Applied Mechanics and Materials Vols. 217-219

Abstract: According to the characteristics of lightning electromagnetic pulse (LEMP) in information systems, the new multilayer composite electromagnetic shielding materials are utilized for the effective protection of the lightning hazards. The lightning protection mechanism and the characteristics of the new electromagnetic shielding materials are investigated. The shielding and reflection principle of the new materials are carried out. The electromagnetic shielding tent which is made of such multilayer composite electromagnetic shielding materials are applied in the integrated lightning protection of information systems, which shows such materials are safe, convenient, practical and worthy of widely application.

Abstract: Diester based magnetic fluid is a novel intelligent material which use diester as carrier liquid and magnetic iron ore as magnetic nano-particles combined together with proper surfactant. Its specially unique characteristic contributes to wide applications in engineering research field such as magnetic fluid based seals, magnetic fluid based dampers and so on. This paper provides a method of diester-based magnetic fluid synthesis and analysis for the properties of prepared diester magnetic fluid as well as effective influencing parameters. The results show that for getting proper size and magnetization of magnetic particles, the proper reacted temperature is around 60~80°C, appropriate molar ratio of reacted solution is 1.75 and concentration of forerunner is about 0.6 mol/L. It is also found that the viscosity of diester-based magnetic fluid is decreased with environment temperature while the viscosity as well as saturation magnetization increases with the increment of density.

Abstract: Paper was removed at authors request.

Abstract: Photocatalytic oxidation of thiophene using Nano-TiO2 at ultraviolet lamp irradiation has been studied. The result showed thiophene was photooxidized successfully. First Nano-TiO2 powder with photocatalytic activity were prepared by sol-gel progress.Second the photo-degradation of thiophene on titanium dioxide was investigated.The reaction also features the photocatalytic activity of Nano-TiO2.

Abstract: Zn2SiO4:Eu3+, Dy3+ phosphors have been prepared through the sol-gel process. X-ray diffraction (XRD), thermogravimetric and ddifferential thermal analysis (TG-DTA), FT-IR spectra and photoluminescence spectra were used to characterize the resulting phosphors. The results of XRD indicated that the phosphors crystallized completely at 1000oC. In Zn2SiO4:Eu3+,Dy3+ phosphors, the Eu3+ and Dy3+ show their characteristic red(613nm, 5D0-7F2), blue (481nm, 4F9/2–6H15/2) and yellow (577nm, 4F9/2–6H13/2) emissions.

Abstract: In this work, a visible light-induced LaVO₄/TiO₂ composite has been characterized by powder X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and spin-trapping electron paramagnetic resonance (EPR) to reveal the structure and visible light photocatalytic mechanism for the decompostion of benzene in gas-phase. Based on the experimental results, a visible light-induced photochemical processes on LaVO₄/TiO₂ are proposed and elucidated.

Abstract: The effects of Y₂O₃ and In₂O₃ on the microstructure and electrical properties of SnO₂-based varistors were investigated. It was observed that the grain size of the samples decreased with doping Y₂O₃ and In₂O₃ and accordingly, the breakdown electrical field E_B increased greatly. The measurements of barrier height and grain size reveal that the variation of grain size was not the only reason for the change of electrical properties of the sample doped with In₂O₃ and, the improvement of nonlinear coefficient α may mainly attribute to the increase of barrier height. Some energy levels of different state defects on the grain boundary were obtained and the energy about 0.15 eV detected here of all the samples may be attributed to the activation of . The different effects of doping Y₂O₃ and In₂O₃ indicate that In₂O₃ is more effective to improve nonlinear electrical behavior and breakdown electrical field of SnO₂-based varistors.

Abstract: As the global shortage of oil resources and the rapid increase in car ownership, using gas as the alternative fuel is getting more and more important. Gas fuel, such as CNG (compressed natural gas)/LNG (liquefied natural gas) and LPG (liquefied petroleum gas), with resource-rich, less pollution and other features, are desirable alternative fuels for cars. Through engine bench test, a comparative analysis of power performance between LPG-single fuel engine and gasoline engine was done. The result shows that, by applying LPG injection on single-fuel engine, the power of the LPG engine increases to a higher level than gasoline engines. And combined with the analysis based on the study of domestic development of NGV, predictions could be made that new fuel vehicles will be well utilized in future.

Abstract: To investigate the influence geometric parameters on the performance of direct methanol fuel cell (DMFC), experimental study and computational fluid dynamics (CFD) based on modeling are conducted in the research. Three types of geometric configurations with serpentine flow channels and similar open areas with different widths are fabricated to be tested. The experimental results show that the geometric configuration with narrower width has better performance. To explain and understand such phenomena, a CFD based modeling is introduced. The model results show that the geometric configuration with narrower width has higher pressure inside the diffusion layers and more delivery of fuel and oxygen to the catalyst layers. Since high pressure and high fuel and oxygen delivery can improve the DMFC performance, the CFD model provides very good explanations to the experimental phenomena. The research results could provide some very useful guidelines for the design and optimization of DMFC system.

Abstract: Lithium titanate (Li4Ti5O12) was synthesized by solid-state method with anatase titanium dioxide and lithium carbonate(Li2CO3) as raw materials at 800°C,900°C and 1000°C for 12h, respectively. The prepared powder was characterized by XRD, SEM and constant current charge/discharge test. The results showed that the calcination temperature effected on the properties of Li4Ti5O12 powder, the crystallinity and particle size of powder were changed with the calcination temperature. Li4Ti5O12 had good performance of 1ithium insertion/extraction, stable charge/discharge platform, excellent multipule cycles of high capacity at 900°C.