This paper researched the effect of aeration frequency on stabilizing process of the aerobic bioreactors, coded Al, A2 and A3 under the condition that the total amount of oxygen supplied by aeration was same. Al was operated at aerating-to-break-operating ratio of 1:5, that aerating was 2 hours and intermittent operating lasted 10 hours. A2 was operated at ratio of 1:3, aerating for 2 hours and intermittent operating for 6 hours. A3 was aerating without break. The results indicated that: (1) the pH values of leachate in A2 and A3 were increasing above 8.0 quickly and fluctuated around pH 8.5 on the 28th day. And the pH of leachate in Al increased slowly near to 8.0 up to the 59th day. (2) COD of leachate in three bioreactors reached the maximum values around the 10th day, and then dropped gradually. COD of leachate produced in A2 dropped rapidly to 6000 mg/L up to the 42nd day and that in A3 declined to 6400 mg/L on the 59th day. COD in Al was above 3000 mg /L before the 56th day and did not decrease to 8000 mg /L until the 66th day. (3) the concentration of ammonia nitrogen in reactor A2 and in reactor A3 decreased below 10.0 mg/L on the 28th day and after the 56th day respectively. For Al, the concentrations of ammonia nitrogen fell down below 10.0 mg/L during 95 days to 105days. (4) On the whole filling process the rate of deposition in reactor A2 was highest than others, and that in Al was lowest. The garbage settlement in A2 also stabilized firstly. In summary the aerating frequency of 1:3 performed better on garbage filled degradation, which the pH of leachate would be stable quickly, the remove rate of COD and concentration of ammonia nitrogen were highest.
Based on Matlab platform, relationship between specific performance and physical fitness of female 100m hurdlers was simulated by the mapping function of the artificial nerual network(ANN). The model is proposed to achieve accurate prediction in female 100m hurdlers' performance and provide valuable references to its scientific training.
Rare Metal Materials and Engineering,2018年47(2):423-430 ISSN：1002-185X
[方鹏均; 徐轶] School of Materials Science & Engineering, Southwest Jiaotong University, Chengdu, 610031;[徐轶] Foundation Institute of Materials Science, Bremen University, Germany, Bremen, 28359;[黎兴刚] General Research Institute for Nonferrous Metals, National Engineering & Technology Research Center for Nonferrous Metal Matrix Composites, Beijing, 100088;[陈亚] Research Institute of Physical Culture, Southwest Jiaotong University, Chengdu, 610031;School of Materials Science & Engineering, Southwest Jiaotong University, Chengdu, 610031
[Xu Yi] Southwest Jiaotong Univ, Sch Mat Sci & Engn, Chengdu 610031, Sichuan, Peoples R China.
Nickel-based superalloy powders have been produced by high pressure argon gas and nitrogen gas atomization, separately. The microstructural characterization of nickel-based alloy powders has been performed by a scanning electron microscope equipped with an EDS microanalysis unit. Based on a Newtonian cooling model, the flight speed and the cooling rate of two kinds of alloy droplets were calculated. The results show that the droplet cooling rate, which depends on atomization medium and droplet size, has an effect on the solidification microstructure. For argon-gas atomized powders, the developed dendrite structure is predominant at a lower cooling rate and a mixed microstructure composed of dendrite structure and cellular structure is observed at a higher cooling rate. For nitrogen-gas atomized powders, the dendrite structure is predominant at a lower cooling rate and a full cellular structure can be observed at a higher cooling rate. According to calculation, the cooling rate of argon-gas atomized droplets is in a range from 1.0×10~5 K·s~(-1) to 4.24×10~6 K·s~(-1), while the cooling rate of nitrogen-gas atomized droplets is from 1.0×10~5 K·s~(-1) to 4.8×10~6 K·s~(-1). The cooling rate increases with decreasing of droplets diameter. Two kinds of atomizing gases have a slight influence on the cooling rate of droplets. The dendrite axis is rich in elements such as Cr, Co, W, Ni and Al while the inter-dendrite region is rich in Ti element.