Jingdezhen Ceramic College

Jingdezhen, China

Jingdezhen Ceramic College

Jingdezhen, China

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Li K.J.,CAS National Astronomical Observatories | Gao P.X.,CAS National Astronomical Observatories | Gao P.X.,Chinese Academy of Sciences | Zhan L.S.,Jingdezhen Ceramic College
New Astronomy | Year: 2010

In the present study, the north-south asymmetry of filaments in solar cycles 16-21 is investigated with the use of the solar filaments observed at the Observatoire de Paris, Section de Meudon from March 1919 to December 1989. Filament activity is found regularly dominated in each of cycles 16-21 in the same hemisphere as that inferred by sunspot activity, and it is found to run in a different asymmetrical behavior at different latitudinal bands, suggesting that the north-south asymmetry of filament activity should be a function of latitudes. The regularity on the north-south asymmetry of sunspot activity given by Li et al. (2002b) is demonstrated by filament activity. The periods in the north-south asymmetry of solar filament activity are 9.13, and 12.8 years without the solar cycle found. © 2009 Elsevier B.V. All rights reserved.


Yu R.,Jingdezhen Ceramic College | Huang P.,Jingdezhen Ceramic College | Ren H.,Nanjing University | Xie Z.,Tsinghua University | And 2 more authors.
Huagong Xuebao/CIESC Journal | Year: 2015

The high cost of magnesium is one of the key problems for the practical application of struvite chemical precipitation. Ammonium in wastewater was recycled by changing the initial conditions of struvite precipitation with cheap magnesia. The results showed that when the initial pH was 2, the removal rate of ammonium was above 90% by struvite precipitation technology with cheap magnesia as magnesium, which was above 82% at the conditions of the mole ratio of Mg2+:NH4 +:PO4 3-:, 1:1:1 and calcination temperature of magnesia of 200-400℃. The XRD and FTIR results also showed that the crystal structure of magnesia was distorted with changed bond length of Mg O at different calcination temperature, leading to redshift and blueshift. A direct correlation was found between Mg O bond length and ammonium removal ratio. © All Right Reserved.


Yu R.,Jingdezhen Ceramic College | Ren H.,Nanjing University | Xie Z.,Tsinghua University | Wang C.,Tsinghua University | Ma X.,Jingdezhen Ceramic College
Chinese Journal of Environmental Engineering | Year: 2015

The effect of Mg(OH)2on struvite decomposition was investigated, anda thermo-kinetics of struvite decomposition was studied.The results showed that degradation process of struvite with Mg(OH)2 addition was three steps, and the temperature of the endothermic peak was 390 K (5 K/min). The mechanism of sturvite decomposition with Mg(OH)2 mediated was an autocatalytic set with a reduction in the reaction rate also, the degradation had more than two pathways, the activation energy of stripping ammonia from struvite was from 34.4 kJ/mol to 112.9 kJ/mol. The kinetics equation was f(α)=k0(1-α)n, the coefficient of linear correlation was 0.994 and the reaction order was 6.12. © 2015, Science Press. All right reserved.


Yu R.,Jingdezhen Ceramic College | Ren H.,Nanjing University | Wang Y.,Nanjing University | Ding L.,Nanjing University
Chinese Journal of Environmental Engineering | Year: 2015

The cost of chemical agent would be decreased by struvite pyrolysate recycling technology. The transformation of magnesium hydrogen phosphate to magnesium pyrophosphate was restrained by Mg(OH)2 medium during struvite pyrolysis, and PO4-P residue in the supernate decreased during the process of ammonium removal by struvite pyrolysate with Mg(OH)2 addition. Ammonium removal rate was about 84%, and PO4-P residue in the supernate was 0.02 mg/L under the conditions of Mg(OH)2:NH4+(mole) of 1:1; temperature of 110℃. ©, 2015, Science Press. All right reserved.


Yu R.,Jingdezhen Ceramic College | Yu R.,Nanjing University | Shen Y.,Nanjing University | Ren H.,Nanjing University
Chinese Journal of Environmental Engineering | Year: 2015

The effects of initial concentration of ammonium, stirring speed, mixing time and reaction temperature on the removal of ammonium by magnesium ammonium phosphate precipitation were investigated from the aspect of engineering application. The results showed that the removal rate of ammonium was more than 90% when the initial concentration of ammonium was above 200 mg/L. An ammonium removal rate of more than 80% was achieved for all test temperatures, and the removal rate increased up to 90% with the increase of reaction temperature. As a key factor, stirring was observed to influence the grain growth in a complicated manner. A complicated effect of stirring speed on grain growth was found, a stirring speed lower than 150 rpm would accelerate the struvite crystal nucleation, with a grain size of 2.25 nm. The grain size decreased to 1.54 nm with the increase of stirring speed. Finally, the grain growth was significantly accelerated by extending the mixing time, from 0.47 nm (5min) to 1.71 nm (120 min). ©, 2015, Science Press. All right reserved.

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