Highly ordered CoFe2O4 nanowire arrays were prepared in anodic aluminum oxide (AAO) templates with two diameters (50 nm and 200 nm) by Sol-gel method. The scanning electron microscope (SEM), transmission electron micr...
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Highly ordered CoFe2O4 nanowire arrays were prepared in anodic aluminum oxide (AAO) templates with two diameters (50 nm and 200 nm) by Sol-gel method. The scanning electron microscope (SEM), transmission electron microscope (TEM) and high-resolution transmission electron microscope (HRTEM) were used to characterize the structures of the nanowire arrays. The hysteresis loops of the CoFe2O4 nanowire arrays reveal that there was no preferential magnetic orientation in both of the nanowire arrays with different diameters. The measured coercivity of CoFe2O4 nanowire arrays with smaller diameter (50 nm) was larger than that of the nanowire arrays with bigger diameter (200 nm). The possible explanation for this behavior was given.
A three-dimensional model on a single channel in proton exchange membrane fuel cell is created, based on the theory of fluid dynamics and heat transfer, and is solved by means of the control volume methods. In general...
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A three-dimensional model on a single channel in proton exchange membrane fuel cell is created, based on the theory of fluid dynamics and heat transfer, and is solved by means of the control volume methods. In general, the temperature difference in a single channel of the fuel cell is very small. The difference of temperature is about 1 K in the catalyst layer of the anode and less than 3 K in that of the cathode. The maximum temperature emerges in the reaction zone of the cathodal catalyst layer. The results are compared with the experiment data in the conferences, and agree well with them.
The article reported a method of boronize medium absorbing microwave to fabricate boronization layer in the steel surface, and compares it with traditional boronization. The results indicated that the boron atoms for ...
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The article reported a method of boronize medium absorbing microwave to fabricate boronization layer in the steel surface, and compares it with traditional boronization. The results indicated that the boron atoms for the development of boronization layer were rooted in those produced by medium decomposition and gaseous boride, just like the traditional boronization. The growth of boronization layer in microwave was characterized with less than or equal 002> crystal orientation. Its growth rate of boronization layer was faster than that in traditional treatment. Besides temperature effect, growth rate was also influenced by activity boron atom in microwave diffusion in boronization layer.
The three-dimensional computing models of the cathode of PEM fuel cell within serpentine flow field and pin flow field are developed. By coupling computation the continuity equation, momentum equation, Darcy equation ...
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The three-dimensional computing models of the cathode of PEM fuel cell within serpentine flow field and pin flow field are developed. By coupling computation the continuity equation, momentum equation, Darcy equation and Stefan-Maxwell equation, the gas velocity distribution in the middle of GDL and concentration distribution of O2 and H2O at the catalyst GDL interface of two different flow fields are displayed. The performance of PEMFC within serpentine flow field and pin flow field are compared experimentally.
Activation process has important impact on the performance of proton exchange membrane fuel cells (PEMFCs). In this paper, an activation procedure was designed and used to primarily investigate the activation process ...
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Activation process has important impact on the performance of proton exchange membrane fuel cells (PEMFCs). In this paper, an activation procedure was designed and used to primarily investigate the activation process of a 25 kW PEMFC stack. The performance of the stack during and after the activation process was examined. The investigation indicates that the forced activation at varied current can finish the activation process quickly. More effective procedure and method should be investigated to quicken the activation process of a PEMFC stack.
Water management is the key for PEMFC to operate efficiently. To maintain a suitable hydrated state for PEM but without flooding in the porous medium polarity is an ideal case which is difficult to achieve. PEMFC is a...
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Water management is the key for PEMFC to operate efficiently. To maintain a suitable hydrated state for PEM but without flooding in the porous medium polarity is an ideal case which is difficult to achieve. PEMFC is a complex system with the characteristics of multi-phases, multi-dimensions, multi-physics fields and dynamics. The flow, heat and mass transfer, phase change, multi-phase flow and electrochemical process inside PEMFC have influences on each other, the mechanism is sophisticated and hard to measure or observe directly. This paper summaries the achievement in respects of water transfer mechanism, humidification methods, measurement and diagnostic of liquid water in PEMFC, methods of discharge liquid water and modeling of the water behaviors inside PEMFC. The water management, heat management, gas management and electricity management are associated each other, therefore the flow, heat and mass transfer, phase change, multi-phase flow and electrochemical process inside PEMFC should be considered systematically, relevant researches are to be carried out continuously.
In this research, we developed a three-dimensional finite-difference-time-domain algorithm that incorporated the Lorentz-Drude model through the use of Z-transform technique. This algorithm was used to compute the spe...
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In this research, we developed a three-dimensional finite-difference-time-domain algorithm that incorporated the Lorentz-Drude model through the use of Z-transform technique. This algorithm was used to compute the spectral response of infrared bandpass filters which consisted of the openings of cross-shaped structures in a thin gold film. In creating structures, a graphical user interface was built using Matlab development environment. The created structures were then simulated by running the simulation code written in Fortran. It was observed that cross-shaped structures with large center-broadening effect yielded the highest transmission intensity among the structures that were simulated with a transmittance of approximately 80% at the wavelength of 1.2 μm.
Water management is critical for high performance of proton exchanges membrane fuel cell (PEMFC). The liquid water transport model for gradient structure gas diffusion layer of PEMFC was established based on the capil...
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Water management is critical for high performance of proton exchanges membrane fuel cell (PEMFC). The liquid water transport model for gradient structure gas diffusion layer of PEMFC was established based on the capillary pressure theory, and then the liquid water flux through GDL was calculated based on the assumption that a fixed liquid saturation difference exists between the interfaces of catalyst layer/GDL and GDL/gas channel, the results were analyzed. Results showed that under steady condition the liquid water flux through GDL increasing with the increasing of porosity, GDL with gradient porosity was more favorable for liquid water to be discharged from MEA to gas channel;the larger the gradient was, the more easily the liquid water was to be discharged out.
This research is that cellulose/poly-silicate hybrid material was prepared with viscose and poly-silicate by sol-gel method. The influence of aluminum salt and poly-silicate on hybrid material thermal property was stu...
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This research is that cellulose/poly-silicate hybrid material was prepared with viscose and poly-silicate by sol-gel method. The influence of aluminum salt and poly-silicate on hybrid material thermal property was studied. Based on the analysis of the DSC and TG curve of hybrid material, we have found that the hybrid material has splendid heat-resistance and fire retardancy.
TiB_2 ceramics powder was synthesized from B_2O_3-TiO_2-Mg system. The effects of TiB_2 addition as diluent on the combustion synthesis process were investigated. The results of thermodynamic calculation and experimen...
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TiB_2 ceramics powder was synthesized from B_2O_3-TiO_2-Mg system. The effects of TiB_2 addition as diluent on the combustion synthesis process were investigated. The results of thermodynamic calculation and experiments show that the increase of TiB_2 content ranging from 0 to 20wt% can reduce the adiabatic temperature T_(ad) from 3100 K to 2896 K and combustion temperature T_c from 2139 K to 1621 K respectively. The particle size and half width of the particle distribution are also increased with the addition of TiB_2 increasing from 0 to 20wt%. The combustion product is a mixture of TiB_2, MgO, and other intermediate phases. The leached product contains mainly TiB_2, TiO_2 and TiN, and its oxygen content is 7.77wt%.
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