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Improved axial force identification method for bar members is proposed based on the analytical method which was established for vibration-based identification of axial force of tie-bars and short thick cables with uncertain boundary conditions. Firstly, modified Timoshenko beam theory was considered by taking the influence of the rotational inertia, shear deformation, the rotational inertia caused by shear deformation and sensor mass on structural dynamic characteristics into account to establish an improved dynamic equation. Then, the characteristic equation can be solved to identify axial force. The first five-order natural frequencies and modal parameters of a bar are computed through numerical simulation with Matlab. The improved accuracies of identifying axial force by modified Timoshenko beam theory compared, to that of traditional Timoshenko beam theory are discussed from four aspects. Finally, a laboratory experiment is employed to investigate the feasibility and accuracy of the proposed method. One significant advantage of the proposed method is that there is no prerequisite information about the boundary condition required, but only the relative locations of sensors to identify the axial force. Therefore, the method can be widely applied to many beam or truss elements. [ABSTRACT FROM AUTHOR]

Abstract: The high discharge potential of LiMnPO4, 4.1 V vs. Li/Li+, and its theoretical capacity of 170 mAh g−1 make it a promising candidate as a cathode material in lithium-ion batteries. But extremely low electronics conductivity, slow lithium diffusion kinetics, and the Jahn-Teller effect of Mn3+ limit the electrochemical performances of LiMnPO4. In this work, the pre-synthesized and defined FePO4·2H2O nanocrystallites are used as one of the raw materials to synthesize LiFe1−x Mn x PO4/C (x = 0.85, 0.75, 0.65) composites via solid-state reactions. The synthesized LiFe1−x Mn x PO4 samples show well-crystallized structures and have enhanced electrochemical properties. There exist two plateaus around 3.5 and 4.1 V on both of their charge and discharge curves. Among the samples, the Fe0.25Mn0.75PO4 one exhibits the longest high-voltage charge/discharge plateau at 4.10 V/4.05 V, and has an average discharge voltage of ∼3.78 V vs. Li/Li+ and a discharge capacity of ∼130 mAh g−1 at 0.05 C rate. For the Fe0.25Mn0.75PO4 sample, the noticeable improvement of its electrochemical performances is mainly attributed to iron substitution, the appropriate Mn/Fe ratio, and the well-ordered crystal structure forming by using FePO4·2H2O nanocrystallites as one of the raw materials. [Copyright &y& Elsevier]

Pollution characteristics of heavy metals in the farmland soil nearby a metal smelter were studied. Soil samples were collected and the contents of elements V, Cr, Mn, Co, Ni, Cu, Zn, Rb, Sr, Mo, Cd, Sn, Sb, Pb, U and As in the bulk samples of soil profiles were measured, with the objectives to identify the pollution status and pollution characteristics of the farmland soil that were suffered from smelter effluents flooding, an acute pollution accident. The results indicate that the concentrations of heavy metals Zn, Mn, As, Pb, Cd,Sb in the soil were 113.28-212.22, 251.67-2 429.29, 34.44-130.28, 50.63-544.74, 63.44-317.33, 39.41-551.17 mg/kg, respectively, higher than the background level. These polluted soils not only have high concentrations of As, but also of the Zn, Mn, Pb, Cd and Sb. According to correlation analysis, pollution level is closely with local nonferrous metal exploitation, and principal pollutants have the same source. Some trace metals, such as Zn, Cr, Cd, show increasing concentration first and then decreasing trend in the soil profile. Soil acidification appears in the topsoil. This study has characterized the metal pollution in soils flooded by sudden smelting effluents spilling, and provided a theory base for pollution treatment.