Applied Mechanics and Materials Vols. 217-219

Abstract: A differential thermal analyzer was used to analyse the thermal decomposition properties of samples mixed barium nitrate with 2 percent of CuO, Cu2O, Fe2O3, Fe3O4, CoO, NiO, SnO2, PbO, and MnO2 respectively. The samples were then made into firecrackers and tested on its displaying effect and mechanic sensitivity. The results show that the thermal decomposition temperature of barium nitrate added with Cu2O decreases by 45°C. Besides, the explosive sound ratio of CoO increases to 85% and its paper scrap ratio reaches to 65%. The mechanic sensitivity of all the samples increases slightly.

Abstract: The study of Proton Exchange Membrane Fuel Cell (PEMFC) faults mechanism and diagnosis can afford theoretical and technical supports for the future mass production and applications of PEMFC stacks and systems, which need modularization and high reliability. Most of the existing fault diagnosis methodologies, such as Cell Voltage Monitoring (CVM) method, require the knowledge of numerous parameters which may lead to a special inner parameter monitoring setup. The corresponding devices increase the cost and are not suitable for stack modularization and system application. In this paper, a simple and low-cost PEMFC faults diagnosis method using discrete wavelet transform is described. The method only uses the stack information for signal feature extraction. After that, by faults identification and classification, several typical faults including temperature fault, inlet flow inefficiently supplying fault and membrane dehydration fault have been distinguished. A semi-empirical distributed parameter stack model is employed for simulating typical faults that may occur. The simulation results demonstrate that the application of wavelet theory to PEMFC diagnosis is feasible, reliable and promising.

Abstract: The process of smelting reduction by electric arc furnace was adopted to enriching vanadium to iron from vandium tailings,study the effect of vanadium recovery in the carbon-bearing pellet with different coal ratio、alkalinity and smelting time.Design experimental scheme using orthogonal test principle and experimental results was systematically analysed by the comprehensive methods of intuitive analysis and the optimum process parameters were determined. The optimized process conditions are obtained by one-factor at a time tests for recovery vanadium from vanadium tailings as follows: coal ratio of 12%, alkalinity of 1.5, roasting time of 15min.

Abstract: The thermal stability and thermal degradation kinetics of proton-exchange membrane were investigated, as the membrane reacted with Fenton reagent at 80°C. Non-isothermal kinetic data of the membrane were analyzed by using the thermo-gravimetry analysis and the Kissinger、Flynn-Wall-Ozawa and Friedman methods under the conditions of flowing gas nitrogen and the heating rate of 5、10 and 20°C/min. The minimum temperature of the thermal degradation is greater than 360.8°C in the conversion rate of 10%. The thermal decomposition process occurred one step. The average value of apparent activation energy is 245.48kJ/mol, pre-exponential factor is 2.52×1018 min-1, the reaction mechanism is controlled by D4.

Abstract: LiFePO4/C composite was synthesized by an easy sol-gel method using FeC2O4•H2O as iron source, citric acid and ethylene glycol as carbon source. The results showed that citric acid was inclined to leave more carbon in the synthesized material than ethylene glycol was and the carbon content increased greatly with the increasing amount of citric acid. When ethylene glycol was applied as carbon source, it left only a few amount of carbon (1.6 wt%) in the material. By optimizing the addition of carbon source, LiFePO4/C particles with uniform carbon coating and a little carbon content was obtained. The LiFePO4/C composite synthesized with 1/1 ratio of ethylene glycol to cations demonstrated the best electrochemical performance with its capacity of 143 mAh/g at 0.1C and 110 mAh/g at 1C within the voltage range of 2.5-4.2V (vs. Li/Li+). The results will provide ideas for the improvement of overall properties of LiFePO4 material for its application in the field of electric vehicles.

Abstract: LiFePO4 is a promising cathode material for the next generation of a lithium-ion rechargeable battery. This paper introduces the research progress in recent years on LiFePO4 as positive electrode materials for lithium ion batteries. The methods of the preparation and modification, relation ship between structure and performance, and prospect of olivine-type lithium iron phosphate cathode materials was reviewed. Porous structures offer the potential to improve the electrochemical properties of LiFePO4.

Abstract: In order to reduce effectively the particulate ignition temperature of Diesel Particulate Filter containing MnO_x-CeO₂ catalysts，the physical and mathematical calculation models of MnOx-CeO₂ catalysts were established on Diesel Particulate Filter，and according to bench tests, the activity measurements of the five different concentrations were processed for MnOx-CeO₂ catalyst. The results indicated that when concentration is 20ppm, the ignition temperature can be droped about 105°C, activity measurements of Kp、Kpm and ΔKp decrease 10%, 8% and 7% respectively. Meanwhile, regeneration time can be shortened to 7min. It shows that Diesel Particulate Filter which contains concentration of this type not only has higher regeneration rate and level , but also decrease effectively exhaust back pressure.

Abstract: It is reported that large quantities of valve regulated lead-acid batteries used in the substations shall be harmlessly treated, for lead plates, sulfuric acid and other compositions are direct hazard for the environment. Herein, we have carried out the investigation on the reconstruction and reuse of the used VRLA, battery reconditioning, influence of spent VRLA to the environment, storage condition obeying to environment of state grid and directed cycle model of recycling technologies.

Abstract: The output characteristics of photovoltaic cells varies with the load and the external environment.In order to improve the conversion efficiency of PV cells , it is necessary to keep the system working in maximum power point(MPP) nearby.According to maximum power point tracking for PV systems,a new intelligent control method based on dynamic recurrent fuzzy neural network is proposed.The simulation results show that when the external environment changes ,the system can make rapid response and accurately track the maximum power point of PV cells.What's more,it has good control accuracy and stability.

Abstract: Photovoltaic cell is the central part of solar photovoltaic power generation system, so how to establish effective and accurate photovoltaic cell model is crucial. Based on the research of PV cell characteristic as well as the mind evolutionary algorithm and neural network, this paper put forward a new kind of BP neural network modeling method based on MEA, and used for photovoltaic battery modeling. In this model, using MEA for neural network parameter optimization to overcome defects of the traditional BP neural network which has slow convergence speed, easy to fall into local optimal solution and other shortcomings, and then improved the modeling accuracy and reliability. The test and simulation results showed that the improved neural network model is high precision, little error, short training time and it is effective.