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Oxygen-enriched combustion can improve thermal efficiency and reduce CO, unburned hydrocarbons and soot emissions in internal combustion engines. There are significant differences in the combustion process and pollutant emissions between oxygen-enriched and air condition. In order to develop an improved understanding of the effect of oxygen concentration on n-heptane oxidation, the jet-stirred reactor oxidation characteristics of n-heptane were experimentally tested at temperatures of 450-950 K and pressures of 1.03 atm with the residence time (τ) of 2 s, under the condition of oxygen mole fractions from 0.055 to 0.6. Meantime, the simulations were performed on CHEMKIN. Results show that, firstly, with the increase of oxygen concentration, the NTC (Negative Temperature Coefficient) effect is weakened, mainly due to the strengthening of low-temperature reaction path, which is also the reason for the improvement of ignition stability in cold-start condition of engines. Secondly, the activity of the reaction system improves with the increase of oxygen concentration. Within 500-750 K, it is due to enhancement of the low-temperature reaction path. When the temperature is higher than 750 K, the improvement is due to the enhancement of decomposition of H2O2 and addition reaction of H and O2. Thirdly, with the increase of oxygen concentration, both the generation and consumption of CO are strengthened, which leads to the tip of the diesel spray flame changing from soot area under air condition to the CO chemiluminescence.

The classical ground soil shear mechanics model is difficult to predict the maneuverability of vehicles under high-speed driving conditions. The shear mechanical properties of soil under dynamic loading are the key factor to research on the ground attachment characteristics of vehicles under high-speed driving conditions. The relationship between the shear properties of the ground soil and the loading rate was analyzed by numerical simulation method. Based on the Janosi shear model of the ground soil, the loading rate and shear rate were supplemented to establish the applicable driving conditions for high-speed and heavy-duty vehicles. The ground soil shearing characteristics model provides a theoretical basis for researching on the vehicle's driving maneuverability under high-speed driving conditions.

There is a great relationship between the passing capacity of vehicles on the ground deformation road and the properties of confined and shear of ground soil, so it is necessary to establish a model that can reflect the soil pressure of the deformation. Physical significance of classic soil pressure experience parameters model is indeterminate, it was generally obtained by a lot of specific soil test. In this paper a new analysis model was built though introducing the maximum stress value of the crawler board and soil surface on basis of a kind of existing analysis model. This model reveals the relations among the confined characteristics of soil, soil parameters and the geometry of confined crawler board. These soil parameters can be obtained through the conventional soil mechanics test without a large number of specific soil test. Through the contrast experiment and predictions results, this model can effectively predict the sinkage of ground soil under the load, and provide a theory basis for the prediction of vehicle mobility.

SrMnO3/Polyvinylpyrrolidone (PVP) composite nanofibers have been prepared successfully by electrospinning from Cerous(II) nitrate and Manganese(II) acetate tetrahydrate, after the heat treatment at 800 °C for 3 h, the hexagonal SrMnO3 nanofibers was obtained. The effect of PVP concentration was investigated. The size and morphology, phase information, thermal properties of nanofibers were characterized by SEM, EDX, XRD, TGA, FT-IR, respectively.