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Feng D.,China City Environment Protection Engineering Ltd Company | Xia S.,Huazhong University of Science and Technology | Chen L.,Huazhong University of Science and Technology | Tang L.,Huazhong University of Science and Technology | And 2 more authors.
Gaodianya Jishu/High Voltage Engineering | Year: 2015

To improve the design of C-shaped monolithic armatures used in rectangular-bore railguns, we studied the non-uniformity of contact pressure distribution in armature assembly based on numerical simulation. The simulation was conducted using the finite element analysis software ABAQUS to calculate the pressure distribution on the contact surface between assembled armature and rail in static state. The simulation verifies the non-uniformity of the contact pressure distribution. On the basis of the contour pattern of pressure distribution, we proposed four coefficients to represent the non-uniformity of transvers-direction, launch-direction, overall, and local contact pressure distributions, respectively. All of these coefficients range between 0~1, and the higher their values are, the more non-uniform the corresponding distributions are. Based on further calculation, we also obtained the relation between these coefficients and some basic structural parameters of armature: the four coefficients are barely influenced by the interference of armature, decrease with increasing the tail length, increase with increasing the bulk depth, but vary in different pattern with increasing the rear radial depth. ©, 2015, Science Press. All right reserved.

Meng W.,Wuhan University of Technology | Meng L.,Wuhan University of Technology | Chen C.Z.,China City Environment Protection Engineering Ltd Company
Advanced Materials Research | Year: 2014

With the development of power electronics technology, a variety of unbalanced load are connected to the grid, causing the grid voltage imbalance and power quality decline, seriously affect the user's normal use. Traditional three-leg inverter can output three-phase symmetrical voltage in the case of three-phase symmetrical load. But it is difficult to output three-phase symmetrical voltage when the three-phase load is asymmetric. In order to solve the impact of unbalanced load on the power quality, the three-phase four-leg inverter which is obtained with the addition of a bridge arm on the basis of traditional three-leg inverter is adopted in this paper. Therefore, the three-phase symmetrical voltage can be acquired in the case of unbalanced load, at the same time, with the advantages of simple structure, small size, light weight, higher voltage utilization. © (2014) Trans Tech Publications, Switzerland.

Yang S.,CAS Qingdao Institute of Oceanology | Yang S.,Ocean University of China | Yang S.,Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering MEGE | Li L.,Ocean University of China | And 4 more authors.
Applied Surface Science | Year: 2016

A commercial activated carbon fiber (ACF-0) was modified by three different methods: nitration treatment (ACF-N), heat treatment (ACF-H) and heat treatment after nitration (ACF-NH), and the effects of textural and chemical properties on the ability of the metal-free ACF-catalyzed peroxymonosulfate (PMS) oxidation of Reactive Black 5 (RB5), an azo dye being difficultly adsorbed onto ACF, in aqueous solution were investigated in this work. Surface density of functional groups, surface area changes, surface morphology and the chemical state inside ACF samples were characterized by Boehm titration, N2 adsorption, scanning electron microscopy in couple with energy dispersive spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS), respectively. XPS spectra deconvolution was applied to figure out the importance of surface nitrogen-containing function groups. We found that π-π, pyridine and amine have promoting effect on the catalytic oxidation while the -NO2 has inhibitory effect on the ACF/PMS systems for RB5 destroy. Sustainability and renewability of the typical ACF-NH for catalytic oxidation of RB5 were also discussed in detail. Information about our conclusions are useful to control and improve the performance of ACF-catalyzed PMS oxidation for organic pollutants in wastewater treatment. © 2016 Elsevier B.V.

Nie X.-B.,Changsha University of Science and Technology | Nie X.-B.,Xian University of Architecture and Technology | Li Z.-H.,Changsha University of Science and Technology | Ding L.-J.,China City Environment Protection Engineering Ltd Company | Huang T.-L.,Xian University of Architecture and Technology
Zhongguo Huanjing Kexue/China Environmental Science | Year: 2016

Recently, the leakage risk for copepods is becoming a challenging problem for drinking water plants in China. In order to prevent drinking water distribution systems from copepods' efflux, the control of copepods with traditional drinking water treatment processes was investigated by using Harpacticoida as a research subject. More attention was paid to the relationship between the removal of Harpacticoida and morphological characteristics of flocs in a coagulation tank, and distribution of Harpacticoida in a sand filter bed. The results showed that high removal efficiency of 99% was obtained under the optimum operational conditions, which includes fast stirring of 300 r/min (1 min), moderate stirring of 150 r/min (5 min) and slow stirring of 75 r/min (5 min), polymeric aluminium chloride dosage of 10 mg/L, sedimentation time of 0.5 h, filtration rate of 9 m/h, and filtration cycle of 1d. The removal efficiency of coagulation on Harpacticoida was mainly determined by the effective adsorption of Harpacticoida onto flocs, and the larger particle size and the lower fractal dimension of flocs, the higher removal efficiency of Harpacticoida. During filtration, the passive migration of Harpacticoida in a sand filter bed, primarily induced by scouring and carrying of filtration flow, was the major factor resulting in copepods' efflux eventually. Therefore, high removal efficiency would be promised by decreasing the filtration rate and shortening the filtration cycle, because such operations could limit passive migration scale of Harpacticoida. © 2016, Chinese Society for Environmental Sciences. All right reserved.

Shen D.,Nanjing Southeast University | Hu J.,Nanjing Southeast University | Xiao R.,Nanjing Southeast University | Zhang H.,Nanjing Southeast University | And 2 more authors.
Bioresource Technology | Year: 2013

Thermogravimetric-Mass Spectroscopy (TG-MS) study on lignin decomposition under different (oxygen-containing) atmospheres was carried out to investigate thermal performance of lignin during pyrolysis, oxidative gasification, oxy/fuel combustion and CO2 gasification. Only one significant mass loss stage was observed for lignin decomposition under helium (He), while another stage, representing char oxidation, appeared under oxygen and CO2 conditions. No significant variation of the activation energy was presented for the first pyrolysis stage under different atmospheres (from 40.4 to 53.2kJ/mol). A much higher temperature was required for char oxidation under CO2 than those under O2 atmospheres, giving the activation energy of 541.9kJ/mol as compared to around 160kJ/mol for O2-containing atmospheres. The evolution profiles of CO and CO2 under different atmospheres were in good accordance with the DTG curves regardless of atmospheres. © 2012 Elsevier Ltd.

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