both boosted soil microbial population and activity. Microbial biomass carbon increased significantly by 327% （I-treatment） and 451% （IP-treatment）, while soil respiration increased significantly by 316% （I-treatment） and 386% （IP-treatment）. Urease and dehydrogenase activities in both I-treatment and IP-treatment were significantly higher than that in CK. Phosphatase in IP-treatment was significantly higher than that in CK. Compared to I-treatment, IP-treatment improved all of the soil properties except for soil organic matter. The key to remediation of degraded sa- line-alkaline wetlands is to decrease soil salinity and sodicity; thus, irri- gation plus plowing could be an ideal method of soil remediation.
文摘ALTHOUGH Zhao Zijian＇s business card shows his office is in Beijing, he spends half the year on business trips to Africa. Zhao, who hails from central ChinEs Henan Province. has been in the agricultural and construction machinery business for decades, and is now the general manager of China- Africa Machinery Corp. （CAMACO）. He is involved in agricultural and construction machinery investment and trade in Africa.
基金support by the National Natural Science Foundation of China(51975488 and 51991373)National Key R&D Program of China(2020YFA0711001)Fundamental Research Funds for the Central Universities(2682021CG011).
文摘With the rapid development of semiconductors,the number of materials needed to be polished sharply increases.The material properties vary significantly,posing challenges to chemical mechanical polishing(CMP).Accordingly,the study aimed to classify the material removal mechanism.Based on the CMP and atomic force microscopy results,the six representative metals can be preliminarily classified into two groups,presumably due to different material removal modes.From the tribology perspective,the first group of Cu,Co,and Ni may mainly rely on the mechanical plowing effect.After adding H_(2)O_(2),corrosion can be first enhanced and then suppressed,affecting the surface mechanical strength.Consequently,the material removal rate(MRR)and the surface roughness increase and decrease.By comparison,the second group of Ta,Ru,and Ti may primarily depend on the chemical bonding effect.Adding H_(2)O_(2)can promote oxidation,increasing interfacial chemical bonds.Therefore,the MRR increases,and the surface roughness decreases and levels off.In addition,CMP can be regulated by tuning the synergistic effect of oxidation,complexation,and dissolution for mechanical plowing,while tuning the synergistic effect of oxidation and ionic strength for chemical bonding.The findings provide mechanistic insight into the material removal mechanism in CMP.
