Soil-Pile Interaction in Vertical Vibration

This paper deals with the theoretical study concerning soil-pile interaction in vertical vibration for both the floating pile and the pile group. The analysis is made by applying the elastic wave theory to the viscoelastic layer overlying on the rigid bedrock. Further, the displacement responses of the pile and the complex stiffness at the pile head subjected to the harmonic excitation at the top of the pile are obtained for various parameters

The effects of water and microstructure on the performance of polymer electrolyte fuel cells

n this paper, we present a comprehensive non-isothermal, one-dimensional model of the cathode side of a Polymer Electrolyte Fuel Cell. We explicitly include the catalyst layer, gas diffusion layer and the membrane. The catalyst layer and gas diffusion layer are characterized by several measurable microstructural parameters. We model all three phases of water, with a view to capturing the effect that each has on the performance of the cell. A comparison with experiment is presented, demonstrating excellent agreement, particularly with regard to the effects of water activity in the channels and how it impacts flooding and membrane hydration. We present several results pertaining to the effects of water on the current density (or cell voltage), demonstrating the role of micro-structure, liquid water removal from the channel, water activity, membrane and gas diffusion layer thickness and channel temperature. These results provide an indication of the changes that are required to achieve optimal performance through improved water management and MEA-component design. Moreover, with its level of detail, the model we develop forms an excellent basis for a multi-dimensional model of the entire membrane electrode assembly

A New Soil Model and Dynamic Soil Properties

A series of cyclic triaxial loading tests with varying strain amplitude were performed on samples of clay and sand. Three types of polynomial functions and a hyperbolic function were applied to express the experimental nonlinear hysteresis curve of soils under cyclic loading conditions. These functions were used for the earthquake response analysis of the actual ground containing alluvial clay layer and of the idealized saturated sandy soil ground whose stiffness gradually decreases as the development of pore-water pressure. The results of the dynamic responses and the liquefaction potential were compared for a particular actual site and an idealized site by using the presented models and the hyperbolic function model

Synthesis and microstructure of metal oxide thin films containing metal nanoparticles by liquid phase deposition (LPD) method

Au nanoparticles dispersed SiO2-TiO2 composite films have been prepared by a novel wet process, Liquid Phase Deposition (LPD) method. The composite films were characterized by XRD, XPS, TEM, ICP, SEM and UV-VIS absorption spectroscopy. The results showed that the SiO2-TiO2 composite films containing AuIII and AuI ionic species were co-deposited from a mixed solution of ammonium silicofluoride, ammonium hexafluorotitanate, boric acid and tetrachloroauric acid. The heat treatment induced the reduction of Au ions and formation of Au nanoparticles in the film. TEM observation revealed that the Au nanoparticles with 5-10 nm in diameter were found to be dispersed uniformly in the SiO2-TiO2 matrix. The optical absorption band due to the surface plasmon resonance of dispersed Au particles were observed at the wavelength of 550 nm and shifted toward longer wavelength with increasing heat treatment temperature