Advanced Materials Research Vols. 622-623

Abstract: Recent studies have shown that the surface/interface free energy plays an important role in the effective mechanical properties of solids with nanosized inhomogeneity. In the present study, an analytical model is developed for 3D axisymmetric analysis of short fiber nanocomposites including the fiber end region, subjected to an applied axial load considering surface effects. Closed form expressions are obtained for 3D stress filed in the fiber and matrix. Moreover, performing numerical examples, it is shown that the elastic stress field is size dependent in both the fiber and matrix especially for fiber radii less than 50 nm.

Abstract: BaFe₁₂O₁₉ ceramic foam was synthesized from the mixture of Fe₂O₃ and BaCO₃ using polymeric sponge replication technique. Effect of 1, 1.5, 2, 2.5, and 3 wt.% of SiO₂ addition on foam lattice shape and magnetic properties of foams were investigated. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating samplemagnetometer (VSM) and Brunauer–Emmett–Teller (BET) techniques.Addition of 3 wt.% SiO₂ can completely maintain the foam lattice shape at lower calcination temperature of 1075 °C. It resulted in higher values of coercivity and saturation magnetization. Moreover, BET analysis of the foam sample with 3 wt.% SiO2 demonstrate a specific surface area of 0.3 m²g^-1.

Abstract: Barium carbonate (BaCO₃) nano-particles were synthesized from the mixture of Ba(OH)2.8H₂O and Na₂CO₃ by mechano-chemical route without any subsequent heat treatment of the as-milled powders. Effects of milling time and addition of process control agents (PCA) on the phase composition and morphology of products have been investigated. The samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD results show that BaCO₃ nano-particles were synthesized only after 10 minutes of mechanical milling and phase evolution was not taken place by further milling. SEM results indicated that pencil-like and globular-like were two major morphologies of the particles. Addition of stearic acid as a PCA resulted in homogenized globular-like nano-particles with a mean particle size of 54 nm.

Abstract: Modification of the asphalt binder is one approach taken to improve Asphalt pavement performance. Rutting is one of the most important factors that could reduce the life of asphalt pavements.Nowadays, the application of nanotechnologyto achieve materials that are more resistant is expanding in asphalt pavement thatNano-TiO₂ is among the most exciting and promising classes of materials discovered recently. The purpose of this study is laboratory research on the effect of Nano-TiO₂ in improving Bitumen property and rutting resistance in Asphalt pavement under dynamic loading. For this purpose, the wheel-tracking test was carried outon ordinary and Nano-TiO₂ modified hot mix asphalt samples.The results illustrate that using Nano-TiO₂in asphaltbinder samples cause to an improvement in ruttingdepth in comparison with theordinarymixtures.

Abstract: The TiO₂-calcium phosphate (TiO₂/CP) nanocomposites with different ratios were prepared by precipitation of calcium phosphate in the presence of nano-sized TiO₂. The products were characterized by BET, XRD, SEM and EDX techniques. Photocatalytic activity of the nanocomposites was evaluated as a rate constant of decomposition reaction of methylene blue (MB) in aqueous suspensions under UVA irradiation. It was observed that all of the nanocomposites showed higher photocatalytic activity in comparison to pure TiO₂ catalyst. In particular, the rate constant photodecomposition of MB on TiO₂/CP composite at 9:1 ratio (w/w) was above five times higher than on pure TiO₂.

Abstract: Sn nano particle coatings on MCMB powder, as anodes of lithium ion battery are carried out in SnSO₄ solutions by using cathodic electrochemical synthesis and subsequently dried at 100°C. The electro-deposition reaction was follow: Sn²⁺ + H2O ↔ SnOH⁺_aq + H⁺; SnOH⁺_aq ↔ SnOH+aqs + e-; SnOH+ads + e- → SnOH; SnOH + H+ + e- → Sn + H₂O. The Sn-coated MCMB specimens are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), and charge/discharge tests. The nano-sized Sn particles coated on MCMB powder are obtained in 0.2M SnSO₄ solutions and desoition current 0.5A. An important parameter in electrode preparation is the adhesion of the coating to the current collector, which greatly affects the cyclability of the electrode. Therefore, the relationship between adhesion strength and cycle performance was investigate in this study. Charge/discharge cycle tests elucidated that Sn-coated MCMB showed higher capacity than MCMB. Compared with MCMB, the second discharge capacity of Sn–coated MCMB increased about 28.8%. After 50 cycles, the reversible capacity was about 339.6 mAhg-1. The capacity retention ratio C25/C2 was about 80.87%. It was shown good cycle life due to the nano-particles effects retarded to Sn aggregation.

Abstract: In this present investigation, at first, Dially bisphenol A (DABA)/Bismaleimide (BMI) system was modified with gamma-aminopropyltriethoxy silane (KH550). The objective of the work was to study the effect of addition of various weight percentages of KH550 into BMI/DABA composites on its mechanical properties, thermal properties and morphorogy. Further modification was carried out with fumed silica. The role of KH550 was discussed in these composites prepared. Nancomposites were characterized by differential DSC, TGA, and scanning electron microscopy SEM. TGA results confirmed that the heat stability of the nano composite DABA/BMI/KH550 is improved compared with DABA/BMI system. SEM results indicated that the fumed silica dispersed homogeneously in DABA/BMI/KH550 matrix on nanoscale. Mechanical results shows that newly developed system has improved bending modulus to 4.0GPa, while with incorporation of fumed SiO₂ impacted strength also improved to 20.60kJ/m².

Abstract: This paper investigates how society engenders demands for energy services that vary with time and climate, and how renewable and other energy resources can be deployed to meet these demands. Because the whole people-energy system is modeled, there is little detail about any component, instead an overall picture of how the entire system works is presented in this paper. It became apparent that the design and performance of dwelling energy systems, and to some extent the behavior of people, cannot be considered in isolation from the whole system. In order to get a picture of how the entire system works, the greater the diversity better overview can be obtained. But, from a practical perspective it is difficult to simultaneously model in detail a large number of people-dwelling combinations, alongside all other demands and electricity and other supply.

Abstract: This paper proposes a modeling and controller design approach for a wind-diesel hybrid system including dump load. The proposed control scheme for power quality is fuzzy PI controller which has advantages of PI and fuzzy controller. Simulation results show that the proposed controller is more effective against disturbances caused by wind speed and load variation than the PI controller, and thus it contributes to a better quality wind-diesel hybrid power system.

Abstract: Esterification of carboxylic acids with alkyl halides were studied using dicationic ionic liquid 1,1’-decane-1,10-diylbis (3-butylpyridinium) dibromide-[C10(Bpy)2] (Br)2 in the presence of triethylamine. Good conversion rates and yields were obtained. The ionic liquid could be reused after removal of water under vacuum.