Changes in the surface chemistry of LiFePO4 cathodes in an aqueous medium for lithium ion battery are investigated based on a quantitative evaluation of surface functional groups of LiFePO4 as a function of pH. It is found that, while the dissolution of Li ions from LiFePO4 increases the number of acidic surface groups, the dissolution of Fe ions reduces the number of basic surface groups. The pK a values for various processing conditions are calculated. Interestingly, none of the investigated processing conditions changes the characteristic acid moieties on the particles (pK a ∼ 2.8). However, the processing condition strongly impacts the chemistry of the basic surface groups showing three distinct basic surface groups with pK b values of 0.1, 0.9, and 1.5, respectively. Correlation is made between dissolution behavior, surface groups, dispersion properties, and electrochemical properties. It is found that Li-and Fe-ion depleted LiFePO4 powder increases the viscosity in N-methylpyrrolidone pastes 5-fold and results in a looser and less homogeneous microstructure. This results from a lower zeta-potential of LiFePO4 paste at pH 7−8 caused by an increased number of acid groups and decreased number of basic groups. The changes in surface acid and base properties of LiFePO4 caused by significant dissolution and readsorption of Li and Fe ions in aqueous processing lead to a degraded rate capability for LiFePO4 cathodes, especially at 5 and 6C.

This study analyzed the temperature distribution in DPF with five partitioned electric heaters. The temperature distribution in DPF is an important design factor for regeneration and durability of filter. The design Factors that influence the temperature distribution in DPF there are several. In this study, the characteristics of temperature distribution in DPF were analyzed according to the following changes. First, the thermal conductivity of the filter was analyzed about effect on the durability of the filter. Second, the length from exhaust manifold to inlet of DPF was analyzed about effect on the temperature distribution in DPF. The boundary conditions of analysis has been verified with comparison to the results of existing experimental study and the numerical analysis. Based on the identified boundary condition, on assuming the condition of the actual driving, the temperature distribution in DPF was analyzed according to material properties of filter and the position of DPF.

Gas explosion accidents have been recognized as a major hazard of offshore facilities in oil & gas industries. Due to the nature of offshore topside structures, even a single collapse of structural members or equipments may lead to enormous economic and environmental losses. Therefore, such potential hazards that cause the accidental collapse need to be evaluated closely. Gas explosion has been categorized as an important issue of the design of offshore structures regarding the severity of the accident. This paper presents practical considerations for the nonlinear dynamic structural analysis of offshore structures under blast loadings from gas explosion accidents. Numerical investigations including modeling of blast loads and idealization of structural materials and members have been conducted for the overall topside structures. As a design step for offshore structures under blast loadings, an applicable guidance on the finite element analysis (FEA) is described in this study.

This paper presents several investigations for improved structural analysis method of wheel loaders based on the static and dynamic measurements including strength and motion characteristics. Physical quantities such as stresses, hydraulic cylinder pressures and strokes were obtained from static tests for prepared operating scenarios. The dynamic measurements were also carried out for two types of motions: simple reciprocations of a boom and a bucket and actual working motion including traveling, digging and dumping. It was shown from static measurements that static stress level induced by the bucket cylinder operation was higher than that by the boom cylinder operation. It was confirmed from dynamic measurements that stress histories during actual working seemed to be static rather than dynamic. A fully assembled finite element model was prepared for structural analysis. A practical trial and error scheme was adopted in order to handle non-linearity caused by lift-up of wheels. For both measurements and structural analysis, it was shown that structural behaviors with the brake on were quite different from those with brake off. Sensitivity analysis showed that there was much difference between digging forces from conventional formula and structural analysis.